| Threaded Headsets | ||||||
|---|---|---|---|---|---|---|
| Size Steerer O.D. | Stem diameter Steerer I.D. | Crown race Inside diameter | Frame Cup Outside Diameter | Threads Per inch | Notes | |
| BMX/ O.P.C. bikes | .833" (21.15 mm) | 26.4 mm | 32.7 mm | 24 | Used mainly on bicycles with one-piece cranks, also some early mountain bikes. | |
| French 25 mm | 22 mm | 26.5 mm, 27.0 mm | 30.2 mm | 25.4 (1 mm) | Obsolete. French steerers usually have a flat filed on the back, rather than a grooved keyway as with other threaded systems. | Interchangeability note: These 5 sizes of forks since the head tube |
| 1" ISO Standard (25.4 mm) | 7/8"(22.2 mm) | 26.4 mm | 30.2 mm | 24 | This is the standard 1" size. | |
| 1" Italian (25.4 mm) | 7/8"(22.2 mm) | 26.5 mm, 27.0 mm | 30.2 mm | 24 | Obsolete. Threads are cut at 55 degrees, but ISO or J.I.S. headsets can be used. | |
| 1" J.I.S. (25.4 mm) | 7/8"(22.2 mm) | 27.0 mm | 30.0 mm | 24 | Older or lower-quality bicycles from Asia | |
| 1" Raleigh (25.4 mm) | 7/8"(22.2 mm) | 26.4 mm | 30.2 mm | 26 | Proprietary size used on Raleighs made in Nottingham, England | |
| Austrian (26 mm) | 22 mm | 26.7 mm | 30.8 mm | 25.4 (1 mm) | Higher quality Austrian bikes use English/ISO | |
| French Tandem 28 mm | 22 mm | 25.4 (1 mm) | Obsolete and rare. | |||
| 1 1/8" (28.6 mm) | 1" (25.4 mm) | 30.0 mm | 34.0 mm | 26 | "Oversized" (This size is more often used for threadless systems.) | |
| 1 1/4" (31.8 mm) | 1 1/8" (28.6 mm) | 33.0 mm | 37.0 mm | 26 | Mainly used on tandems | |
| Size/Stem diameter | Steerer O.D. Crown race | Inside diameter Frame Cup | Outside Diameter Notes
| BMX/ | 26.4 mm | 32.7 mm | Used mainly on bicycles with one-piece cranks.
| 1" ISO Standard (25.4 mm) | 26.4 mm | 30.2 mm | This is the standard 1" size.
| 1 1/8" (28.6 mm) | 30.0 mm | 34.0 mm | Most newer mountain bikes use this size.
| 1 1/4" (31.8 mm) | 33.0 mm | 37.0 mm | Mainly used on tandems
| 1.5"
(38.1 mm) | 39.8 mm | 49.6 mm | Proposed OnePointFive standard
for downhill and freeride applications.
| | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Handlebar dimensions | ||||
|---|---|---|---|---|
| Stem Clamp Size | Grip Area Size | Application | ||
| 22.2 mm | 7/8" | 22.2 mm | 7/8" | Steel bars. Mainly BMX, older Mountain bike bars. |
| 23.8 mm | 15/16" | 22.2 mm | 7/8" | Obsolete British size for steel handlebars, common on older 3-speeds. This size was also used for older British steel drop bars. |
| 25 mm | 23.5 mm | Obsolete French size. | ||
| 25.4 mm | 1" | 22.2 mm | 7/8" | Standard I.S.O. size, used on the vast majority of newer bicycles with upright handlebars. This size was formerly common for steel drop bars. |
| 25.4 mm | 1" | 23.8 mm | 15/16" | Standard I.S.O. size, used on most bicycles with drop handlebars. Also used on older British aluminium upright handlebars. |
| 25.8 mm | 23.8 mm | 15/16" | Unofficial in-between size used by some Italian handlebar makers for handlebars designed to be usable in either ISO (25.4) or Italian (26.0) size stems. | |
| 26.0 mm | 23.8 mm | 15/16" | Italian standard for drop bars, other bars made to fit Italian stems and some high-end aftermarket drop bars. This is sometimes incorrectly called "road" size. | |
| 26.4 mm | 23.8 mm | 15/16" | Older Cinelli and Cinelli copies. Cinelli changed over to 26.0 mm in 1998. | |
| 27 mm | 23.8 mm | 15/16" | Titan (obsolete). | |
| 31.8 mm | 1 1/4" | 23.8 mm | 15/16" | Road oversized. |
This page is intended as a quick reference primarily for the benefit of folks in the bicycle business. Feel free to print it out, but please don't reproduce it without proper credit and linkage.