If a Varia could determine left-right "anticpated hit" instead of just closing distance I'd be down for using it. Maybe in a TT with TT helmet it would help since you don't want to drift into traffic as someone is coming. Road with road helmet, I can hear cars and hold my line. I'd be more interested in knowing the car will miss left, or if it presents an immediate strike danger.

I used it for Alaskaman in 2017
It was great, not much shoulder on those roads so I took a generous chuck of the road until my radar beeped. I have not used it in an IM, no idea if it’s legal.

I am not sure this would work well. I have had it on during some group rides and people behind you can set it off. If it was a sparse race or you were in the front and not around others, maybe it would work.

A draft pack would probably set it off.
Otherwise, the only times a single rider has set it off meant there was a considerable closing speed.

I haven't seen a rule against it, though for WTC races it feels like it could violate the spirit of the no mirrors rule. For that reason (and the small aero penalty) I haven't raced with mine.

In my last race, I was passed at close range by a pickup while descending at 40 mph. Really hard to hear them coming at that speed. If racing a similar course again, I would seriously consider using the radar.

I use a taillight on all open road courses. But if I had a varia I might use too

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http://www.TriScottsdale.org

I use mine every time I ride. Kind of like di2, you don't think you need it till you try it.

+1

They are brilliant.

I’ve never raced with mine, but the device itself is phenomenal. If I was on a course with close and fast traffic, I would use it, no-brainer. It sees cars and ignores riders almost perfectly.