New crankset question

jay-ninja

Hi All. I’m a newbie here. I’ve just bought a GT Avalanche 3.0 to restore and I want to replace the crankset as its knackered.

I counted the rings teeth which are 28/38/48. My question: Does it matter if I fit a 44/32/22 or 42/32/24?

I plan to replace the chain too if that matters.

Thanks.

Wheelspinner

No, it shouldn’t matter since you are going to smaller sizes. If you are replacing the cranks and chain, should also do the cassette as well most likely.

It can sometimes be a minor problem if you go the other way and fit larger rings, since they may not clear the chain stay where it flares out around the rear tyre. Solution there can (sometimes) be to fit a different wider axle BB in the square taper designs.

jay-ninja

Okay, thanks Wheelspinner. I’ve just had the idea to go with a single ring upfront - Like the idea of a simple set up and ditching the front mech and shifter. With 9 speed at the back any thoughts on ring size and other pros and cons.

Wheelspinner

Depends a little on what kind of stuff you ride on. The common size for single front ring is a 32T (middle ring size from your triple). If you're riding a lot of hilly and steep trails, a 30T might help, or if fairly flat and easy a 34.

Might be able to use the cranks you have and find a (single) chain ring to replace the worn stuff if the actual crank arms etc are ok. Fit it to where the middle ring is bolted on now, and just use (probably) shorter chainring bolts. Hard to see in that photo if it's a square taper BB or a Shimano Hollowtech type crank with external bearing BB?

If you go single ring and ditch the front mech/shifter, worth getting a "narrow/wide" style ring to help with chain retention. They also work a little better with the wider variation in chain line that comes from only a single front ring and using all the cogs in the cassette from there.

Some people even leave the front mech on as a chain guide, even without a shifter connected. Just fiddle with the limit screws so it's in the right position and can't move. If your rear derailleur is NOT a clutch type, (and I don't think 9 speed ever were) then you may find some chain jumping and dropping issues with the single front ring and no guide on rougher ground.

With 9 speed cassettes you're unlikely to get anything more than either an 11-34 or perhaps 11-36 range, so be prepared for some hard work if you do hit a serious hill. I'd guess the one fitted in that pic is probably an 11-32 or 34 at most.