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Discussion Starter #1
Here is the website I am using. Very very useful tool. Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator
Here is the original post that got me onto the subject.

On the gear commander page, I loaded the stock specs for a tw200. It puts the correct tire size and stock sprocket ratios and allows for input of different combination of sprocket size and chain length.

By playing around with different combos it is easy to see which ones produce the optimal chain and sprocket wear combos.

It seems that the consensus on here is that larger sprockets equal less wear, but I seem to have discovered info contrary to that point, or at least leaning in the direction of "not necessarily"

A 125 link chain revolves 14 times before touching the same tooth of a 14t countershaft sprocket.
the same 125 link chain revolves 52 times before touching the same tooth of a 52t rear sprocket.

same results using a 127 link chain, 14t countersprocket and 55t rear.

compare this to a stock setup

the stock 125 chain revolves 7 times before touching the 14t countersprocket and 25 times for the rear sprocket. not bad, but definitely room for improvement.

if we go by the running opinion that a 15t front sprocket is best, then we need to bounce around with some chain lengths and rear sprockets to get close to the 14/52.

A 126 link chain revolves 5 times before touching the same tooth of a 15t countersprocket. It beats out the first example by 4 revolutions at 59 per same tooth touched on a 59t rear.
A 58t makes things worse, with 5 revs up front and 29 in the rear per same tooth touched.

I tried to play around with different lengths to get the 15t countershaft sprocket to beat out the 14t but that requires a 124 link chain, combined with a 58t rear. the numbers are 15 revs up front and 59 revs in the rear per same tooth touched... and I'm pretty sure (although not 100%) that 124 links is too short when running a 15t with a large rear to accommodate.

Simply put, the 15t countershaft sprocket actually wears faster than a 14t but will extend the life of a rear sprocket when used with the right chain length and tooth count. I don't know if that is good enough, considering the trouble I have sourcing a 15t and anything larger than a 55t..

The 14t countershaft sprockets are CHEAP, as are 52t rear sprockets.

All these factors and the close numbers make me think that there isn't really much to be gained from running bigger sprockets

If I've made a miscalculation or a mistake I welcome the input and corrections. This may be old news to some of you but to me it's fresh info and I'm still working through it all.

Thanks, and happy number crunching! :p

281 Posts
Interesting site, thanks for the link!
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