# Rear sprocket diameters

5 replies to this topic
• # 426 NOOB

Posted March 16, 2010 - 06:49 PM

Has anybody ever done measurements on a rear sprocket to see what a difference 1 tooth makes in the sprockets diameter? Just curious as to what the diameter difference would be going from a 52 to a 51 tooth. My guess would be 1/8 inch.

• # grayracer513

Posted March 16, 2010 - 07:35 PM

Has anybody ever done measurements on a rear sprocket to see what a difference 1 tooth makes in the sprockets diameter? Just curious as to what the diameter difference would be going from a 52 to a 51 tooth. My guess would be 1/8 inch.

Do the math:

You know that the pitch of your 520 chain is 5/8". That being the case, a 52 tooth sprocket will have a circumference of 52x.625=32.5", and a 51 would be 5/8 shorter at 31.875. Dividing by Pi, that gives you 10.345" and 10.146" respectively for the diameters, and the difference is .199", or just over 3/16".

• # 426 NOOB

Posted March 16, 2010 - 08:13 PM

Do the math:

You know that the pitch of your 520 chain is 5/8". That being the case, a 52 tooth sprocket will have a circumference of 52x.625=32.5", and a 51 would be 5/8 shorter at 31.875. Dividing by Pi, that gives you 10.345" and 10.146" respectively for the diameters, and the difference is .199", or just over 3/16".

damn, gray you are smart. I would have never figured out how to do that. Thank you.

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• # grayracer513

Posted March 16, 2010 - 09:02 PM

Geometry 101

They told you you'd want to know it later.

• # CaptainKnobby

Posted March 17, 2010 - 05:33 AM

Geometry 101

They told you you'd want to know it later.

Yeah!.....but how do you still remember it after all those years?

All those formula's?

• # grayracer513

Posted March 17, 2010 - 09:36 AM

If you just remember that they exist, you can look them up when you want them.

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