Trek CarBack Radar Rear Bike Light

Looking for USB-C, longer battery life, nice if it would be smaller and even more accurate. The basics I guess.

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Would maybe get me off the fence

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USB-C would be nice, its on the more expensive Varia camera version.

FWIW I’ve been using my gen1 (rtl500) and gen3 (rtl515) Varia 4-5 times a week since 2016. A little more in 2016-2017 because I was doing 2-a-days. A little less during 2018-2019.

Never once did I think “wish it was more accurate” - never ever. Works great. The gen3 is more sensitive versus the gen1, for example I can walk behind it in the garage and that will generate an alert. However on the road the gen1 and gen3 have been great, no complaints about accuracy or range.

Battery life on the gen1 was ok, bought it in 2016 and did a double century in 2017. Back then I was able to get ~8 hours out of the gen1 unit, which was fine for century rides. The lights were dim on the older units, so I disabled the lights and used a separate rear light (Flare RT). For the double I used an Anker lipstick battery to charge my phone and Garmin 520 and Varia 500. In 2022 I gave the gen1 to a forum member, battery was still good for 3-4 hour rides.

Battery life on the gen3 has been great, no battery alerts on long 6-8 hour century rides. After 2 years the battery still shows as New on bike computer, and opening FIT file its still reaching a very high voltage at the start of ride the next day or two.

I’ve always come home, let Garmin bike computer turn off the radar (put it in standby mode), charge it fully, and then take it off the charger.

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Mentioned earlier in the thread, but on the EC Geek Warning podcast Dave Rome made the point that Garmin in general has really low margins for retailers. So the point of the CarBack is probably not to compete with Varia on performance or consumer price, but to give Trek stores and other retailers an option to sell that puts more money in their pockets.

Radar is something you want to work right every single time, so I see absolutely no reason to buy this thing.

For me to upgrade my aging Varia I would want USB-C and, ideally, better battery life.

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Yep. I will upgrade for longer battery life, usb-c, and if they make the camera version higher quality and long battery life I would go with that so I can record close passes etc.

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Yes, a good camera would be an absolute game changer and probably sell a new unit to many, many, current Varia owners.

I know lots of people complain that Garmin stuff isn’t USB-C, but can someone tell me why? I know it’s slightly easier to insert (because you don’t have to join up the angles), but is there another reason? No way I would spend an extra $100 to replace something I already own that is nearly perfect just for that little change.

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Most of my stuff is usb c now so it would be one less cable. Sure I won’t upgrade if that is literally the only difference but I would be rather upset if they came out with a new unit and it didn’t have type c.

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It isn’t?

The newest Varia (2022) is the one with a camera, the 715, it is usb-c. The older Varia 515 was released in 2020 and not.

My 840 (2023) is usb-c, as is the 540 (2023) and 1040 (2022).

Do you see a pattern?

Yes. The pattern is that the new stuff is usb-c. The complaint is that the old stuff isn’t. People raise it constantly, including above.

it seems USB-C is on Varia or Garmin Edge stuff released 2022 or later. Thats why peeps want Garmin to release a Varia 515 upgrade.

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I don’t care about usb-c, and I went out today with my 4 year old varia at half charge, and did a 5:30 minute ride and it was running until the end.

Now a more usable camera (and associated software) would have me considering an upgrade.

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What are you using to open the FIT file and which column has that data? I tried checking one of my files for that info and didn’t see it there. Perhaps it was the viewer I used or perhaps Wahoo doesn’t record that data field.

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Read this post Trek CarBack Radar Rear Bike Light - #35 by WindWarrior and let me know if you have questions

It turns out that’s the same website I had already tried. But my FIT file lists “Battery Status” and all it says is “Good” instead of giving any voltages. There’s also a “battery SOC” field but that has no data for the radar, only the Wahoo and Di2.

Maybe it’s a RTL510 vs RTL515 difference or maybe it’s Garmin vs Wahoo.

Maybe its a Wahoo thing. Not that its likely to help, but you could try toggling to Developer Mode (upper right).

Here is an old one from 8 years ago, an RTL500 Varia (gen1) and recorded on Garmin 520 bike computer

about 1.5 months after buying mine in March 2016. Device index 6 is the radar, started at 4.11 volts (“new”) and ended at 3.89 volts (“new”).

Must be Garmin vs Wahoo. This is what I get in developer mode.

Yes, it appears the radar started “good” (battery status = 2). Those IQ fields appear to be data that Wahoo added to the fit file, and perhaps related to your Assioma power pedals.

Anything in this message?

device index 4 is my Rally 200 power pedals, and device index 6 is SRAM shifting.

You might try putting fitfileviewer back in User Mode and opening messages and inspecting the header column names. Long shot.

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I prefer USB-C because it’s more fool proof with cable orientation not mattering, and it feels less like you’ll damage the connector. I know DCRainmaker mentioned about having damaged a mini-USB to the point it didn’t work before.

Also, given the current Varian is 3 years (or is it 4?) since release, and they previously released a new model every 2 years, it seems an update shouldn’t be far away (provided they have things that they could update).

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Maybe older, I got mine in a Black Friday sale pre the 1st lockdown and think it had been out for a while.

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