https://pacenticycledesign.com/collections/handlebars

Any engineers out there? What am I missing?
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

On Tuesday, October 18, 2022 at 8:38:14 AM UTC-4, AMuzi wrote:
> https://pacenticycledesign.com/collections/handlebars
>
> Any engineers out there? What am I missing?
> --
> Andrew Muzi
> <www.yellowjersey.org/>
> Open every day since 1 April, 1971

Looks like they are trying to achieve as short a reach as possible by notching out the back of the handlebar. In terms of stem length, it would be a negative number. There are top view pictures of both products showing them integrated into the stem. Seems like a solution in search of a problem, but I guess having the pivot of the steering axis inside the actual steerer tube diameter is helpful for some people.

On Tue, 18 Oct 2022 07:38:08 -0500, AMuzi <am@yellowjersey.org> wrote:

>https://pacenticycledesign.com/collections/handlebars
>
>Any engineers out there? What am I missing?

I wouldn't try to guess, but do they also make some of those super
lightweight carbon fiber bottle cages? Asking for a friend.

On 10/18/2022 8:38 AM, AMuzi wrote:
> https://pacenticycledesign.com/collections/handlebars
>
> Any engineers out there? What am I missing?

I'm having trouble decoding their advertisement blabbing. So the
handlebar center is almost on the steering axis? Is that it?

"... 15% less input to effect a 10° directional change at the front
wheel when compared to a similar 40mm stem ..." isn't a very clear
explanation. Perhaps they're talking about the motion along the arc
length of the rider's hand? The hand moves through a 15% smaller
distance because it's at a smaller radius? Got me, and I'm not motivated
to work out the geometry right now.

But if that were the objective, ISTM you could get the same effect more
easily by shortening the bars.

BTW, as I've said, I seem to be extremely tolerant of changes in bike
geometry. I've changed stem length without noticing any difference in
handling "feel."

Even weirder, at least a couple times I've turned stems completely
around to put the handlebars behind the steering axis, to allow kids to
reach handlebars on frames that were too long for them. (Those were
temporary solutions until the kids grew.) I briefly test rode those
bikes. As I recall, it felt a little weird, but it was perfectly rideable.

--
- Frank Krygowski

On 10/18/2022 11:28 AM, Frank Krygowski wrote:
> On 10/18/2022 8:38 AM, AMuzi wrote:
>> https://pacenticycledesign.com/collections/handlebars
>>
>> Any engineers out there? What am I missing?
>
> I'm having trouble decoding their advertisement blabbing. So
> the handlebar center is almost on the steering axis? Is that
> it?
>
> "... 15% less input to effect a 10° directional change at
> the front wheel when compared to a similar 40mm stem ..."
> isn't a very clear explanation. Perhaps they're talking
> about the motion along the arc length of the rider's hand?
> The hand moves through a 15% smaller distance because it's
> at a smaller radius? Got me, and I'm not motivated to work
> out the geometry right now.
>
> But if that were the objective, ISTM you could get the same
> effect more easily by shortening the bars.
>
> BTW, as I've said, I seem to be extremely tolerant of
> changes in bike geometry. I've changed stem length without
> noticing any difference in handling "feel."
>
> Even weirder, at least a couple times I've turned stems
> completely around to put the handlebars behind the steering
> axis, to allow kids to reach handlebars on frames that were
> too long for them. (Those were temporary solutions until the
> kids grew.) I briefly test rode those bikes. As I recall, it
> felt a little weird, but it was perfectly rideable.
>

Yeah I get that part (which as you note could have been done
with a shaped bar or a reverse short stem). ISTR there was
a faceplate stem with bars directly above steerer for that
matter.

The part which caught my eye is the severely reduced minor
diameter right smack in the middle of a 20~28cm lever on
both sides with significant cyclic load at the ends. Looked
like a potential failure point but what do I know?

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

On Tuesday, October 18, 2022 at 12:28:41 PM UTC-4, Frank Krygowski wrote:
> On 10/18/2022 8:38 AM, AMuzi wrote:
> > https://pacenticycledesign.com/collections/handlebars
> >
> > Any engineers out there? What am I missing?
> I'm having trouble decoding their advertisement blabbing. So the
> handlebar center is almost on the steering axis? Is that it?

Yes, there are top-view pictures on the website that show the back edge of the handlebar nearly at the center of the steerer tube.

>
> "... 15% less input to effect a 10° directional change at the front
> wheel when compared to a similar 40mm stem ..." isn't a very clear
> explanation. Perhaps they're talking about the motion along the arc
> length of the rider's hand? The hand moves through a 15% smaller
> distance because it's at a smaller radius?

That's the implication. It seems they are claiming there is better leverage as you move the handlebar closer to the steerer tube axis. I was under the impression that applied torque was a function of the total length of the lever, so it really doesn't make that much sense to me. This seems contradicts the fad for wide bars on an MTB - very specifically stated that less effort (albeit more travel) was required to control the steering with a long bar.

I would think that modern CAD tools would have figured out that placing the bar center on the steering axis center gave better handling characteristics and would have suggested longer top tube lengths by now if there was really something to it.

> Got me, and I'm not motivated
> to work out the geometry right now.
>
> But if that were the objective, ISTM you could get the same effect more
> easily by shortening the bars.
>
> BTW, as I've said, I seem to be extremely tolerant of changes in bike
> geometry. I've changed stem length without noticing any difference in
> handling "feel."
>
> Even weirder, at least a couple times I've turned stems completely
> around to put the handlebars behind the steering axis, to allow kids to
> reach handlebars on frames that were too long for them. (Those were
> temporary solutions until the kids grew.) I briefly test rode those
> bikes. As I recall, it felt a little weird, but it was perfectly rideable..
>
> --
> - Frank Krygowski

On Tuesday, October 18, 2022 at 2:22:31 PM UTC-4, AMuzi wrote:
> On 10/18/2022 11:28 AM, Frank Krygowski wrote:
> > On 10/18/2022 8:38 AM, AMuzi wrote:
> >> https://pacenticycledesign.com/collections/handlebars
> >>
> >> Any engineers out there? What am I missing?
> >
> > I'm having trouble decoding their advertisement blabbing. So
> > the handlebar center is almost on the steering axis? Is that
> > it?
> >
> > "... 15% less input to effect a 10° directional change at
> > the front wheel when compared to a similar 40mm stem ..."
> > isn't a very clear explanation. Perhaps they're talking
> > about the motion along the arc length of the rider's hand?
> > The hand moves through a 15% smaller distance because it's
> > at a smaller radius? Got me, and I'm not motivated to work
> > out the geometry right now.
> >
> > But if that were the objective, ISTM you could get the same
> > effect more easily by shortening the bars.
> >
> > BTW, as I've said, I seem to be extremely tolerant of
> > changes in bike geometry. I've changed stem length without
> > noticing any difference in handling "feel."
> >
> > Even weirder, at least a couple times I've turned stems
> > completely around to put the handlebars behind the steering
> > axis, to allow kids to reach handlebars on frames that were
> > too long for them. (Those were temporary solutions until the
> > kids grew.) I briefly test rode those bikes. As I recall, it
> > felt a little weird, but it was perfectly rideable.
> >
> Yeah I get that part (which as you note could have been done
> with a shaped bar or a reverse short stem). ISTR there was
> a faceplate stem with bars directly above steerer for that
> matter.
>
> The part which caught my eye is the severely reduced minor
> diameter right smack in the middle of a 20~28cm lever on
> both sides with significant cyclic load at the ends. Looked
> like a potential failure point but what do I know?

I saw that too, but assumed they would have beefed up that section somehow.

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

On 10/18/2022 1:27 PM, funkma...@hotmail.com wrote:
> On Tuesday, October 18, 2022 at 12:28:41 PM UTC-4, Frank Krygowski wrote:
>> On 10/18/2022 8:38 AM, AMuzi wrote:
>>> https://pacenticycledesign.com/collections/handlebars
>>>
>>> Any engineers out there? What am I missing?
>> I'm having trouble decoding their advertisement blabbing. So the
>> handlebar center is almost on the steering axis? Is that it?
>
> Yes, there are top-view pictures on the website that show the back edge of the handlebar nearly at the center of the steerer tube.
>
>>
>> "... 15% less input to effect a 10° directional change at the front
>> wheel when compared to a similar 40mm stem ..." isn't a very clear
>> explanation. Perhaps they're talking about the motion along the arc
>> length of the rider's hand? The hand moves through a 15% smaller
>> distance because it's at a smaller radius?
>
> That's the implication. It seems they are claiming there is better leverage as you move the handlebar closer to the steerer tube axis. I was under the impression that applied torque was a function of the total length of the lever, so it really doesn't make that much sense to me. This seems contradicts the fad for wide bars on an MTB - very specifically stated that less effort (albeit more travel) was required to control the steering with a long bar.
>
> I would think that modern CAD tools would have figured out that placing the bar center on the steering axis center gave better handling characteristics and would have suggested longer top tube lengths by now if there was really something to it.
>
>> Got me, and I'm not motivated
>> to work out the geometry right now.
>>
>> But if that were the objective, ISTM you could get the same effect more
>> easily by shortening the bars.
>>
>> BTW, as I've said, I seem to be extremely tolerant of changes in bike
>> geometry. I've changed stem length without noticing any difference in
>> handling "feel."
>>
>> Even weirder, at least a couple times I've turned stems completely
>> around to put the handlebars behind the steering axis, to allow kids to
>> reach handlebars on frames that were too long for them. (Those were
>> temporary solutions until the kids grew.) I briefly test rode those
>> bikes. As I recall, it felt a little weird, but it was perfectly rideable.
>>
>> --
>> - Frank Krygowski

I think that idea is wrong, just as angled or curved cranks:

https://images.squarespace-cdn.com/content/560f1941e4b0e75bc493a695/1443833463203-SLTPF4IS4ORWE1EHBG5P/pmp-bicycle-cranks.jpg?content-type=image%2Fjpeg

Behave as if the point of load and the axis of rotation are
along a straight line, no matter the aesthetic. Ditto for
any bar shape- they act as if on a straight line from hands
to steerer center.

My concern was the big dimple in the middle of the handlebar.

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

On Tuesday, October 18, 2022 at 2:49:01 PM UTC-4, AMuzi wrote:
> On 10/18/2022 1:27 PM, funkma...@hotmail.com wrote:
> > On Tuesday, October 18, 2022 at 12:28:41 PM UTC-4, Frank Krygowski wrote:
> >> On 10/18/2022 8:38 AM, AMuzi wrote:
> >>> https://pacenticycledesign.com/collections/handlebars
> >>>
> >>> Any engineers out there? What am I missing?
> >> I'm having trouble decoding their advertisement blabbing. So the
> >> handlebar center is almost on the steering axis? Is that it?
> >
> > Yes, there are top-view pictures on the website that show the back edge of the handlebar nearly at the center of the steerer tube.
> >
> >>
> >> "... 15% less input to effect a 10° directional change at the front
> >> wheel when compared to a similar 40mm stem ..." isn't a very clear
> >> explanation. Perhaps they're talking about the motion along the arc
> >> length of the rider's hand? The hand moves through a 15% smaller
> >> distance because it's at a smaller radius?
> >
> > That's the implication. It seems they are claiming there is better leverage as you move the handlebar closer to the steerer tube axis. I was under the impression that applied torque was a function of the total length of the lever, so it really doesn't make that much sense to me. This seems contradicts the fad for wide bars on an MTB - very specifically stated that less effort (albeit more travel) was required to control the steering with a long bar.
> >
> > I would think that modern CAD tools would have figured out that placing the bar center on the steering axis center gave better handling characteristics and would have suggested longer top tube lengths by now if there was really something to it.
> >
> >> Got me, and I'm not motivated
> >> to work out the geometry right now.
> >>
> >> But if that were the objective, ISTM you could get the same effect more
> >> easily by shortening the bars.
> >>
> >> BTW, as I've said, I seem to be extremely tolerant of changes in bike
> >> geometry. I've changed stem length without noticing any difference in
> >> handling "feel."
> >>
> >> Even weirder, at least a couple times I've turned stems completely
> >> around to put the handlebars behind the steering axis, to allow kids to
> >> reach handlebars on frames that were too long for them. (Those were
> >> temporary solutions until the kids grew.) I briefly test rode those
> >> bikes. As I recall, it felt a little weird, but it was perfectly rideable.
> >>
> >> --
> >> - Frank Krygowski
> I think that idea is wrong, just as angled or curved cranks:
>
> https://images.squarespace-cdn.com/content/560f1941e4b0e75bc493a695/1443833463203-SLTPF4IS4ORWE1EHBG5P/pmp-bicycle-cranks.jpg?content-type=image%2Fjpeg
>
> Behave as if the point of load and the axis of rotation are
> along a straight line, no matter the aesthetic. Ditto for
> any bar shape- they act as if on a straight line from hands
> to steerer center.

That's what I meant, I probably should have written 'vector' of the sections rather than 'function'. And FWIW, that crank design was exactly what I was thinking of (you have one impressive photo collection!). That said, you get a longer 'vector' distance with a longer stem, so shortening that lever distance seems contradictory to the fad for longer bars these days. I'm not a fan of that BTW - I'm a firm believer that bar length should more closely match shoulder width for both road and off-road. The last MTB I bought was a Cannondale Habit 3 which came with 780 mm bars. I went on one ride, then took a hacksaw and cut them down to 580. At least once every group ride I get the question "where did you get those narrow bars?" I answer "my basement".

>
> My concern was the big dimple in the middle of the handlebar.
> --
> Andrew Muzi
> <www.yellowjersey.org/>
> Open every day since 1 April, 1971

On 10/18/2022 3:08 PM, funkma...@hotmail.com wrote:
> On Tuesday, October 18, 2022 at 2:49:01 PM UTC-4, AMuzi wrote:
>> On 10/18/2022 1:27 PM, funkma...@hotmail.com wrote:
>>> On Tuesday, October 18, 2022 at 12:28:41 PM UTC-4, Frank Krygowski wrote:
>>>> On 10/18/2022 8:38 AM, AMuzi wrote:
>>>>> https://pacenticycledesign.com/collections/handlebars
>>>>>
>>>>> Any engineers out there? What am I missing?
>>>> I'm having trouble decoding their advertisement blabbing. So the
>>>> handlebar center is almost on the steering axis? Is that it?
>>>
>>> Yes, there are top-view pictures on the website that show the back edge of the handlebar nearly at the center of the steerer tube.
>>>
>>>>
>>>> "... 15% less input to effect a 10° directional change at the front
>>>> wheel when compared to a similar 40mm stem ..." isn't a very clear
>>>> explanation. Perhaps they're talking about the motion along the arc
>>>> length of the rider's hand? The hand moves through a 15% smaller
>>>> distance because it's at a smaller radius?
>>>
>>> That's the implication. It seems they are claiming there is better leverage as you move the handlebar closer to the steerer tube axis. I was under the impression that applied torque was a function of the total length of the lever, so it really doesn't make that much sense to me. This seems contradicts the fad for wide bars on an MTB - very specifically stated that less effort (albeit more travel) was required to control the steering with a long bar.
>>>
>>> I would think that modern CAD tools would have figured out that placing the bar center on the steering axis center gave better handling characteristics and would have suggested longer top tube lengths by now if there was really something to it.
>>>
>>>> Got me, and I'm not motivated
>>>> to work out the geometry right now.
>>>>
>>>> But if that were the objective, ISTM you could get the same effect more
>>>> easily by shortening the bars.
>>>>
>>>> BTW, as I've said, I seem to be extremely tolerant of changes in bike
>>>> geometry. I've changed stem length without noticing any difference in
>>>> handling "feel."
>>>>
>>>> Even weirder, at least a couple times I've turned stems completely
>>>> around to put the handlebars behind the steering axis, to allow kids to
>>>> reach handlebars on frames that were too long for them. (Those were
>>>> temporary solutions until the kids grew.) I briefly test rode those
>>>> bikes. As I recall, it felt a little weird, but it was perfectly rideable.
>>>>
>>>> --
>>>> - Frank Krygowski
>> I think that idea is wrong, just as angled or curved cranks:
>>
>> https://images.squarespace-cdn.com/content/560f1941e4b0e75bc493a695/1443833463203-SLTPF4IS4ORWE1EHBG5P/pmp-bicycle-cranks.jpg?content-type=image%2Fjpeg
>>
>> Behave as if the point of load and the axis of rotation are
>> along a straight line, no matter the aesthetic. Ditto for
>> any bar shape- they act as if on a straight line from hands
>> to steerer center.
>
> That's what I meant, I probably should have written 'vector' of the sections rather than 'function'. And FWIW, that crank design was exactly what I was thinking of (you have one impressive photo collection!). That said, you get a longer 'vector' distance with a longer stem, so shortening that lever distance seems contradictory to the fad for longer bars these days. I'm not a fan of that BTW - I'm a firm believer that bar length should more closely match shoulder width for both road and off-road. The last MTB I bought was a Cannondale Habit 3 which came with 780 mm bars. I went on one ride, then took a hacksaw and cut them down to 580. At least once every group ride I get the question "where did you get those narrow bars?" I answer "my basement".

When I got my first mountain bike, I think it took me less than a week
to hacksaw the handlebars. In my case, it was because most of my riding
would be in our local forest preserve. The single track paths are dense
with vegetation.

Or perhaps I should say they _were_ dense, before the local White Tailed
Deer population exploded and stripped away most of the undergrowth.

We need more predators. The coyotes aren't doing their job.

--
- Frank Krygowski

On 10/18/2022 2:48 PM, AMuzi wrote:
> On 10/18/2022 1:27 PM, funkma...@hotmail.com wrote:
>> On Tuesday, October 18, 2022 at 12:28:41 PM UTC-4, Frank Krygowski wrote:
>>> On 10/18/2022 8:38 AM, AMuzi wrote:
>>>> https://pacenticycledesign.com/collections/handlebars
>>>>
>>>> Any engineers out there? What am I missing?
>>> I'm having trouble decoding their advertisement blabbing. So the
>>> handlebar center is almost on the steering axis? Is that it?
>>
>> Yes, there are top-view pictures on the website that show the back
>> edge of the handlebar nearly at the center of the steerer tube.
>>
>>>
>>> "... 15% less input to effect a 10° directional change at the front
>>> wheel when compared to a similar 40mm stem ..." isn't a very clear
>>> explanation. Perhaps they're talking about the motion along the arc
>>> length of the rider's hand? The hand moves through a 15% smaller
>>> distance because it's at a smaller radius?
>>
>> That's the implication. It seems they are claiming there is better
>> leverage as you move the handlebar closer to the steerer tube axis. I
>> was under the impression that applied torque was a function of the
>> total length of the lever, so it really doesn't make that much sense
>> to me. This seems contradicts the fad for wide bars on an MTB - very
>> specifically stated that less effort (albeit more travel) was required
>> to control the steering with a long bar.
>>
>> I would think that modern CAD tools would have figured out that
>> placing the bar center on the steering axis center gave better
>> handling characteristics and would have suggested longer top tube
>> lengths by now if there was really something to it.
>>
>>> Got me, and I'm not motivated
>>> to work out the geometry right now.
>>>
>>> But if that were the objective, ISTM you could get the same effect more
>>> easily by shortening the bars.
>>>
>>> BTW, as I've said, I seem to be extremely tolerant of changes in bike
>>> geometry. I've changed stem length without noticing any difference in
>>> handling "feel."
>>>
>>> Even weirder, at least a couple times I've turned stems completely
>>> around to put the handlebars behind the steering axis, to allow kids to
>>> reach handlebars on frames that were too long for them. (Those were
>>> temporary solutions until the kids grew.) I briefly test rode those
>>> bikes. As I recall, it felt a little weird, but it was perfectly
>>> rideable.
>>>
>>> --
>>> - Frank Krygowski
>
> I think that idea is wrong, just as angled or curved cranks:
>
> https://images.squarespace-cdn.com/content/560f1941e4b0e75bc493a695/1443833463203-SLTPF4IS4ORWE1EHBG5P/pmp-bicycle-cranks.jpg?content-type=image%2Fjpeg

Those cranks always astounded me.

> My concern was the big dimple in the middle of the handlebar.

I'm sure that's a stress riser, but stress risers can be accounted for.
As Funk said, a bit more material can add enough strength to make it
fine. If they sell enough of those bars, we'll eventually hear whether
they were strong enough.

--
- Frank Krygowski

funkma...@hotmail.com <funkmasterxx@hotmail.com> wrote:
> On Tuesday, October 18, 2022 at 2:49:01 PM UTC-4, AMuzi wrote:
>> On 10/18/2022 1:27 PM, funkma...@hotmail.com wrote:
>>> On Tuesday, October 18, 2022 at 12:28:41 PM UTC-4, Frank Krygowski wrote:
>>>> On 10/18/2022 8:38 AM, AMuzi wrote:
>>>>> https://pacenticycledesign.com/collections/handlebars
>>>>>
>>>>> Any engineers out there? What am I missing?
>>>> I'm having trouble decoding their advertisement blabbing. So the
>>>> handlebar center is almost on the steering axis? Is that it?
>>>
>>> Yes, there are top-view pictures on the website that show the back edge
>>> of the handlebar nearly at the center of the steerer tube.
>>>
>>>>
>>>> "... 15% less input to effect a 10° directional change at the front
>>>> wheel when compared to a similar 40mm stem ..." isn't a very clear
>>>> explanation. Perhaps they're talking about the motion along the arc
>>>> length of the rider's hand? The hand moves through a 15% smaller
>>>> distance because it's at a smaller radius?
>>>
>>> That's the implication. It seems they are claiming there is better
>>> leverage as you move the handlebar closer to the steerer tube axis. I
>>> was under the impression that applied torque was a function of the
>>> total length of the lever, so it really doesn't make that much sense to
>>> me. This seems contradicts the fad for wide bars on an MTB - very
>>> specifically stated that less effort (albeit more travel) was required
>>> to control the steering with a long bar.
>>>
>>> I would think that modern CAD tools would have figured out that placing
>>> the bar center on the steering axis center gave better handling
>>> characteristics and would have suggested longer top tube lengths by now
>>> if there was really something to it.
>>>
>>>> Got me, and I'm not motivated
>>>> to work out the geometry right now.
>>>>
>>>> But if that were the objective, ISTM you could get the same effect more
>>>> easily by shortening the bars.
>>>>
>>>> BTW, as I've said, I seem to be extremely tolerant of changes in bike
>>>> geometry. I've changed stem length without noticing any difference in
>>>> handling "feel."
>>>>
>>>> Even weirder, at least a couple times I've turned stems completely
>>>> around to put the handlebars behind the steering axis, to allow kids to
>>>> reach handlebars on frames that were too long for them. (Those were
>>>> temporary solutions until the kids grew.) I briefly test rode those
>>>> bikes. As I recall, it felt a little weird, but it was perfectly rideable.
>>>>
>>>> --
>>>> - Frank Krygowski
>> I think that idea is wrong, just as angled or curved cranks:
>>
>> https://images.squarespace-cdn.com/content/560f1941e4b0e75bc493a695/1443833463203-SLTPF4IS4ORWE1EHBG5P/pmp-bicycle-cranks.jpg?content-type=image%2Fjpeg
>>
>>
>> Behave as if the point of load and the axis of rotation are
>> along a straight line, no matter the aesthetic. Ditto for
>> any bar shape- they act as if on a straight line from hands
>> to steerer center.
>
> That's what I meant, I probably should have written 'vector' of the
> sections rather than 'function'. And FWIW, that crank design was exactly
> what I was thinking of (you have one impressive photo collection!). That
> said, you get a longer 'vector' distance with a longer stem, so
> shortening that lever distance seems contradictory to the fad for longer
> bars these days. I'm not a fan of that BTW - I'm a firm believer that bar
> length should more closely match shoulder width for both road and
> off-road. The last MTB I bought was a Cannondale Habit 3 which came with
> 780 mm bars. I went on one ride, then took a hacksaw and cut them down to
> 580. At least once every group ride I get the question "where did you get
> those narrow bars?" I answer "my basement".
>
>>
>> My concern was the big dimple in the middle of the handlebar.
>> --
>> Andrew Muzi
>> <www.yellowjersey.org/>
>> Open every day since 1 April, 1971
>

It’s probably not a big deal for reasonable stem lengths, but there is a
difference in how you steer as the stem gets longer. If stem length is
zero, it’s truly an offset motion (you push one hand forwards and pull the
other one back). However, if you imagine a 20’ long stem, it would act
like a tiller (the whole assembly swings side to side). I haven’t played
with variable stem lengths enough to see if any difference is noticeable,
but there should be a difference.

On Tuesday, October 18, 2022 at 5:38:14 AM UTC-7, AMuzi wrote:
> https://pacenticycledesign.com/collections/handlebars
>
> Any engineers out there? What am I missing?
I am definitely not clear what you're asking. Those ultrashort stems have been used for years on full suspension bikes since the geometry changes drastically and being able to hold the front end straight is more important than modifying the geometry with placing the bar at or near the tire contact point which makes the steering light.

On Tue, 18 Oct 2022 13:48:54 -0500, AMuzi <am@yellowjersey.org> wrote:

(chomp...)
>I think that idea is wrong, just as angled or curved cranks:
>https://images.squarespace-cdn.com/content/560f1941e4b0e75bc493a695/1443833463203-SLTPF4IS4ORWE1EHBG5P/pmp-bicycle-cranks.jpg?content-type=image%2Fjpeg

Agreed. Odd shaped handlebars have the same problem as odd shaped
cranks.

Put a torque gauge on the stem or fork. For a given location of the
handlebar grips:
Torque = rotational_radius * force_applied
For a given location of the handlebar grips, the shape of the
handlebars and the stem offset length have no effect on the force
required to provide the turning torque. The handlebars could be in
the shape of a pretzel, and they would works the same as straight bars
(except for additional springiness). The only thing that matters is
the rotational radius of the handlebar grips about the center of
rotation.

If someone really wanted a customizable torque curve, then the
handlebars would be in the shape of an asymmetric pantograph or other
kinematic nightmare, where the radius of rotation (distance between
center of rotation of the fork/stem and the handlebar grips) changes
as the front wheel turned.

>Behave as if the point of load and the axis of rotation are
>along a straight line, no matter the aesthetic. Ditto for
>any bar shape- they act as if on a straight line from hands
>to steerer center.

Yep. As long as the location of the handlebar grip doesn't change,
the forces involved also don't change.

>My concern was the big dimple in the middle of the handlebar.

That makes the handlebar tube easier to buckle, bend and break by
negating the increased strength of a uniform tubular cross section and
replacing it with what looks like a stress concentrator. It's the
shape I would expect from a tube just before it buckles.

<https://pacenticycledesign.com/pages/p-dent>
"The P-Dent handlebar is specifically designed with a dent that allows
riders to have a shorter stem (20mm) effective length, this could be
reduced to 15mm..."

It seems like the main benefit is that it allows the use of a shorter
stem length. In my never humble opinion, the same effect could be
achieved bending the handlebars so that the grips are in the desired
position.

Patent: Bicycle handlebar, stem, and fork arrangement
<https://patents.google.com/patent/US9764792B2/en>

"Review: Pacenti PDent Handlebar and Stem" (Sep 30, 2015)
<https://www.pinkbike.com/news/pacenti-pdent-handlebar-stem-review-2015.html>

"Pacenti Cycle Design relaunches website, adds products and co-owners"
(Nov 28, 2017)
<https://www.bicycleretailer.com/industry-news/2017/11/28/pacenti-cycle-design-relaunches-website-adds-products-and-co-owners#.Y08LYUzMJaQ>

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

On Tue, 18 Oct 2022 15:55:10 -0400, Frank Krygowski
<frkrygow@sbcglobal.net> wrote:

>We need more predators. The coyotes aren't doing their job.

I offered to help, but since I could only work one night per month,
the authorities declined my offer:
<http://www.learnbydestroying.com/jeffl/pics/jeffl/jeffl-wolf.gif>

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

On Tue, 18 Oct 2022 14:12:35 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

>On Tue, 18 Oct 2022 15:55:10 -0400, Frank Krygowski
><frkrygow@sbcglobal.net> wrote:
>
>>We need more predators. The coyotes aren't doing their job.
>
>I offered to help, but since I could only work one night per month,
>the authorities declined my offer:
><http://www.learnbydestroying.com/jeffl/pics/jeffl/jeffl-wolf.gif>

I've seen one regulary on my last three rides. Cute little devil. A
good sized white tail would tear him to shreds.

On 10/18/2022 2:08 PM, funkma...@hotmail.com wrote:
> On Tuesday, October 18, 2022 at 2:49:01 PM UTC-4, AMuzi wrote:
>> On 10/18/2022 1:27 PM, funkma...@hotmail.com wrote:
>>> On Tuesday, October 18, 2022 at 12:28:41 PM UTC-4, Frank Krygowski wrote:
>>>> On 10/18/2022 8:38 AM, AMuzi wrote:
>>>>> https://pacenticycledesign.com/collections/handlebars
>>>>>
>>>>> Any engineers out there? What am I missing?
>>>> I'm having trouble decoding their advertisement blabbing. So the
>>>> handlebar center is almost on the steering axis? Is that it?
>>>
>>> Yes, there are top-view pictures on the website that show the back edge of the handlebar nearly at the center of the steerer tube.
>>>
>>>>
>>>> "... 15% less input to effect a 10° directional change at the front
>>>> wheel when compared to a similar 40mm stem ..." isn't a very clear
>>>> explanation. Perhaps they're talking about the motion along the arc
>>>> length of the rider's hand? The hand moves through a 15% smaller
>>>> distance because it's at a smaller radius?
>>>
>>> That's the implication. It seems they are claiming there is better leverage as you move the handlebar closer to the steerer tube axis. I was under the impression that applied torque was a function of the total length of the lever, so it really doesn't make that much sense to me. This seems contradicts the fad for wide bars on an MTB - very specifically stated that less effort (albeit more travel) was required to control the steering with a long bar.
>>>
>>> I would think that modern CAD tools would have figured out that placing the bar center on the steering axis center gave better handling characteristics and would have suggested longer top tube lengths by now if there was really something to it.
>>>
>>>> Got me, and I'm not motivated
>>>> to work out the geometry right now.
>>>>
>>>> But if that were the objective, ISTM you could get the same effect more
>>>> easily by shortening the bars.
>>>>
>>>> BTW, as I've said, I seem to be extremely tolerant of changes in bike
>>>> geometry. I've changed stem length without noticing any difference in
>>>> handling "feel."
>>>>
>>>> Even weirder, at least a couple times I've turned stems completely
>>>> around to put the handlebars behind the steering axis, to allow kids to
>>>> reach handlebars on frames that were too long for them. (Those were
>>>> temporary solutions until the kids grew.) I briefly test rode those
>>>> bikes. As I recall, it felt a little weird, but it was perfectly rideable.
>>>>
>>>> --
>>>> - Frank Krygowski
>> I think that idea is wrong, just as angled or curved cranks:
>>
>> https://images.squarespace-cdn.com/content/560f1941e4b0e75bc493a695/1443833463203-SLTPF4IS4ORWE1EHBG5P/pmp-bicycle-cranks.jpg?content-type=image%2Fjpeg
>>
>> Behave as if the point of load and the axis of rotation are
>> along a straight line, no matter the aesthetic. Ditto for
>> any bar shape- they act as if on a straight line from hands
>> to steerer center.
>
> That's what I meant, I probably should have written 'vector' of the sections rather than 'function'. And FWIW, that crank design was exactly what I was thinking of (you have one impressive photo collection!). That said, you get a longer 'vector' distance with a longer stem, so shortening that lever distance seems contradictory to the fad for longer bars these days. I'm not a fan of that BTW - I'm a firm believer that bar length should more closely match shoulder width for both road and off-road. The last MTB I bought was a Cannondale Habit 3 which came with 780 mm bars. I went on one ride, then took a hacksaw and cut them down to 580. At least once every group ride I get the question "where did you get those narrow bars?" I answer "my basement".
>
>>
>> My concern was the big dimple in the middle of the handlebar.

Thanks, and I do have a good photo library, but that's not
mine- Top of a web image search.

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

On Tuesday, October 18, 2022 at 7:49:01 PM UTC+1, AMuzi wrote:
>
> I think that idea is wrong, just as angled or curved cranks:
>
> https://images.squarespace-cdn.com/content/560f1941e4b0e75bc493a695/1443833463203-SLTPF4IS4ORWE1EHBG5P/pmp-bicycle-cranks.jpg?content-type=image%2Fjpeg
>
> Behave as if the point of load and the axis of rotation are
> along a straight line, no matter the aesthetic. Ditto for
> any bar shape- they act as if on a straight line from hands
> to steerer center.
>
> My concern was the big dimple in the middle of the handlebar.
> --
> Andrew Muzi
> <www.yellowjersey.org/>
> Open every day since 1 April, 1971
>
The longer the leverage of the actual bar (not your virtual bar) on the weakened centre of the bar, the greater the chance of a mishap. The obverse of the argument is that the straighter the bar, the shorter the distance from leverage to pivot, so the stronger, the bar until actual and virtual bar coincide. The difference would however be marginal, I think, at bicycle lengths and forces. You should count the stem length twice into the leverage forces. The designer of that handlebar may have reasoned that the closer the handlebar centre is over the head tube centre, the shorter the leverage to the rolling surface point of maximum interface friction, and the less the input force of control/turning friction. I am not so sure I want to swallow that whole -- it seems to me that any kind of practical bicycle steering/suspension geometry involves a hook at the road interface at least the length of the trail. Because rubber is involved, in motorcars the graph of the resulting friction force of a turn is always S shaped; I see no reason why it would be a different graph in bicycles, albeit shallower because of the smaller forces and especially lower heat. I think it possible that we're looking a component in search of a problem to solve, boutique gear rather than cutting edge engineering. In short, you didn't miss anything because it wasn't there to miss. -- AJ
>

On 10/18/2022 4:05 PM, Ralph Barone wrote:
>
> It’s probably not a big deal for reasonable stem lengths, but there is a
> difference in how you steer as the stem gets longer. If stem length is
> zero, it’s truly an offset motion (you push one hand forwards and pull the
> other one back). However, if you imagine a 20’ long stem, it would act
> like a tiller (the whole assembly swings side to side). I haven’t played
> with variable stem lengths enough to see if any difference is noticeable,
> but there should be a difference.

I've wondered about a steering stability effect. Since most cyclists
lean forward on the handlebars, having them forward of the steering axis
probably tends to center the steering when the bars are turned.

But as I said, a bike with a reversed stem is still very rideable.

--
- Frank Krygowski

On 10/18/2022 4:34 PM, Jeff Liebermann wrote:
> On Tue, 18 Oct 2022 13:48:54 -0500, AMuzi <am@yellowjersey.org> wrote:
>
> (chomp...)
>> I think that idea is wrong, just as angled or curved cranks:
>> https://images.squarespace-cdn.com/content/560f1941e4b0e75bc493a695/1443833463203-SLTPF4IS4ORWE1EHBG5P/pmp-bicycle-cranks.jpg?content-type=image%2Fjpeg
>
> Agreed. Odd shaped handlebars have the same problem as odd shaped
> cranks.
>
> Put a torque gauge on the stem or fork. For a given location of the
> handlebar grips:
> Torque = rotational_radius * force_applied
> For a given location of the handlebar grips, the shape of the
> handlebars and the stem offset length have no effect on the force
> required to provide the turning torque. The handlebars could be in
> the shape of a pretzel, and they would works the same as straight bars
> (except for additional springiness). The only thing that matters is
> the rotational radius of the handlebar grips about the center of
> rotation.

It's not clear to me what you mean by "rotational radius." It's not
generally going to be the straight line distance from the grip to the
steering axis.

The relevant distance for computing the torque of a force is the
distance from the axis of rotation (or other relevant axis) when
measured _perpendicular_ to the line of action of the force.

To explain: Imagine a set of handlebars with a 90 degree bend on each
side - so, shaped like this bracket ] - but with the grips' extensions
about a foot back from the transverse part of the bar. Clamp it so the
bar center is on the steering axis.

For a forward force applied to a handgrip, the relevant distance would
_not_ be the distance measured directly from the grip to the steering
axis. For the bars I described, it would be half the width of the
handlebar. That's the distance from the line of action of the force to
the steering axis.

--
- Frank Krygowski

On 10/18/2022 7:56 PM, Frank Krygowski wrote:
> On 10/18/2022 4:34 PM, Jeff Liebermann wrote:
>> On Tue, 18 Oct 2022 13:48:54 -0500, AMuzi <am@yellowjersey.org> wrote:
>>
>> (chomp...)
>>> I think that idea is wrong, just as angled or curved cranks:
>>> https://images.squarespace-cdn.com/content/560f1941e4b0e75bc493a695/1443833463203-SLTPF4IS4ORWE1EHBG5P/pmp-bicycle-cranks.jpg?content-type=image%2Fjpeg
>>
>> Agreed.  Odd shaped handlebars have the same problem as odd shaped
>> cranks.
>>
>> Put a torque gauge on the stem or fork.  For a given location of the
>> handlebar grips:
>>    Torque = rotational_radius * force_applied
>> For a given location of the handlebar grips, the shape of the
>> handlebars and the stem offset length have no effect on the force
>> required to provide the turning torque.  The handlebars could be in
>> the shape of a pretzel, and they would works the same as straight bars
>> (except for additional springiness).  The only thing that matters is
>> the rotational radius of the handlebar grips about the center of
>> rotation.
>
> It's not clear to me what you mean by "rotational radius." It's not
> generally going to be the straight line distance from the grip to the
> steering axis.
>
> The relevant distance for computing the torque of a force is the
> distance from the axis of rotation (or other relevant axis) when
> measured _perpendicular_ to the line of action of the force.
>
> To explain: Imagine a set of handlebars with a 90 degree bend on each
> side - so, shaped like this bracket ]  - but with the grips' extensions
> about a foot back from the transverse part of the bar. Clamp it so the
> bar center is on the steering axis.

Handlebars like this:
https://www.rivbike.com/products/z312ytuylzkj-d3113-l-n-kn
but with zero stem extension.

>
> For a forward force applied to a handgrip, the relevant distance would
> _not_ be the distance measured directly from the grip to the steering
> axis. For the bars I described, it would be half the width of the
> handlebar. That's the distance from the line of action of the force to
> the steering axis.
>

--
- Frank Krygowski

On Tue, 18 Oct 2022 19:36:08 -0400, Frank Krygowski
<frkrygow@sbcglobal.net> wrote:

>On 10/18/2022 4:05 PM, Ralph Barone wrote:
>>
>> It’s probably not a big deal for reasonable stem lengths, but there is a
>> difference in how you steer as the stem gets longer. If stem length is
>> zero, it’s truly an offset motion (you push one hand forwards and pull the
>> other one back). However, if you imagine a 20’ long stem, it would act
>> like a tiller (the whole assembly swings side to side). I haven’t played
>> with variable stem lengths enough to see if any difference is noticeable,
>> but there should be a difference.
>
>I've wondered about a steering stability effect. Since most cyclists
>lean forward on the handlebars, having them forward of the steering axis
>probably tends to center the steering when the bars are turned.
>
>But as I said, a bike with a reversed stem is still very rideable.

Well, the distance the hands have to move is dependent on the width of
the handle bars and the length of the "gooseneck" this shorter bars or
gooseneck make for "quicker" steering regardless of whether the bars
are in front or behind the center line of the fork pivot. In either
case you push on the right bar to steer left (:-)
--
Cheers,

John B.

On Tuesday, October 18, 2022 at 3:58:06 PM UTC-7, Andre Jute wrote:
> On Tuesday, October 18, 2022 at 7:49:01 PM UTC+1, AMuzi wrote:
> >
> > I think that idea is wrong, just as angled or curved cranks:
> >
> > https://images.squarespace-cdn.com/content/560f1941e4b0e75bc493a695/1443833463203-SLTPF4IS4ORWE1EHBG5P/pmp-bicycle-cranks.jpg?content-type=image%2Fjpeg
> >
> > Behave as if the point of load and the axis of rotation are
> > along a straight line, no matter the aesthetic. Ditto for
> > any bar shape- they act as if on a straight line from hands
> > to steerer center.
> >
> > My concern was the big dimple in the middle of the handlebar.
> > --
> > Andrew Muzi
> > <www.yellowjersey.org/>
> > Open every day since 1 April, 1971
> >
> The longer the leverage of the actual bar (not your virtual bar) on the weakened centre of the bar, the greater the chance of a mishap. The obverse of the argument is that the straighter the bar, the shorter the distance from leverage to pivot, so the stronger, the bar until actual and virtual bar coincide. The difference would however be marginal, I think, at bicycle lengths and forces. You should count the stem length twice into the leverage forces. The designer of that handlebar may have reasoned that the closer the handlebar centre is over the head tube centre, the shorter the leverage to the rolling surface point of maximum interface friction, and the less the input force of control/turning friction. I am not so sure I want to swallow that whole -- it seems to me that any kind of practical bicycle steering/suspension geometry involves a hook at the road interface at least the length of the trail. Because rubber is involved, in motorcars the graph of the resulting friction force of a turn is always S shaped; I see no reason why it would be a different graph in bicycles, albeit shallower because of the smaller forces and especially lower heat. I think it possible that we're looking a component in search of a problem to solve, boutique gear rather than cutting edge engineering. In short, you didn't miss anything because it wasn't there to miss. -- AJ
> >
Those stubby stems are for full suspension MTB's. Since there is no "geometry" as such. you want a lever to hold the fork in the direction you want to go. On a road bike, on a properly fitting stem and bar - the idea is to put the bar in the spot that requires the least amount of pressure to steer. Road bike geometries are more or less fixed discounting changes from tires and flexing in the frame and fork,

But I don't know what Andrew wanted to know since surely he already knows all of that.

Frank Krygowski <frkrygow@sbcglobal.net> wrote:
> On 10/18/2022 4:05 PM, Ralph Barone wrote:
>>
>> It’s probably not a big deal for reasonable stem lengths, but there is a
>> difference in how you steer as the stem gets longer. If stem length is
>> zero, it’s truly an offset motion (you push one hand forwards and pull the
>> other one back). However, if you imagine a 20’ long stem, it would act
>> like a tiller (the whole assembly swings side to side). I haven’t played
>> with variable stem lengths enough to see if any difference is noticeable,
>> but there should be a difference.
>
> I've wondered about a steering stability effect. Since most cyclists
> lean forward on the handlebars, having them forward of the steering axis
> probably tends to center the steering when the bars are turned.
>
> But as I said, a bike with a reversed stem is still very rideable.
>

With a long stem, forward force on the bars will result in self-centering
of the steering. Also, a sideways force on the bars will result in the
bike steering away from the force (pushing the left side of the rider
should result in the bike steering to the left and back underneath the
rider). Again, this is probably a subtle effect, but it should be
measurable.

On Tue, 18 Oct 2022 13:22:23 -0500, AMuzi <am@yellowjersey.org> wrote:

>On 10/18/2022 11:28 AM, Frank Krygowski wrote:
>> On 10/18/2022 8:38 AM, AMuzi wrote:
>>> https://pacenticycledesign.com/collections/handlebars
>>>
>>> Any engineers out there? What am I missing?
>>
>> I'm having trouble decoding their advertisement blabbing. So
>> the handlebar center is almost on the steering axis? Is that
>> it?
>>
>> "... 15% less input to effect a 10° directional change at
>> the front wheel when compared to a similar 40mm stem ..."
>> isn't a very clear explanation. Perhaps they're talking
>> about the motion along the arc length of the rider's hand?
>> The hand moves through a 15% smaller distance because it's
>> at a smaller radius? Got me, and I'm not motivated to work
>> out the geometry right now.
>>
>> But if that were the objective, ISTM you could get the same
>> effect more easily by shortening the bars.
>>
>> BTW, as I've said, I seem to be extremely tolerant of
>> changes in bike geometry. I've changed stem length without
>> noticing any difference in handling "feel."
>>
>> Even weirder, at least a couple times I've turned stems
>> completely around to put the handlebars behind the steering
>> axis, to allow kids to reach handlebars on frames that were
>> too long for them. (Those were temporary solutions until the
>> kids grew.) I briefly test rode those bikes. As I recall, it
>> felt a little weird, but it was perfectly rideable.
>>
>
>Yeah I get that part (which as you note could have been done
>with a shaped bar or a reverse short stem). ISTR there was
>a faceplate stem with bars directly above steerer for that
>matter.
>
>The part which caught my eye is the severely reduced minor
>diameter right smack in the middle of a 20~28cm lever on
>both sides with significant cyclic load at the ends. Looked
>like a potential failure point but what do I know?

The only thing signifiant here, is the relationship of the grips to
the headset. One could duplicate the effect of that $200+ nonsense
with a $25 handlebar from Walmart and some serious bending.