I have Garmin cadence and speed sensors on my track bike. Given that the gearing is fixed speed can be calculated from cadence but i have both anyway..
The problem comes when i look at the data after training sessions - the recorded speed varies a lot for the same cadence - for example on a 90" gear and 100rpm speed can be anything from 28 - 46km/h!
My assumption is that the cadence sensor is the one most likely to be accurate, and therefore the problem is with the speed sensor (also the particular training efforts back this up).
The speed sensor is mounted one the front wheel axle and appears to be secure, i'd be grateful if anyone has any idea how i could fix this?
Thanks