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Circumference of a 622-32 tyre

Kieran_BurnsKieran_Burns Posts: 9,757
edited August 2009 in Commuting chat
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?
Chunky Cyclists need your love too! :-)
2009 Specialized Tricross Sport
2011 Trek Madone 4.5
2012 Felt F65X
Proud CX Pervert and quiet roadie. 12 mile commuter

Posts

  • RoastieRoastie Posts: 1,968
    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 RougeEau Rouge Posts: 1,118
    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.
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