Axle to Hub Sizing

[mavila83]

Hey Folks,
I work with a Bicycle Collective in Seattle and we are putting together a Hub intensive class. Because we work with a milieu of mismatched parts one of the things that sometimes comes up, that I would like to cover in this class, is sizing axles to hub shells. I know how to size a standalone axle's length to a frame but because axles come in different diameters, how does one know which axle diameter is compatible with which hub? Does anyone know the answer?

Thanks!!

[Alex Ramon]

Most road and mountain bikes use a 9mm axle diameter on the front, and a 10mm axle on the rear. BMX bikes use a 3/8" (9.5mm) or sometimes a larger 14mm diameter front or rear.

There are other uncommon sizes for rare and specialized bicycles.

[Bill]

Just to add to Alex's post, you can always use a micrometer and convert it to its fraction or mm equivalent.

[mavila83]

Thanks so much, that info is great! Just to continue the question, are there any charts for the odd or specialty sizing?

[jr14]

Well, I'll be damned. I finally stumped Sheldon Brown's website. He actually never listed different axle sizes. But Harris cyclery on the same site http://www.sheldonbrown.com/harris/axles.html seems to have the most common axle types. There doesn't seem to be much difference. I may be wrong, but that's what I dug up.

[ydrive]

I think he didn't list the axle widths because it wasn't necessary. Even better, he showed how axles should be 11mm longer then the dropout spacing, or 5mm - 5.5mm on each end, yielding the correct axle length. A 126mm rear dropout would then have a 137mm wide axle by simply adding 11mm. Came in handy when I had to cut down an axle for 130mm dropouts, to replace the broken one my 73 Schwinn six speed.