This is more for myself so I don’t lose this information, but who knows, you might find it helpful. I’m reprogramming a Blackburn Delphi 4.0 cyclocomputer, specifically, I’m setting the estimated tire circumference in mm. I’m running a 700×44c WTB Mutanoraptor tire (on the Tricross fixie), which means ISO 44-622. So a little quick math and we have 622 + (44 X 2) = 710, multiplied by pi (3.142) to get the circumference in mm 2230.53078, or you can just go to Sheldon Brown’s website, which gives me 2224 mm. Close enough for me!
If I wanted to be super accurate, the easiest thing to do would be to plop down some ketchup or mustard on the ground, ride through the blob for a full tire rotation, and then measure between two blob spots. That would give me the weighted tire circumference. But since I don’t have a ruler that can measure in mm AND I’m at work, the estimated tire circumference will work just fine.
Hopefully this will spur me to keep better track of mileage this year, something I’ve said I’ll do in the past a few times, only to break the cyclocomputer or ride one of my bikes without a computer.
Make sure you measure center-to-center on those condiments gobs, ha.
Damn, just 11,567 other tires to go, and you’ve got yourself a database!