Originally Posted by
Jarrett2
I just called their support number.
The guy said speed sensor is only used on a trainer. Useless on an actual ride.
If you have the sensor you could prove that this isn't true by riding through a tunnel. If the speed sensor isn't used, your speed will drop to zero or null.
Originally Posted by
DonBjr
If you have a gps, the speed sensor is not required, but if you're riding where the GPS signal isn't reliable, you're better off with a speed sensor if you're interested in things like your max speed since a GPS glitch will often trigger some max speed reading that isn't reality.
I used to use older hiking GPS units and this would happen occasionally. With newer units, it doesn't happen. They've gotten pretty good at filtering the most obvious noise out of the signal. The latest Garmin units seem to use accelerometers (and even the compass) to predict where you're about to be and ignore GPS points that are wildly out of line from the predictions.