Circumference of a 622-32 tyre

Kieran_Burns

I'm asking as my cateye is set to 2155 but there's a question (see ride reports about its accuracy)

When I check the manual it confuses me even more....

18-622- 2070
19-622 - 2080
20-622 - 2086
23-622 - 2096
25-622 - 2105
28-622 - 2136
30-622 - 2170 (!) 700 * 30c
32-622 - 2155
37-622 - 2168 700 * 35 (!)

I'm stumped.... have I got my cycle comp set right?

Roastie

My calc gives 2155.

Bead dia = 622
Nominal tyre profile = tyre width = 32
Overall dia = 622 + (2 x 32 ) = 686
Circum = dia x pi = 2155

Eau Rouge

The best way to do this is to have the valve at the bottom of the wheel, and line it up with a mark in the ground. Then roll the bike forward until the valve is again at the bottom of the wheel and then measure the disatance between these two points, and use that number.
If the sensor is on the back wheel, you could sit on the saddle as you roll the bike forward.