What is the true diameter of B123's?
 

I just realized that businesscycles/various other reference pages list the clamp diameter of these bars to be 25.4mm. Which is impossible since I just tried a 25.4mm brake lever on my bars and it doesn't fit. The bar itself cannot be larger than the clamp diameter since the clamp "sleeve" is clearly larger than the rest of the bar. So after going through 2 brake levers that don't fit, I was wondering if anyone out there has calipers/micrometer to actually measure the diameter of the bars and report back to us so we can have correct information regarding these handlebars.

Im beginning to think the clamp diameter is more around 27/28mm and the bar itself is 26.0mm standard road diameter but I can't be sure. I want to order a set of cross levers since I think that those will fit properly. The only issue is that I've seen some people say they run 24mm clamp cross levers on B123's, how is this possible when my 25.4mm clamp brake lever would not fit on these bars? (the bars have the same diameter through the whole bar, with the exception of the clamp sleeve which is hidden by the stem when installed.)

Also, in keeping this thread as a reference thread, I was hoping that people could list what brake lever they use on their B123's so other's who buy this bar and need a brake lever don't have to go through the trouble that I did. Thanks

I'm using a Cane Creek Crosstop lever; the Cane Creek web site says it's 26.0. It's never slipped on my bars at all, and I don't need to use a shim or anything. Maybe it's working because I have a right-hand lever mounted upside-down on the left-hand side. :rolleyes:

I haven't seen my Vernier calipers since I moved in June, so I can't help you there.

I just measured mine - with a metric ruler, sorry no calipers. The clamp area is 25.4mm, the rest of the bar seems to be 23.0mm. I measured outside diameter at the end of the bar (where you would insert the plugs) with the tape removed.

These are the steel B123s.

Nitto track bars are 25.4mm at the clamp - the rest of the bar is 23.8mm. The truth, Ruth.

can someone explain why a 25.4mm clamp brake lever wouldn't fit? and with this information should I be looking for a 24mm cross lever or a 26mm cross lever?

Because a MTB lever meant for 25.4mm bars has an inside diameter of 22.2 mm, only the clamp is 25.4mm, whereas the rest of the bar is 22.2mm. Got it?