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Bicycle drive chain standard dimensions

Updated: 05/01/2021.

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 width

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

For inner chain width there are the following standard dimensions:

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

3. Chain outer width

Chains for one and multiple speeds differ from each other by the outer width. 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 width of all the multi speed chains is almost the same – with only single speed chains having a significantly larger inner 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 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
Picture 3

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.

As can be seen from the picture 3, the outer width 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.

 Number of sprockets (speeds) a chain is designed forChain outer 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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15 thoughts on “Bicycle drive chain standard dimensions”

  1. I ordered a sprocket using the dimensions provided on this page. I was disappointment when after waiting for it to be milled and shipped the sprocket did not fit my application. When I back tracked I realized because the word inner “diameter” was used. I thought this page was referring to the chain roller. After all diameter is used to describe geometry that is circular and the chain width is not circular. The illustration served to perpetuate the illusion because the lines are coming off the roller. Any ways could you update this page with the roller dimensions.

    • I have edited the article. In spite of having put “diameter (width)” on two occasions, I agree it is most probably not clear enough. So I have replaced the (confusing, leading to a wrong impression) word “diameter” with the word “width”.

      Thank you very much for taking the time to report the problem. I’m sure it will help and prevent anyone else from making a (costly) mistake.

  2. Thank you for the input – any corrections are welcome.
    Sorry for your trouble.

    I’ll sleep on this and try to understand what was pointing in the wrong direction and how to improve the explanation. Now I still don’t see it – with all the text and images.

  3. I am attempting to source chain suitable for use with indexing shifters that has a 7.3mm pin length .

  4. Hi, this article got me closer than any other, however, the single thing I wanted to know is missing. I wanted to find out what the outer width of a single speed chain was. Table 3 skipped this entry 🙁 Do you happen to have that chain and could you measure it (not only) for me and fill in the blank in the table?
    Thank you very much!

    • By counting pixels in the picture here I came to a size of 1/3″ (0.3277), that’s 8.3236 mm. Further googling found someone mention it’s about 9 mm. Sounds simillar enough. The maximum width might be even more on the wider join links.

    • New, KMC single speed is 8.7 mm, while an old one from a kids single speed bike measures at 10.7 mm.
      Connect link from the KMC is 9.7 mm wide, so that is effectively the chain’s width for most practical use case considerations.

      Single speed chains don’t need to run between (tightly) spaced sprockets so I suppose the outer width is not as crucial.
      And it seems to vary quite a bit.

    • They indeed vary. For example KMC uses indication H for “Heavy Duty” chains and their pin is 9,35mm instead of standard 8,6mm. I suppose other manufacturers have other dimensions. The same goes for 3/32″ chains designed for single-speed use.

  5. Any updates on 12 speed chain dimensions, specifically 12 speed Campagnolo vs KMC 12 speed Missing Link and SRAM 12 speed Power Link?

    I just ordered a 12 speed Campagnolo group, and since I need to separate my chain quasi frequently to wax it, I want solution other than riveting Campagnolo pins.

    • Still haven’t got any reliable data. No 12 speed drivetrains in my shop so far. 🙁

      Will have to ask trusted fellow mechanics for measurements and will carry a precise vernier caliper on my next travel abroad and use the occasion and double check.
      Only Shimano 12 speed is available in some shops here – didn’t see SRAM, or Campagnolo – Campagnolo is sort of a cycling unicorn in Serbia: everyone knows it’s cool and nice, but (almost) no one has seen it. 🙂

  6. For the purpose of Narrow Wide drivetrains, should more consideration to the width between the inside edges of the “outer plates” be noted? Most Narrow Wide Chainrings state compatibility with 9-11 or 12 speeds. I assume that the “wide” (which I take to mean “thick”) tooth profile fits inside of the “outer plates.” Perhaps these chainrings are not compatible with 8 speed chains because the rings do not fully fill the gap in such chains. Less likely, the “narrow” tooth of such a NW chainring may be 11/128″ thick instead of 1/8″ again not filling the gap between (this time between the inner plates) even if those don’t vary by much. Failure to fully fill either gap may result in failure to retain the chain, thus incompatibility.

    • It makes sense – narrow wide chainrings only come in even tooth counts (no odd ones), for exactly the reason that it’s the only way to make sure that wide teeth always go between the wider (outer) chain plates, and narrow teeth between the narrower (inner) chain plates.

      I would expect 8 (and fewer) speed chains (with 3/32″ i.e. 2.38 mm inner width) to be a less tight fit on those chainring teeth, designed for 9+ speed chains (with 1/128″ i.e. 2.18 mm inner width).

      Unfortunately I haven’t had much experience with the modern 1x drivetrains. Probably will in a few years, as more and more people get that stuff 2nd hand from Germany and the likes. The very thing that made me experiment and document compatibility – a constant lack of “proper” components availability – is what makes it difficult for me to test the newest stuff as it comes out to the market. And the fact I make sure to note all the downsides, and call out any marketing gimmicks I notice, makes me believe that it’s not very likely for the manufacturers to be sending me samples for testing, as they do with some other websites/companies. 🙂

      So I haven’t made any measurements, or experiments with 1x drivetrains yet. I have found an article that does show a few types and different 1x solutions, though without considering compatibility at all, but it’s a start:

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