Originally Posted by
coffeesnob
For those with the garmin 530 do the speed and cadence automatically calibrate on their own?
Yes.
By default, the Garmins determine the wheel circumference using the GPS in the first 0.1 miles. The wheel rotation sensor needs an accurate wheel circumference. You can also enter the circumference manually.
The devices can also determine speed from the GPS alone. That works fine except it won't be quite as sensitive to quick changes in speed.
The cadence sensor doesn't need calibrating.
Note that you have to pair the wheel rotation sensor and the cadence sensor to the device (the "headunit").