Wheel Size for the Computer?

Neal in New Zealand has a problem with the settings for his bike computer; he needs to know what numbers to put in for a 700 x 23 rim. These are our suggestions to Neal and anyone else with a similar quandary!

Question:
what would be the circumference of a 700×23 rim as my cycle computer book does not have that size in it.

Hi Neal,

Yes, sometimes the instruction books are not very helpful, I think this is why most men don’t read them and just get stuck in to whatever they have just bought!

First thing is that I must correct you, its not the rim that is 700 x 23, well the rim is 700, but this refers to the size of your tire, so you could have 700 x 19, or 700 x 25 etc. I must agree with you choice of tire size as the 23 has to be the most comfortable of tires.

The most accurate way of finding what size you need for your computer is to first make sure the tire is blown up to the correct pressure, this is very important as it will affect the measurement. Make a mark on the ground and place the bike so that the valve of the front wheel is on that mark. Then push the bike forward until the valve has done one revolution and is back down at the ground, then make another mark. Measure the distance between the marks in millimetres and you will have the distance of one wheel revolution and this should be the number you need to put into your bike computer. I would think that the measurement will be around 2096; this is what I have in my Polar for Hutchinson Fusion 700 x 23. There can be differences between tires that say they are the same size, so measuring one revolution is the most accurate method.