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I seem to have developed a problem with my rear shifter. It doesn't index correctly in the centre gears and also I can only select very bottom gear or the very top gear, never both, this is even with the H and L screws set up correctly. Basically the problem appears to be within the shifter, ie it isn't coiling or releasing the correct amount of cable. Is there anyway of adjusting this? Tightening or slackening the cable at the 2 adjustment kernels doesn't work as it just moves the whole cassette indexing.
Do I just need to buy new shifters? If I do that Ill need to buy a new cassette, derailleur and chain also as I'm only on an 8speed currently...
Something has worn out beyond what its meant to deal with.
Shifters almost - almost! - never wear out. Also derailleurs rarely die except for jockey wheel wear / crash damage.
Do you have a chain wear checker (if not get one now).
How old / 1000 miles is the chain, cassette, chainrings?
##Edit - start with the obvious. Sheldon Brown has some good advice. If you are still stuck - or find the usual or an unusual problem please let us know. Cheers,
Ron
I'd start by replacing the cables- inners and outers. At the same time you can open up the shifter pods and degrease/ clean thoroughly before relubing and reassembling.
Chain and cassette are fairly new, probably less than 200 miles on them. Derailleur and shifters are heavily used now and are not the greatest to start with, Shimano Acra if I recall as they came as an emergency from another bike and I never got round to changing them. It appears as though the shifter is no longer able to wind up the correct length of cable. Shifting down from 4th to 1st is exceedingly painful on the thumb!!
Thanks for the follow up.
Well the new stuff narrows it down by about 90%!
How old are the cables? Outers and inners.
That's the cheapest and most probable next source of your problem.
Ambrose is probably right above. What's your bike got? 7 or 8 speed? how old is it?
Before you fork out money replacing anything, check that you haven't bent your mech hanger, as this can give similar symptoms to yours.
The outers are as new as the cassette and but I'm not sure about the inners, I don't know whether my LBS changed them or not when they put the outers on.
Its an 8 speed, I've been meaning to change to XT stuff but as it will be all 9 speed stuff I cant change bit by bit I'd need to buy shifter(s), cassette, chain all in one go and I'm a bit skint at the moment!
I have no idea how I'd check the hanger, guess that would be a LBS job. Maybe I'll replace that when I replace the other stuff. Just have to run on 7 speed at the moment!!
To check the hanger just look at it. It needs to be straight. If you can't tell by eye, put something you know to be straight (like a ruler) next to it.
Shifters normally fail completely and stop working. They never normally go gradually in my experience. My money would be on the rear mech being worn and having play in the pivots leading to poor shifting.
There's quite a bit of play in the rear mech, the jockey wheels and there housing can move quite a bit from side to side. Does this sound like the cause?
Im rather stuck with it though as I'm not going to replace it with another 8 speed mech to then change it to a 9 speed soon. But then I need a 9 speed cassette and chain to go with it.
On another note, ignorant question, what is the difference between 8 speed and 9 speed parts? Does a 9 speed cassette have thinner gears and thinner chain in order to fit the extra gear in? If this is the case I am assuming the chain rings dont matter as they're further apart.
IIRC a 9 speed mech will work just fine on an 8 speed block as the overall shift is the same, it's the shifter which is the difference (and yes, the cassette rings and the chain are thinner) Chain rings. Hmmm. Modern rings will work with both 8 and 9, but older stuff might be a bit too thick to take a 9spd chain.
If you have lots of play in the mech, that could certainly cause mis-shifts and mis-indexing. However, with the shift from 4th to 1st being so hard, and assuming the mech has enough clearance from the cassette (b-screw), I'd go for something being wrong in the shifters/cables.
Thanks for all your responses! Much appreciated! I shall endeavour to fix it when finances allow, and for now I'll put up with fewer gears and use it to increase my fitness!
I enquired at the bike shop at Whinlatter yesterday while riding about my gears. Bloke reckons its mud and crap that has worked its way inside the outers causing the cable to become difficult to move within it. Had a big crash so wont be riding for a while anyway so no hurry to sort it out!