It needs to ‘see’ the objects to measure their speed. Sitting at the front of a paceline isn’t going to work out well. You might get some reports on things coming up, but it could also be someone in the paceline.
I had a v1, and it would false on other riders occasionally. I got to the point where I would be near or at the end, and it worked the best at the end. Other head units can share the connection to the varia also which helps distribute the functionality, but yeah, it should be at the end of the line.
On falsing: The v2 didn’t false as much as the v1. I don’t know if that was fixed by firmware or was an issue with the v1. Other riders would ‘test’ the alert by speeding up on me, I swear. Hah hah, let’s make this a screaming joke (though had to admit, hearing the alerts did get old on some roads). But the biggest thing that I like about the varia is what someone upstream said: Not getting surprised anymore AND I had a guy in a huge pickup truck stalk me only to tell me the light was ‘really bright’. Scared the hell out of me to compliment me on the brightness of my light? Thanks, but you nearly had me filling my bibs. (Hint: It’s MEANT to be noticeable )
Yup, a bike rider closing at a quick enough rate difference is a possible trigger and proper result AFAIC. I don’t know the rate difference of the trigger, but slow approaching riders are not alerts while ones with some faster rate are.
I have never had a rider in the paceline set off my Varia…the speed differential isn’t high enough to trigger it IME.
The biggest issue when riding in a group is the reduced distance to receiving alerts…but it is still pretty far back when you do get the alerts, just not as much as when riding solo.
Can confirm from the weekend. A guy on a TT bike did it to me.
Additionally, I’ve also had it where a car has caught me up, and not been able to overtake and has sat at the exact same distance/speed behind me and not flagged a subsequent ping until it accelerated past me.
Yup, if a faster vehicle slows to a comparable speed, it will ‘disappear’ until a point that it accelerates up to that trigger delta speed again. This is another reason I prefer pairing my Varia with a helmet mounted mirror.
I was the first rider in the group I tried hard not to be dropped by, and they quickly thought it was a joke. Yes, if I was buried in the group (sometimes as many as a dozen riders) it didn’t work, which I knew was going to happen) but it also did what it was designed to do: detect motion from an object that returns enough signal, and the change in that signal to my current pace was higher than the limit programmed in to it. Yeah it falsed on riders. It also falsed on a few surprising things, and at intersections, depending on the angle to the road, would false on traffic crossing behind us as it had a ‘speed’ and apparent mass to fit the criteria.
But it also picked up multiple hits, and tracked them. It had a tendency to ‘ghost’ hits as they slowed down, preparing to pass us. Once their speed increased, they popped up again.
There are several, to my knowledge, that did buy varia units a few years after I quit riding with them, after many swore it was junk and would never want one, ever.
It completely depends on the return signal strength, and aspect ratio from the ‘hit’ to the varia. IF it has enough of a clear view (signal), it will ‘see’ the hit, and alert if it meets the criteria, but it will most certainly NOT ‘see’ through humans, or trees, etc. I use mine on a rail trail that has optional portions that involve riding on and paralleling roads, and it will pick up hits that are parallel to my direction of travel because it can ‘see’ them. It’s not annoying, to me, because I know what it’s doing, but I can see where it could be to others. (I do believe that the earlier varia firmware did false more. It does seem to be more discriminating especially in the v2, it’s gotten better)
My biggest concern was that the varia and other ‘radar’ units would instill a false sense of security in some riders. (Emergency rooms saw an increase in skiing related injuries (and deaths) after helmet use was required. People that would never ski under the lift thought they were ‘safe/safer’ to try it after strapping an insulated cup on their heads. (Stupid human tricks)) I don’t have any info to back up that opinion, but I’m sure it is happening. There are roads around here I’m not comfortable having my bike on the back of my car, and yet I see people occasionally riding them. Alerting isn’t physically avoiding. If they are going to hit you, they will hit you, but if you have a device that will warn you of their approach, at least you could potentially avoid them. It shouldn’t mean that a rider can ride the worst road in their area and feel safe.
As far as radar, in private pilot ground school, they spent a couple days going over what the different radar is, how they work, what they see, and how to interpret what you are being shown. It was fascinating. It’s made me way more aware of what they show of severe weather and why they can seem to be so inaccurate. (I would recommend ground school to anyone, and especially people that are afraid of flying)
Ive had it occasionally but cars mostly stay visible on the screen. I cant say for certain but, I think maybe when a driver drops way back on a bend and does not close again. I don’t think Garmin cancels the alert from a driver that approaches to within a distance and sits at the same speed as me. Ray’s review suggests it doesn’t cancel an alert either until a car has passed.
I think you’re right, it is bend related. But thinking about it, it doesn’t have to be “way back”, as long as its going the same speed as you are then it wont register until there is a differential. I’ve had it with a car relatively close and tight bends
FWIW I bought the gen1 in early 2017 or late 2016. And then upgraded to gen2 within the last 2 years or so. Long time user and I mostly trained outside except in 2018 and 2019.
Yes. Both the gen1 (RTL500) and gen2 (RTL515). It has always worked that way. While I can still easily see and read my Garmin computer, helmet mirrors don’t work for me. So I turn my head and look over shoulder.
In the garage, after a ride, walking behind my bike, my gen2 will generate an alert. That never happened with my gen1. Picking up my bike and spinning it around will generate an alert with my gen2. My gen2 is more sensitive.
Rarely, if ever on my gen1. On the other hand, the gen2 will detect riders coming up behind me, reliably and almost always even when the speed gap is narrow. For example in a paceline if a rider exits the paceline and slowly rolls to the front, I’ll get an alert. Reliably.
Personally I wouldn’t call that a false. It is a radar and objects are moving behind you, so it alerts you.
IMHO a false is when the radar gives an alert, and no objects are moving behind you. That happens to me in 1 very specific location at the edge of town, with both the gen1 and gen2, so something is going on with the house at that location or something reflecting the signal (mailbox?).
Thinking back on it all, I actually do remember it falsing on other riders more than the v1. That was why I usually tended to drift to the back and stayed there mostly. I got incredibly ripped by one of the more aggressive riders about sandbagging, and that and other issues, I dropped out. I could handle some drama, but good grief, they either complained about the varia alerts, or complained about me covering their butts at the back, but I couldn’t seem to please some of them so BYE!! (Like a bunch of 3 year-olds… On mirrors, I used to ride with the mirror that stuck on the side of the helmet, but lost it once and just never thought the money spent was really worth it. Looking around through it with glasses on plus sweat wasn’t exactly easy.
Common scenario while in the city… a car approaches and radar alerts, an intersection is ahead and the car slows to match my speed (20-25mph), being courteous as they intend to turn right and don’t want to pass and turn in front of me, after a few seconds (3-sec? 5-sec?) they disappear from the radar but I know they are still behind me.
Another one that happens a lot - I live near old town, and one of the main roads leaving my neighborhood is very narrow for cars:
bikes take the full lane for a solid 30-60 seconds. Cars w/o bikes on the road are doing 20-25mph, and I’m doing 20-25mph. Most cars shadow me, the cars disappear from my radar.
Scared the hell out of me to compliment me on the brightness of my light? Thanks, but you nearly had me filling my bibs. (Hint: It’s MEANT to be noticeable 
)
(Stupid human tricks)) I don’t have any info to back up that opinion, but I’m sure it is happening. There are roads around here I’m not comfortable having my bike on the back of my car, and yet I see people occasionally riding them. Alerting isn’t physically avoiding. If they are going to hit you, they will hit you, but if you have a device that will warn you of their approach, at least you could potentially avoid them. It shouldn’t mean that a rider can ride the worst road in their area and feel safe.
On mirrors, I used to ride with the mirror that stuck on the side of the helmet, but lost it once and just never thought the money spent was really worth it. Looking around through it with glasses on plus sweat wasn’t exactly easy. 
