Bicycle Mechanics - 7-9 speed compatibility

I have a bike in need of a new crankset and cassette. The bike is currently a 7 speed. I am upgrading to a 8 speed cassette since I know the chain can handle it, but I also wanted to uy a new crankset. The crankset I want to buy says 9-speed. Any problems using a 9-speed crankset with a 8-speed chain?

Shimano I presume? Go to Sheldon Brown's website and look for compatibility issues.

yes, shimano. I've been all over sheldon's website -I can never find a darned thing there. His links for cranks are very light on info. I can't find anything on compatibility at all.

yes, shimano. I've been all over sheldon's website -I can never find a darned thing there. His links for cranks are very light on info. I can't find anything on compatibility at all.

It's there somewhere. His basic point, if I recall correctly, is that cranks and chainrings don't care much about speeds. I have run 9 sp chain on a 7 sp crank with no issues. What you want to do should be fine - at least as far a the crankset is concerned. Shifter/hub/derailleur/cassette compatibility is another question. I could be wrong, but I didn't think that Shimano 8 speed cassettes would fit on a 7speed freehub.

I have a bike in need of a new crankset and cassette. The bike is currently a 7 speed. I am upgrading to a 8 speed cassette since I know the chain can handle it, but I also wanted to uy a new crankset. The crankset I want to buy says 9-speed. Any problems using a 9-speed crankset with a 8-speed chain?

no

I have a bike in need of a new crankset and cassette. The bike is currently a 7 speed. I am upgrading to a 8 speed cassette since I know the chain can handle it, but I also wanted to uy a new crankset. The crankset I want to buy says 9-speed. Any problems using a 9-speed crankset with a 8-speed chain?

No, there shouldn't be any problems.

As far as Campy or Shimano goes 5-9 sp cranks are really the same. Most, but not all, 5-7 sp cranks aren't ramped or don't have the pins. These were designed to aid in moving the narrower 9 sp chain. Most 10 sp specific cranks have the chainrings closer in addition to being ramped and pinned.

Good luck

Tim

sheldon brown's article on shimano compatibility (http://sheldonbrown.com/k7.html)

Here's what you want. For chainrings, the width/thickness for different speeds are the same as the cassette sprockets in his table. You will notice a shifting difference if you try to run a narrower chain than chainwheel, eg. a 9 speed chain on an 8 speed chainwheel. Not so much the other way around. The crankset is not important, the rings are.

If you are going to change the cassette, by all means change the chain too. Going to 8-speed instead of 9, just because your current chain will work is the wrong kind of economy.

Chains wear quickly and a new cassette with a worn chain is a sure recipe for skipping. The chain is the least expensive component available. Get a new one.

Thanks y'all! That link was just what I needed, Vpiuva.

Hillrider - it's a recumbent and a brand new chain, so I don't feel like spending the $$$ to chain that as well, and am not bothered by 9 or 8 speed, but since I'm buying new stuff anyway I figured I'd try and squeeze a bit extra hillclimbing ability into it.