nodnerb

I was wondering if the chainrings from a 9 speed drivetrain would work with an 8 speed. I want to swap over my crank and am hoping not to have to buy rings.

Thanks for any help.

MattP.

Yes.

nodnerb

Thanks, that's good news. How about using a full 9 speed drivetrain(chain, chainrings, cassette) with 8 speed shifter and deraileur? Would I just have to tune out either the highest/lowest gear or would the shifting be all screwed up?

never

No, chains and cassettes are different.

MattP.

no you would need new shifters and derailleur.

Gorsar

I think what nodnerb is saying is can he use the 8 speed shifters and derailleur but NOT use one of the 9 speed cogs, making the bike effectively an 8 speed. If that is the question then yes. There is also a very good chance (Depending on the derailleur) that you could use it for the 9 speed, in which case you'd only need new 9 speed shifters to fully utilize the bike as a 9 speed.

nodnerb

Yep. That's what I'm asking. I have 8 speed xt shifters/brake levers, and xt deraileurs still in perfect working and cosmetic condition. Plus they look and feel way better than the new xt stuff. I'm parting my other new bike and would love to swap all the new 9 speed drivetrain stuff from it and just use the 8 speed xt shifters and derailleurs for now. I actually can't ever see myself *needing* the extra three gears other than to keep it updated so I may never do it for what it would cost. I know the cogs are closer together on a 9 speed cassette so I was thinking it might not shift right into higher gears. Shifting from high to low gears should be ok I would think becasue you can adjust pretty much infinately with the thumb lever. Its up shifting where the steps are set to release X amount of cable each shift of the index finger I was worried about.

Thanks for all the help. Anymore info is appreciated.

Gorsar

Ahhh, you know what, I could be wrong because that's a great point. I was thinking that simply using the 9 speed chain would be good enough to overcome the closer gears, but you're right, the indexing could be off. Anyone?

willtsmith_nwi

There is no such thing as a 8 vs 9 speed derailleur. The derailleur doesn't index, it just moves over a distance in response to cable pull. 8 speed and 9 speed systems have the SAME spacing between the biggest and smallest cog. 9 speed just squeezes one more in.

The indexing is handled by the shifter. And of course, the shifter is indexing over the spacing on the rear cassette. So to change from one to another, you need to change:
a) Shifters
b) Cassette
c) Chain


There IS such a thing as a 7 speed derailleur. You don't want that at all because the spacing for a 7 speed is different than an 8/9 speed. It IS possible to upgrade from such a system. But any bike that came as a 7 speed isn't worth upgrading.


Don't expect to see 10 speed on mountain bikes anytime soon. There is a big "retro" movement going on right now of individuals who feel that 9 cogs is one too many. SRAM has pushed it's 8 speed stuff up into the X.9 group. Mountain Bike Action ran an article this month on "downgrading" your bike to 8 speed.

Bottom line ... if you have an 8 speed, you probably don't need nine. It bends/wears easier, and snaps easier. It's easier to fall out of alignment because the indexing tolerances are smaller.

willtsmith_nwi

Yes the indexing would be off.

Chain, cassette, shifters ... these things are mated.

derailleur - universal over 8/9 speed equipment. (Except Rapid Rise. Rapid Rise derailleurs must use Rapid Rise shifters. Otherwise your shifting will be 'backwards').

rings - 9 speed rings work just fine with 8 speed equipment. Some report that 8 speed rings work fine with 9 speed chains.