I have a seven speed cassette and 3 speed chainring how many teeth should there be on the largest chainring. I am asking because I think I need to get a new chainring.

  • 2
    Just count them. Jun 25, 2019 at 8:44
  • 2
    We need more information - Gearing depends on bicycle type and use. A x3 MTB will have around 42 or 44 teeth, a non-compact road bike typically 52-54.
    – mattnz
    Jun 25, 2019 at 9:25
  • 4
    Are you asking if some teeth are missing, or if you need a different size? If teeth are missing, there'll be a gap where they snapped off. If you want a different size, you must have some reason for wanting that - what is it?
    – Useless
    Jun 25, 2019 at 10:02
  • One thing to keep in mind: The new chainring also needs the correct number of bolt holes and Bolt Circle Diameter (BCD). There’s also a difference between inner and outer rings.
    – Michael
    Jun 26, 2019 at 7:53
  • Some chainrings have the number of teeth stamped on.
    – Carel
    Jun 26, 2019 at 8:05

1 Answer 1


There's no universal correct number of teeth for the largest chainring. For MTB triples 42 teeth is common, while road triples usually have 50 to 53 teeth.

If you think that the chainring needs replacing because teeth are worn off, then counting isn't the way to check. Teeth are evenly spaced, so if one has broken off, then it should be easy to spot. You also need to look at the profile of the teeth. They shouldn't be too sharp or more worn on one side than the other. Google has plenty of pictures of new chainrings and worn ones if you're unsure.


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