How do i find out the MM on my wheel size?

[RabbitFood]

I am seting up my cycle comp and i cant find out the size of my wheels,i have RIMS Alex S500, sleeve joint, CNC sidewalls, 28/32h and FRONT TYRE Specialized Mondo Sport, 700x23c, wire bead, 60TPI, Flak Jacket .

But i cant seem to find the size in MM anywhere, help would be great

thanks
Rabbit

 

[mr Mag00]

a chlk line on the floor lined up with the valve. rotate wheel along floor one rotaion, mark this place. measure between the 2 chalk lines





oh and write it down as you will need it again when you change the batteries on ur computer

 

[HLaB]

Your computer should have came with a guide that says what 700x23 is equivelant to, its about 2096mm. Alternatively and more accurate you can measure the circumferance by rolling the bike along a flat surface for one circumferance, say valve at the bottom to through a revolution to valve at the bottom.

 

[ChrisKH]

You should rotate wheel with you sitting on it to exactly mimic the wheels rotation in practice, I read somewhere.

 

[byegad]

Measure the diameter of the tyre and multiply by pi.

 

[RabbitFood]

bloody genius why did i not think off that

thanks, im off to test my cycles comp

 

[Globalti]

Put a blob of paint, jam, mustard or something on the tyre, roll forwards and measure the distance between the blobs on the floor.

 

[Randochap]

You should rotate wheel with you sitting on it to exactly mimic the wheels rotation in practice, I read somewhere.

That's right.

Make sure your tyres are inflated to the regular pressure.

Put a piece of tape on the floor precisely at the stem hole in the rim, making sure the edge you will measure from is aligned "outside." Sit on the bike and do a full rollout. (Maybe get someone to help) put another piece of tape down at the same marker (stem). Measure between (inside edges of) the two pieces of tape.

If you do this properly, it will give you the closest calibration possible. Any other method just gives an approximation of mileage.

 

[inaperfectworld]

it makes a surprising, but ? significant, difference whether or not you sit on the bike. sit on it the bikefor measurement and push it back unseated and see. if you are a real precision man measure measure 2 or 3 wheel revolutions and divide accordingly by 2 or 3 as it reduces measuring error (1cm out in measuring the smaller distance of one revolution eg 2 metres is in percentage terms greater than the larger figure figure from 2 or 3 revolutions(4 or 6 metres
only for the obssessives like me though

 

[jimboalee]

Hire a day at Millbrook proving ground. Ride your bike down the Measured Kilometer and count the wheel revolutions as you go.

Divide 1,000,000 mm by the number of revolutions.

 

[Davidc]

Once you've set it up take a satellite device (eg Garmin Foretrex) with you on your next long ride and compare the two. (Borrow one if needs be!). If there's a significant difference re check your calibration, if a small one be more careful as the satellite devices can get fooled.

 

[Amanda P]

Put a blob of paint, jam, mustard or something on the tyre, roll forwards and measure the distance between the blobs on the floor.

Ketchup is best. Preferably Heinz, of course.