# Bicycle handlebar diameters: 22.2, 23.8, 25.4, 26.0, 31.8 and 35.0 mm

> What diameter is a bike handlebar?

- Category: Everyday mounts › Bicycle
- Kind: Standard part
- Basis: Clamp and grip diameters from Sheldon Brown's handlebar crib sheet and BikeGremlin's handlebar standards; current popularity of 31.8 and 35 from Bikepacking.com's stem-clamp survey
- Page: https://xemstudio.com/objects/bicycle-handlebar-diameters/ · JSON: https://xemstudio.com/api/geometry?object=bicycle-handlebar-diameters · Plain text: https://xemstudio.com/objects/bicycle-handlebar-diameters/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**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.

## Notes

- A bar has two diameters that matter: the clamp section in the middle (where the stem holds it) and the grip section out to the ends (where grips, brake levers, shifters, lights and phone mounts go).
- Flat and riser bars are Ø22.2 (7/8 in) at the grips whatever their clamp size; drop bars are Ø23.8 (15/16 in) at the hoods and drops.
- Clamp sizes in use: 22.2, 23.8, 25.4 (the ISO size), 26.0 (Italian drop bars), 31.8 (oversized, the most common today) and 35.0 (modern trail bars). Older bars also came in 25.0 (French), 25.8, 26.4 and 27.0, not drawn here.
- Files: each diameter as a Ø × 100 mm section, axis on X, plus a DXF of the circle. They are the outside of the bar only: wall thickness differs between bars and is not part of the interface, so the inside is not drawn.
- Most bars swell or taper between the clamp and the grip section; measure where your part will sit. A clamp drawn to the bar Ø closes onto the bar: see handlebar-clamp-rings.

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| bar outside | Ø22.2 / 23.8 / 25.4 / 26.0 / 31.8 / 35.0 | stem, lever, grip or mount clamp of the same Ø | clamp | bar-* |

## Sizes

| clamp or section Ø (mm) | inch | where it is used | from |
|---|---|---|---|
| Ø22.2 | 7/8 in | BMX bars, older mountain bikes and small children's bikes; also the flat-bar grip, brake-lever and shifter section | Sheldon Brown, BikeGremlin |
| Ø23.8 | 15/16 in | the drop-bar grip, brake-lever and bar-end section; also an older British clamp size on 3-speeds | Sheldon Brown, BikeGremlin |
| Ø25.4 | 1 in | the ISO clamp size: most upright bars, older drop bars | Sheldon Brown, BikeGremlin, Bikepacking.com |
| Ø26.0 | — | the Italian drop-bar clamp size | Sheldon Brown, BikeGremlin |
| Ø31.8 | 1 1/4 in | the oversized clamp: the most common clamp size today on road, gravel and mountain bars | Sheldon Brown, BikeGremlin, Bikepacking.com |
| Ø35.0 | 1 3/8 in | the 35 mm clamp on modern mountain (trail) bars | Sheldon Brown, BikeGremlin, Bikepacking.com |
| grip section, flat bars | Ø22.2 (7/8 in) | with clamp 22.2, 25.4, 31.8 or 35.0 | Sheldon Brown, BikeGremlin |
| grip section, drop bars | Ø23.8 (15/16 in) | with clamp 23.8, 25.4, 26.0 or 31.8 | Sheldon Brown, BikeGremlin |

## Where the files are

- Sheldon Brown (Harris Cyclery): [Handlebar and stem dimension crib sheet: clamp and grip diameters](https://www.sheldonbrown.com/cribsheet-handlebars.html) — web — reference (verify at link)
- BikeGremlin: [Bicycle handlebar dimension standards: clamp 22.2 to 35 mm, grip 22.2 / 23.8 mm](https://bike.bikegremlin.com/3784/bicycle-handlebar-dimension-standards/) — web — reference (verify at link)
- Bikepacking.com: [Stem clamp diameters: a brief history and survey results (31.8 most common, 35 on trail bikes)](https://bikepacking.com/gear/stem-clamp-diameters/) — web — reference (verify at link)

## Free STEP/STL (6 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/index.json

- bar-22.2-L100: [STEP](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-22.2-L100.step) · [STL](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-22.2-L100.stl) · [DXF](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-22.2-L100.dxf) — Handlebar section Ø22.2 (7/8 in) × 100 long, axis on X: the outside of the bar (the wall is not drawn); DXF = the exact Ø22.2 circle
- bar-23.8-L100: [STEP](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-23.8-L100.step) · [STL](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-23.8-L100.stl) · [DXF](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-23.8-L100.dxf) — Handlebar section Ø23.8 (15/16 in) × 100 long, axis on X: the outside of the bar (the wall is not drawn); DXF = the exact Ø23.8 circle
- bar-25.4-L100: [STEP](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-25.4-L100.step) · [STL](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-25.4-L100.stl) · [DXF](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-25.4-L100.dxf) — Handlebar section Ø25.4 (1 in) × 100 long, axis on X: the outside of the bar (the wall is not drawn); DXF = the exact Ø25.4 circle
- bar-26.0-L100: [STEP](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-26.0-L100.step) · [STL](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-26.0-L100.stl) · [DXF](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-26.0-L100.dxf) — Handlebar section Ø26.0 (—) × 100 long, axis on X: the outside of the bar (the wall is not drawn); DXF = the exact Ø26.0 circle
- bar-31.8-L100: [STEP](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-31.8-L100.step) · [STL](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-31.8-L100.stl) · [DXF](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-31.8-L100.dxf) — Handlebar section Ø31.8 (1 1/4 in) × 100 long, axis on X: the outside of the bar (the wall is not drawn); DXF = the exact Ø31.8 circle
- bar-35.0-L100: [STEP](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-35.0-L100.step) · [STL](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-35.0-L100.stl) · [DXF](https://xemstudio.com/files/hardware/bicycle-handlebar-diameters/bar-35.0-L100.dxf) — Handlebar section Ø35.0 (1 3/8 in) × 100 long, axis on X: the outside of the bar (the wall is not drawn); DXF = the exact Ø35.0 circle

## How it fits

### Connects to
- [Handlebar clamp rings: split rings for 22.2 to 35.0 mm bars, M4 / M5](https://xemstudio.com/objects/handlebar-clamp-rings/): split clamp ring with the bore = the bar Ø (clamp)

### Alternatives
- [Bicycle seatpost diameters: 25.4, 26.8, 27.2, 28.6, 30.9, 31.6 and 34.9 mm](https://xemstudio.com/objects/bicycle-seatpost-diameters/): the other round tube people clamp to

### Also needed
- [17 mm ball joint for phone mounts (ball stud)](https://xemstudio.com/objects/phone-mount-ball-17mm/): a 17 mm ball on the clamp for a phone head

## Questions

**What diameter is a bike handlebar?**

At the grips: Ø22.2 mm on flat bars, Ø23.8 mm on drop bars. At the stem clamp: 31.8 mm on most current bikes, 35.0 mm on many modern mountain bikes, 25.4 or 26.0 mm on older bikes.

**What size is a 31.8 handlebar at the grips?**

Ø22.2 mm on a flat bar and Ø23.8 mm on a drop bar: 31.8 is only the clamp section in the middle.

**What diameter should a phone or light mount clamp be?**

The diameter where it sits: Ø22.2 out on a flat bar, Ø23.8 on a drop bar, or the clamp size (usually 31.8 or 35.0) next to the stem.

**Is 25.4 the same as 1 inch?**

Yes: 25.4 mm is exactly 1 in, the ISO clamp size.

## Fits with

- [Handlebar clamp rings: split rings for 22.2 to 35.0 mm bars, M4 / M5](https://xemstudio.com/objects/handlebar-clamp-rings/)
- [Bicycle seatpost diameters: 25.4, 26.8, 27.2, 28.6, 30.9, 31.6 and 34.9 mm](https://xemstudio.com/objects/bicycle-seatpost-diameters/)
- [Bicycle fork steerer, 1 1/8 in (28.6 mm), threadless](https://xemstudio.com/objects/bicycle-steerer-1-1-8/)
- [Bicycle bottle-cage bosses: M5 × 0.8 on 64 mm](https://xemstudio.com/objects/bicycle-bottle-cage-bosses/)
- [17 mm ball joint for phone mounts (ball stud)](https://xemstudio.com/objects/phone-mount-ball-17mm/)
- [GoPro-style three-finger mount](https://xemstudio.com/objects/gopro-mount/)