Rover88

I've got a 2011 Cannondale Trail SL4 with an 8 speed Shimano Alivio group with a triple FSA Alfa Drive crank. A while back I took a spill and managed to wedge the chain between the large and middle rings. Apparently I bent the two rings in the process. I've been on the road bike pretty heavily this year and need to get my MTB going again for an upcomming trip.

The FSA has a 42, 32, 22 chainring set. I'm not sure I would not be better off just upgrading the crank instead of trying to replace the chainrings. What is compatible with my setup? My best guess would be any 8-9 speed crank.

Thanks in advance for your help.

ColinL

7000-series AL rings are tougher and do cost quite a bit, but not as much as a crankset that would be a worthwhile upgrade. My favorite 'good enough' crank on a budget is SRAM/Truvativ X5. It's the cheapest SRAM crank that comes with a GXP bottom bracket, and a triple 9 speed will run about $150 new. You will need specific tools to remove the FSA crank and also to install the GXP bottom bracket cups.

Going down the new chainring path, you'll need a chainring nut wrench. The park tool cnw-2 is basic but works fine.

If you mix brands on the chainrings, there is a risk that the ramps and pins will be spaced the same between all of them, causing a loss in shift performance. However, if you rarely use your small ring, this may not be a big concern. I like race face turbine chainrings, assuming you can get them in 9 speed. A 9-speed specific chainring or crankset is ideal, since 9 speed chains are a bit wider than 10 speed. This will reduce chain drop.

Rover88

Just to double check, will the 9 speed crank will work with my 8 speed chain?

Rover88

What about a Shimano Deore 9 sp triple?

ColinL

It depends. A number of late-model bikes with 8 speed drivetrains actually have 9-speed chains installed from the factory. My FIL's Felt 29er was this way, so when I upgraded him to 9-speed (using parts I had sitting around), his existing chain did actually work. Check your chain for a model number and see if it's 8 or 9 speed.

ColinL

It would be fine, I just happen to prefer the Truvativ GXP bottom bracket over Shimano's Octalink. I actually think the SRAM crankset is a bit lighter as well.