Broken front SLX derailleur?

Mr Plum

About a week ago I got on my hardtail MTB just to nip out somewhere but literally as I got to the end of my road and tried to change down on the front something gave-way and I could no longer change gear - it was stuck on the big ring. I just assumed that I'd snapped a cable, so I carried on with what I was doing and also picked up a gear cable from Halfords whilst I was out and I've been using my CX bike since.

Now in hindsight I must not have been thinking properly at the time, because my understanding of a front derailleur is that it's sprung to be in the low (small ring) position when there's no cable tension... (?) ...well there is no cable tension and it's stuck on the big ring.

I've now got the bike up on my workstand and no amount of GT85 is getting any movement out of the derailleur. I physically pushed it into the low position and re-set the cable and then tried to change gear... nothing, no movement, not even a slight inclination that it's ever going to move - the shifter even gave way and lost all cable tension, but it now seems to be ok, I'm just a bit concered that I might have damaged that now as well :roll:

Am I looking at a replacement derailleur or is there something really obvious that I've missed?

CraigXXL

Might have had something trapped in the pivots.

Chunkers1980

THis happen to me after the snow - crap from the road after/during got in to the pivots.

Remove, fully clean and lube all the pivots and cycle it through it's motions a few times job done.

Also check the spring is enagaged and it's not just muck that's stopping it.

nicklouse

sounds like a shifter problem.

disconnect the cable from the mech and apply tension and shift does it give or take up cable?

remove the chain. can you move the mech easily?

but if the bike is new just return it for fixing.

Mr Plum

Cheers for the quick replies.

Craig and Chunkers - yeah this is what I thought/am thinking it might be. I've given it a good scrub and sprayed a bit of GT85 at it - hasn't done a thing. About to take it off but can't find my chain tool!!

Nick - I don't think it's a shifter problem. With a disconnected cable at the mech end I can apply tension with my hand and the shifter can happily take up the tension up to a larger load than I can apply with my hand - more than is needed to shift a front mech. The mech won't budge at all now it's in the low position.


Give me 10 mins and I'll post some pics - I don't know if it looks right, but I have a limited knowledge of how the mech works and where the springs should be etc...

Chunkers1980

Can't find your chain tool? You should be using a quick link of some description, much much better.

Looking forward to it!

Chunkers1980

Just a thought - have the stopper (H/L) screws moved?

Neily03

I had the same problem one, a stone was stuck inside the pivots jamming it.

Mr Plum

Sorry for the delayed reply - just gave it a couple of thorough scrubs as I didn't realise how filthy it still was after the first time I 'cleaned' it until I took some pics with the macro...

Not sure if the chain has a quick link - I've never taken it off! :P Totally OT and a real noooob question, but how would I do that? It's only about 8 months old and covered about 1000 miles, so should be good for a little while longer.

Anyways, here's some pics of the derailleur before I gave it a good clean:






What do you reckon?

nicklouse

well first things first give it a clean.

and is the cage touching the teeth?

looks like it is almost in the small cog position.

Mr Plum

Yeah I've cleaned it thoroughly now, got an old tooth brush out...

It's in the lowest position I think it can physically be in, so kind of very badly adjusted so the cage scrapes along the chain, and it won't budge from this position.

Can you tell from those pics if the spring is where it should be?

Chunkers1980

You need to totally move it from the frame. Then cycle it through its movement and check there's spring tension.

Mr Plum

The chain that's on it doesn't have any quick links of any kind, so I guess I'll have to find that bloody chain tool...

Chunkers1980

you don't 'need' the take the chain off. With chain as lose as poss slide it along.

02gf74

you are saying that you cannot move the cage at all?

that can only happen if there is something jammed in the mechanism - assuming it is not moving because the chain is stoping it. or the cable is taut - os the cable slack? you can alays undo the cable from the mech.


check the back end of the cage - on more expensive cages there isa small screw that allows the cage to be opened to allow the chain to pass through - I suspect on lower range stuff there is a rivet so you can't do that.

a side view of the mech showing the chain ring would help - I cannot make much sense from the photos you posted.

i

Mr Plum

Yeah the cage will not move at all, even with considerable force. I think the only way will be to take it off and have a proper look, as others have suggested. I've found my chain tool now but I've sacked off doing anything till tomorrow.

Does this pic help:



It's not straight because I loosened the clamp to take it off but then absently mindedly forgot I couldn't get it off without removing the chain...

A few more for good measure:

ricardo_smooth

Looking at your previous pictures it looks like a build up of crap and grime has done you no favors! Get it taken off and inspect around the springs and use a small screwdriver to scrape out and lodged in dirt and grime, cylcle it through it's movements numerous times and it should sort it, if not the. It's time for the bin for it!