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Bicycle fork steerer, 1 1/8 in (28.6 mm), threadless
What diameter is a 1 1/8 inch steerer tube? · Standard part · basis: White Industries star nut spec (1 1/8 in = 28.6 mm steerer, M6 × 1 thread, nominal Ø26.7 × 15) and Cane Creek top cap spec (S.H.I.S. stem clamp diameter 28.6)
Exact dimensions. Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part. Mating features
- sizes
- 4 in table
Notes
- The threadless 1 1/8 in steerer is Ø28.6 mm outside (1 1/8 in is 28.575 mm; the industry writes 28.6). The stem clamps around it, so a stem-cap or top-cap mount clamps the same Ø.
- The top cap bolt is M6 × 1 into a star nut pressed inside the steerer; White Industries gives the star nut a nominal Ø26.7 × 15. The star nut and top cap are not drawn (their fingers and caps differ by maker).
- File: the steerer as a Ø28.6 × 100 section, axis on X, plus a DXF of the circle (the outside only). Stem faceplate bolt patterns are not standardized between makers and are not drawn.
Sizes
| feature | mm | from |
|---|---|---|
| steerer outside | Ø28.6 (1 1/8 in) | White Industries, Cane Creek |
| top cap bolt | M6 × 1 | White Industries |
| star nut (nominal) | Ø26.7 × 15 | White Industries |
| stem clamp on the steerer | 28.6 | Cane Creek (S.H.I.S.) |
Mating features
Drawn at the exact size. Open press, slide, run and socket features by your process's clearance; leave designed gaps and clamp fits as drawn.
| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| steerer outside | Ø28.6 (1 1/8 in) | stem clamp, headset top cap | clamp | steerer-* |
Where the files are
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| White Industries | Headset star nut: 1 1/8 in (28.6 mm) steerer, M6 × 1 thread, nominal Ø26.7 × 15 | web | manufacturer spec verify |
| Cane Creek (listing by Velomine) | Headset top cap 28.6 mm: S.H.I.S. stem clamp diameter 28.6, fits 1 1/8 in threadless | web | reference verify |
Free files
★ Free files 1 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json
| steerer-28.6-L100 | 1 1/8 in steerer section Ø28.6 × 100 long, axis on X: the outside of the steerer (the wall is not drawn); DXF = the Ø28.6 circle | STEP · STL · DXF |
Plain text: sheet.txt · JSON: /api/geometry?object=bicycle-steerer-1-1-8
How it fits
Connects to
Socket head cap screws, M2–M8M6 top cap bolt into the star nutAlternatives
Bicycle handlebar diametersmount on the bar instead of the stemYou might also need
Questions
What diameter is a 1 1/8 steerer?
28.6 mm outside (1 1/8 in = 28.575 mm).
What thread is a bike top cap bolt?
M6 × 1 into the star nut, on 1 1/8 in steerers.
Can a mount replace the headset top cap?
A top-cap mount takes the place of the cap under the same M6 × 1 bolt; it must still let the bolt preload the headset as the cap does.