So, i'm just getting started and I have an expensive ($20) computer on my bike. I thought I had it set up correctly, followed all the instructions, measured the circumference of my tires with me on the bike. I compared it's calculated distance against Strava (Iphone GPS app) and they don't match up. I think they were off 3/10 over a 10.5 mile ride.
I'm sure I'm over scrutinizing at 3/10 difference in 10 miles, but I'm not sure which one would be correct.
On the mathematical side, I'm not completely sure I have my tire circumference correct. When I compared my measurement to the suggested measurement in the instructions for 700x32 tires mine was a little less. I figured it was do to compression of me being on it. Admittedly I don't know if a few mm's would be throwing it off that much.