Garmin Edge 500 mileage and speed problem

ForumNewbie

I've had a Garmin Edge 500 for over 18 months with no problems until today. I was out for a short ride and about 3 miles from home my speed started showing as very low - 6 mph and under and going to zero and auto-pause when I was on a fast descent and then fast flat. It kept going to autopause and then bleeping back on with very low single figure speeds showing when I was definitely riding at 15-18 mph. I then noticed my distance was not recording accurately as the last 3 miles of my ride only increased the distance on my Garmin by about half a mile, which seem to be the reason very low speeds were showing.

Anyone know what could have caused that problem with the distance not registering remotely accurately?

dyrlac

Do you havea GSC-10 speed/cadence sensor? If so, it needs a new battery (or is water damaged, or the speed magnet needs repositioning) and if you upload to something like strava, the GPS data (including speed) will be preserved. If not, you should do a master reset (Google this), as it's struggling to hold onto a GPS signal.

ForumNewbie

Dyrlac wrote:

Do you havea GSC-10 speed/cadence sensor? If so, it needs a new battery (or is water damaged, or the speed magnet needs repositioning) and if you upload to something like strava, the GPS data (including speed) will be preserved. If not, you should do a master reset (Google this), as it's struggling to hold onto a GPS signal.

I do have a cadence sensor but it was still recording the cadence okay so I don't think it is the battery. When I uploaded to Strava it did record the correct mileage, despite what was showing on my Garmin. My average speed was only slightly down due to the fact that Strava seems to have recalculated average speed on Elapsed Time rather than Moving Time. I'll check my wheel magnet just in case that has been knocked a bit off centre, but as it was calculating distance and speed from the GPS data I wouldn't have thought that mattered too much.

craker

I had the same issue in the week, the speed was all over the place and the distance was down. I stopped and repositioned the cadence sensor arm and the wheel magnet, completely sorted (though the battery suggestion above is worth a punt).

I'm surprised it was calculating distance from my wheel sensor though, would have expected it to use its GPS.

dyrlac

Head unit will use the speed sensor to calculate on-bike displayed distances (and speed) although GPS distance will be recorded in the .FIT file. Had tgevsame thing recently: 90+ rpm cadence and zero speed, turned out the speed sensor in the GSC-10 was buggered, but cadence sensor still worked.

ForumNewbie

Thanks, it may be the wheel magnet position or speed sensor then. But if just the speed sensor in the speed/cadence unit is buggered can that get fixed?

I've also got a Garmin 200 which I still use sometimes, and that wouldn't get the same problem as the live on-bike Garmin display of speed and distance on the 200 is calculated from the GPS as there is no cadence/speed sensor or wheel magnet. However I prefer the 500 as I can get cadence and heart rate and there are better display screen options, but if the speed sensor can't get fixed I'd be as well removing the speed/cadence unit from the bike and then the on-screen speed/distance would calculate from the GPS, just like the 200 does.

dyrlac

Not sure if you can get it fixed. Might try ringing Garmin, although, since the new sensors came out, you can get a new-in-the-box GSC-10 for £20-£30. On mine, the speed sensor just packed it in entirely without affecting the cadence sensor, so I was content just to let it be.

drlodge

Try "disconnecting" the GSC10 sensor in the Garmin configuration so it just uses GPS for speed, and see if the problem still exists.

Shtukka

I had the same problem on my 500 - for me it was an issue with the magnet on the rear wheel for the cadence sensor.

That magnet gives the Garmin data on your speed and is typically more accurate than GPS speed data especially when going through a tunnel or something else that momentarily obscures GPS reception.

You'd have thought that the Garmin would use whatever data is "better" between that sensor or GPS data however it doesn't: if it's getting data from the cadence sensor, it uses that no matter what.

Check that both magnets are securely fitted and aligned with the corresponding line on the sensor. Press the grey button on the sensor and check that you get a red light (only) when you spin the wheel, and green light (only) when you turn the pedals. (Red/Green might be the other way around, I don't recall).

Note also that Garmin have a new range of cadence sensors which appear to be much be designed. No more sticky out arms or magnets, it's accelerometers now. http://www.amazon.co.uk/Garmin-Bike-Spe ... in+cadence

Cartebleu

I experienced this problem for the first time this weekend. I knew something was wrong when it recorded my max speed as 100.9 mph :shock: :shock: :shock:

Is there a way to get the speed to be recorded by GPS (instead of via the sensor), yet still keep the cadence turned on?

I appreciate this may be a backward step, but I'm just curious.

ManOfKent

+1 for checking the position of the magnet on the wheel relative to the sensor. Unfortunately I did this after changing the battery not before.

Shtukka

Cartebleu wrote:

I experienced this problem for the first time this weekend. I knew something was wrong when it recorded my max speed as 100.9 mph :shock: :shock: :shock:

Is there a way to get the speed to be recorded by GPS (instead of via the sensor), yet still keep the cadence turned on?

I appreciate this may be a backward step, but I'm just curious.

Yes - remove the magnet from the wheel and it won't try to use sensor speed. There is a risk though - and the symptoms are the same as the OP: the magnet from the pedal might trigger the sensor on the arm looking for the (non-existent) wheel magnet. This risks fooling the garmin into thinking it's getting speed data and then your speed/dist readings will be off. Pretty obvious though , possibly worth a try.

Mikey23

Ooerr didnt know there was a new one out! Might be useful as the chainstays on my roubaix curve in so cant fit the gsc10 has to sit upright which isnt ideal...

Mikey23

Pretty good reviews from dcrainmaker... Will be ordering today!