SoSmellyAir

I definitely see your point about too many warnings being worse than no warning at all. While a Varia (or another rear-facing radar) cannot predict which (if any) approaching object will collide with me, I still find it invaluable for the times I have to cross traffic lanes to turn left or leave the bike lane temporarily to avoid obstructions.

PromptCritical 

Yes, I totally agree with that. There is one ride that I do weekly, where that will be invaluable, and likely other similar situations.

I'll have to play with it to see what works best.

Atlas Shrugged

Please note that I'm not trying to change your opinion (as if that was an option). However, for those who are curious about bike radars, I'd like to share some information. In an urban area, the notification alarm is turned off, but it still appears on your bike computer. This feature is helpful when you have to deviate from your path due to obstacles. It's much more reliable than relying on a quick shoulder check or using your hearing. In addition, when you hear a truck or other vehicle approaching, it's natural to move slightly to the right if it's safe. The display shows if there are multiple vehicles behind the truck. Most people who use a radar find it helpful, and only a very few outliers regret purchasing one. This validation speaks for itself. There is a theme among a very vocal minority of BF members that anything new is unnecessary. However, in this case, a very useful tool is being missed.

SoSmellyAir

Prior to getting the Varia, I wasted too much time studying maps to plot routes to avoid left turns.

FBinNY 

It is an option. Changing minds, or at least, providing info and broadening the knowledge base on which people form opinions is what forums are about.

So, I'm not trying to convince anyone to use or not use new tech. However, I'm not as sold as many others are. Part of that is because use of tech leads to reliance on tech, so it can become zero sum.

I agree with your point about left turns and lane changes, which I also could use help from time to time. OTOH, I don't know if and how much I'd rely on that info vs. trying to be an owl. I also don't know if the quality of the info is good enough to bet my life on.

All in all, I'm not arguing against tech, just giving my personal perspective and reminding folks to think before deciding.
‐‐-------------
Side story below, read only if you care.

Besides bicycling I engage in various "dangerous" activities, one of which is SCUBA diving. When I started we had to manually track depth and time, then use tables to manage dives.
Then, dive computers thad did that for you became popular, allowing much better dive management. The expectation was that better management would reduce dive accidents. The opposite happened, and the rate of decompression went up instead. It turns out that working somewhat blind made divers err to the side of caution. With a dive computer, divers felt empowered to work closer to line.

Koyote

I've not read the whole thread, so perhaps this was already answered by others...But I'll chime in, since you've described my use-case. I ride mostly on quiet rural roads, usually very quiet gravel roads, with little traffic. I have poor hearing, and there is a near-constant wind around here, and also usually the sound of my tires crushing the gravel -- all of which means that I might not hear an approaching car until it's nearly on me. For this riding, I find the Varia very useful. If I'm riding a rough road and find the best (smoothest) line in the center, or even on the left side, it feels much safer to have an alert when a vehicle approaches from the rear.

To address your concerns over the audibility of the beeping sound, I will mention that the visual display on my Edge 1040, which is on an out-front mount and so in my sight line, almost always catches my attention.

When I ride my commuter bike through town, I find the Varia far less useful -- to the point that I rarely use it. There will always be cars approaching, so I always ride all the way to the right and assume there are approaching vehicles. The Varia might offer a bit of benefit by virtue of its flashing pattern, which changes (for max visibility) as a vehicle approaches, but since I typically run two tail lights (one solid, one flashing) I'm not too worried about it.

Koyote

Please provide a link, as I've never heard of this and an internet search turns up nothing.

Troul 

the sudden alert of the tail light flashing in itself is worth it imo. The radar adds on top of it. A single rear facing light in solid or flashing might be enough for some, but for my areas of riding you should have one steady on 200+ lumens tail light & a flash upon close range distance 200+ lumens tail light. it'll have a better chance in "waking up" a driver.
I will say this, if* you don't see me as you approach, you either are having a medical issue, intoxicated, or are deliberate in your attempt in checking off a vindictive box.

PeteHski

A bike radar is one of those tech products that you really need to try for yourself before making up your mind either way. I was curious enough to purchase a Varia RTL515 a couple of years ago and now wouldn’t want to ride without it. That doesn’t mean I am dependent on it. It just means that I find the info it provides very useful and it is also a very effective rear light.

They have become very popular over the last few years for good reason and I haven’t come across anyone in real life who has regretted buying one. But this is BF, so I’m fully expecting someone to hate their Varia😂

PromptCritical 

So, we just finished a 20 mile ride and the Varia significantly improved my awareness. It let me know when a car was approaching so I could check my mirror.

It was also very helpful in seeing vehicles approaching on the right when they are exiting the freeway.

The app is a little kludgy and doesn’t give any indication of lateral position. Does anyone with more experience know if there is setting that will show lateral position?

Update:

We just finished a 52 mile ride, and the Varia lasted 7 hours (I left it on during lunch). On the way home, the traffic was much heavier and the alerts became almost constant, rendering it much less useful.

The lack of lane advice is disappointing, so I'm going to try the Trek CarBack. The advertising for that clearly states it give lane information. Will have to see how accurate it is.

SoSmellyAir

The Varia detects and track vehicles based on closing speed. It cannot distinguish which lane an approaching vehicle is in; no rear facing bike radar in the market can. Implementing this additional capability would require either (a) the radar to sweep back and forth and a processor to calculate the resulting differences in the Doppler shifts or (b) adding a rear facing camera and a processor to correlate the respective data stream from the radar and the camera.

PromptCritical 

The advertising for the Trek Carback expicitly states it can discern which lane the car is in. See minute 1:58 in this video. https://www.trekbikes.com/us/en_US/carback/

Not that I believe much advertising, but a false claim like this would be a huge issue for Trek.

Steve B.

UPS does the same

SoSmellyAir

I had heard that Trek has recently released a rear-facing radar but this is the first time I have seen any details. The audio says that the radar can tell whether the car is your lane or has moved over, and the visual of the app shows the car is in the next lane even though the car is only straddling the center lane in the video. I wonder if it can detect the lateral position if there are multiple vehicles approaching side-by-side.

howaboutme

Check the GPLama youtube channel. He has a thorough review of Trek, Garmin and Bryton together. The lane feature is only on the app, which means you have to use it w/ your phone.

PeteHski

You might find this review video useful. He mentions the lateral lane detection on the Trek, but he didn’t think it was effective and that feature only works with the phone app, not cycle computers.

SoSmellyAir

I am still curious how the Trek CarBack accomplishes the lane or lateral position feature. One can imagine the consequences of getting this wrong.

PromptCritical 

Great video - thanks!

Sounds like the CarBack is bit disappointing. I'll stick with the Varia for now.

PeteHski

Yeah, the CarBack doesn’t appear to offer any real world advantages over the similarly priced Varia. despite claims of longer detection range and lane position. The Varia seems more sorted, which is not surprising since it’s now a 3rd gen product. I expect the CarBack will probably improve with updates. In practice they both appear to work almost identically when paired with a Garmin computer.

tomato coupe

Garmin or Avidyne avionics?

PromptCritical 

Avidyne

Troul 

Soon enough we'll be roped into an agency paid by taxes that monitors pov ground transportation... ATC... Automotive Traffic Control

I don't foresee a free future anytime soon...

PromptCritical 

Yep, that's when my '69 Alfa Romeo becomes my daily driver. Pretty tough to monitor a car with no electronics.

13ollocks

I found this one on Amazon: angled for a 73 degree STA and mounts the Varia low enough to clear the saddle bag but above the rear wheel.

13ollocks

I think the Varia is great for as far as it goes, but it's not infallible. There's the lane issue, there's cars disappearing off radar when they track your speed, and, in my experience, there are the albeit-rare instances where the radar simply fails to register a car even when it's plainly visible in the rear-view. I think radar in its current form powerfully augments, but doesn't replace, a rear-view mirror and/or a look behind before you maneuver.