I now have the brightest taillight in our riding group, though I'd like to set it lower and then brighten or flash when the radar is triggered (and maybe I haven't found that setting). The radar function works really well and integrates with my Garmin 1040 perfectly. You get an audible notification from the Garmin then a dot (or dots for multiple cars) that rises up the side of the display signifying as the car approaches. When paired, the taillight powers on and off automatically with the Garmin. There are frequent "false positives", but they are easily discernable as the cars don't advance. And I am OK with that and don't callout to the group until the car advances halfway up the screen (30-50 yards) when its more actionable and I pretty certain that its not a false positive. Of course, sometimes a car pulls off once it's been detected. Battery life is good, seemingly lasting 15+ hours on my setting. I'm in a habit, however, to charge when I charge my Garmin. A little bulkier than the Garmin Vario but much, much brighter and much cheaper.
Have owned multiple 'generations' of the Varia Radars and this 515 is the best radar unit on the market. This is my third purchase of this model, one for myself, one for my son-in-law, and this one for my grandson. HE lives in the country where it's easiest for cars/trucks/motorcycles to sneak up on a cyclist. It was the final way to get my daughters (his moms') approval to ride the roads.
The only two downsides are the low volume of the warning 'beep' and the old-style mini USB charge port. While the cable is provided with the unit, it's slightly annoying to have to switch to this antique tech to recharge. As for the beep, it's easily drowned out by wind, so regular 'glances' to the computer need to become part of your awareness. FWIW we all use it with a variation of the 8XX series of Garmin computers, so the volume is an issue with them.
Still... a five star purchase.
I feel a lot safer riding with this unit. The only time it doesn't pick up traffic behind me is when I'm riding on a bike path separated from the the road by large concrete barriers (it will still pick up taller vehicles in those conditions). It will still pick up traffic several lanes over on the same separated bike path, so I'm not sure how wide of a view the radar has, but it picks up everything. I like the alerts it gives me on my Garmin computer (I haven't tried it with a phone or other GPS brands).
I thought after pressing the buy button that this was one of those silly clever, but useless tech purchases that would end up in my dustbin of gadgets. However, In conjunction with my ELEMNT Roam 3, it provides me with a measure of safety I just didn't expect. The TRACKR not only alerts you of oncoming vehicles, it tells you how many, how close, and when the coast is clear. I wasn't sure how the brake light aspect worked until I was behind another TRACKR user and darned if that didn't work too! Safety is priceless, but at $249 the TRACKR is a bargain.
