I have a 2x9 crank and cassette system. And I can't get it to go on the last cog because my rear derailer is maxed out. I bought a used and altered MTB and I can see the chain is short. So typically how many links are in a chain for this crank system?

  • There’s no one answer to this question. It depends on the geometry of the frame (chainstay length) and the size of the largest cogs front and rear.
    – Paul H
    Apr 20 at 4:57
  • Welcome to the site - it may help to include a clear and well-lit photo of your drivetrain from the right-hand side, about level with the chainstay. There may be items we can see that might not be obvious to you.
    – Criggie
    Apr 20 at 9:31

1 Answer 1


We can't know, there are too many variables.

There are however plenty of methods to determine a suitable chain length. One of the simplest is to make sure that it's just long enough to go round the big chainring and the big sprocket, with the derailleur pretty much as stretched as it goes. So it sounds like you need a slightly longer chain. It may be that someone bought a 112 link chain and you need 114 (for example), or it may be that they shortened it too much on installation. They may even have taken out a broken link and lost some length.

  • 1
    Additionally, grafting in a short extra piece of chain generally doesn't work because the new links will be worn a different amount, and are likely a different brand/model of chain. Best option is a complete new chain and very likely a new cassette too.
    – Criggie
    Apr 20 at 9:30

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