Bicycle Mechanics - Has anyone combined a 9spd crank and 7 spd rear successfully?

Right now i'm running a rear 7 speed set up. HG70 cassette and chain, with STX components. And recently i just bought a XT mega 9 crank. The question is, has anyone successfully combined a 9speed crank and 7 speed rear successfully? If not, i think i'll have to upgrade the rest of the bike. Getting the crank soon, so i'll let you know if i'm successful.

What do you all think?

Ok, This could be an answer. Is there a 7spd cassette that is thin enough for use with a 9spd chain? Or can we use a 9spd cassette minus 2 of the gears?

Please help me resolve my foolishness!

One of my friends uses a nine speed rear hub, crank, and deraillures with a spaced seven speed cassette and thumb shifters. He has had no problems but is thinking of finally making the change to eight speed due to a short supply of seven speed shifters.

I install 9 speed cranks on 7 and 8 speed system all the time, they shift great, just use a quality 9 speed shimano chain and you won't have any issues. Teh systems work well together.

Thanks guys, you make me feel a lot better. HAHAHA!

So what's the best 9 speed chain?

CN-7701 shimano, 6.6mm wide with hardened pins. Nothing shifts or improves shifting on a shimano system more.

In general front cranksets are not 7,8, or 9-speed specific. They're either doubles or triples. As all above have mentioned...it'll work fine.

Thanks for all the help guys. Basically, i always freak out. I should be getting my crank in a couple of days and will update the outcome. Yeah, I found some websites saying that all i need is a nine speed chain and that should work.

stick with your 7-speed chain if your keeping a 7-speed rear. I ran a 9 speed xt crank / 7 speed stx rear for almost two years with no problems at all.

A crank is a crank.

I would think a seven speed chain would be better.

In general front cranksets are not 7,8, or 9-speed specific. They're either doubles or triples. As all above have mentioned...it'll work fine.

The 9 speed cranks have slightly narrower teeth for optimal derailment of the narrower chain on and off the chainrings and the chainrings are spaced slightly closer for faster shifting with the narrower chain. Going in the direction you are, you are less likely to notice the difference than someone going the other direction. Most people going in the opposite direction of you find the shifting change tolerable. You should be able to keep the same indexed shifters up front, just less tolerance in the calibrations than with shifters designed for 9 speed chainring intervals. The worst problem you would have with the off size Chainrings is SLIGHTLY rougher shifting. And you will get a slightly better Q-factor.

I’d stay with the wider chain since the tighter spaced cassette is apt to be more temperamental with the off size chain than the chainrings.