Author Topic: Chain and sprocket periodicity  (Read 5713 times)


  • When n+1 gets out of hand
Chain and sprocket periodicity
« on: 22 July, 2019, 08:45:38 pm »
OK, so the track bike has 96 links of chain (48") and an 18T sprocket.  This means that, regardless of chainring size, the same sprocket teeth hit the same bit of chain for every 3 laps the chain makes and (importantly) the inner links of the chain, which are the ones that make noise against the sides of the teeth, always hit the same nine teeth.

If your chain is suddenly noisier after a wheel or chain removal, try refitting the wheel so the chain is one tooth along on the sprocket (use the master link as an index, and any engraving on the sprocket).  it may suddenly become quiet again.
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.


  • عربللا
  • onwendeð wyrda gesceaft weoruld under heofonum
Re: Chain and sprocket periodicity
« Reply #1 on: 26 July, 2020, 08:23:16 pm »
I think I read somewhere once that ideally you'd have a prime number of teeth to get maximum evenness of wear eg 47x17
Any fool can admire a mountain.  It takes real discernment to appreciate the fens.


  • Whimsy Rider
Re: Chain and sprocket periodicity
« Reply #2 on: 26 July, 2020, 08:37:16 pm »
Prime numbers spread the wear as evenly as possible but I don’t know if that minimises wear overall. Chains can wear differently around the chain just from manufacturing variations. Inner and outer links wear differently to each other. As long as everything runs nicely and you don’t need to interchange with anything else (e.g. run on a different cog or chainring), I figure the amount of wear is almost irrelevant. I kind of lean towards Roger’s approach.
Wheel meet again, don't know where, don't know when...

Chris N

Re: Chain and sprocket periodicity
« Reply #3 on: 10 August, 2020, 09:32:28 am »
There's something satisfyingly geeky about having two primes.  43/17 is also a really nice gear on 700C wheels.