Strange Shimarno Shifting

Sie

I'm currently riding an 07 Dawg Delux, still with the good (kinda) Deore rear shifter and XT mech.
The problem I've been having is that for some reason I can be riding along perfectly in gear, with no problems what so ever, and then *bang* the chain just jumps about like a mad thing. I'm able to re-shoft back into a stable gear again but the problem keeps happening.

I've (with the kind help of my housemates) changed the shifter, cleaned out and greased the cable, checked the mech for any alignment problems. Hell 3 of us have gone over the cable ajustment mid ride but without any sucess.

Have you got any ideas what could be causing this, or have seen this kind of problem before? Ilike I say it holds in gear for a period of time, doens't continually hunt for a gear.

I am going to swap out for SRAM in the near future bit in the mean time this is driving me nuts. :x :evil:

Cheers, Sie

nicklouse

sounds like it could be poor routing or too short outers.

supersonic

COuld it be flex in the suspension? Or does it gradually just get worse? If it is a cable tension wandering thing, then usually half a turn of the barrel on the shifter will sort it.

Definitely need to identify what it is before changing components (or change for known ones form mates that work to compare)

LordBanks

I had a similar thing, when i used to back peddle, sometimes the rear mech would just loose tension and the chain would drop into the frame/wheel sorta area. I couldn't work it out, turns out the jockey wheels where stiff as funk, stripped them and it was sorted, dunno if that helps like. As well, check your chain, i also had 3 split links once which i hadn't noticed, and that was making me chain do odd stuff too.

stumpyjon

Sounds like Nick has a plausible suggestion, what's the terrain like when it ghost shifts? If the suspension is active then cable routing sounds like it needs looking at. Also have you checked the chain for stretch, as it gets longer it won't neatly fit between the sprocket teeth and the roller part of the chain can hang up on the teeth (ultimately wearing the teeth).

Sie

stumpyjon wrote:

Sounds like Nick has a plausible suggestion, what's the terrain like when it ghost shifts? If the suspension is active then cable routing sounds like it needs looking at. Also have you checked the chain for stretch, as it gets longer it won't neatly fit between the sprocket teeth and the roller part of the chain can hang up on the teeth (ultimately wearing the teeth).

the chain it's self is relatively new... But the cassette might be the problem as it might well be just jumping teeth.

the terrain varries alot, it seems to happen when climbing, on smooth runs, down hills, you name it it happens so I have my doubts about it being down to the cable routing, yet it is something to consider none the less.

thanks for the advice guys, given me a couple more options to think about...

Anonymous

Ideally, you should change your cassette, chain, and chainrings at the same time.

BigStu2

Hows the actual deraileur mounting pivot bolt, is it free to pivot as it should. The XTR on my epic semi siezed and hardly moved fowards and back allowing the chain to make a hell of a sound, after a thorough stripdown and regrease all was well.
Also check the conditions of your cables, if they are dirty on the inside they will be slow to move thus giving only a partial gear selection.
If you havent replaced them after a season nows the time as they could be worn inside the housings giving the same results as a dirty cable without any visual evidnce.

gkf9

Sie wrote:

stumpyjon wrote:

Sounds like Nick has a plausible suggestion, what's the terrain like when it ghost shifts? If the suspension is active then cable routing sounds like it needs looking at. Also have you checked the chain for stretch, as it gets longer it won't neatly fit between the sprocket teeth and the roller part of the chain can hang up on the teeth (ultimately wearing the teeth).

the chain it's self is relatively new... But the cassette might be the problem as it might well be just jumping teeth.

the terrain varries alot, it seems to happen when climbing, on smooth runs, down hills, you name it it happens so I have my doubts about it being down to the cable routing, yet it is something to consider none the less.

thanks for the advice guys, given me a couple more options to think about...

I fitted a new chain on my bike Fri but didnt change the cassette coz it looked ok.

Went on a ride sat ,when in the small cog at the rear felt like it wanted to skip or jump off all the time but ok in other cogs, Called in at bike shop on the way and fitted new cassette...all ok now!!

Dont know if thats your prob? Sometimes you get away without fitting a new cassette if your lucky.

BigStu2

1 more thing, have you had the bike since new and have you changed the chain since then and now your having problems, I bet the chain is 1 link too long, this can be seen in top gear if the jockey wheels contact each other.... or if youve tried to correct the problem by fiddling with your High/Low setting screws your deraileur will not shift into top gear fully as it is now restricted in its movement....My mind keeps on working.

supersonic

Jockey wheels contact each other??

Anonymous

Jockey wheels contacting each other sounds like a knackered mech!