I am using a power meter paired with garmin 510 and the speed/cadence sensor.
How do you put in tire/wheel circumference? I am using 650 wheels and the default seems to be 700 wheels. A quick Internet search tells me that it automatically calibrates wheel circumference. However, from my ride last night, there is no way that happened. The distance and speed was about 20% lower than it should have been.
Thanks for any help/intel you can provide!