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Varia RTL511 messes up distance on Edge 510

I've been using my Edge 510 for many years, and on my current bike I have used three devices connected to it (heart rate strap, power meter and speed sensor on the rear hub). This has worked flawlessly, except that the Edge 510 needs to be reformatted once in a while (I think it just corrupts the file system).

For the last handful of rides, I also added a Varia RTL511 to the mix, and it has worked quite well, however something very odd is happening:

After the radar was added, the Edge consistently under-reports the distance. And it's quite bad, for one of my standard routes that is around 48 km long, the Edge reports just 46 km with the radar attached. If I upload to Strava, I have to click the button to have them re-calculate the distance, or else my stats are messed up (average speed, for instance).

Has anyone heard of this before? Could the radar be messing with the speed sensor somehow? I haven't yet tried moving the speed sensor to the front wheel, but I will do that.

0 aweatherall over 4 years ago

Can you post the FIT activity file for this ride?

0 fallingrock over 4 years ago

I would venture to guess that something else changed ... the radar should NOT effect distance calculations at all.

Additionally, you should *NEVER* have to 'reformat' an Edge unit. I've had them for years and haven't ever had to do that. I suspect something else is happening for both the problems you are describing.

0 mroek72 over 4 years ago in reply to aweatherall

I'm not sure I want to post the file publicly, but I can send it to you on your email if you want to take a look. Is your email still the same (the mindspring address)?

0 mroek72 over 4 years ago in reply to mroek72

fallingrock I agree, but I have had to reformat my Edge 510 many times over the years, and I strongly suspect that it could be due to issues with the file system, especially when space is getting low. It could of course also be issues with the flash memory, but it always works OK for a long time after a reformat.

Anyways, it is perhaps time to replace the old 510 anyways, but this radar issue is an odd one.

0 aweatherall over 4 years ago in reply to mroek72

Send me a private message with the file if you like.

0 aweatherall over 4 years ago in reply to aweatherall

I would recommend checking the following setting.

The wheel circumference value. What does the value show and is the setting configured for manual or automatic?

0 mroek72 over 4 years ago in reply to aweatherall

It is set to automatic, as it has been for years. Never had any problems with that. It currently shows 2090 mm, which should be a reasonable value. And even if that was a few millimeters off, it doesn't even begin to explain the big discrepancy.

0 mroek72 over 4 years ago in reply to mroek72

Ok, so now I did another ride, but I moved the speed sensor to the front hub instead of the rear. The ride was 64 km, but the Edge only counted it as 62 (so average speed is also wrong).

Next ride will have to be without the speed sensor, but I would be surprised if the distance is still wrong then. I really don't get this. Ok, I added one more unit which also transmits signals to the Edge, but I'd imagine the Ant+ protocol has been designed to handle this situation. I don't know if the speed sensor transmits a pulse type signal and leaves the counting up to the Edge, or if it instead transmits a count value so that the Edge can detect if it missed some pulses. If it's the former, then I guess some amount of pulses could be lost due to interference, which would cause the Edge to record a lower distance, but that sounds a bit far fetched, I think.

0 mroek72 over 4 years ago in reply to mroek72

Another (shorter) ride today, this time without the speed sensor. The Edge still miscalculated the distance by quite a bit (kilometers), so it seems clear that the Edge simply acts up when the radar is connected.

0 mroek72 over 4 years ago in reply to mroek72

And yesterday I did a new ride with the original setup again (speed sensor, no radar), and distance was again correct.

My best guess is that the Edge either has a bug when the radar is connected, or for some reason it lacks processing power to handle the radar, and that causes it to mess up the distance calculation.

I guess I have no other option than to buy a new head unit.