What is the correct handlebar measurement?

Question

I'm trying to buy a cyclocomputer online. The handlebar specifications say that they will fit a 20-30mm handlebar. Does that mean the circumference of the handlebar? When I measure my handlebar circumference it's about 100mm! Not sure why there is this much of a difference.

Answer 1

It the diameter, so relax, it'll fit.

Answer 2

Pi x D = Circumference

The specs are referring to diameter of course.  The "difference" is multiplication by Pi.

Is human intelligence devolving?

Answer 3

It's the diameter, not the circumference. Your handlebar is fairly typical. 100 mm / 3.1416 = 31.8 mm.

HTH