9 speed XT/LX indexing problems - help!

Gary P

Über Member
I've been trying to get my 9 speed MTB set up to index properly and it's giving me real grief.

It's a nearly new block/cassette and chain. Both are Shimano 9 speed, as are the shifters. However, the rear derailleur is a long arm MTB but the block is a 12-28 close ratio.

Do I need to change either the block to a 12-34 to accommodate the mech or vice/versa with a road (short) mech to accomodate the block?

It's quality equipment as it's an XT/LX set up so it should all work. Perhaps I'm ambitious trying to fit a more raod-geared cassette?

Any opinions and/or help appreciated.
 

RecordAceFromNew

Swinging Member
Location
West London
You do not need a short mech to index properly. There are a few possible reasons why you are having problems.

Have you ensured the chain is of the right length? You might want to check using this calculator. Each link is half an inch.

Have you followed a good guide on setting up the rear mech step by step? This is a great guide.

If the above can't fix it, please describe the problem you are having with more details.
 

Steve Austin

The Marmalade Kid
Location
Mlehworld
Its should all work fine together. its more of a setup problem, not a component problem. FWIW i've run a 12/25 cassette on similar components with no issue

As RAFN said, what s the problem?
 
OP
Gary P

Gary P

Über Member
I'm using the following process.

1. Set rear derailleur wit grub screw to check for alignment with bottom gog on cassette.

2. Adjust cable play

3. Shifts up towards larger cogs are fine - I can get all 9

4. Shifts down are erratic, sometimes not wanting to go down towards smaller cogs without 2 clicks instead of 1.

Normally to solve this I'd just either adjust the grub screw out or give the cable less tension but whatever I do I can't seem to fix it. If I give it too much adjustment or slack it just won't shift up and down shifting's not much improved.

I think the chain length idea might have some credence.
 

Steve Austin

The Marmalade Kid
Location
Mlehworld
Generally speaking, if its having difficulty going down the block, its stiction in the cable. Can be caused by an old cable set, or a tight loop somewhere
Have you tried smearing a little oil on the cable?
 
OP
Gary P

Gary P

Über Member
OK, so I've checked the cable routing, lubed all the cables, set deraileur alignment and cable tension. I am still able to get positive up-shifts but down shifts are still a bit rubbish, though a little improved. Any ideas left?
 

Welsh Pirate

Well-Known Member
Have you checked that the cable at the nipple end hasn't frayed inside the gear shifting housing?
 

NickM

Veteran
Kinked inner cable is another possibility. Some kinks, hidden inside the outer, are not very obvious.

If in any doubt, save yourself a lot of grief and just replace the inners. There's a very good chance that doing so will make everything hunky-dory once set up.

The rear inner, if OK, can be re-used on the front mech.
 
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