Triathlon - Tire size

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brigoody
03-07-06, 09:24 PM
I have a Cateye Cordless computer that I have moved from my road bike to my tri bike. The manual doesn't list the tire circumference for 650X23. How accurate would my numbers be if I put in 700X23? The manual does list 650X35A, 650X38A, 650X38B. Would any of the sizes be more accurate? thanks

Triguy
03-07-06, 09:51 PM
since 650 is a about %92 of 700, thats how accurate it would be. 600x35 would probably be closer but there should also be a manual rollout method as well.
Gonzo Bob
03-08-06, 12:26 PM
You don't have 650A or 650B. You have 650C. The bead diameter for 650C is 571mm. To get a good estimate for circumference, add twice the tire width (23mm) to the bead diameter and multiply by pi. (571 + 2*23)*3.1416 = 1938mm. Some Cateyes take cm, so that would be 194cm.

SoonerBent
03-08-06, 01:50 PM
I have 650c Kenda's on my Corsa. I used the roll out method and came up with 1921.

SB