Picked up a bike computer today. The calibration instuctions were pretty straight-forward, so my wife and I got out in the drive and I rolled off one revolution. We measured, came up with 80 inches, multiplied times 25.4 to get a result of 2032mm.
My tire is the IRC Fiesterra, 26 x 1.95. The instructions that came with my 'puter list some "popular tire brands" and their calibrations. Here is an excerpt from the table:
ATB 26 x 1.40 = 1995mm
ATB 26 x 1.50 = 2030mm
ATB 26 x 1.75 = 2045mm
ATB 26 x 2.00 = 2099mm
I wasn't sure if "ATB" was a brand or a type; my search for "atb" on the MTBReview site revealed only a single reference ("Panaracer Duster II ATB tire"). But -- please correct me if I'm wrong -- numbers are numbers. If an "ATB 26 x 1.75" translates to a circumference of 2045mm and an "ATB 26 x 2.00" translates to 2099mm... shouldn't my IRC Fiesterra lie somewhere between 2045mm and 2099mm, instead of the 2032mm that my measurement produced?
Pardon my newbie ignorance, and thanks in advance!