# RideSense sensor error



## youngmth (May 22, 2012)

I have recently bought a TCR SLR2 and installed a RideSense Sensor. I use a Mio Cyclo 105 (aka Magellan Cyclo 105), very similar to Garmin 500. I use this same cyclo-computer interchangeably with another bike which has the speed/cadence combo sensor that came with the cyclo-computer.

I noticed that whenever I ride the Giant, the distance clocked on the computer would be a lot more than what the GPS logs (via Strava). For instance, on one of my usual routes yesterday, the computer logged 55.9 miles while the GPS (uploaded to Strava) logged only 41.7 mile. When I rode the same route with the other bike, I'd be logging 43 miles and 41.7 mile respectively.

I looked all my rides in the past month, ~200 miles on each bike, the Giant consistent has an error of +30% while the other bike only as about +10%. I understand the nature of riding distance logged by GPS vs by wheel-circumference, which is why I have always been OK with that 10% discrepancy. But 30% is just way too much.

Any ideas?


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## Sun Rider (Jul 8, 2012)

You do have the correct tire size programed into the RideSense?


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## youngmth (May 22, 2012)

Yes, like I said, I use the same GPS/cyclo-computer on two different bikes, both bikes on 700C/23 tires. It's set at 82.2-in circumference.


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## r1lee (Jul 22, 2012)

You are using the magnets that came with the sensor right? I find that the giants rs can be finicky using other magnets.


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## youngmth (May 22, 2012)

No I was not. I was too lazy and just kept the magnet I had on the wheels I put on the Giant.:blush2:

I didn't think it was going to be an issue.. after all, a magnet is a magnet, right? Anyway, I swapped it with the magnet that came with RideSense and will see what happens.

Thanks.


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## youngmth (May 22, 2012)

OK. Put on the Giant magnet that came with RideSense and went out for a quick ride. Computer logged 25.1 miles and once uploaded to Strava... 18.3 miles! That's 37% margin.. argh...

Another thing interesting is that if the sensor is sending 30% extra signals to the computer, I should see my speed 30% faster on the computer. But I am not.

I just reversed the magnet (if polarity matters) and try again tomorrow.. :mad2:


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