chain and sprocket ?

[HajiWasAPunk]

I've read and heard that it's a good idea to change the sprockets and chain all at once, less one of the unchanged parts cause premature wear in the other new one.

That said, I assumed our local shops had this stuff and stock and waited until the last minute to get sprockets and chain for my son's CR 85 and they didn't have the front sprocket in. So how bad is it if I go ahead and use the 2 month old front sprocket? The rear sprocket is the one that was shot anyway.

Also, how much longer do steel ones last versus aluminum. The sunstar sprocket seemed to only last a couple of months (he rides 2-3 times a week for usually around 2-3 hours a time).

 

[FruDaddy]

I assumed our local shops had this stuff and stock

Need I address this. If it is only 2 months old, it will probably be OK as the front tends to be steel, not aluminum. Most shops can get the parts in within a week. Often my shops can get my stuff is 2-3 days.

 

[Jaybird]

His sprockets should not be wearing out that soon. There must be something causing it, and it's obviously not the brute force of the bike.

Make certain that the tension adjustment is correct. Just 1/4 of an adjuster bolt turn past perfect can hose the whole set-up. This is probably the single biggest reason for early sprocket wear.

If there is no visible damage to the teeth of the CS sprocket, it should be fine for continued use.
Bear in mind that if you change to a steel rear sprocket without making sure the tension is proper, you risk even more damage to the drive, as the hard steel sprocket will resist any sort of undue stress and pass it along to other components of the bike. Faster wearing chain, seals, wheel bearings, etc...

The steel rear is a bandaid at best. Yes, it will absolutely last longer than any aluminum will when it sees any sort of undue stress. But, the aluminum will last a good long time if the chain is properly cleaned/lubed, and the adjustments for alignment and tension are correct.
Also, the added weight of the steel rear is far more noticible on a mini, than it would be on a full framed bike.