Help, I need a tire size setting

Triathlon Forum
1

I cant find the manual to my Cateye bike computer. Can anyone tell me the # to put in for a 700 X 21 tubular?

Thanks in advance,

                         Dennis
2

Take your bike outside. Set the rear wheel so that the valve is at dead bottom. Mark ground with chalk. Get on bike. Roll forward until rear wheel makes two (2) revolutions. Get off bike. Mark ground with chalk. Measure distance between marks, using metric system. Divide by 2. Enter number in computer.

3

Thanks Ken,

              Thats good info to know. I'll try that.

Thanks again,

                 Dennis
4

2080 mm will get you pretty close.

5

2130 is the setting from the cateye manual. But the measurement technique mentioned earlier is more accurate.

6

I actually came up with 2089 doing it like Ken described.

7

The lazy man’s way is to take the bead diameter, add twice the tire width, and multiply by pi to get a pretty good approximation of the circumfrence. For a 700C tubular, use the bead diameter of a 700C clincher.

(622+2*21)*3.14159 = 2086

8

I use 2090. It is pretty accurate.