Chains vs. Wheel Sizes
Comparing 2 standards across 20 specifications. 20 key differences identified.
Bicycle roller chains are standardized under ANSI B29.1 and ISO 9633. Across all modern bicycles, the chain pitch (distance between consecutive pin centers) is strictly 1/2 in (12.7 mm). Drivetrain speeds (1-speed to 13-speed) differ in internal roller width (1/8" for single-speed down to 11/128" for 11/12/13-speed) and external pin length (tapering from 8.6 mm on 1-speed to 5.25 mm on 12-speed chains).
Bicycle tire and rim dimensions are standardized internationally under ISO 5775 and the ETRTO (European Tyre and Rim Technical Organisation) system. Sizing is defined by two numbers: nominal tire width and Bead Seat Diameter (BSD) in millimeters (e.g. 28-622). Major standards include 700c / 29er (BSD 622 mm), 27.5" / 650b (BSD 584 mm), 26" MTB (BSD 559 mm), 650c (BSD 571 mm), and 20" BMX (BSD 406 mm).
Specification Comparison Table
20 Parameters| Parameter / Spec | ||
|---|---|---|
|
Chain Pitch (All Speeds)
|
12.70 mm (0.500 in / 1/2 in pin-to-pin pitch universal) | — |
|
Single-Speed (1s / BMX / Track) Inner Width
|
3.18 mm (1/8 in / 0.125 in roller width) | — |
|
Single-Speed External Pin Length
|
8.60–9.40 mm | — |
|
6/7/8-Speed Inner Width
|
2.38 mm (3/32 in / 0.0938 in roller width) | — |
|
6/7/8-Speed External Pin Length
|
7.10–7.30 mm | — |
|
9-Speed External Pin Length
|
6.50–6.70 mm | — |
|
10-Speed External Pin Length
|
5.88–6.10 mm | — |
|
11-Speed External Pin Length
|
5.50–5.65 mm | — |
|
12-Speed External Pin Length (Shimano / SRAM)
|
5.15–5.30 mm (e.g. SRAM Flattop / Shimano HG+) | — |
|
Maximum Wear / Elongation Threshold
|
0.5–0.75 % elongation (replace at 0.5% on 11/12-speed to save cassette) | — |
|
700c Road / 29" MTB BSD
|
— | 622.0 mm Bead Seat Diameter (ISO xx-622) |
|
27.5" MTB / 650b Gravel BSD
|
— | 584.0 mm Bead Seat Diameter (ISO xx-584) |
|
26" Mountain Bike BSD
|
— | 559.0 mm Bead Seat Diameter (ISO xx-559 classic MTB) |
|
650c Triathlon / Road BSD
|
— | 571.0 mm Bead Seat Diameter (ISO xx-571) |
|
20" BMX (Standard) BSD
|
— | 406.0 mm Bead Seat Diameter (ISO xx-406) |
|
20" BMX (Race / Junior) BSD
|
— | 451.0 mm Bead Seat Diameter (ISO xx-451) |
|
16" Folding Bike (Brompton) BSD
|
— | 349.0 mm Bead Seat Diameter (ISO xx-349) |
|
Road Tire Width Range
|
— | 23.0–32.0 mm (e.g. 25-622, 28-622, 32-622) |
|
Gravel Tire Width Range
|
— | 35.0–50.0 mm (e.g. 40-622, 47-584) |
|
MTB Tire Width Range
|
— | 53.0–66.0 mm (2.1–2.6 in / e.g. 60-622, 65-584) |