Bicycle drive chain standard dimensions

Bicycle drive chain standard dimensions

Updated: 08/11/2018.

This post will give overview of bicycle driving chains standard dimensions. Each chain has three important dimensions: pitch, inner diameter and outer diameter.

 

1. Bicycle driving chain pitch

Chain pitch is the distance at which the pins are placed. It is measured by measuring the distance between 3 links, then dividing it by two.

Chain pitch is shown with green markers, though it is determined by measuring the distance between 3 adjacent pins (blue mark) and dividing it by two. Picture 4
Chain pitch is shown with green markers, though it is determined by measuring the distance between 3 adjacent pins (blue mark) and dividing it by two.
Picture 1

For detailed explanation of chain pitch, and why measuring three pins gives a more accurate result read the post Chain wear (“stretching”). For this post it suffices to say that bicycle chain pitch is exactly 1/2 inch (12.7 mm). This goes for all the bicycle chains, regardless of the speed number.

 

2. Chain inner diameter

Inner chain diameter is the spacing between a pair of inner plates. It is marked in the picture 2.

Inner chain diameter, marked with blue arrows and lines Picture 2
Inner chain diameter, marked with blue arrows and lines
Picture 2

For inner chain diameter there are the following standard dimensions:

  • Single speed chains have inner diameter of 1/8″ (3.175 mm).
  • Multi speed chains, from 5 to 8 have inner diameter of 3/32″ (2.38 mm).
  • Multi speed chains from 9 to 12 speeds have inner diameter of 11/128″ (2.18 mm).
  • “Exotic” standard for freight bicycles is 5/32″ (4 mm).

 

3. Chain outer diameter

Chains for one and multiple speeds differ from each other by the outer diameter. The more “speeds” a chain is designed for, the thinner the outer plates and shorter the pins are (and they protrude less) – so the outer chain width is smaller (i.e. chain is narrower). Inner diameter (width) of all the multi speed chains is almost the same – with only single speed chains having a significantly larger inner diameter.

From left to right: Campagnolo 11 speed, SRAM 10 speed, Shimano 9 sp, SRAM 6/7/8 sp, old 5 speed, 1/8" single speed chain. Note how rollers of all the multispeed chains are of the same width.
From left to right:
Campagnolo 11 speed, SRAM 10 speed, Shimano 9 sp, SRAM 6/7/8 sp, old 5 speed, 1/8″ single speed chain.

Note how rollers of all the multispeed chains are of almost the same width, only single speed chain being significantly wider on the inside.

Pitch is the same for all the chains – they are aligned by length.
Picture 3

As can be seen from the picture 3, the outer diameter differs mostly. This is important for bikes with multiple sprockets, so the chain doesn’t get stuck (too wide), or drop between the sprockets (too narrow). Table 1 gives an overview of chain outer dimensions, by number of speeds.

TABLE 1
 Number of sprockets (speeds) a chain is designed forChain outer diameter (width) in mm
All 6 speed7.8
All 7 speed7.3
All 8 speed7.1
All 9 speed6.6 – 6.8
10 speed old Campagnolo standard6.2
All other 10 speed5.88
All 11 speed5.62
SRAM 12 speed MTB5.25
Shimano 12 speed MTBn/a

For overview of which chains can be combined with which sprockets, read this post: Bicycle chains compatibility:

Bicycle chain compatibility - which chains can be combined with which cassettes (sprockets)
Bicycle chain compatibility – which chains can be combined with which cassettes (sprockets)

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