How can I tell which size chain my bike uses?

  • After learning how to break a chain and reattach it, and also how to add and remove a master link, I find that I can now do much more in the way of maintenance at home. I'll no longer need to bring my bikes into the shop simply for a new chain... if I can only figure out how to identify what size chain I'll need to order.

    Is there a simple way of telling what size and type of chain I'll need to order to replace the chain on a bike? Do I measure the chain links? Count links? Count gears on the cogs?

    If it helps, some of my bikes' drivetrains have internal hubs, some have derailer gears.

    @hhh - Definitely related. Good background info there, but the question doesn't get into how to ID a given chain's size. (Thanks for the link, I added the [chain] tag to that question to make it easier to find.)

    Bought a used carbon bike and I'm going through the motions of customizing it. I'm new to cycling but have the mechanical aptitude/ "fix it myself" curiosity. Chain broke on my first ride, for the first time ever. All other tri or steel road bikes I use, have never done that. I've repaired a link on a mountain bike once but I was overwhelmed w/ all the different type of chains online. I feel bad asking these questions to my LBS, due to the fact I'm spending my money online. This page answered all of my questions (although I have questions to many other cycling needs). Thank you so much!!!

    Actually 10 speed is not "one more" than a 9 speed. What people call 10 speed is a "2 chainrings x 5 sprockets" bike, and what is called 9 speed is a "(N) chainrings x 9 sprockets" bike. Since there are 9 sprockets on the rear, the chain for a 9 speeder is narrower than chain for a 10 speed bike.

  • pdw

    pdw Correct answer

    10 years ago

    If you are using a bike with a derailleur the number of cogs on the rear hub will determine the chain size you will need. They are always 3/32" chains.

    You can get a 5/6/7-speed, 8-speed, 9-speed, or 10-speed chains.

    If you can't find a chain that matches your cluster pick a chain for a larger number, for example if you have an eight-cog cluster you can use a eight, nine or ten-speed chain, but you shouldn't use a 6 or 7-speed chain.

    Internally geared hubs will have their own specification for the size chain they require, and single-speed, fixie, BMX bikes, and probably some older bikes use 1/8" chains.

    I have some IGH bikes and some derailer bikes; will add that to my original question to help clarify what I'm looking for.

    and 11 speed chains. You can probably also get 5 speed chains but I think they might be the same width as 6 speed (SRAM and Shimano both just sell 5-6-7 speed chain these days). Campagnolo 10 speed chain is not compatible with Shimano 10 speed chain, and there's a third brand of chain/cassette/derailleur/shifter that's not compatible with either despite claiming to be. Summary: 10 speed is a pain.

    A few hub gears use 8 speed chain, most use 1/8". It's determined by the cog thickness, as a 1/8" chain will tend to catch on the teeth of a 3/32" cog. Similarly with chainrings.

    The info regarding number of gears for a chain here is incorrect. 5,6, and 7 speed chains can use the 7 speed. 7,8,9,10 and 11 speed chains each use a specific chain. None of these are compatible with each other. I might use a 7 or 8 speed interchangeably, in an emergency, but I wouldn't recommend it.

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Content dated before 6/26/2020 9:53 AM