Bottom bracket sizes

I am about to to replace the bottom bracket on my first build, but don’t know the specs of the frame. I want to make sure I get the right size bb and was wondering if there is a way to measure it.


Sheldon will explain it better than any of us.

Also, search the forums, it’s been discussed before.

3 important things, width of shell, length of axle, and thread types which must match to female thread in shell. Easiest to make sure you get it right would be to take the removed bb to your LBS or take the whole bike in.
Most threads are english, perhaps frame type will help indicate what type?
Also should replace axle with matching ISO or JIS, see thread just down the list by stk101.

cheers guys. Was hoping to get it done on my own but LBS might be the go. Frame is Allegro btw.

if you’re going to take the frame to your LBS don’t forget to take your crankset too

I got a good price on a Sugino 75 BB last night so I ordered it. If it doesn’t fit, I’ll on-sell it. Should be cool though I reckon.

An unsealed track bottom bracket?

Hmmmm… you might wanna a) check to see if you really need an unsealed BB (especially if you are riding on the street), especially when you can get nice cheap(ish) sealed BB’s, and b) your cranks are ISO taper, cause Sugino 75 cranks and BB’s are ISO.

I’ve got messenger cranks.

Sugino Messenger

  • 165mm and 170mm arm lengths
  • JIS square taper bb
  • 103 bb spindle recommended

It won’t work properly. Sorry dude.

PM user “Nexus”. He’s got a Sugino JIS 103mm spindle 68mm wide, sealed BB for sale.

Thanks for the tip. I think I bought his regal saddle a couple of weeks ago.

Also, next time, Google stuff. I spent about 6 seconds searching (and I even spelt “messenger” wrong) and it gave me the above information about the BB and taper.

It’ll save you money.

why are sugino iso doesnt jis stand for japanese industry standard? also any tricks to getting the chainline right?

NJS Sugino parts (cranks, BB’s) are ISO. All other Sugino parts are JIS (from here).

This is handy.

Also, from the same Sheldon page…

And… all about chainline.