Aluminum rear sprocket?

I just ordered a front sprocket/rear sprocket/o-ring chain combo from Renthal Express. They insisted the rear sprocket was steel when I ordered it. It arrived today and of course it is aluminum. I need to replace the very worn chain before this weekends race.

Question: Should I use the aluminum sprocket? I've always used steel and have been warned against aluminum. Or should I make an attempt to trade it in locally for a steel version (and probably loose bucks in the process)? Am I going to rip that sucker up in one ride? Or do they just have a reduced life span. I weigh about 185 lbs.


If you're interested in shaving off unsprung weight just use it. It should hold up well with the o-ring chain.

Steel versus Aluminium


- Longer life

Aluminium :D

- Weight loss

- Not just general weight saving but rotational mass, inertia and circular momentum. The more weight on the sprocket, the slower the rotation and the greater the effort on the bike to accelerate. Thus, the true saving is for acceleration purposes.

Another aspect to consider. People say to swap out your chain every time you change your sprocket... I have my doubts if you run a steel sprocket. Ckeck the teeth, If both sides of the teeth are still proportional (menaning you cant tell if there is any wear) then dont change the sprocket. Simple... :)


I run an aluminum sprocket on my CBR900RR. I get about 2 seasons out of a rear. Thats dealing with a lot more weight & horsepower. The aluminum sprockets do wear more than steel, but not that quickly. If you have a new o-ring chain the aluminum will last a long time. Years ago, with the cheap non o-ring chains I could chew up an aluminum rear pretty quikly. The newer o-rings don't stretch like the old ones used to, so chains & sprockets last much longer.


I put on the DID X-ring that Clark recommended and the AL sprocket on my bike seems to be holding up well.


Chris in the Mojave

'98 YZ400F

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