The Garmin Varia RTL515 combines a radar and a rear light. The light is
bright, while the radar gives you an effective early warning for
'objects' overtaking. Both work well, and made me feel safer on the
road, but the price is premium.

When the Garmin detects something, it'll give you a distinct multi-tone
sound that is loud enough to hear over any wind noise.

The radar doesn't know what is coming up behind you. It just knows that
there is something that is going faster than you, closing the distance,
and will have to get around you if it is continuing at the same speed.

The radar also attempts to tell you how fast the overtake is going to
be, by changing the colour in the sidebar of whatever you've paired the
radar with from amber to red.

Also, the radar can't tell you how dangerous the overtake is going to
be, as that depends on the conditions and how close the pass will be –
all things the radar can't predict. In other words, it just tells you
something's coming up behind; it's not going to stop a crash – you still
need to keep your wits about you.

What's also useful is that in this situation you can mute the sound from
your chosen head unit.

The RTL515 connects over Bluetooth and Ant+. You can pair it with your
Garmin head unit or watch of choice, but also a Wahoo Elemnt, Hammerhead
Karoo or Stages head unit. There's a phone app, and thanks to the
Bluetooth connectivity, third party apps can connect too – RideWithGPS,
for example. You can also buy a separate dedicated head unit (link is
external) for £44.99 if you prefer riding without a phone or GPS unit,
but you do want radar.

Obviously not visible to you, the flash pattern changes when a
vehicle/object approaches, to try to make you even more visible.

Charging is via the Micro USB port on the back of the light; it'd be
nice to see USB-C here, but as the form factor is exactly the same as
the previous version, I can sort of see why it isn't.

There are plenty of other mounts available from Garmin and third parties
for attaching it to your saddle, saddle bag, child seat and so on.

Value

Okay, £169.99 is a lot of money, and that is assuming you already have a
head unit or phone to pair it with.

Although at £169.99 it's expensive, it's not as costly as being hit from
behind. It's up to you whether you want to spend your hard-earned on
making that less likely.

Verdict

Reliable alert system for being overtaken, with a very good rear light.

<https://road.cc/content/review/garmin-varia-rtl515-291455>

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Spike