I bought an Edge 1000 with a sensor for the wheel, this takes over the distance/speed calculations from GPS.
The sensor can be automatic or you can enter a wheel size. My tyres at 700x25c, using the Garmin table, it should be 2105.
However, if I let it auto calibrate, it auto calculates to 2085, which would be 700x20c. On a route that has always measured 18.6 miles via GPS, it comes out with this as 18.75 miles.
If I enter 2105 and turn off the auto calibrate, the same route measures 18.9 miles.
That appears to be quite a discrepancy, there are no steep hills on the route and there is 152m of elevation gain in total. I guess the only way to be 100% accurate is to measure the tyre its self!?
The sensor can be automatic or you can enter a wheel size. My tyres at 700x25c, using the Garmin table, it should be 2105.
However, if I let it auto calibrate, it auto calculates to 2085, which would be 700x20c. On a route that has always measured 18.6 miles via GPS, it comes out with this as 18.75 miles.
If I enter 2105 and turn off the auto calibrate, the same route measures 18.9 miles.
That appears to be quite a discrepancy, there are no steep hills on the route and there is 152m of elevation gain in total. I guess the only way to be 100% accurate is to measure the tyre its self!?
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