On Sunday, March 6, 2022 at 3:58:17 PM UTC, AMuzi wrote:
>
> Crashed frames with damaged forks and changed head angles
> exhibit wild changes, as do specialty machines designed for
> over- or under- steer effect.
>
No, that is only half right. A slightly oversteering bike may be desirable for the fast reflexes and close quarters of a domestique in professional bike racing, but a point will soon arrive where oversteer is counterproductive, strictly for posers who want to pretend they're faster than the laws of physics. An understeering bike, by contrast, is designed for stability and any declared "understeering" bike which "exhibit[s] wild changes" is either not understeering at all but neutral, or has been so incompetently designed -- or implemented -- with such a huge excess of understeer that the steering would be very heavy and the bike in general would be tiresome to ride. The idea is really to move the bike away from true neutral steering, which is unpredictable and unmanageable, by the smallest amount which will suffice, and beyond that in small steps to an accommodation with environments both natural like my hills and small roads and manmade like professional bike racing, without compromising manageability too much.

One day, when the wretched Vehicular Cycling movement is only a memory, and those who think they have a right to a road clear of slower cyclists in order to proceed to the office at 25mph have gasped their last, all bikes will at last be like mine if not in appearance, at least close in amount of understeer. This is already the case on the majority of bikes sold in the bicycling nations.

Andre Jute
Moderation is the watchword. My experimental sidekick, Franki-boy, will shortly be along with an algorithm.

On Sunday, March 6, 2022 at 5:47:23 PM UTC, AMuzi wrote:
> On 3/6/2022 11:10 AM, Sir Ridesalot wrote:
> >
> > I have a red Bianchi that was given to me as a frameset because the owner ran into a parked car and bent the downtube and the headtube a bit. Just for fun I built the frameset up with some spare components I had lying around. I took it out to a parking lot to try riding it and I was amazed at how well it tracked and how easy it was to ride no hands. I liked the ride so much t hat I'm restoring it back to its original Suntour Cyclone components.
> >
> > Cheers
> >
> A 'field enhancement' of Bianchi's design!
> A few minutes with a protractor, tape measure and a similar
> road bicycle might show you why.
> --
> Andrew Muzi
> <www.yellowjersey.org/>
> Open every day since 1 April, 1971
>
"It's not a bug! It's a feature!" -- Bill Gates
"It's not a crash, it's a field enhancement of Bianchi's design!" -- Andrew Muzi
'Heh-heh!" -- Andre Jute

On 3/6/2022 11:53 AM, Frank Krygowski wrote:
> On 3/6/2022 10:58 AM, AMuzi wrote:
>> On 3/5/2022 8:45 PM, Frank Krygowski wrote:
>>> On 3/5/2022 2:25 PM, AMuzi wrote:
>>>> On 3/5/2022 12:25 PM, Frank Krygowski wrote:
>>>>> On 3/5/2022 11:02 AM, AMuzi wrote:
>>>>>> On 3/5/2022 9:11 AM, Dieter Britz wrote:
>>>>>>> On Sat, 05 Mar 2022 02:50:18 -0800, Andre Jute wrote:
>>>>>>> [...]
>>>>>>>> My own bikes are all set up to understeer. The
>>>>>>>> consequential
>>>>>>>> predictability and stability of line almost regardless
>>>>>>>> of road surface
>>>>>>>> makes the essential difference on downhill
>>>>>>>> descents at
>>>>>>>> speed on bad
>>>>>>>> roads when I'm leaving the road racers behind with
>>>>>>>> white
>>>>>>>> brackets of
>>>>>>>> fear beside their lips.
>>>>>>> [...]
>>>>>>>> Andre Jute Ah, them were the days!
>>>>>>>
>>>>>>> How do you set a bike up for understeer? I don't know
>>>>>>> what under-
>>>>>>> or oversteer means.
>>>>>>>
>>>>>>
>>>>>>
>>>>>> Standard front geometry should be neutral[1] and
>>>>>> designers
>>>>>> know the system well.
>>>>>> https://dclxvi.org/chunk/tech/trail/image/trail.jpg
>>>>>>
>>>>>> In that case, when turning the wheel side to side, the
>>>>>> frame will neither rise nor fall.
>>>>>>
>>>>>> In an understeer design like this:
>>>>>> http://www.yellowjersey.org/gcdl1.html
>>>>>>
>>>>>> The frame rises when the handlebar is turned, which is to
>>>>>> say the bicycle travel in a straight path unless coerced
>>>>>> otherwise. This may be desired for unpaved roads and/or
>>>>>> heavy cargo loads. Put another way, the
>>>>>> rider/bicycle/cargo weight must be lifted to turn the
>>>>>> handlebar.
>>>>>>
>>>>>> The inverse, oversteer, makes a bicycle less stable
>>>>>> (='more responsive') and rider effort is needed to
>>>>>> keep it
>>>>>> in a straight path. When the fork turns, the frame falls:
>>>>>> http://1.bp.blogspot.com/-WJp92Vd-dMI/TtlTUAlSArI/AAAAAAAADLE/WmujhKVkXGg/s1600/sanrensho2.jpg
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> Sorry, I think "the frame will neither rise nor fall" is
>>>>> incorrect. If the front end geometry generates any "trail"
>>>>> at all, the frame must fall.
>>>>>
>>>>> Look at http://www.yellowjersey.org/gcdl1.html again.
>>>>> Draw a
>>>>> line representing the steering axis down to the ground.
>>>>> Next, draw a line from the tire contact point directly to
>>>>> (and perpendicular to) the steering axis. I suppose we
>>>>> could
>>>>> call that the 'lever arm' of the contact point.
>>>>>
>>>>> That 'lever arm' slants upwards from the contact point to
>>>>> the steering axis. If you 'swing' it to the side by
>>>>> turning
>>>>> the handlebars, it rises relative to the bike. IOW, if you
>>>>> clamped the top tube in a fixed position and height, the
>>>>> 'swing' would cause the contact point to rise. Or,
>>>>> switching
>>>>> reference frames, if you leave the tire normally on the
>>>>> ground, the frame will fall.
>>>>>
>>>>> I don't have a bike with a head angle as slack as the
>>>>> black
>>>>> one in the photo, but I just measured my touring bike. As
>>>>> with every other bike I've checked, turning the bars
>>>>> causes
>>>>> the frame to drop a bit.
>>>>>
>>>>> See "Wheel Flop" at
>>>>> https://cyclingtips.com/2018/11/the-geometry-of-bike-handling-its-all-about-the-steering/
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> "Wheel flop is similar to trail in that it is
>>>>> determined by
>>>>> the combination of head tube angle and fork rake,
>>>>> however it
>>>>> is concerned with how the position of the front axle
>>>>> changes
>>>>> as the handlebars are turned. In almost all instances, the
>>>>> height of the front axle is lowered when this happens"
>>>>>
>>>>
>>>> Experiment report:
>>>>
>>>> Using a four-foot aluminum level I put one end on a table
>>>> and the other end on the front of the top tube of a medium
>>>> (56cm) Gunnar Road with Michelin 23 tires. Turning the
>>>> handlebar, I observe the bubble doesn't move.
>>>
>>> OK, help me understand.
>>>
>>> Again, ISTM that if we marked the tire-to road contact point
>>> with chalk, then rotated the bars 360 degrees, that chalked
>>> point would describe a circle. The circle would be
>>> inclined
>>> to horizontal by (90 - head tube angle), with its high point
>>> directly forward. The marked point on the tire would be
>>> farthest below the head tube's height with the bars straight
>>> ahead. It would get closer to the head tube (or IOW the head
>>> tube would drop) at any other steering angle.
>>>
>>> Is there some other factor I'm not visualizing that would
>>> apply a contrary action, to cancel out this effect? So far I
>>> can't think of one.
>>>
>>> I checked my Cannondale again. I held a meter stick
>>> vertically, using my fingers to pinch it to the top tube. I
>>> can easily feel the relative motion. At a 45 degree steering
>>> angle (admittedly, used only for balancing at super slow
>>> speeds) it seems the frame drops between one and tow
>>> millimeters. At lesser steering angles the motion is almost
>>> imperceptible, but as I visualize the geometry, it seems it
>>> must be there.
>>>
>>> One thing I just noticed: The tire contact point actually
>>> changes as the steering angle increases. Judging by the
>>> spokes' position, at 45 degrees steering, the contact point
>>> has moved forward about 10 degrees. Does this somehow affect
>>> things?
>>>
>>
>> On a 360-degree fork turn I have no idea but you're
>> probably right. For normal range, as you note 45 deg left
>> or right, any height change is between zero and negligible.
>
> I just did more geometry work. For now, I'm treating the
> front wheel as a pure circle, i.e. a disc of zero thickness,
> or a tire of zero width. (I'm not sure what difference tire
> width will make, if any.)
>
> You're certainly right that the height change is small, at
> least for small steering angles. The obvious limit is zero
> height change for zero steering angle. But ISTM that as
> steering angle increases from zero, there must be _some_
> drop in frame height. Here's some of the geometry.
>
> The contact point of the tire on the road occurs at the back
> of the "trail," and the trail value is often easy to look up
> for a given bike. Alternately it's easy to calculate from
> head angle H and fork offset.
>
> Let's call the trail value T.
>
> Spinning the fork all the way around makes the contact point
> trace a circle. Its radius is R=T*cos(90-H) and that circle
> tilts upward 90-H degrees. That upward tilt is the basis of
> what I've been saying.
>
> Steering angle S causes the contact point to swing a bit
> upward along that circle. I'll give details if desired, but
> using two projected views and some fairly simple trig, the
> change in height as that contact point swings up (i.e.
> closer to the top tube) is the amount the frame drops. Call
> it D.
>
> I get D = R * (1-cos (S)) * sin(90-H)
> or
> D = T * cos(90-H) * (1-cos (S)) * sin(90-H)
>
> As I see it, for any conventional bike this is going to
> cause the frame height to drop just a bit. It's not much,
> because the circle tilts up only about 17 or 18 degrees, and
> for most riding S is small. But it must be there.
>
> Plugging in an extreme steering angle of 45 degrees with a
> 73 degree head angle and 60 mm trail, this gives a drop of
> 4.91mm. Plugging in the same values but with a more typical
> 10 degree steering angle gives a drop of 0.25mm which is
> small indeed, but not zero. (The controlling term is (1 -
> cos(S)), which is very small for normal steering angles.)
>
> BTW, I just held the meter stick against the top tube of my
> ancient Raleigh commuter/grocery bike. It too exhibited a
> drop as I turned the handlebars. It's almost undetectable
> for small steering angles, but it's there. It doesn't seem
> to be as large as 5mm, but then I don't know the bike's head
> angle or trail. (Yet.)
>
>

On 3/4/2022 7:53 AM, AMuzi wrote:
> On 3/4/2022 8:49 AM, Dieter Britz wrote:
>> I hear and read mention of a "responsive frame". What does
>> this mean, and what kind of frame is responsive, and not?
>>
>
> It's a marketing term, unrelated to quantifiable values.

I think that generally "responsive" is thought to mean stiff, short
chain stays, and a steep head angle. As opposed to a touring frame that
is less stiff, has longer chain stays, and a more slack head tube angle.

The steering responsiveness, based on the stem length, is another
factor. I recall my first folding bicycle, the orginal Dahon
<https://upload.wikimedia.org/wikipedia/commons/1/1d/Dahon_Classic_III_drive_side_bicycle_bootiebike_com_1000.jpg>
with almost no stem length. Took a bit of getting used to how responsive
the steering was. That folding frame member actually made the frame
pretty stiff, stiffer than most modern folders with the very long steer
tube.

On 3/6/2022 2:21 PM, AMuzi wrote:
> On 3/6/2022 11:53 AM, Frank Krygowski wrote:
>> On 3/6/2022 10:58 AM, AMuzi wrote:
>>> On 3/5/2022 8:45 PM, Frank Krygowski wrote:
>>>> On 3/5/2022 2:25 PM, AMuzi wrote:
>>>>> On 3/5/2022 12:25 PM, Frank Krygowski wrote:
>>>>>> On 3/5/2022 11:02 AM, AMuzi wrote:
>>>>>>> On 3/5/2022 9:11 AM, Dieter Britz wrote:
>>>>>>>> On Sat, 05 Mar 2022 02:50:18 -0800, Andre Jute wrote:
>>>>>>>> [...]
>>>>>>>>> My own bikes are all set up to understeer. The
>>>>>>>>> consequential
>>>>>>>>> predictability and stability of line almost regardless
>>>>>>>>> of road surface
>>>>>>>>> makes the  essential difference on downhill
>>>>>>>>> descents at
>>>>>>>>> speed on bad
>>>>>>>>> roads when I'm leaving the road racers behind with
>>>>>>>>> white
>>>>>>>>> brackets of
>>>>>>>>> fear beside their lips.
>>>>>>>> [...]
>>>>>>>>> Andre Jute Ah, them were the days!
>>>>>>>>
>>>>>>>> How do you set a bike up for understeer? I don't know
>>>>>>>> what under-
>>>>>>>> or oversteer means.
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Standard front geometry should be neutral[1] and
>>>>>>> designers
>>>>>>> know the system well.
>>>>>>> https://dclxvi.org/chunk/tech/trail/image/trail.jpg
>>>>>>>
>>>>>>> In that case, when turning the wheel side to side, the
>>>>>>> frame will neither rise nor fall.
>>>>>>>
>>>>>>> In an understeer design like this:
>>>>>>> http://www.yellowjersey.org/gcdl1.html
>>>>>>>
>>>>>>> The frame rises when the handlebar is turned, which is to
>>>>>>> say the bicycle travel in a straight path unless coerced
>>>>>>> otherwise. This may be desired for unpaved roads and/or
>>>>>>> heavy cargo loads. Put another way, the
>>>>>>> rider/bicycle/cargo weight must be lifted to turn the
>>>>>>> handlebar.
>>>>>>>
>>>>>>> The inverse, oversteer, makes a bicycle less stable
>>>>>>> (='more responsive') and rider effort is needed to
>>>>>>> keep it
>>>>>>> in a straight path. When the fork turns, the frame falls:
>>>>>>> http://1.bp.blogspot.com/-WJp92Vd-dMI/TtlTUAlSArI/AAAAAAAADLE/WmujhKVkXGg/s1600/sanrensho2.jpg
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>> Sorry, I think "the frame will neither rise nor fall" is
>>>>>> incorrect. If the front end geometry generates any "trail"
>>>>>> at all, the frame must fall.
>>>>>>
>>>>>> Look at http://www.yellowjersey.org/gcdl1.html again.
>>>>>> Draw a
>>>>>> line representing the steering axis down to the ground.
>>>>>> Next, draw a line from the tire contact point directly to
>>>>>> (and perpendicular to) the steering axis. I suppose we
>>>>>> could
>>>>>> call that the 'lever arm' of the contact point.
>>>>>>
>>>>>> That 'lever arm' slants upwards from the contact point to
>>>>>> the steering axis. If you 'swing' it to the side by
>>>>>> turning
>>>>>> the handlebars, it rises relative to the bike. IOW, if you
>>>>>> clamped the top tube in a fixed position and height, the
>>>>>> 'swing' would cause the contact point to rise. Or,
>>>>>> switching
>>>>>> reference frames, if you leave the tire normally on the
>>>>>> ground, the frame will fall.
>>>>>>
>>>>>> I don't have a bike with a head angle as slack as the
>>>>>> black
>>>>>> one in the photo, but I just measured my touring bike. As
>>>>>> with every other bike I've checked, turning the bars
>>>>>> causes
>>>>>> the frame to drop a bit.
>>>>>>
>>>>>> See "Wheel Flop" at
>>>>>> https://cyclingtips.com/2018/11/the-geometry-of-bike-handling-its-all-about-the-steering/
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> "Wheel flop is similar to trail in that it is
>>>>>> determined by
>>>>>> the combination of head tube angle and fork rake,
>>>>>> however it
>>>>>> is concerned with how the position of the front axle
>>>>>> changes
>>>>>> as the handlebars are turned. In almost all instances, the
>>>>>> height of the front axle is lowered when this happens"
>>>>>>
>>>>>
>>>>> Experiment report:
>>>>>
>>>>> Using a four-foot aluminum level I put one end on a table
>>>>> and the other end on the front of the top tube of a medium
>>>>> (56cm) Gunnar Road with Michelin 23 tires. Turning the
>>>>> handlebar, I observe the bubble doesn't move.
>>>>
>>>> OK, help me understand.
>>>>
>>>> Again, ISTM that if we marked the tire-to road contact point
>>>> with chalk, then rotated the bars 360 degrees, that chalked
>>>> point would describe a circle.  The circle would be
>>>> inclined
>>>> to horizontal by (90 - head tube angle), with its high point
>>>> directly forward. The marked point on the tire would be
>>>> farthest below the head tube's height with the bars straight
>>>> ahead. It would get closer to the head tube (or IOW the head
>>>> tube would drop) at any other steering angle.
>>>>
>>>> Is there some other factor I'm not visualizing that would
>>>> apply a contrary action, to cancel out this effect? So far I
>>>> can't think of one.
>>>>
>>>> I checked my Cannondale again. I held a meter stick
>>>> vertically, using my fingers to pinch it to the top tube. I
>>>> can easily feel the relative motion. At a 45 degree steering
>>>> angle (admittedly, used only for balancing at super slow
>>>> speeds) it seems the frame drops between one and tow
>>>> millimeters. At lesser steering angles the motion is almost
>>>> imperceptible, but as I visualize the geometry, it seems it
>>>> must be there.
>>>>
>>>> One thing I just noticed: The tire contact point actually
>>>> changes as the steering angle increases. Judging by the
>>>> spokes' position, at 45 degrees steering, the contact point
>>>> has moved forward about 10 degrees. Does this somehow affect
>>>> things?
>>>>
>>>
>>> On a 360-degree fork turn I have no idea but you're
>>> probably right. For normal range, as you note 45 deg left
>>> or right, any height change is between zero and negligible.
>>
>> I just did more geometry work. For now, I'm treating the
>> front wheel as a pure circle, i.e. a disc of zero thickness,
>> or a tire of zero width. (I'm not sure what difference tire
>> width will make, if any.)
>>
>> You're certainly right that the height change is small, at
>> least for small steering angles. The obvious limit is zero
>> height change for zero steering angle. But ISTM that as
>> steering angle increases from zero, there must be _some_
>> drop in frame height. Here's some of the geometry.
>>
>> The contact point of the tire on the road occurs at the back
>> of the "trail," and the trail value is often easy to look up
>> for a given bike. Alternately it's easy to calculate from
>> head angle H and fork offset.
>>
>> Let's call the trail value T.
>>
>> Spinning the fork all the way around makes the contact point
>> trace a circle. Its radius is R=T*cos(90-H)  and that circle
>> tilts upward 90-H degrees. That upward tilt is the basis of
>> what I've been saying.
>>
>> Steering angle S causes the contact point to swing a bit
>> upward along that circle. I'll give details if desired, but
>> using two projected views and some fairly simple trig, the
>> change in height as that contact point swings up (i.e.
>> closer to the top tube) is the amount the frame drops. Call
>> it D.
>>
>> I get D = R * (1-cos (S)) * sin(90-H)
>> or
>> D = T * cos(90-H) * (1-cos (S)) * sin(90-H)
>>
>> As I see it, for any conventional bike this is going to
>> cause the frame height to drop just a bit. It's not much,
>> because the circle tilts up only about 17 or 18 degrees, and
>> for most riding S is small. But it must be there.
>>
>> Plugging in an extreme steering angle of 45 degrees with a
>> 73 degree head angle and 60 mm trail, this gives a drop of
>> 4.91mm. Plugging in the same values but with a more typical
>> 10 degree steering angle gives a drop of 0.25mm which is
>> small indeed, but not zero. (The controlling term is (1 -
>> cos(S)), which is very small for normal steering angles.)
>>
>> BTW, I just held the meter stick against the top tube of my
>> ancient Raleigh commuter/grocery bike. It too exhibited a
>> drop as I turned the handlebars. It's almost undetectable
>> for small steering angles, but it's there. It doesn't seem
>> to be as large as 5mm, but then I don't know the bike's head
>> angle or trail. (Yet.)
>>
>>
>
> That's all well considered and well written.
>
> Generally if one can readily observe rise or fall through 90 degrees,(45
> each side) something is wrong/ damaged.
>
> Outliers such as classic roadsters are obvious in their rise without
> measuring tools. The effect on handling is apparent and dramatic
> immediately to riders inexperienced with the design.
>
Well, I don't have a roadster to measure, but I still don't see how a
rise is possible.

On Sunday, March 6, 2022 at 11:21:14 AM UTC-8, AMuzi wrote:
> On 3/6/2022 11:53 AM, Frank Krygowski wrote:
> > On 3/6/2022 10:58 AM, AMuzi wrote:
> >> On 3/5/2022 8:45 PM, Frank Krygowski wrote:
> >>> On 3/5/2022 2:25 PM, AMuzi wrote:
> >>>> On 3/5/2022 12:25 PM, Frank Krygowski wrote:
> >>>>> On 3/5/2022 11:02 AM, AMuzi wrote:
> >>>>>> On 3/5/2022 9:11 AM, Dieter Britz wrote:
> >>>>>>> On Sat, 05 Mar 2022 02:50:18 -0800, Andre Jute wrote:
> >>>>>>> [...]
> >>>>>>>> My own bikes are all set up to understeer. The
> >>>>>>>> consequential
> >>>>>>>> predictability and stability of line almost regardless
> >>>>>>>> of road surface
> >>>>>>>> makes the essential difference on downhill
> >>>>>>>> descents at
> >>>>>>>> speed on bad
> >>>>>>>> roads when I'm leaving the road racers behind with
> >>>>>>>> white
> >>>>>>>> brackets of
> >>>>>>>> fear beside their lips.
> >>>>>>> [...]
> >>>>>>>> Andre Jute Ah, them were the days!
> >>>>>>>
> >>>>>>> How do you set a bike up for understeer? I don't know
> >>>>>>> what under-
> >>>>>>> or oversteer means.
> >>>>>>>
> >>>>>>
> >>>>>>
> >>>>>> Standard front geometry should be neutral[1] and
> >>>>>> designers
> >>>>>> know the system well.
> >>>>>> https://dclxvi.org/chunk/tech/trail/image/trail.jpg
> >>>>>>
> >>>>>> In that case, when turning the wheel side to side, the
> >>>>>> frame will neither rise nor fall.
> >>>>>>
> >>>>>> In an understeer design like this:
> >>>>>> http://www.yellowjersey.org/gcdl1.html
> >>>>>>
> >>>>>> The frame rises when the handlebar is turned, which is to
> >>>>>> say the bicycle travel in a straight path unless coerced
> >>>>>> otherwise. This may be desired for unpaved roads and/or
> >>>>>> heavy cargo loads. Put another way, the
> >>>>>> rider/bicycle/cargo weight must be lifted to turn the
> >>>>>> handlebar.
> >>>>>>
> >>>>>> The inverse, oversteer, makes a bicycle less stable
> >>>>>> (='more responsive') and rider effort is needed to
> >>>>>> keep it
> >>>>>> in a straight path. When the fork turns, the frame falls:
> >>>>>> http://1.bp.blogspot.com/-WJp92Vd-dMI/TtlTUAlSArI/AAAAAAAADLE/WmujhKVkXGg/s1600/sanrensho2.jpg
> >>>>>>
> >>>>>>
> >>>>>
> >>>>>
> >>>>> Sorry, I think "the frame will neither rise nor fall" is
> >>>>> incorrect. If the front end geometry generates any "trail"
> >>>>> at all, the frame must fall.
> >>>>>
> >>>>> Look at http://www.yellowjersey.org/gcdl1.html again.
> >>>>> Draw a
> >>>>> line representing the steering axis down to the ground.
> >>>>> Next, draw a line from the tire contact point directly to
> >>>>> (and perpendicular to) the steering axis. I suppose we
> >>>>> could
> >>>>> call that the 'lever arm' of the contact point.
> >>>>>
> >>>>> That 'lever arm' slants upwards from the contact point to
> >>>>> the steering axis. If you 'swing' it to the side by
> >>>>> turning
> >>>>> the handlebars, it rises relative to the bike. IOW, if you
> >>>>> clamped the top tube in a fixed position and height, the
> >>>>> 'swing' would cause the contact point to rise. Or,
> >>>>> switching
> >>>>> reference frames, if you leave the tire normally on the
> >>>>> ground, the frame will fall.
> >>>>>
> >>>>> I don't have a bike with a head angle as slack as the
> >>>>> black
> >>>>> one in the photo, but I just measured my touring bike. As
> >>>>> with every other bike I've checked, turning the bars
> >>>>> causes
> >>>>> the frame to drop a bit.
> >>>>>
> >>>>> See "Wheel Flop" at
> >>>>> https://cyclingtips.com/2018/11/the-geometry-of-bike-handling-its-all-about-the-steering/
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>> "Wheel flop is similar to trail in that it is
> >>>>> determined by
> >>>>> the combination of head tube angle and fork rake,
> >>>>> however it
> >>>>> is concerned with how the position of the front axle
> >>>>> changes
> >>>>> as the handlebars are turned. In almost all instances, the
> >>>>> height of the front axle is lowered when this happens"
> >>>>>
> >>>>
> >>>> Experiment report:
> >>>>
> >>>> Using a four-foot aluminum level I put one end on a table
> >>>> and the other end on the front of the top tube of a medium
> >>>> (56cm) Gunnar Road with Michelin 23 tires. Turning the
> >>>> handlebar, I observe the bubble doesn't move.
> >>>
> >>> OK, help me understand.
> >>>
> >>> Again, ISTM that if we marked the tire-to road contact point
> >>> with chalk, then rotated the bars 360 degrees, that chalked
> >>> point would describe a circle. The circle would be
> >>> inclined
> >>> to horizontal by (90 - head tube angle), with its high point
> >>> directly forward. The marked point on the tire would be
> >>> farthest below the head tube's height with the bars straight
> >>> ahead. It would get closer to the head tube (or IOW the head
> >>> tube would drop) at any other steering angle.
> >>>
> >>> Is there some other factor I'm not visualizing that would
> >>> apply a contrary action, to cancel out this effect? So far I
> >>> can't think of one.
> >>>
> >>> I checked my Cannondale again. I held a meter stick
> >>> vertically, using my fingers to pinch it to the top tube. I
> >>> can easily feel the relative motion. At a 45 degree steering
> >>> angle (admittedly, used only for balancing at super slow
> >>> speeds) it seems the frame drops between one and tow
> >>> millimeters. At lesser steering angles the motion is almost
> >>> imperceptible, but as I visualize the geometry, it seems it
> >>> must be there.
> >>>
> >>> One thing I just noticed: The tire contact point actually
> >>> changes as the steering angle increases. Judging by the
> >>> spokes' position, at 45 degrees steering, the contact point
> >>> has moved forward about 10 degrees. Does this somehow affect
> >>> things?
> >>>
> >>
> >> On a 360-degree fork turn I have no idea but you're
> >> probably right. For normal range, as you note 45 deg left
> >> or right, any height change is between zero and negligible.
> >
> > I just did more geometry work. For now, I'm treating the
> > front wheel as a pure circle, i.e. a disc of zero thickness,
> > or a tire of zero width. (I'm not sure what difference tire
> > width will make, if any.)
> >
> > You're certainly right that the height change is small, at
> > least for small steering angles. The obvious limit is zero
> > height change for zero steering angle. But ISTM that as
> > steering angle increases from zero, there must be _some_
> > drop in frame height. Here's some of the geometry.
> >
> > The contact point of the tire on the road occurs at the back
> > of the "trail," and the trail value is often easy to look up
> > for a given bike. Alternately it's easy to calculate from
> > head angle H and fork offset.
> >
> > Let's call the trail value T.
> >
> > Spinning the fork all the way around makes the contact point
> > trace a circle. Its radius is R=T*cos(90-H) and that circle
> > tilts upward 90-H degrees. That upward tilt is the basis of
> > what I've been saying.
> >
> > Steering angle S causes the contact point to swing a bit
> > upward along that circle. I'll give details if desired, but
> > using two projected views and some fairly simple trig, the
> > change in height as that contact point swings up (i.e.
> > closer to the top tube) is the amount the frame drops. Call
> > it D.
> >
> > I get D = R * (1-cos (S)) * sin(90-H)
> > or
> > D = T * cos(90-H) * (1-cos (S)) * sin(90-H)
> >
> > As I see it, for any conventional bike this is going to
> > cause the frame height to drop just a bit. It's not much,
> > because the circle tilts up only about 17 or 18 degrees, and
> > for most riding S is small. But it must be there.
> >
> > Plugging in an extreme steering angle of 45 degrees with a
> > 73 degree head angle and 60 mm trail, this gives a drop of
> > 4.91mm. Plugging in the same values but with a more typical
> > 10 degree steering angle gives a drop of 0.25mm which is
> > small indeed, but not zero. (The controlling term is (1 -
> > cos(S)), which is very small for normal steering angles.)
> >
> > BTW, I just held the meter stick against the top tube of my
> > ancient Raleigh commuter/grocery bike. It too exhibited a
> > drop as I turned the handlebars. It's almost undetectable
> > for small steering angles, but it's there. It doesn't seem
> > to be as large as 5mm, but then I don't know the bike's head
> > angle or trail. (Yet.)
> >
> >
> That's all well considered and well written.
>
> Generally if one can readily observe rise or fall through 90
> degrees,(45 each side) something is wrong/ damaged.
>
> Outliers such as classic roadsters are obvious in their rise
> without measuring tools. The effect on handling is apparent
> and dramatic immediately to riders inexperienced with the
> design.

On 3/7/2022 10:52 AM, Tom Kunich wrote:
> On Sunday, March 6, 2022 at 11:21:14 AM UTC-8, AMuzi wrote:
>> On 3/6/2022 11:53 AM, Frank Krygowski wrote:
>>> On 3/6/2022 10:58 AM, AMuzi wrote:
>>>> On 3/5/2022 8:45 PM, Frank Krygowski wrote:
>>>>> On 3/5/2022 2:25 PM, AMuzi wrote:
>>>>>> On 3/5/2022 12:25 PM, Frank Krygowski wrote:
>>>>>>> On 3/5/2022 11:02 AM, AMuzi wrote:
>>>>>>>> On 3/5/2022 9:11 AM, Dieter Britz wrote:
>>>>>>>>> On Sat, 05 Mar 2022 02:50:18 -0800, Andre Jute wrote:
>>>>>>>>> [...]
>>>>>>>>>> My own bikes are all set up to understeer. The
>>>>>>>>>> consequential
>>>>>>>>>> predictability and stability of line almost regardless
>>>>>>>>>> of road surface
>>>>>>>>>> makes the essential difference on downhill
>>>>>>>>>> descents at
>>>>>>>>>> speed on bad
>>>>>>>>>> roads when I'm leaving the road racers behind with
>>>>>>>>>> white
>>>>>>>>>> brackets of
>>>>>>>>>> fear beside their lips.
>>>>>>>>> [...]
>>>>>>>>>> Andre Jute Ah, them were the days!
>>>>>>>>>
>>>>>>>>> How do you set a bike up for understeer? I don't know
>>>>>>>>> what under-
>>>>>>>>> or oversteer means.
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> Standard front geometry should be neutral[1] and
>>>>>>>> designers
>>>>>>>> know the system well.
>>>>>>>> https://dclxvi.org/chunk/tech/trail/image/trail.jpg
>>>>>>>>
>>>>>>>> In that case, when turning the wheel side to side, the
>>>>>>>> frame will neither rise nor fall.
>>>>>>>>
>>>>>>>> In an understeer design like this:
>>>>>>>> http://www.yellowjersey.org/gcdl1.html
>>>>>>>>
>>>>>>>> The frame rises when the handlebar is turned, which is to
>>>>>>>> say the bicycle travel in a straight path unless coerced
>>>>>>>> otherwise. This may be desired for unpaved roads and/or
>>>>>>>> heavy cargo loads. Put another way, the
>>>>>>>> rider/bicycle/cargo weight must be lifted to turn the
>>>>>>>> handlebar.
>>>>>>>>
>>>>>>>> The inverse, oversteer, makes a bicycle less stable
>>>>>>>> (='more responsive') and rider effort is needed to
>>>>>>>> keep it
>>>>>>>> in a straight path. When the fork turns, the frame falls:
>>>>>>>> http://1.bp.blogspot.com/-WJp92Vd-dMI/TtlTUAlSArI/AAAAAAAADLE/WmujhKVkXGg/s1600/sanrensho2.jpg
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Sorry, I think "the frame will neither rise nor fall" is
>>>>>>> incorrect. If the front end geometry generates any "trail"
>>>>>>> at all, the frame must fall.
>>>>>>>
>>>>>>> Look at http://www.yellowjersey.org/gcdl1.html again.
>>>>>>> Draw a
>>>>>>> line representing the steering axis down to the ground.
>>>>>>> Next, draw a line from the tire contact point directly to
>>>>>>> (and perpendicular to) the steering axis. I suppose we
>>>>>>> could
>>>>>>> call that the 'lever arm' of the contact point.
>>>>>>>
>>>>>>> That 'lever arm' slants upwards from the contact point to
>>>>>>> the steering axis. If you 'swing' it to the side by
>>>>>>> turning
>>>>>>> the handlebars, it rises relative to the bike. IOW, if you
>>>>>>> clamped the top tube in a fixed position and height, the
>>>>>>> 'swing' would cause the contact point to rise. Or,
>>>>>>> switching
>>>>>>> reference frames, if you leave the tire normally on the
>>>>>>> ground, the frame will fall.
>>>>>>>
>>>>>>> I don't have a bike with a head angle as slack as the
>>>>>>> black
>>>>>>> one in the photo, but I just measured my touring bike. As
>>>>>>> with every other bike I've checked, turning the bars
>>>>>>> causes
>>>>>>> the frame to drop a bit.
>>>>>>>
>>>>>>> See "Wheel Flop" at
>>>>>>> https://cyclingtips.com/2018/11/the-geometry-of-bike-handling-its-all-about-the-steering/
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> "Wheel flop is similar to trail in that it is
>>>>>>> determined by
>>>>>>> the combination of head tube angle and fork rake,
>>>>>>> however it
>>>>>>> is concerned with how the position of the front axle
>>>>>>> changes
>>>>>>> as the handlebars are turned. In almost all instances, the
>>>>>>> height of the front axle is lowered when this happens"
>>>>>>>
>>>>>>
>>>>>> Experiment report:
>>>>>>
>>>>>> Using a four-foot aluminum level I put one end on a table
>>>>>> and the other end on the front of the top tube of a medium
>>>>>> (56cm) Gunnar Road with Michelin 23 tires. Turning the
>>>>>> handlebar, I observe the bubble doesn't move.
>>>>>
>>>>> OK, help me understand.
>>>>>
>>>>> Again, ISTM that if we marked the tire-to road contact point
>>>>> with chalk, then rotated the bars 360 degrees, that chalked
>>>>> point would describe a circle. The circle would be
>>>>> inclined
>>>>> to horizontal by (90 - head tube angle), with its high point
>>>>> directly forward. The marked point on the tire would be
>>>>> farthest below the head tube's height with the bars straight
>>>>> ahead. It would get closer to the head tube (or IOW the head
>>>>> tube would drop) at any other steering angle.
>>>>>
>>>>> Is there some other factor I'm not visualizing that would
>>>>> apply a contrary action, to cancel out this effect? So far I
>>>>> can't think of one.
>>>>>
>>>>> I checked my Cannondale again. I held a meter stick
>>>>> vertically, using my fingers to pinch it to the top tube. I
>>>>> can easily feel the relative motion. At a 45 degree steering
>>>>> angle (admittedly, used only for balancing at super slow
>>>>> speeds) it seems the frame drops between one and tow
>>>>> millimeters. At lesser steering angles the motion is almost
>>>>> imperceptible, but as I visualize the geometry, it seems it
>>>>> must be there.
>>>>>
>>>>> One thing I just noticed: The tire contact point actually
>>>>> changes as the steering angle increases. Judging by the
>>>>> spokes' position, at 45 degrees steering, the contact point
>>>>> has moved forward about 10 degrees. Does this somehow affect
>>>>> things?
>>>>>
>>>>
>>>> On a 360-degree fork turn I have no idea but you're
>>>> probably right. For normal range, as you note 45 deg left
>>>> or right, any height change is between zero and negligible.
>>>
>>> I just did more geometry work. For now, I'm treating the
>>> front wheel as a pure circle, i.e. a disc of zero thickness,
>>> or a tire of zero width. (I'm not sure what difference tire
>>> width will make, if any.)
>>>
>>> You're certainly right that the height change is small, at
>>> least for small steering angles. The obvious limit is zero
>>> height change for zero steering angle. But ISTM that as
>>> steering angle increases from zero, there must be _some_
>>> drop in frame height. Here's some of the geometry.
>>>
>>> The contact point of the tire on the road occurs at the back
>>> of the "trail," and the trail value is often easy to look up
>>> for a given bike. Alternately it's easy to calculate from
>>> head angle H and fork offset.
>>>
>>> Let's call the trail value T.
>>>
>>> Spinning the fork all the way around makes the contact point
>>> trace a circle. Its radius is R=T*cos(90-H) and that circle
>>> tilts upward 90-H degrees. That upward tilt is the basis of
>>> what I've been saying.
>>>
>>> Steering angle S causes the contact point to swing a bit
>>> upward along that circle. I'll give details if desired, but
>>> using two projected views and some fairly simple trig, the
>>> change in height as that contact point swings up (i.e.
>>> closer to the top tube) is the amount the frame drops. Call
>>> it D.
>>>
>>> I get D = R * (1-cos (S)) * sin(90-H)
>>> or
>>> D = T * cos(90-H) * (1-cos (S)) * sin(90-H)
>>>
>>> As I see it, for any conventional bike this is going to
>>> cause the frame height to drop just a bit. It's not much,
>>> because the circle tilts up only about 17 or 18 degrees, and
>>> for most riding S is small. But it must be there.
>>>
>>> Plugging in an extreme steering angle of 45 degrees with a
>>> 73 degree head angle and 60 mm trail, this gives a drop of
>>> 4.91mm. Plugging in the same values but with a more typical
>>> 10 degree steering angle gives a drop of 0.25mm which is
>>> small indeed, but not zero. (The controlling term is (1 -
>>> cos(S)), which is very small for normal steering angles.)
>>>
>>> BTW, I just held the meter stick against the top tube of my
>>> ancient Raleigh commuter/grocery bike. It too exhibited a
>>> drop as I turned the handlebars. It's almost undetectable
>>> for small steering angles, but it's there. It doesn't seem
>>> to be as large as 5mm, but then I don't know the bike's head
>>> angle or trail. (Yet.)
>>>
>>>
>> That's all well considered and well written.
>>
>> Generally if one can readily observe rise or fall through 90
>> degrees,(45 each side) something is wrong/ damaged.
>>
>> Outliers such as classic roadsters are obvious in their rise
>> without measuring tools. The effect on handling is apparent
>> and dramatic immediately to riders inexperienced with the
>> design.
>
> I'm wondering why Frank would attempt to measure over or under or neutral steering through a 360 degree circle. Why LOGIC would dictate that neutral steering should be the same through 360 degrees simple observation would show you that the rear 180 degrees of the circle must contend with rake and trail. That would cause a rise of the top tube in the back side of the circle. Even the front 180 degrees is somewhat effected by this, you never use more than the front 90 degrees if you are going over 10 mph.

On Monday, March 7, 2022 at 4:38:03 PM UTC, Frank Krygowski wrote:
>
>If you see a mistake in my geometry, please point it out, preferably
using mathematics.
>
Frank-boy, you have a bloody cheek trying to set the rules of converse when you beg us for help with something that is beyond your brainpower and education.
>
> Again, my analysis is for a tire of zero width. If you want to take the
> analysis further, that might be an item to address. I suspect the
> effect, if any, is negligible for common tire sizes.
>
Sure thing, Franki-boy, we all saw you try to pass off a round knife-edge as a wheel. We were just wondering whether you're monumentally slack or without the slightest shred of imagination. See, a bicycle tyre is rounded, which makes for a domed shape when you take a section of the tyre at the contact patch centre, and so the distance from the contact patch to the hub centre varies as the bike leans over in a corner, with a number of consequential effects. It is possible in these circumstances to arrange the dynamic effect of the static geometry so that Andrew Muzi's holy grail of zero rise or fall is achieved at the headset and it seems to me that it is commonly approached, it being another matter whether bike designers even know about it when they slap together some tried and true angles.These effects can possibly be further fine-tuned to zero rise and fall by the obverse of the linkage geometry used in automobiles to keep the wheel upright* but I think that is way beyond your demonstrated capabilities, or rather demonstrated lack of capability.** The math, and piccies for wannabe hotrodders like you, is in my book DESIGNING AND BUILDING SPECIAL CARS. Go look it up, sport.
>
Andre Jute
* In fact, a close approximation of a bicycle which didn't change the wheelbase length with each movement up and down, was possible with a bicycle fork designed by a French auto racer for MTB bikes. It's possible this dual wishbone bicycle fork was called "Cobra" -- one of my googlebugs will be here shortly with the designer's and the fork's names. About twenty years ago I searched for an NOS fork of this design but the only one for sale was ten grand, a bit rich for even my blood. More recently, the same design appeared on the front suspension of the Honda Goldwing.
** For those with greater analytical brainpower than Franki-boy, I suspect that zero rise or fall when the handlebars are turned is a symptom of a genuinely neutral-handling bike, which as I explained before can break unpredictably between over- and under-steer and is therefore undesirable for any but the top rank of professional bike racers. If you want to see neutral handling two-wheelers, watch MotoGP, in which the riders control the characteristics of roadholding and handling by shifting their own bodyweight around in an extreme manner requiring a great deal of skill, knowledge and bravery.. Weight transfer is another name for rise or fall and, to state the obvious, the designer and the cyclist both want it under their own control rather than accept the pitiless physics of hardwiring an error into the frame and the fork.

On Wednesday, March 9, 2022 at 4:24:32 AM UTC-8, Andre Jute wrote:
> On Monday, March 7, 2022 at 4:38:03 PM UTC, Frank Krygowski wrote:
> >
> >If you see a mistake in my geometry, please point it out, preferably
> using mathematics.
> >
> Frank-boy, you have a bloody cheek trying to set the rules of converse when you beg us for help with something that is beyond your brainpower and education.
> >
> > Again, my analysis is for a tire of zero width. If you want to take the
> > analysis further, that might be an item to address. I suspect the
> > effect, if any, is negligible for common tire sizes.
> >
> Sure thing, Franki-boy, we all saw you try to pass off a round knife-edge as a wheel. We were just wondering whether you're monumentally slack or without the slightest shred of imagination. See, a bicycle tyre is rounded, which makes for a domed shape when you take a section of the tyre at the contact patch centre, and so the distance from the contact patch to the hub centre varies as the bike leans over in a corner, with a number of consequential effects. It is possible in these circumstances to arrange the dynamic effect of the static geometry so that Andrew Muzi's holy grail of zero rise or fall is achieved at the headset and it seems to me that it is commonly approached, it being another matter whether bike designers even know about it when they slap together some tried and true angles.These effects can possibly be further fine-tuned to zero rise and fall by the obverse of the linkage geometry used in automobiles to keep the wheel upright* but I think that is way beyond your demonstrated capabilities, or rather demonstrated lack of capability.** The math, and piccies for wannabe hotrodders like you, is in my book DESIGNING AND BUILDING SPECIAL CARS. Go look it up, sport.
> >
> Andre Jute
> * In fact, a close approximation of a bicycle which didn't change the wheelbase length with each movement up and down, was possible with a bicycle fork designed by a French auto racer for MTB bikes. It's possible this dual wishbone bicycle fork was called "Cobra" -- one of my googlebugs will be here shortly with the designer's and the fork's names. About twenty years ago I searched for an NOS fork of this design but the only one for sale was ten grand, a bit rich for even my blood. More recently, the same design appeared on the front suspension of the Honda Goldwing.
> ** For those with greater analytical brainpower than Franki-boy, I suspect that zero rise or fall when the handlebars are turned is a symptom of a genuinely neutral-handling bike, which as I explained before can break unpredictably between over- and under-steer and is therefore undesirable for any but the top rank of professional bike racers. If you want to see neutral handling two-wheelers, watch MotoGP, in which the riders control the characteristics of roadholding and handling by shifting their own bodyweight around in an extreme manner requiring a great deal of skill, knowledge and bravery. Weight transfer is another name for rise or fall and, to state the obvious, the designer and the cyclist both want it under their own control rather than accept the pitiless physics of hardwiring an error into the frame and the fork.

Frank is particularly stupid inasmuch as Andrew explained a simple test and I repeated it of no rise or fall of the top tube at the head tube when the handlebars are turned limit to limit. We both used a 4' bubble level and they are, I'm afraid, of vastly superior accuracy than Frank's approximations of his own false reality. That he could think that neutral steering means 360 degrees means that he hasn't a grasp of rake and trail. This means that neutral geometry could only be maintained through 180 degrees.

One of the projects I completed had 12 directions of motion. I designed the unit to use stepping motors which meant that for accuracy they had to have no gear play beyond tight limits. Now why would I have had to have to explain to supposed trained mechanical engineers what gear play means? Why for the same reason that I ended up being project engineer on so many projects - because it is not a degree that makes an engineer but a quest for knowledge. The ability to think a problem out to its end. These sorts of mechanical engineers go into aerospace firms that will pay them vast sums of money that Frank believes should be given freely to him. Those who I was unfortunate to have working with or for me, either were simply beginning to catch on or like Frank would never make the grade.

On Wednesday, March 9, 2022 at 4:06:00 PM UTC, cycl...@gmail.com wrote:
> On Wednesday, March 9, 2022 at 4:24:32 AM UTC-8, Andre Jute wrote:
> > On Monday, March 7, 2022 at 4:38:03 PM UTC, Frank Krygowski wrote:
> > >
> > >If you see a mistake in my geometry, please point it out, preferably
> > using mathematics.
> > >
> > Frank-boy, you have a bloody cheek trying to set the rules of converse when you beg us for help with something that is beyond your brainpower and education.
> > >
> > > Again, my analysis is for a tire of zero width. If you want to take the
> > > analysis further, that might be an item to address. I suspect the
> > > effect, if any, is negligible for common tire sizes.
> > >
> > Sure thing, Franki-boy, we all saw you try to pass off a round knife-edge as a wheel. We were just wondering whether you're monumentally slack or without the slightest shred of imagination. See, a bicycle tyre is rounded, which makes for a domed shape when you take a section of the tyre at the contact patch centre, and so the distance from the contact patch to the hub centre varies as the bike leans over in a corner, with a number of consequential effects. It is possible in these circumstances to arrange the dynamic effect of the static geometry so that Andrew Muzi's holy grail of zero rise or fall is achieved at the headset and it seems to me that it is commonly approached, it being another matter whether bike designers even know about it when they slap together some tried and true angles.These effects can possibly be further fine-tuned to zero rise and fall by the obverse of the linkage geometry used in automobiles to keep the wheel upright* but I think that is way beyond your demonstrated capabilities, or rather demonstrated lack of capability.** The math, and piccies for wannabe hotrodders like you, is in my book DESIGNING AND BUILDING SPECIAL CARS. Go look it up, sport.
> > >
> > Andre Jute
> > * In fact, a close approximation of a bicycle which didn't change the wheelbase length with each movement up and down, was possible with a bicycle fork designed by a French auto racer for MTB bikes. It's possible this dual wishbone bicycle fork was called "Cobra" -- one of my googlebugs will be here shortly with the designer's and the fork's names. About twenty years ago I searched for an NOS fork of this design but the only one for sale was ten grand, a bit rich for even my blood. More recently, the same design appeared on the front suspension of the Honda Goldwing.
> > ** For those with greater analytical brainpower than Franki-boy, I suspect that zero rise or fall when the handlebars are turned is a symptom of a genuinely neutral-handling bike, which as I explained before can break unpredictably between over- and under-steer and is therefore undesirable for any but the top rank of professional bike racers. If you want to see neutral handling two-wheelers, watch MotoGP, in which the riders control the characteristics of roadholding and handling by shifting their own bodyweight around in an extreme manner requiring a great deal of skill, knowledge and bravery. Weight transfer is another name for rise or fall and, to state the obvious, the designer and the cyclist both want it under their own control rather than accept the pitiless physics of hardwiring an error into the frame and the fork.
> Frank is particularly stupid inasmuch as Andrew explained a simple test and I repeated it of no rise or fall of the top tube at the head tube when the handlebars are turned limit to limit. We both used a 4' bubble level and they are, I'm afraid, of vastly superior accuracy than Frank's approximations of his own false reality. That he could think that neutral steering means 360 degrees means that he hasn't a grasp of rake and trail. This means that neutral geometry could only be maintained through 180 degrees.
>
> One of the projects I completed had 12 directions of motion. I designed the unit to use stepping motors which meant that for accuracy they had to have no gear play beyond tight limits. Now why would I have had to have to explain to supposed trained mechanical engineers what gear play means? Why for the same reason that I ended up being project engineer on so many projects - because it is not a degree that makes an engineer but a quest for knowledge. The ability to think a problem out to its end. These sorts of mechanical engineers go into aerospace firms that will pay them vast sums of money that Frank believes should be given freely to him. Those who I was unfortunate to have working with or for me, either were simply beginning to catch on or like Frank would never make the grade.
>
I saw you guys trying to help Franki-boy and thought I'd better do my bit to show willing. But it is probably wasted time. Krygowski just isn't capable of the subtleties that remain to be explained in bicycle geometry.
>
As an aside, I continue to be amazed by the fact that automobile suspension geometry is so much better understood than bicycle geometry. There's hope of a better future of course, for instance from those scholars in Cologne pushing bikes to each across a hall on a campus in Cologne, and speculating and making prototypes to test bicycle stability, and other academic efforts from people who don't need to earn a commercial income.
>
Andre Jute
I salute a cycling tomorrow.
>
PS. I have a bike application of stepper motors, or possibly just one reversible stepper motor, sitting on the axle of a Shimano Nexus hub and actually changing the gears on my Trek Smover, which is a full service full auto Di2 bike. It's an amazingly small thing, totally enclosed in plastic only a couple of inches to a side and about three-quarters of an inch thick.
>

On Wednesday, March 9, 2022 at 8:45:55 AM UTC-8, Andre Jute wrote:
> On Wednesday, March 9, 2022 at 4:06:00 PM UTC, cycl...@gmail.com wrote:
> > On Wednesday, March 9, 2022 at 4:24:32 AM UTC-8, Andre Jute wrote:
> > > On Monday, March 7, 2022 at 4:38:03 PM UTC, Frank Krygowski wrote:
> > > >
> > > >If you see a mistake in my geometry, please point it out, preferably
> > > using mathematics.
> > > >
> > > Frank-boy, you have a bloody cheek trying to set the rules of converse when you beg us for help with something that is beyond your brainpower and education.
> > > >
> > > > Again, my analysis is for a tire of zero width. If you want to take the
> > > > analysis further, that might be an item to address. I suspect the
> > > > effect, if any, is negligible for common tire sizes.
> > > >
> > > Sure thing, Franki-boy, we all saw you try to pass off a round knife-edge as a wheel. We were just wondering whether you're monumentally slack or without the slightest shred of imagination. See, a bicycle tyre is rounded, which makes for a domed shape when you take a section of the tyre at the contact patch centre, and so the distance from the contact patch to the hub centre varies as the bike leans over in a corner, with a number of consequential effects. It is possible in these circumstances to arrange the dynamic effect of the static geometry so that Andrew Muzi's holy grail of zero rise or fall is achieved at the headset and it seems to me that it is commonly approached, it being another matter whether bike designers even know about it when they slap together some tried and true angles.These effects can possibly be further fine-tuned to zero rise and fall by the obverse of the linkage geometry used in automobiles to keep the wheel upright* but I think that is way beyond your demonstrated capabilities, or rather demonstrated lack of capability.** The math, and piccies for wannabe hotrodders like you, is in my book DESIGNING AND BUILDING SPECIAL CARS. Go look it up, sport.
> > > >
> > > Andre Jute
> > > * In fact, a close approximation of a bicycle which didn't change the wheelbase length with each movement up and down, was possible with a bicycle fork designed by a French auto racer for MTB bikes. It's possible this dual wishbone bicycle fork was called "Cobra" -- one of my googlebugs will be here shortly with the designer's and the fork's names. About twenty years ago I searched for an NOS fork of this design but the only one for sale was ten grand, a bit rich for even my blood. More recently, the same design appeared on the front suspension of the Honda Goldwing.
> > > ** For those with greater analytical brainpower than Franki-boy, I suspect that zero rise or fall when the handlebars are turned is a symptom of a genuinely neutral-handling bike, which as I explained before can break unpredictably between over- and under-steer and is therefore undesirable for any but the top rank of professional bike racers. If you want to see neutral handling two-wheelers, watch MotoGP, in which the riders control the characteristics of roadholding and handling by shifting their own bodyweight around in an extreme manner requiring a great deal of skill, knowledge and bravery. Weight transfer is another name for rise or fall and, to state the obvious, the designer and the cyclist both want it under their own control rather than accept the pitiless physics of hardwiring an error into the frame and the fork.
> > Frank is particularly stupid inasmuch as Andrew explained a simple test and I repeated it of no rise or fall of the top tube at the head tube when the handlebars are turned limit to limit. We both used a 4' bubble level and they are, I'm afraid, of vastly superior accuracy than Frank's approximations of his own false reality. That he could think that neutral steering means 360 degrees means that he hasn't a grasp of rake and trail. This means that neutral geometry could only be maintained through 180 degrees.
> >
> > One of the projects I completed had 12 directions of motion. I designed the unit to use stepping motors which meant that for accuracy they had to have no gear play beyond tight limits. Now why would I have had to have to explain to supposed trained mechanical engineers what gear play means? Why for the same reason that I ended up being project engineer on so many projects - because it is not a degree that makes an engineer but a quest for knowledge. The ability to think a problem out to its end. These sorts of mechanical engineers go into aerospace firms that will pay them vast sums of money that Frank believes should be given freely to him. Those who I was unfortunate to have working with or for me, either were simply beginning to catch on or like Frank would never make the grade.
> >
> I saw you guys trying to help Franki-boy and thought I'd better do my bit to show willing. But it is probably wasted time. Krygowski just isn't capable of the subtleties that remain to be explained in bicycle geometry.
> >
> As an aside, I continue to be amazed by the fact that automobile suspension geometry is so much better understood than bicycle geometry. There's hope of a better future of course, for instance from those scholars in Cologne pushing bikes to each across a hall on a campus in Cologne, and speculating and making prototypes to test bicycle stability, and other academic efforts from people who don't need to earn a commercial income.
> >
> Andre Jute
> I salute a cycling tomorrow.
> >
> PS. I have a bike application of stepper motors, or possibly just one reversible stepper motor, sitting on the axle of a Shimano Nexus hub and actually changing the gears on my Trek Smover, which is a full service full auto Di2 bike. It's an amazingly small thing, totally enclosed in plastic only a couple of inches to a side and about three-quarters of an inch thick.

I'm of the opinion that rear axle 8 speeds with electical shifting would be good commuters but couldn't be constructed to have the gear range and strength of the normal manual derailleur. While electronic shifting such as Di2 works better than manual for less messing about, manual is certainly good enough and requires less messing with.

On Wednesday, March 9, 2022 at 5:06:00 PM UTC+1, Tom Kunich .
>
> One of the projects I completed had 12 directions of motion.

12 direction of motion? I don't understand. I know translation in X,Y and Z and rotation Rx, Ry and Rz. I can position and orientate an object in a 3 D space using these 6 degrees of freedom. What did I miss?

lou

On 3/9/2022 11:05 AM, Tom Kunich wrote:
>
> Frank is particularly stupid inasmuch as Andrew explained a simple test and I repeated it of no rise or fall of the top tube at the head tube when the handlebars are turned limit to limit. We both used a 4' bubble level and they are, I'm afraid, of vastly superior accuracy than Frank's approximations of his own false reality. That he could think that neutral steering means 360 degrees means that he hasn't a grasp of rake and trail. This means that neutral geometry could only be maintained through 180 degrees.

Well, that was completely devoid of facts!

I computed drops of less than a millimeter at a ten degree steering
angle - specifically, 0.6mm for the Raleigh Roadster. It was less for
other frame geometries, but it was always a drop. The trigonometry
wasn't terribly difficult.

As _you_, Tom, can easily show by trigonometry (right?) a 0.6 mm drop at
the end of a four foot level causes the angle of the level to change by
0.03 degrees.

Do you think you can detect an angle of 3/100 degree by reading a level?

My main point was a conventional bike does not _rise_ when the steering
is turned. At least for the case of a vertical bike and negligible tire
width, it must fall. It falls microscopically for small steering angles
and more as the steering angle increases, but it does not rise. And my
simple measurements (more sensitive than yours, BTW) confirm that.

If there's something I'm missing in the geometry or trigonometry, spell
it out. And skip the insults.

--
- Frank Krygowski

On Wednesday, March 9, 2022 at 7:38:14 PM UTC+1, jeff.li...@gmail.com wrote:
> On Wed, 9 Mar 2022 09:34:26 -0800 (PST), Lou Holtman
> <lou.h...@gmail.com> wrote:
>
> >On Wednesday, March 9, 2022 at 5:06:00 PM UTC+1, Tom Kunich .
> >>
> >> One of the projects I completed had 12 directions of motion.
>
> >12 direction of motion? I don't understand. I know translation in X,Y and Z and rotation Rx, Ry and Rz. I can position and orientate an object in a 3 D space using these 6 degrees of freedom. What did I miss?
> >lou
> 12 degrees of freedom would be a Stewart platform, which is used in
> flight simulators:
> <https://en.wikipedia.org/wiki/Stewart_platform>
> It's really only 6 degrees of freedom but Grübler's forumula declares
> it to be 12. The additional 6 degrees are the rotation of the legs,
> which have no effect on the motion of the platform.

Pff… That is a weird definition.

Lou

On Wednesday, March 9, 2022 at 7:43:18 PM UTC+1, jeff.li...@gmail.com wrote:

>
> Also, the 3 rotational axis are commonly called yaw, pitch, and roll.

Not in my line of work.

Lou

On 3/9/2022 11:44 AM, Frank Krygowski wrote:
> On 3/9/2022 11:05 AM, Tom Kunich wrote:
>>
>> Frank is particularly stupid inasmuch as Andrew explained
>> a simple test and I repeated it of no rise or fall of the
>> top tube at the head tube when the handlebars are turned
>> limit to limit. We both used a 4' bubble level and they
>> are, I'm afraid, of vastly superior accuracy than Frank's
>> approximations of his own false reality. That he could
>> think that neutral steering means 360 degrees means that
>> he hasn't a grasp of rake and trail. This means that
>> neutral geometry could only be maintained through 180
>> degrees.
>
> Well, that was completely devoid of facts!
>
> I computed drops of less than a millimeter at a ten degree
> steering angle - specifically, 0.6mm for the Raleigh
> Roadster. It was less for other frame geometries, but it was
> always a drop. The trigonometry wasn't terribly difficult.
>
> As _you_, Tom, can easily show by trigonometry (right?) a
> 0.6 mm drop at the end of a four foot level causes the angle
> of the level to change by 0.03 degrees.
>
> Do you think you can detect an angle of 3/100 degree by
> reading a level?
>
> My main point was a conventional bike does not _rise_ when
> the steering is turned. At least for the case of a vertical
> bike and negligible tire width, it must fall. It falls
> microscopically for small steering angles and more as the
> steering angle increases, but it does not rise. And my
> simple measurements (more sensitive than yours, BTW) confirm
> that.
>
> If there's something I'm missing in the geometry or
> trigonometry, spell it out. And skip the insults.
>

I cannot compose the formulae so I'll trust you on that.

How did you allow for the net rake diminishing as the wheel
turns while simultaneously changing the head angle? Too
complex for me.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On 3/9/2022 1:01 PM, Lou Holtman wrote:
> On Wednesday, March 9, 2022 at 7:38:14 PM UTC+1, jeff.li...@gmail.com wrote:
>> On Wed, 9 Mar 2022 09:34:26 -0800 (PST), Lou Holtman
>> <lou.h...@gmail.com> wrote:
>>
>>> On Wednesday, March 9, 2022 at 5:06:00 PM UTC+1, Tom Kunich .
>>>>
>>>> One of the projects I completed had 12 directions of motion.
>>
>>> 12 direction of motion? I don't understand. I know translation in X,Y and Z and rotation Rx, Ry and Rz. I can position and orientate an object in a 3 D space using these 6 degrees of freedom. What did I miss?
>>> lou
>> 12 degrees of freedom would be a Stewart platform, which is used in
>> flight simulators:
>> <https://en.wikipedia.org/wiki/Stewart_platform>
>> It's really only 6 degrees of freedom but Grübler's forumula declares
>> it to be 12. The additional 6 degrees are the rotation of the legs,
>> which have no effect on the motion of the platform.
>
> Pff… That is a weird definition.
>
> Lou
>
+1

For subtractive machining the tools are now called "5-axis".
I learned X, Y Z axis in machining. I think it's the sales
department more than logicians who describe the ability to
cut double compound curves such as a nuclear submarine
'silent' propeller as "5-axis" machining.

(I'm told this will all be 3D printed at some date hence.)

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On Wednesday, March 9, 2022 at 8:17:53 PM UTC+1, AMuzi wrote:
> On 3/9/2022 1:01 PM, Lou Holtman wrote:
> > On Wednesday, March 9, 2022 at 7:38:14 PM UTC+1, jeff.li...@gmail.com wrote:
> >> On Wed, 9 Mar 2022 09:34:26 -0800 (PST), Lou Holtman
> >> <lou.h...@gmail.com> wrote:
> >>
> >>> On Wednesday, March 9, 2022 at 5:06:00 PM UTC+1, Tom Kunich .
> >>>>
> >>>> One of the projects I completed had 12 directions of motion.
> >>
> >>> 12 direction of motion? I don't understand. I know translation in X,Y and Z and rotation Rx, Ry and Rz. I can position and orientate an object in a 3 D space using these 6 degrees of freedom. What did I miss?
> >>> lou
> >> 12 degrees of freedom would be a Stewart platform, which is used in
> >> flight simulators:
> >> <https://en.wikipedia.org/wiki/Stewart_platform>
> >> It's really only 6 degrees of freedom but Grübler's forumula declares
> >> it to be 12. The additional 6 degrees are the rotation of the legs,
> >> which have no effect on the motion of the platform.
> >
> > Pff… That is a weird definition.
> >
> > Lou
> >
> +1
>
> For subtractive machining the tools are now called "5-axis".
> I learned X, Y Z axis in machining. I think it's the sales
> department more than logicians who describe the ability to
> cut double compound curves such as a nuclear submarine
> 'silent' propeller as "5-axis" machining.
>
> (I'm told this will all be 3D printed at some date hence.)
> --
> Andrew Muzi
> <www.yellowjersey.org/>
> Open every day since 1 April, 1971

We have a couple 5 axis machining tools in our workshop at work; translation in x, y and z direction and rotation around two axis. It is a joy to watch them at work and I can design more complex parts ;-) that can be made in house within a couple of days. 3D printing and rapid prototyping is also amazing. Complex plastic parts available overnight right from my 3D CAD application. I work 41 years now at the company and the progress is amazing during that period. I will be kicked out next year. Hmmm….

Lou

On Wednesday, March 9, 2022 at 12:09:40 PM UTC-8, Lou Holtman wrote:
> On Wednesday, March 9, 2022 at 8:17:53 PM UTC+1, AMuzi wrote:
> > On 3/9/2022 1:01 PM, Lou Holtman wrote:
> > > On Wednesday, March 9, 2022 at 7:38:14 PM UTC+1, jeff.li...@gmail.com wrote:
> > >> On Wed, 9 Mar 2022 09:34:26 -0800 (PST), Lou Holtman
> > >> <lou.h...@gmail.com> wrote:
> > >>
> > >>> On Wednesday, March 9, 2022 at 5:06:00 PM UTC+1, Tom Kunich .
> > >>>>
> > >>>> One of the projects I completed had 12 directions of motion.
> > >>
> > >>> 12 direction of motion? I don't understand. I know translation in X,Y and Z and rotation Rx, Ry and Rz. I can position and orientate an object in a 3 D space using these 6 degrees of freedom. What did I miss?
> > >>> lou
> > >> 12 degrees of freedom would be a Stewart platform, which is used in
> > >> flight simulators:
> > >> <https://en.wikipedia.org/wiki/Stewart_platform>
> > >> It's really only 6 degrees of freedom but Grübler's forumula declares
> > >> it to be 12. The additional 6 degrees are the rotation of the legs,
> > >> which have no effect on the motion of the platform.
> > >
> > > Pff… That is a weird definition.
> > >
> > > Lou
> > >
> > +1
> >
> > For subtractive machining the tools are now called "5-axis".
> > I learned X, Y Z axis in machining. I think it's the sales
> > department more than logicians who describe the ability to
> > cut double compound curves such as a nuclear submarine
> > 'silent' propeller as "5-axis" machining.
> >
> > (I'm told this will all be 3D printed at some date hence.)
> > --
> > Andrew Muzi
> > <www.yellowjersey.org/>
> > Open every day since 1 April, 1971
> We have a couple 5 axis machining tools in our workshop at work; translation in x, y and z direction and rotation around two axis. It is a joy to watch them at work and I can design more complex parts ;-) that can be made in house within a couple of days. 3D printing and rapid prototyping is also amazing. Complex plastic parts available overnight right from my 3D CAD application. I work 41 years now at the company and the progress is amazing during that period. I will be kicked out next year. Hmmm….

X, Y, Z and rotation. Y motion occurs in two different areas moving sample plates back and forth into different areas. Another plane of motion is heating another cooling Picking up platelet sample nozzles and ejecting them etc. etc. etc. Frank seems to think only in 3 dimensions and not actual activities of motor drives. Picking up primer in on platelet, moving it over and depositing an exact amount into the actual samples, moving the table to move the platelet from one table onto another that places the samples in a thermocycler, moving the main table over to the nozzle container and ejecting only the number of nozzles that have been used. The first company I did this for it was all written in assembly language and at another company I did a far more complex firmware in C and it took up less memory and used a far faster microprocessor. These were all considered planes of motion because they all had to occur with perfect timing and perfect volume exchanges. You can trust the blood you get from a blood bank because of my work. The first example of the Pro/Pette https://www.ebay.com/itm/163276237068?hash=item260405a90c:g:yBYAAOxy7AxSK3wI was the one that two PhD's said could not be accomplished with less than TWO IBM supercomputers. The Pro/pette was a bit smaller than that.

On 3/9/2022 2:11 PM, AMuzi wrote:
> On 3/9/2022 11:44 AM, Frank Krygowski wrote:
>> On 3/9/2022 11:05 AM, Tom Kunich wrote:
>>>
>>> Frank is particularly stupid inasmuch as Andrew explained
>>> a simple test and I repeated it of no rise or fall of the
>>> top tube at the head tube when the handlebars are turned
>>> limit to limit. We both used a 4' bubble level and they
>>> are, I'm afraid, of vastly superior accuracy than Frank's
>>> approximations of his own false reality. That he could
>>> think that neutral steering means 360 degrees means that
>>> he hasn't a grasp of rake and trail. This means that
>>> neutral geometry could only be maintained through 180
>>> degrees.
>>
>> Well, that was completely devoid of facts!
>>
>> I computed drops of less than a millimeter at a ten degree
>> steering angle - specifically, 0.6mm for the Raleigh
>> Roadster. It was less for other frame geometries, but it was
>> always a drop. The trigonometry wasn't terribly difficult.
>>
>> As _you_, Tom, can easily show by trigonometry (right?) a
>> 0.6 mm drop at the end of a four foot level causes the angle
>> of the level to change by 0.03 degrees.
>>
>> Do you think you can detect an angle of 3/100 degree by
>> reading a level?
>>
>> My main point was a conventional bike does not _rise_ when
>> the steering is turned. At least for the case of a vertical
>> bike and negligible tire width, it must fall. It falls
>> microscopically for small steering angles and more as the
>> steering angle increases, but it does not rise. And my
>> simple measurements (more sensitive than yours, BTW) confirm
>> that.
>>
>> If there's something I'm missing in the geometry or
>> trigonometry, spell it out. And skip the insults.
>>
>
> I cannot compose the formulae so I'll trust you on that.
>
> How did you allow for the net rake diminishing as the wheel turns while
> simultaneously changing the head angle? Too complex for me.

It wasn't necessary for the analysis. All I had to do was determine the
path of the tire-to-ground contact point.

BTW, I later found in _Bicycle Technology_ by Van der Plas & Baird,
~p.138, the authors give a name to the radius of the circle I described.
Interestingly, they say it's the "effective trail" or "Stability Index."

They claim this is the quantity that I referred to weeks ago when I
mentioned its graph in DeLong's _Guide to Bicycles and Bicycling_. (I
haven't confirmed that.) Their book reprints DeLong's graph, and his
graph of "handling qualities" vs. trail.

--
- Frank Krygowski

On 3/9/2022 3:09 PM, Lou Holtman wrote:
> On Wednesday, March 9, 2022 at 8:17:53 PM UTC+1, AMuzi wrote:
>> On 3/9/2022 1:01 PM, Lou Holtman wrote:
>>> On Wednesday, March 9, 2022 at 7:38:14 PM UTC+1, jeff.li...@gmail.com wrote:
>>>> On Wed, 9 Mar 2022 09:34:26 -0800 (PST), Lou Holtman
>>>> <lou.h...@gmail.com> wrote:
>>>>
>>>>> On Wednesday, March 9, 2022 at 5:06:00 PM UTC+1, Tom Kunich .
>>>>>>
>>>>>> One of the projects I completed had 12 directions of motion.
>>>>
>>>>> 12 direction of motion? I don't understand. I know translation in X,Y and Z and rotation Rx, Ry and Rz. I can position and orientate an object in a 3 D space using these 6 degrees of freedom. What did I miss?
>>>>> lou
>>>> 12 degrees of freedom would be a Stewart platform, which is used in
>>>> flight simulators:
>>>> <https://en.wikipedia.org/wiki/Stewart_platform>
>>>> It's really only 6 degrees of freedom but Grübler's forumula declares
>>>> it to be 12. The additional 6 degrees are the rotation of the legs,
>>>> which have no effect on the motion of the platform.
>>>
>>> Pff… That is a weird definition.
>>>
>>> Lou
>>>
>> +1
>>
>> For subtractive machining the tools are now called "5-axis".
>> I learned X, Y Z axis in machining. I think it's the sales
>> department more than logicians who describe the ability to
>> cut double compound curves such as a nuclear submarine
>> 'silent' propeller as "5-axis" machining.
>>
>> (I'm told this will all be 3D printed at some date hence.)
>> --
>> Andrew Muzi
>> <www.yellowjersey.org/>
>> Open every day since 1 April, 1971
>
> We have a couple 5 axis machining tools in our workshop at work; translation in x, y and z direction and rotation around two axis. It is a joy to watch them at work and I can design more complex parts ;-) that can be made in house within a couple of days. 3D printing and rapid prototyping is also amazing. Complex plastic parts available overnight right from my 3D CAD application. I work 41 years now at the company and the progress is amazing during that period. I will be kicked out next year. Hmmm….

I agree, this stuff is great fun to watch, especially (for me) the
machining.

I first saw 3d printing at a place I worked in 1990. Photosensitive
plastic resin was hit with a laser beam, with each layer then lowered a
few thousandths of an inch and the process repeated. The part took many
hours, then needed to be "baked" in a UV oven to fully harden. It was
expensive and slow, but it allowed faster prototypes of complex
electrical connectors.

Now both CNC and 3D printing are done by home hobbyists. (I'm still
feeding my lathe cutting tool by hand most of the time.)

--
- Frank Krygowski

On Thursday, March 10, 2022 at 1:39:47 AM UTC+1, jeff.li...@gmail.com wrote:
> On Wed, 9 Mar 2022 11:03:40 -0800 (PST), Lou Holtman
> <lou.h...@gmail.com> wrote:
>
> >On Wednesday, March 9, 2022 at 7:43:18 PM UTC+1, jeff.li...@gmail.com wrote:
> >> Also, the 3 rotational axis are commonly called yaw, pitch, and roll.
>
> >Not in my line of work.
> >Lou
> Not a problem. In robotics and machining, the rotational axes are a,
> b, and c. In maritime, aircraft and satellite, they're roll, pitch,
> and yaw.
> <https://en.wikipedia.org/wiki/Ship_motions>
> <https://en.wikipedia.org/wiki/Aircraft_principal_axes>
> There are also those who favor the Greek letters, alpha, beta, and
> gamma:
> <https://i.stack.imgur.com/2b9B5.png>
> <http://lavalle.pl/vr/node77.html>
> --
> Jeff Liebermann je...@cruzio.com
> PO Box 272 http://www.LearnByDestroying.com
> Ben Lomond CA 95005-0272
> Skype: JeffLiebermann AE6KS 831-336-2558

‘We’ define a X, Y and Z axis and then translation and rotation is also defined. Everyone knows what you mean.

Lou

On Thursday, March 10, 2022 at 12:39:47 AM UTC, jeff.li...@gmail.com wrote:
> On Wed, 9 Mar 2022 11:03:40 -0800 (PST), Lou Holtman
> <lou.h...@gmail.com> wrote:
>
> >On Wednesday, March 9, 2022 at 7:43:18 PM UTC+1, jeff.li...@gmail.com wrote:
> >> Also, the 3 rotational axis are commonly called yaw, pitch, and roll.
>
> >Not in my line of work.
> >Lou
> Not a problem. In robotics and machining, the rotational axes are a,
> b, and c. In maritime, aircraft and satellite, they're roll, pitch,
> and yaw.
> <https://en.wikipedia.org/wiki/Ship_motions>
> <https://en.wikipedia.org/wiki/Aircraft_principal_axes>
> There are also those who favor the Greek letters, alpha, beta, and
> gamma:
> <https://i.stack.imgur.com/2b9B5.png>
> <http://lavalle.pl/vr/node77.html>
> --
> Jeff Liebermann je...@cruzio.com
> PO Box 272 http://www.LearnByDestroying.com
> Ben Lomond CA 95005-0272
> Skype: JeffLiebermann AE6KS 831-336-2558
>
And in the theatre, as of today when I made it up, roll, pitch and yaw will be incredulity, death spiral and fan. But we'll continue with the well-established stage right and stage left.-- AJ

On Wed, 9 Mar 2022 22:37:00 -0800 (PST), Lou Holtman
<lou.holtman@gmail.com> wrote:

>On Thursday, March 10, 2022 at 1:39:47 AM UTC+1, jeff.li...@gmail.com wrote:
>> On Wed, 9 Mar 2022 11:03:40 -0800 (PST), Lou Holtman
>> <lou.h...@gmail.com> wrote:
>>
>> >On Wednesday, March 9, 2022 at 7:43:18 PM UTC+1, jeff.li...@gmail.com wrote:
>> >> Also, the 3 rotational axis are commonly called yaw, pitch, and roll.
>>
>> >Not in my line of work.
>> >Lou
>> Not a problem. In robotics and machining, the rotational axes are a,
>> b, and c. In maritime, aircraft and satellite, they're roll, pitch,
>> and yaw.
>> <https://en.wikipedia.org/wiki/Ship_motions>
>> <https://en.wikipedia.org/wiki/Aircraft_principal_axes>
>> There are also those who favor the Greek letters, alpha, beta, and
>> gamma:
>> <https://i.stack.imgur.com/2b9B5.png>
>> <http://lavalle.pl/vr/node77.html>

>‘We’ define a X, Y and Z axis and then translation and rotation is also defined. Everyone knows what you mean.
>Lou

We beg to differ, somewhat. X, Y, and Z locate a position or linear
movement in space. Roll, pitch, and yaw define a rotational movement
in space. You cannot have movement without first locating the object
that moves. Therefore, as you indicate, X, Y, and Z must be specified
before A, B, and C. As I vaguely recall, G code use A, B, and C.

Whether one uses roll pitch yaw, A B C, or Alpha Beta Gamma are
religious issues similar to the direction of current flow, where those
in electronics use Ben Franklin's convention of "hole" flow (plus ->
minus), while most other disciplines use electron flow (minus ->
plus).

Some of my background is marine radio, where vessel roll, pitch, and
yaw are the common terms.

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

On Thursday, March 10, 2022 at 1:22:39 AM UTC-8, Andre Jute wrote:
> On Thursday, March 10, 2022 at 12:39:47 AM UTC, jeff.li...@gmail.com wrote:
> > On Wed, 9 Mar 2022 11:03:40 -0800 (PST), Lou Holtman
> > <lou.h...@gmail.com> wrote:
> >
> > >On Wednesday, March 9, 2022 at 7:43:18 PM UTC+1, jeff.li...@gmail.com wrote:
> > >> Also, the 3 rotational axis are commonly called yaw, pitch, and roll..
> >
> > >Not in my line of work.
> > >Lou
> > Not a problem. In robotics and machining, the rotational axes are a,
> > b, and c. In maritime, aircraft and satellite, they're roll, pitch,
> > and yaw.
> > <https://en.wikipedia.org/wiki/Ship_motions>
> > <https://en.wikipedia.org/wiki/Aircraft_principal_axes>
> > There are also those who favor the Greek letters, alpha, beta, and
> > gamma:
> > <https://i.stack.imgur.com/2b9B5.png>
> > <http://lavalle.pl/vr/node77.html>
> >
> And in the theatre, as of today when I made it up, roll, pitch and yaw will be incredulity, death spiral and fan. But we'll continue with the well-established stage right and stage left.-- AJ

The people here who have done nothing with their lives are comedic is response to people who have.

Now that Pfizer has been forced to release papers concerning their vaccine. Of less that 50,000 investigated cases there were about 160,000 physical abnormal responses to it. Now some of these were no doubt abnormal injection site pain. But there were 100,000 concerning musculature and neurological responses that could be permanent disabilities both physical and mental and 1,223 people died of this specific vaccine in only 48,000 investigations! This is FAR above (greater than or equal to 2%) the acceptable limits for vaccines.

What this tells me is that those who know medicine PRACTICE medicine and those who don't go into civil service to garner large salaries despite their incompetence. This information was supposed to be public information and it took a group of THOUSANDS of doctors to sue under the Freedom of Information Act to get it release before 2097! What we are seeing is that Frank's favorite belief that we should have socialized medicine means that we should have socialized incompetent medicine. This suggests to me that Frank has a personal reason to want to void the 2nd Amendment.

This has become not a debate about a questionable illness that appears to have been developed under US taxpayer money, but a level of attempting to hide how badly mRNA vaccines actually are. They are stiff today trying to force your children to take a fake vaccine that could be responsible for the death of your children. And who is pressing these sorts of things? The PRESIDENT! This is clear and present grounds for impeachment.