09 sprockets

berglsmerg · Mar 1, 2011

Due to perfect riding conditions today I went out riding. About 15 minutes in there were some strange noises coming from the back of the bike. What I found was uh... messed up. Every tooth on the counter shaft sprocket had sheared off, all that was left was maybe 2-3 mm of the base of the tooth. The chain and sprockets have 93 hours on them which I know is a good innings but why would they suddenly shear off like that ? I ride fairly aggressivley, yet I have never stuck this even on more powerful bikes.

n4hhe · Mar 6, 2011

The teeth didn't just shear off, they were worn down to the point that they were too thin to carry the load.

Haven't run a countershaft sprocket down like that since my 1974 Kawasaki 100 G4TR which had an excessively complex and expensive countershaft sprocket due to the outboard 2:1 gear reduction box. In 1976 a sprocket was $25. Strongly suspect these days it would be cheaper to replace the countershaft with one from a G5 than to find a G4TR countershaft sprocket. Then again I don't really know the G5 part would fit.

Ran the original sprocket on my 2003 KTM 450 down to its very last until it was missing 2 out of 3 teeth. Kept that sprocket out in the garage just for laughs.

steve · Mar 6, 2011

I undertsand that the LDCs have a 13 t cs, and IMHO that is too few. My rule of thumb is to change a cs sprocket 2, or 3 times to a chain, and if I'm using my preferred Chaingang sprockets, I'll get 2 or even 3 chains to one of those.

A cs sprocket typically has 1/3 as many teeth as the rear, and therefore 3 times the load per tooth. As the teeth count goes down, it not only loads each tooth proportionately more, but forces the chain to change direction faster, and further. I believe that with modern chains like an RK EXW, or DID VM that the weakest link in the final drive is the cs sprocket. By changing it before it looks worn, you'll end up with the best value. They are also the cheapest bit to change.

Steve

berglsmerg · Mar 7, 2011

n4hhe said:
The teeth didn't just shear off, they were worn down to the point that they were too thin to carry the load.

Trust me dude they got pulled off I'll post a detail picture

Chaingang are they go hey steve.

steve said:
They are also the cheapest bit to change.

I looked at it the day before and thought it looks like it needed changing. I have been doing a lot of bitumen k's latley on a really worn knobby, maybe they were work hardened and a good blast up the dirt was "enough"

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09 sprockets

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