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PostPosted: Wed Aug 08, 2012 12:15 pm 
retrobike rider / Gold Trader
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First up, apologies it's not a proper retro, but I cannot seem to get Kiran's gears shifting properly at both top and bottom of the cassette - it's either one or the other and then it runs out as if it's pulling/releasing too much cable per shift :?

Set up is:
m770 shifters
m770 rear mech (tried two with various jockeys - OEM, Tacx, KCNC)
Various cassettes including m770, m760, m970 and SRAM XO
Few chains, new and used, KMC 9SL, SRAM, Shimano XTR
Swapped from ordinary cables to i-Link, no change
Two OEM mech hangers and a new BETD

The only thing I haven't swapped (yet) is the shifters themselves, nothing else has made any difference. It's very much like the time I mounted a gear cable the wrong side of the clamp bolt (some road mechs gave you two options to work with both 7 and 8 speed without changing shifters).

Am I missing something? The frame's ally so shouldn't be bent (although I am checking now)!


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PostPosted: Wed Aug 08, 2012 12:24 pm 
retrobike rider / Gold Trader
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Interesting. Only thing I can think of would be to check the limit screws and make sure I was using compatible gear, ie 7 speed shifters and cassette, not 7sp shift and 8 speed cassette etc. Other than that, I would be curious to hear the solution to this.

Shifter missing a 'click'?


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PostPosted: Wed Aug 08, 2012 12:32 pm 
King of the Skip Monkeys
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Location: Moomin Valley
sticky cables?

Kink in the cable?

sticky rear mech (almost impossible to detect)?

Always use Shimano jockey wheels for proper shifting btw.


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PostPosted: Wed Aug 08, 2012 12:33 pm 
retrobike rider / Gold Trader
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Whatleymeister wrote:
Interesting. Only thing I can think of would be to check the limit screws and make sure I was using compatible gear, ie 7 speed shifters and cassette, not 7sp shift and 8 speed cassette etc. Other than that, I would be curious to hear the solution to this.

Shifter missing a 'click'?


That is the phenomena for sure, but it's all matching m770 9sp (shh!).


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PostPosted: Wed Aug 08, 2012 12:35 pm 
King of the Skip Monkeys
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double check your cable clamping as above. that will ruin it.


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PostPosted: Wed Aug 08, 2012 12:36 pm 
retrobike rider / Gold Trader
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Location: Stockport, staring at the Peaks
legrandefromage wrote:
sticky cables?

Kink in the cable?

sticky rear mech (almost impossible to detect)?

Always use Shimano jockey wheels for proper shifting btw.



Changed mechs and fitted new cables and outers. You're suggesting the mech isn't pulling strongly enough due to stiction somewhere? That makes sense to me too but I haven't managed to track it down :?

Might fit a bigger rear loop or a rollermajig this afternoon....


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PostPosted: Wed Aug 08, 2012 12:58 pm 
retrobike rider / Gold Trader
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Location: Getting fitter, I will beat the Surrey Hills....
elPedro666 wrote:
Whatleymeister wrote:
Interesting. Only thing I can think of would be to check the limit screws and make sure I was using compatible gear, ie 7 speed shifters and cassette, not 7sp shift and 8 speed cassette etc. Other than that, I would be curious to hear the solution to this.

Shifter missing a 'click'?


That is the phenomena for sure, but it's all matching m770 9sp (shh!).

Don't worry mate. Between you and me, I am running 9sp too... :oops:
The purists will see us burn if it ever gets out!


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PostPosted: Wed Aug 08, 2012 1:11 pm 
BoTM Winner
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Location: Guernsey
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


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PostPosted: Wed Aug 08, 2012 1:42 pm 
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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!


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PostPosted: Wed Aug 08, 2012 2:25 pm 
retrobike rider
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weird, but i had a similar problem with my M770 transmission set, it wasnt shifting to the last gear (smallest cog on rear cassette).
the shifter was mega stiff toward the end of the shifting too.

i opened up the shifter and found a long spring wedged in it. removed it and the problem was solved.
Have no idea why the spring was there/how it was located. but it works fine now.
when i first had the problem i swapped it for a deore shifter (9spd) and that worked fine:

like this:

Image

here is my thread about the problem i had, not sure if this will help at all:

http://www.retrobike.co.uk/forum/viewto ... highlight=


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