Originally Posted by
msu2001la
I have a Garmin Edge 520 and use the ANT speed sensor on the rear wheel, and a cadence sensor on the crank arm.
It works fine for measuring/displaying speed and distance while riding on indoor rollers and stationary trainer.
I think that's the only purpose of the wheel sensor, right? It works outside too if I forget to turn the GPS back on, but I assume when I have GPS on, the head unit is using that to measure speed/distance and not the rear wheel. Hmm...
On a Garmin it uses in this order: power meter, ANT+ wheel sensor, GPS. My Edge has a setting (Automatic) which causes the device to calculate the correct tire size using the GPS. Thus if you're riding in thick forest or along cliffs, it keep track of your distance correctly even if it loses its satellites temporarily.