how springy ?

crispy1980

basically, my rear derailluer is still giving me problems. its been to lbs a few times and they have set it up each time and replaced the inner and outer cable ( last one before the derailleur ) ,the last time they said the last section was full of water / grit. i had only ridden it once since the previous visit and it had started to give me problems pretty early on in the ride. ( although it was cannock and very wet ) .
went to llandegla this week and again early on i started having problems. these were exasperated when the chain got jammed round the front chainring pulling the derailleur forward and snagging everything up. it seems i cant get a single ride in without issues. am i just really unlucky or could the derailleur be at fault as i have always suspected? the reason i ask is that it feels a bit sloppy. there doesnt seem to be much spring in it? ie if , when the bike is upside down, you pull on the mech it doesnt spring back to place, you can actually pull it slightly away form the cassette and it will stay there?
help much appreciated as its slowly driving me mad!

cooldad

Doesn't sound right.

crispy1980

this is what i think, but each time i take it to lbs it comes out working fine, it seems to go downhill pretty quick once things start getting rough, which is why im thinking maybe the derailleur is getting knocked out of position? its starting to really annoy me now,the gear change wasfaultlesswhen ihad it and now it seems to be one thing after another. imwondering whether it would be better to replace the lot, but this would mean that i would have to keep the bike long term. cant afford to be spending muchat the moment really.

steelie600

What derailleur is it?? maybe get a cheap replacement off ebay??

crispy1980

its a shimano alivioso pretty cjeap.is it worth paying for a more expensive one? would there be much gain? i was under the impression that shifters are where the gains could be made? cheers, chris

Chunkers1980

More gain in the mech if it does nt work. Id check the cables too

YeehaaMcgee

FYI, the chain sticking to the chainring, whilst not related to the rear derailleur, is also indicative that the drivetrain is in dire need of something. It's usually a sign that the chain and/or the chainrings are worn out.

cooldad

Does sound like a maintenence issue. Bikes need some regular tweeking - if you are taking it in to get cables replaced and mech indexed I'd have a read of the Parktools website and learn to DIY. A bit of regular maintenence stops most annoying hassles. I have perfectly functioning mechs, chainrings etc that are older than most of the forum members.

crispy1980

had another look today, as i would like to get to gripswith it myself. the rear now changes up the gears with noissue. its changing back down thats still a bit niggly and i think i know why now. there seems to be a tension issue as the first click of the down shifter barely moves the cable at all, the second shift then takes up the slack plus shifts gear. this leads to a problem when approaching the biggest cog as the shifter has used up all of itsclicks but the rear is still in second . a further push and hold of the gear changer sends the chain onto the first ring. this is what is then casuing it to make noise andjump about as it is somewhere between the gears. im guessing i need to add a little tension to the cable but which gear should i be in to do this and which way to turn the barrel adjuster? many thanks.

Chunkers1980

Yes more tension.

Barrel adjuster anti clockwise while looking at it.

crispy1980

right, just had a go at this. not sure what to try now. adding tension does get the down changes better, but then ruins the up shifts. turning the barrel clockwise to release tension then sorts this out but ruins the down shifts. i have tried making tiny adjustments and i can get most of the ups and downs fine but whatever i do there seems to be a couple of shifts that still require a double click or the chain jumps about a bit before actually shifting. im thinking that the best way forward maybe to replace the lot and maintain it better ( i bought the bike second hand and im guessing the chain has never been changed, which prob means the cassette is knackered)
quick question,would the front chain rings need replacing as well as the cassette?

mrmonkfinger

Time for a fresh clean cable for the rear mech, from the sound of things.


Usually, if the drivetrain is really worn, its time for new chainrings + chain + cassette all at once... and often it is cheaper to get a whole new crank than it is to buy separate chainrings.

benpinnick

From your first post - check the b-tension screw is in the right place. On more recent mechs its possible to attach them without the screw butting up to the tab. This will leave you with a limp mech so to speak. Also, sounds like you have a slack cable.

.blitz

The mechanism is fairly straightforward to select a lower gear the shifter pulls the cable and the mech moves/extends, to select a higher gear the shifter disengages and the spring in the mech makes it contract, moving the chain onto a smaller cog.

Selecting a lower gear will nearly always work because you're using your thumb to overcome any friction in the cables and tension in the mech.

Selecting a higher gear depends a lot on the mech and the state of the cables.

If it's any help a new mech has quite a bit of return tension in it - much more than turning a door handle for example - but inexpensive ones tend to relax after a short time.

If the chain & cassette have never been changed it's time for some new ones and some clean, fresh cables. Budget for a new mech as well if your old one is like an overcooked noodle. The chainrings usually last longer than the chain & cassette but if they teeth are hooked they'll need replacing

When you're done with your bike, park it with the smallest cog selected at the back it takes all the tension out of the system and will make it last longer.

cooldad

Sometimes it's best to get some new cables, undo everything and set up from scratch, rather than fiddling.

apple eater

cooldad wrote:

Sometimes it's best to get some new cables, undo everything and set up from scratch, rather than fiddling.

I second this. Two hours of ruddy fiddling in the car park at FOD was no good. 5 minutes with a new cable and sorted

crispy1980

http://www.chainreactioncycles.com/Mode ... elID=68154

may be a dumb question, but would this be ok? imalso guessing that the only way to find out which teeth combo ineed is to count the teeth on the current one?

cooldad

If you have eight speed yes, but I would sort out the other problems first.

crispy1980

quick update, i checked the chain to put my mind at ease. used a chain wear checker and the 1.0 side fits in with ease so im guessing it is pretty worn! i know this isnt the root cause of the problems im having but if i replace the lot and start from fresh im sure i can get it sorted. im going to use the bike for a bit yet until it becomes a real nuisance then replace all the drive train at once and see how i go on