Computer wheel size query

stevenb

My previous tyres were both 700cx23mm.
My computer reads off the rear wheel (Cateye V3).
My new tyres are the Conti GP Force/Attack combo 24mm rear and 22mm front.
Should I leave the wheel setting as it is on the computer or do I need to change it to accomodate the 24mm rear tyre?

Cheers

Steve

John.T

Reset it. Preferably by measureing the circumference of the tyre. See here.
http://sheldonbrown.com/cyclecomputer-calibration.html#rollout

stevenb

Thanks John.

I did a rolling test...albeit on my spare room carpet but I leaned on my bike as I was only one around to take measurements so leaning my weight across the saddle I marked out from the start to finish one revolution.

It came back with 2120mm.....which seems way too high to me.....hmmm
Typical that there is no 24mm setting on the computer 23 and 25 mm are there and of course the 4 digit code entered is the circumference like any other bike computer.
Mind you....my Velomann V1.23 computer says 2100 for a 700x23c whereas the Cateye V3 is 2096 for a 700x23c.

Next question is though.......can I enter the exact 4 digit code into my computer? It lets me do it but whether it will default to the nearest programmed setting I do not know... :?
I should have thought about this before I bought the tyres.....

mattsccm

Just bung in the measurement. It will stay as that. If you are fussy put a bit of paint on the tyre and ride it on a clean dry surface. Really fussy? Do that then check over a measured distance

stevenb

I think I have sorted it out now.
I measured the role out at 2100.5mm (sitting on the bike now) so I entered 2101 on the computer which when compared to the tyre widths in the manual is an almost perfect match. I was just goin got enter 2100...but I put the extra 1 in on the end.

Cheers for your help.