SLX/LX compatability problem

topsey_turvey

I'm trying to fit an SLX front mech and am using a nearly new LX shifter. Whatever I do shifting misses out the middle ring. I've tried marking the cable when disconnected and it appears that only one shift is being used (if that makes sense!), with approx half the marking not being pulled through.

The only thing I can think of is that the throw on SLX mechs is different from the throw on LX shifters. This could well be Shimano making us buy extra bits that we don't really need.

Anyone else have similar problems, or suggest a solution?

nicklouse

they should work.
start again and redo it after re reading the info on Parktools.

make sure the cable is the correct side of the clamping bolt on the mech.

topsey_turvey

The Park Tools website doesn't cover it.
There's only one way to connect the cable.
I've disconnected and reconnected several times. Changed the cable for a new one and greased the outers.
The throw on the mech still seems to be out of kilter with the throw on the shifter.
I put my old knackered Deore mech back on, and it works perfectly.

I've been setting front mechs for far too many years to remember, but am totally confused by this.

nicklouse

I am not aware that the LX have gone all rodie flat bar style with the trimming clicks as well?

How many clicks can you get out of it without the mech attached? keep tension on the cable so as not to jam it in the shifter.

Bobhellen

what slx mech are you useing?

m660
M661
m665
m667

nicklouse

Bobhellen
good point if it is the 665/7 then you could have problems as they are for 2 cogs only..

Bobhellen

That’s what I thought Nick as the slx series was originally made for the downhill boys who mostly use 2 cogs.

nicklouse

but it should not miss out the middle ring as per the OP but should work fine on the granny and the middle.

lets see which it is.

topsey_turvey

I'm using a M661 mech.

I've tried two different shifters, and both do the same thing. Both shifters give the normal three clicks. I can measure the take up of cable without the mech attached, and have marked it with a bit of masking tape. When I connect the mech the tape is short of full take up. I put the mech into granny and there is a lot of play in the cable. I take up the play, and when I try and change into middle with just one click on the shifter the mech moves approx 1.85 clicks worth of movement. The big ring scrabbles on the chain, but eventually takes it up. When I click the release the chain goes all the way back to the granny ring. The chain never sits on the middle ring. The mech would move further on another click if the limit screw was to be eased. The cable is showing that only half of the maximum movement has been used up, with just the one click.

It looks as though one click on the shifters is moving the mech far more than one position, which looks like the throw on SLX is different from Deore/XT etc.

stumpyjon

Looks like it needs a fresh pair of eyes. Probably something simple like a limit stop screw is too far in or something. I spent over an hour trying to index my rear mech which I'd just serviced. Couldn't get it to work, all sorts of weird shifting at the bottom of the cassette. Went back to basics and realised that limit screw wasn't adjusted properly.

Back the limits screws right off and have another go. I can't imagine Shimano have changed the shifting ratios.

topsey_turvey

Doesn't appear to be that simple. I've now tried three different shifters; an old battered Deore, a fairly new LX and a 12month old XT. I've used an old battered Deore mech, a 12 month old XT mech and the SLX mech.

All three shifters work with both the Deore and XT mechs. None of the shifters work properly with the SLX - they all miss out the middle ring.

Limit screws don't control the throw, and it's the throw that is causing the problems. One click on the shifters is moving the SLX mech further than the other mechs move. That to me is Shimano changing the ratios, probably to make us buy new shifters when we buy a new mech. Don't know about the rears, but I can't imagine it's any different.

Has anyone else bought SLX mechs without buying shifters as well? It's early days for the SLX range so maybe everyone is buying complete sets at present.

Bobhellen

you sure the cabel is run right

nicklouse

Ok lets take a different look what is the crankset set up.

supersonic

Can we have a close up pic of the mech and especially the cable route into it too?

topsey_turvey

Cables are as near as dammit new. Chainset is bog standard XT, with the correct spacers on B/B.

Photos are a bit of a problem. Mech is now off the bike, and on the desk in front of me. It is set up as a pretty standard top pull unit. It's not the first mech I've had on the frame. If you're desperate for a piccie I'll set it up again tomorrow.

Not wishing to boast, but I've been setting up front mechs since before Bike Radar, and even the internet, existed and I've never seen one work like this. Even if I were a complete mechanical numptyI've tried enough variations today to prove to myself that I can set a mech up properly. Even the battered old Deore that I wish to replace still works. Unless there's some peculiar knack to setting up SLX mechs I don't know what else I can do.

PS. How do you post piccies?

nicklouse

posting pics is in the BR FAQ's

and i bet it is a simple set up problem.

ian_worby

Topsey Turvey wrote:

I put the mech into granny and there is a lot of play in the cable. I take up the play, and when I try and change into middle with just one click on the shifter the mech moves approx 1.85 clicks worth of movement. The big ring scrabbles on the chain, but eventually takes it up. When I click the release the chain goes all the way back to the granny ring. The chain never sits on the middle ring.

Just a thought, but have you tried it without taking up the slack on the cable? i know on couple of my bikes when in the granny ring the cable is fairly slack.

i.e. set it up so the first click puts it on the middle ring (regardless of how much initial play in thecable there may be) an work from there fine tuning as required

Slo rider

Have you checked for the markings on the mech body, a two ring mech could have been put in the wrong packet perhaps??
Also, put the shifter in the middle setting, put the chain on the middle ring and pull the cable nice and tight with the bottom stop screw holding the mech on the central position, back off the stop screw and see what happens when you try the shifting, that may work or throw up some answers.

topsey_turvey

Sorted it, after a fashion.

Seeing as nobody on here believed that I know how to set a front mech up, I asked for help. I got one of my riding mates down this morning with his bike. I didn't touch either bike, but he took his LX mech off his bike and fitted it to mine. Result - perfect shifting. He then put my SLX on his bike. Result - crap shifting. The two of us must have built 25 bikes between us so we must be credited with some mechanical aptitude.

Conclusion:- so many combinations of shifter and mech have been tried and the only trouble is with the SLX mech. It's difficult to see how this isn't causing the problem.

Then I got to thinking....I bought this from Merlin in the shop. I was given just the mech. No packaging or instructions. Even OEM stuff comes in a plastic bag with the part description on it, but this was just plonked on the counter. I'm beginning to wonder if there's a problem with the mech itself, maybe it had been tried elsewhere and been found to be troublesome. Just guessing.

Unfortunately I paid cash and didn't keep the receipt, so can't go back and ask. I'll just have to put it down to experience, and wait for the delivery of a new LX mech from CRC tomorrow. Good job it's not going on my "best" bike!!!