putting a 9 speed rear mech on 7 speed system

[e-rider]

THIS SHOULD BE IN 'KNOW HOW' - I KNOW; MY MISTAKE - SORRY!

As title.

My hydrid commuter is 7 speed but it needs a new rear mech. I have seen a Shimano Deore mech for £25 but they are made for 9 speed setups.

Will it work ok?

Can I use a 7/8 speed (3 3/2") chain with a 9 speed mech?

 

[Wobblers]

THIS SHOULD BE IN 'KNOW HOW' - I KNOW; MY MISTAKE - SORRY!

As title.

My hydrid commuter is 7 speed but it needs a new rear mech. I have seen a Shimano Deore mech for £25 but they are made for 9 speed setups.

Will it work ok?

Can I use a 7/8 speed (3 3/2") chain with a 9 speed mech?

In a word, yes.

My Galaxy is a 7 speed setup at the back. When it gave up the ghost last winter I replaced it with a new 9 speed Deore rear mech. No problems encountered - even the indexing wasn't far out. You'll be fine with an 8 speed chain and shifters. Just remember to make sure that the limit screws on the derailleur are set correctly.

 

[mr_cellophane]

Don't you have to change the gear levers on the handlebars when you do that ?

 

[e-rider]

I want to keep my 7 speed set-up

just need to buy a new rear mech and they all seem to be 9 spped ones - will it work with my 7 speed stuff, is my Q

ie. will it chnage the 7 gears nicely? or is the 9 speed design going to mess up my gear changes?

 

[Hacienda71]

The rear mech is not indexed it is the levers that are so imho subject to chain width it should work fine. I used a mtb mech on a road bike once with no adverse effects. I would probably stick with the same make levers to mech. Have you looked on Sheldon? The only concern I would have is if the thinner chain of a 9 speed set up means the mech will not take a fatter 7/8 speed chain, short of measuring the clearance I have no idea where you would find the specs to confirm this one way or the other.

 

[RecordAceFromNew]

THIS SHOULD BE IN 'KNOW HOW' - I KNOW; MY MISTAKE - SORRY!

As title.

My hydrid commuter is 7 speed but it needs a new rear mech. I have seen a Shimano Deore mech for £25 but they are made for 9 speed setups.

Will it work ok?

Can I use a 7/8 speed (3 3/2") chain with a 9 speed mech?

Yes and yes.

The difference in width of an 8 and 9 speed chain is typically (because different makes/models have different widths) only 0.5mm.

 

[e-rider]

cheers - off to buy a new rear mech now then (9 speed Deore); all of 0m; just a few clicks away from shiny new bike components - love the interweb!