Cateye Astral set up ?

dogfood · Post by **dogfood** » 6 Jul 2007, 11:13pm

I just fitted Schwalbe marathon 26 x 2.25 tyres to my bike but in the Cateye manual there is no stated circumference for this size tyre. Only 2.15 and 2.3 I think, I've temporarily misplaced said manual. Anybody know this setting ?
Thanks.

dkmwt · Post by **dkmwt** » 7 Jul 2007, 1:23am

The way to measure your wheel circumference is to take a 3 metre tape measure. Extend it to it's max and lock it. Then place the valve of your wheel at the begining of the tape and run it along the tape until you get to the valve again. Read the tape measure and there's your wheel circumference.

Post by **ncutler** » 9 Jul 2007, 9:38am

If you want to be really accurate, and take account of your weight on the wheels and any compression of the tyre that this causes:

Pump the tyre to the pressure you normally use.

Find a reasonable clean, dry, road surface.

Make a mark on the wheel using something like white paint ( water based variety borrowed from friendly child is best, but almost anything will do ).

Ride bike for a few feet.

Measure the gap between the marks on the road.

Alternatively, paint a line on the road surface, cycle over it, and measure the distance to the mark printed by the tyre. If you are being really nit-picking this is probably more accurate as you can get a bit of a run at the first mark, and don't wobble about so much.

Nick

dogfood · Post by **dogfood** » 9 Jul 2007, 11:20am

Thanks, I'll try that.

PW · Post by PW » 9 Jul 2007, 11:59am

The easy way is to put the valve at the bottom of the wheel alongside a crack in the kerbstones. Sit on the bike & roll forward 2 wheel revolutions,mark the kerb with a penknife where the valve finishes up, then measure between the two points & divide by 2.