9spd Chainset and 7Spd Freewheel ? HELP

[clarkythe1st]

I have stripped an old GT frame and need some help ! I have two sets of wheels both with Shimano 7sp Freewheels. Im about to buy a new chainset and was wondering if I can use a 9speed chainset with a 7 speed Freewheel ? The front and rear mech are still 7 speed. Any help appreciated..

 

[cachehiker]

Originally posted by clarkythe1st
I have stripped an old GT frame and need some help ! I have two sets of wheels both with Shimano 7sp Freewheels. Im about to buy a new chainset and was wondering if I can use a 9speed chainset with a 7 speed Freewheel ? The front and rear mech are still 7 speed. Any help appreciated..

My experience has been with 8 speed but this is how things have worked for me.

A 9 speed chain with a 7/8 speed crankset and front derailleur will not shift as well as it is supposed to. The rear will shift just fine. If you go to a 9 speed crank and front derailleur and leave the back as a 7/8 speed, everything will work much better.

Unless you actually want to upgrade the crank and derailleur, I'd use a SRAM PC-68 chain on it. My Shimano chains have shifted quicker, but the SRAM chains have tolerated marginal chain lines and other anomalies better.

 

[ireman_1]

The "official" answer is likely no, but there have been weirder combinations that (anecdotally) have worked. The rings/cogs are somewhat thinner on most of the 9 speed stuff you will deal with and the chains allow for smaller widths in them. I have witnessed this translating into "sticky" shifting or crappy shifting altogether. You can easily find 7/8 speed chains out there at any LBS or any of the discount web places. They are cheaper as well, typically. If you are sticking with the 7 speed derailluers and such there is no need to buy a 9 speed chain, in my experience. Good luck.

K.

 

[clarkythe1st]

Originally posted by ireman_1
The "official" answer is likely no, but there have been weirder combinations that (anecdotally) have worked. The rings/cogs are somewhat thinner on most of the 9 speed stuff you will deal with and the chains allow for smaller widths in them. I have witnessed this translating into "sticky" shifting or crappy shifting altogether. You can easily find 7/8 speed chains out there at any LBS or any of the discount web places. They are cheaper as well, typically. If you are sticking with the 7 speed derailluers and such there is no need to buy a 9 speed chain, in my experience. Good luck.

K.

Whoops.. Being in the UK I've got my terminology wrong !! I meant buy a 9 speed Crankset and use it with a 7spd freewheel at the rear. I'm understanding you are right though that the 9spd crank set will use a narrow chain which wont be too happy on the standard width 7spd rear set up. Especially when down shifting under pressure I guess. Back to the drawing board..

 

[dabac]

Originally posted by clarkythe1st
I meant buy a 9 speed Crankset and use it with a 7spd freewheel at the rear. I'm understanding you are right though that the 9spd crank set will use a narrow chain which wont be too happy on the standard width 7spd rear set up. Especially when down shifting under pressure I guess. Back to the drawing board..

No, I think you got it wrong. At the front you shift by putting pressure on the outside of the chain, so a thinner (9spd) chain will perhaps not work as well with a wider (7spd) front derailleur). At the rear shifting is done by moving the chain from its centre line, you have the pulley wheels that "should" be able to keep a thinner chain reasonably centered even in a wider 7spd rear derailleur. As long as the shifter matches the frewheel/cassette there is a good chance that it will work.

 

[boudreaux]

Originally posted by dabac
No, I think you got it wrong. At the front you shift by putting pressure on the outside of the chain, so a thinner (9spd) chain will perhaps not work as well with a wider (7spd) front derailleur). At the rear shifting is done by moving the chain from its centre line, you have the pulley wheels that "should" be able to keep a thinner chain reasonably centered even in a wider 7spd rear derailleur. As long as the shifter matches the frewheel/cassette there is a good chance that it will work.

Correcto, a 9 speed chain works fine on a 7 speed rear. sometimes even ok on the front even with a 7 or 8 speed FD, depending on the shifters being used.