Upgrade - which rear mech to choose?

dodgyknees

Following a run in with a branch at the weekend I seem to be in need of a new rear mech.

Bike is a GT Aggressor XC3 fitted with a Shimano Acera rear mech and Shimano EF-50 shifters. As the Acera mech is now a bit mangled I thought I'd take the opportunity to do my first bit of an 'upgrade' on the bike.

I've been looking at the following mechs on the Chain Reaction site as possible replacements.Your thoughts on these or other options would be appreciated.
Shimano LX Rear Derailleur M571 (M580 Colour)
Shimano Deore Rear Derailleur M531
Shimano LX Rear Derailleur M581

Really just looking for a good quality reliable mech that isn't too expensive and will fit back onto the bike with minimal fuss.

Splasher

Presumably your current drivetrain is 8 speed. I can't remember whether a 9sp mech works with a thicker 8 speed chain (I think it does but there are others on here that know better) so you need to check.

Of the 3 I'd go with the M581 since it's a 2007 design.

Cornish Trekker

just to confirm that you can use a 9 speed mech on an 8 speed setup, I have an LX rear mech which works beautifully (long cage version)

dodgyknees

Thanks for the advice Splasher & Cornish Trekker.

Current drivetrain is 8 speed (24 gears).
I must admit I was leaning towards the LX M571 (M580 Colour) mainly because it's selling for £19.99 on Chain Reaction when the RRP is £34.95, hence sounds like a good deal.

However the M581 sounds (and looks) good and is presumably the later model.

supersonic

Cant go wrong for 20 quid - I wouldnt spend any more than that, given the Acera EF50 shifters, you wouldnt notice much improvement in shifting.

Underscore

dodgyknees wrote:

Your thoughts on these or other options would be appreciated.
Shimano LX Rear Derailleur M571 (M580 Colour)
Shimano Deore Rear Derailleur M531
Shimano LX Rear Derailleur M581

Really just looking for a good quality reliable mech that isn't too expensive and will fit back onto the bike with minimal fuss.

Well, I have first hand experience of the two LX mechs. I have the M581 on my MTB and very nice it is too.

I have also recently replace the Acera mech on my commuter with the M571. I works fine with the 8 speed drivetrain on that bike and shifts very nicely - though not as well as the MTB. My guess is that this is due to two things: 1) The newer 9spd drivetrain and Deore shifters on the MTB, and 2) even with the angle-of-dangle screw (a.k.a. B-screw) loosened off to the max, I wasn't able to get the mech quite as close to the cassette as I would like. It is on my list to revisit this.

So, in short, I think that you will be more than happy with either of the LX mechs.

HTH,

_

dav1

are you ever planning to go 9 speed? If so you can get a decent rerart mech now to take the blow off the rest of the upgrade when the time comes.

cee

Dav1 wrote:

are you ever planning to go 9 speed? If so you can get a decent rerart mech now to take the blow off the rest of the upgrade when the time comes.

Surely with any of those mechs, you just need the rear shifter, cassette and the indexing will take care of where the mech goes?

dodgyknees

I'm trying hard to resist the siren voices pulling me onto the 'upgrade' path, very tempting though it is. So at present I've no plans to go to 9 speed.

That said though I have been looking at gear shifters, but no..........I must resist.

cee

dodgyknees wrote:

I'm trying hard to resist the siren voices pulling me onto the 'upgrade' path, very tempting though it is. So at present I've no plans to go to 9 speed.

That said though I have been looking at gear shifters, but no..........I must resist.

Fair enough.......but just in case you want to in the future, I reckon any of those mechs will do you fine (i have been known to wrong in the past......it could happen again i suppose)

stumpyjon

Surely with any of those mechs, you just need the rear shifter, cassette and the indexing will take care of where the mech goes?

I think the jockey wheels are narrower on a 9 speed mech to cope with the narrower chain, hence a 9 speed mech will work with an 8 speed set up but an 8 speed mech may not work so well with a 9 speed setup. There again I may just be talking b*ll*cks.

dav1

9 speed mechs are fine on an 8 speed setupas the spacing of the cassettes is the same.

My poiunt asbout going to 9 speed is if you want to go to 9 speed in the future you may as well get a good mech now. Waste of money to buy one, then upgrade the shifter and cassette only then to want a better rear mech to go with the new shifter.

cee

stumpyjon wrote:

I think the jockey wheels are narrower on a 9 speed mech to cope with the narrower chain, hence a 9 speed mech will work with an 8 speed set up but an 8 speed mech may not work so well with a 9 speed setup. There again I may just be talking b*ll*cks.

That sounds reasonable to me.

Dav1 wrote:

9 speed mechs are fine on an 8 speed setupas the spacing of the cassettes is the same.

My poiunt asbout going to 9 speed is if you want to go to 9 speed in the future you may as well get a good mech now. Waste of money to buy one, then upgrade the shifter and cassette only then to want a better rear mech to go with the new shifter.

Apologies.

We are saying the same thing I think

dav1

dodgyknees wrote:

I'm trying hard to resist the siren voices pulling me onto the 'upgrade' path, very tempting though it is. So at present I've no plans to go to 9 speed.

That said though I have been looking at gear shifters, but no..........I must resist.

im going to wait tillive worn my drivetrain to death then think about 9 speed when i need a new chain, block and chainrings anyway.

dodgyknees

Thanks for your views guys, I think I'm going to go for the Shimano LX Rear Derailleur M571 which should also enable me to upgrade to a 9 speed setup later.

Just hope I can get the new mech attached and setup without too much hassle.

supersonic

If you do plan to go the whole hog, will need new chain, shifters, cassette and maybe chainrings. The cassettes, though the same width, have different cog spacings 9spd shifters pull a diferent amount of cable per click.. Mechs are dumb - they do whatever the shifter tells it! 9spd mechs are perfectly fine on 8spd set ups.

Will Snow

dodgyknees wrote:

Thanks for your views guys, I think I'm going to go for the Shimano LX Rear Derailleur M571 which should also enable me to upgrade to a 9 speed setup later.

Just hope I can get the new mech attached and setup without too much hassle.

welcome to the dark art of... rear deraliuer setting up

ride_whenever

Should've gone for an xt shadow mech...

Super sexy, harder to hit and less rattley...