I bought 2 different computers, one for my bike and one for my daughters. Mine reads about 2 MPH faster than my daughters (not sure which is correct, but I suspect my daughters is closer). I have a recumbent with a 20" front street tire, and hers is a Mountain bike with a 20" front knobby. Both computers were set to the default (in the manual, yes I read it ) for a 20" tire. So why the 2 Mph differance? Is there a way to get them closer? The instructions in both (different brands) have something about setting it to the MM of your tire rather than using the defaults, would that help, and the largest thing I have with MM on it is a 12 inch rule, so can I you measure in Inches and convert with enough accuracy?
ToPeak Panoram and Sigma BC600 are the computers if that matters.
Thanks