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PostPosted: Wed Aug 08, 2012 2:26 pm 
retrobike rider / Gold Trader
retrobike rider / Gold Trader
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Location: Stockport, staring at the Peaks
Eeee, a multi-quote reply, everybody loves these :oops:

legrandefromage wrote:
double check your cable clamping as above. that will ruin it.


I did, once bitten... :wink:


biglev wrote:
Yeah what the big cheese said plus:

Check chain alignment
Is the bottom bracket axel the right lengh to give a good chain line
is the hanger bent (or nto tight if its replacable)
Is the rear axel bent affecting alignment

cheers
pete


All done yesterday, including a new hanger and a different wheel (that's been working fine elsewhere).

Reluctant wrote:
That's a Shadow type rear mech, right? The cable goes "in front" of the pinch bolt as you look at it from the drive side. Ummmm - check that the last loop of outer is long enough to allow free movement, but not too long. All the parts you're using should be compatible, so it's most likely an excess friction/routing type issue. Good luck!


Not a shadow, no, but I think you have to be right with the friction issue as Cheesy mentioned earlier too.

What put me off that idea is that I can get the top three/four or bottom three/four sprockets shifting smoothly, but the difference between the adjustment is 16 clicks, so two & a half full turns! This has got me chasing the bent/alignment side of things, plus the original hanger was one I'd straightened so initially wasn't 100% on that. New hangers made no odds though, tried both an OEM (crap) and a BETD.

However I've lengthened the last loop anyway (no better) and stripped the shifter which does seem to be snapping very strongly into place. So it has to be cable drag or the mech and the mech feels strong & smooth.

So I've employed an assistant to pedal/shift whilst I apply the gentlest pressure to the mech, to assist the spring and guess what? It seems to be doing the trick! 8)

So the simplest solution, as always seems to be the correct one. In the old cables this would make sense (hence the change), not sure why I'd have drag in brand new cables though :? Nice stuff too:
http://www.alligatorcables.com/i_link.h ... 1&KindID=1
The last open section does touch the chainstay, but pretty sure it's not enough to cause any trouble and wouldn't differ between gears anyway

So - Bullet tensioner? :wink: :lol:


Chasing a bit more info then I might have to own up to what I think I've done wrong...

Thanks for all the ideas so far :D


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 Post subject:
PostPosted: Wed Aug 08, 2012 2:29 pm 
retrobike rider / Gold Trader
retrobike rider / Gold Trader
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Twain, that's very interesting, cheers for the link. Sort of the opposite problem though! The shifters half apart at the moment so that I could watch it working so I'll go and have a look for that anomalous (or superfluous) spring!


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PostPosted: Wed Aug 08, 2012 2:45 pm 
retrobike rider
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if you see the spring - bung us a pic to show us how its installed before you remove it. i havent taken apart my other shifter yet to see if its had the same treatment (haven't had any problems with it to warrant taking it off and looking)
kinda thought it wasn't the solution you were looking for, but interesting issue you might wanna check up on all the same! i quite like it as a group set, nice light shifting (when it eventually works!)


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PostPosted: Wed Aug 08, 2012 2:54 pm 
retrobike rider
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If an outer cable isn't quite long enough and doesn't go all the way into the cable boss it can cause this (or something similar).


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PostPosted: Wed Aug 08, 2012 5:10 pm 
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My guess would be limit screws too tight and hence cable set incorrectly. I've done this so many times I can basically do the limit screws by eye, tension the cable with pliers and not need any further adjustment.

Limit screws, set this by moving the mech by hand and comapring the jockeys to the gears, the jockey should ever so slightly reach the outside of the cassette (both sides).

With the limit screws set, pedalling the bike by hand upside down or in a stand you should be able to reach all the gears by moving the mech with your hand.

Once here, pedal and let the mech return to it's resting position, pull the cable tight with pliers so any loose sections twang like piano wire, do the clamp up and you should be away.


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PostPosted: Wed Aug 08, 2012 5:49 pm 
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Best off reset and start from scratch/zero

no chain or cables plugged in - set rear mech hi and low limits screws
check mech fro tight spots in the pivots/parallelogram and/or excessive play in same- it is possible for there to be play only in certain arcs of movement.

Check shifters operate correctly up and down the gears - lube if necessary. could be some crud or gunk sticking it up or the cable is being fouled (shimano ar great in that no 2 are the same for more than 2 years in a row)

Fit cables - tension adjusters screwed in. Make sure routing is smooth and free of tight turns or excessively long runs. Make sure ferrules are tight on the outers and that they themselves are seated in the cable stops properly - I had a massive ball ache with my LTS getting the front to rear triangle cable just right without it being interfered with by the suspension action adjusting the tension (but only in certain gears under chatter bumps)

If the gears are set up roughly right you should be able to select each gear on the block and see if the problem is there before fitting the chain - i.e the jockey wheel sho0uld line up wiht the selected cog (or at least


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PostPosted: Sun Oct 07, 2012 9:30 am 
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Right ive just had a huge bout of this myself.

I could get the mech to shift all the way down the block to the lower gars fine but half way up it would slow down then basically miss a gear.

I suspected the casette as i was using a 7 speed 12 t to make up an 8 speed cassette
then graunchy shifter - cleaned and lubed - nope
Then the rear mech - some worn and wobbly pivots- a good possibility - cleaned (utterly manky! no grinding now though!) it so so improvement at best
I replaced the mech with an LX one which was in fine order and the same thing :(

After tearing my hair out for hours i replaced the last loop of outer cable housing (as in - i re sued one taken from my - looks ok hasn't been used much pile)

A fresh section of outer and it worked flawlessly. so on went he wobblyish rear mech and it shifts fine with that too. Seems it was causing too much drag for some reason and despite being throughly lubes was causing the greif.

Did you sort your mates out?


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PostPosted: Sun Oct 07, 2012 1:59 pm 
National & North West AEC
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I'd first suspect that it's your cables dragging. As you've tried new ones then this kind of eliminates it, assuming the routing and cable outers are all in good order.

Check the B-tension screw too as well as the B-tension pivot. This can often get corroded and sticky and it's easy to overlook.
A sticky pivot can cause the problems you describe.

Image

It's always good fun taking this apart...

Failing all that it could be a shifter issue. Flush it through with WD-40 or GT-85 and see if that improves matters.

Pop round and I'll have a look at it if you're head is still hurting


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 Post subject:
PostPosted: Sun Oct 07, 2012 2:38 pm 
Gold Trader / rb Rider / Special
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Beat me to it ^ b tension and or chain length?


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PostPosted: Wed Oct 10, 2012 12:59 pm 
Gold Trader
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Pete, are you just still hungover from that fine whisky you were gargling with?


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