[CR]Sheldon Brown needs your bottom bracket info

Example: Framebuilders:Alberto Masi
Date: Sat, 23 Feb 2002 15:37:46 -0500
To: Classicrendezvous <classicrendezvous@bikelist.org>
From: "Sheldon Brown" <CaptBike@sheldonbrown.com>
Subject: [CR]Sheldon Brown needs your bottom bracket info

There is a great deal of confusion around the issue of what size/type of bottom bracket goes with what make/model of crankset. Mechanics and cyclists waste many, many hours using trial and error methods for this, or digging through greasy old catalogues.

I'm creating a database of different makes/models of crank sets, with information about which bottom bracket size each requires.

I've made a start on this, but it is too large a job for one person.

You can see what I've got so far at http://sheldonbrown.com/bbsize

If you have information on older models, other makes, whatever, please email me at the special email address I've created for this project:


Don't use that address for any inquiries that require an answer, just for submission of crank/bottom bracket data.

To be useful, your submission must include the following information:

Crank Make

Crank Model


Spindle/BB Code and Size

Spec or Measurement ("Spec" indicates that you got the information from a manufacturer's data sheet or other publication. "Measurement" indicates that you have measured a crank installed on a bicycle. Please measure everything in millimieters.)

Tapered square or splined? Most cotterless cranks use tapered square axles. Some newer models are splined. For splined cranks, it would be helpful to specify the spline pattern if known.

The items above in red are essential. If you can't supply all 6 of these bits of info, don't bother submitting.

If you can fill in any of the additional items below, it will make your submission more useful:

Chainline See the chart at http://sheldonbrown.com/bbsize.html#chainline for an explanation of how to measure chainline

Chainring Clearance This would be the distance from the inner surface of the innermost chainring to the centerline of the seat tube or down tube. (In practice, clearance to the chainstay is the concern, but there is too much variation among frames to make that a useful reference point.)

Right Crank clearance This would be the distance from the inside of the right crank to the centerline of the seat tube or down tube, measured where the pedal screws in.

Left Crank clearance This would be the distance from the inside of the left crank to the centerline of the seat tube or down tube, measured where the pedal screws in.

Tread (a.k.a. "Q factor") This is the horizontal width of the crankset from pedal mount to pedal mount. It is equal to the sum of the crank clearances above, plus the thickness of each crank. I can do the math if you provide the measurements.

Bolt Circle Diameter This is a useful item if you know it. See: http://sheldonbrown.com/gloss_bo-z.html#bcd

With your help, this database will become a great aid to mechanics and cyclists the world over!

Sheldon "Numbers" Brown Newtonville, Massachusetts +--------------------------------------------+ | If it can't be expressed in figures, | | it is not science; it is opinion. | | --Robert A. Heinlein | +--------------------------------------------+
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