Threaded Headsets/Steerers
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|---|---|---|---|---|---|---|
| Standard | Frame Cup Outside Diameter |
Crown race Inside diameter |
Steerer O.D in mm | Threads Per inch |
Stem diameter, Steerer I.D. |
Notes |
| 1" J.I.S. |
30.0 mm | 27.0 mm | 25.4 mm | 24 | 22.2 mm (7/8") | Older or lower-quality bicycles from Asia. Can be milled to ISO standard. |
| 1" ISO Standard |
30.2 mm | 26.4 mm (varies) |
25.4 mm (varies) |
24 | 22.2 mm (7/8") | This is the standard 1" size. |
| 1" Professional/ Campagnolo |
30.2 mm | 26.4 mm |
25.4 mm | 24 | 22.2 mm (7/8") | Obsolete. Threads are cut at 55 degrees, but an ISO headset can be used. |
| 1" Raleigh |
30.2 mm | 26.4 mm | 25.4 mm | 26 | 22.2 mm (7/8") | Proprietary size used on Raleighs made in Nottingham, England |
| 1" Italian | 30.2 mm | 26.5 mm, 27.0 mm |
25.4 mm | 24 | 22.2 mm (7/8") | Obsolete. Threads are cut at 55 degrees, but an ISO or J.I.S. top headset can be used. Fork can be milled to ISO. |
| French | 30.2 mm | 26.5 mm, 27.0 mm |
25.0 mm | 25.4 (1 mm) |
22 mm | Obsolete. French steerers usually have a flat filed on the back, rather than a grooved keyway as with other threaded systems. The bottom headset parts wear faster; you can replace them with ISO parts and use the old top headset. |
| East German (DDR) | 30.6 mm | 26.8 mm (1 1/8") |
26 mm | 26 | 22 mm | Very similar to or the same as Austrian. 0.2 mm discrepancy may result from measuring the I.D. of the head tube (press fit). See page on German site. |
| Austrian |
30.8 mm | 26.7 mm | 26 mm | 25.4 (1 mm) |
22 mm | These are found on bicycles sold by Sears, made by Steyr in Austria. Higher quality Austrian bikes use English/ISO. |
| BMX/ O.P.C. bikes | 32.6 mm (varies) |
26.4 mm (varies) | 25.4 mm | 24 | 21.15 mm (.833") |
Used mainly on bicycles with one-piece cranks, also some early mountain bikes. |
| French Tandem | Let us know, if you do! | 28 mm | Let us know, if you do! | 25.4 (1 mm) |
22 mm | Obsolete and rare. |
| 1 1/8" | 34.0 mm | 30.0 mm | 28.6 mm | 26 | 25.4 mm (1") | "Oversized" (This size is more often used for threadless systems.) |
| Moulton | 30 mm top, 36.4 bottom |
33.0 mm | 25.4 mm | 24 | 22.2 mm (7/8") |
Moulton Mark III and earlier. Top headset is standard ISO. |
| 1 1/4" | 37.0 mm | 33.0 mm | 31.8 mm | 26 | 28.6 mm (1 1/8") | Mainly used on tandems |
| Threadless Headsets/Steerers | ||||
|---|---|---|---|---|
| Size/Stem diameter Steerer O.D. |
Frame Cup Outside Diameter |
Crown race Inside diameter |
Notes | |
| BMX/O.P.C | 32.7 mm | 26.4 mm | Used mainly on bicycles with one-piece cranks. | |
| 1" ISO Standard (25.4 mm) | 30.2 mm | 26.4 mm | This is the standard 1" size. | |
| 1 1/8" (28.6 mm) | 34.0 mm | 30.0 mm | Most newer mountain bikes use this size. | |
| 1 1/4" (31.8 mm) | 37.0 mm | 33.0 mm | Mainly used on tandems | |
| 1.5" (38.1 mm) | 49.6 mm | 39.8 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. |
Last Updated: by Harriet Fell
