Front Mech Setup Help

[Ian W]

Firstly, apoligise if this is the wrong section, can't find a techy part.

I'm building up my Zaskar and I can't get the front mech working correctly.

Its a XTR bottom pull, appear to move freely and I have unscrewed both limiting screws.

When I try to shift up from the smallest chainring to the middle it jumps my chain all the way up to the granny ring?

Do I need to adjust the limits on it? Sorry if this is a silly question, front mechs are like a dark art to me, just can't get them right !

 

[eightiesman]

Is the cable too tight? it may be hence the shifting too far up. Have you changed the bottom bracket? if so is it the same lenght spindle as the previous one?

 

[Ian W]

The bottom bracket has been changed as the bike has been built up from a frame. I've never had the front mech working.

The cable appears ok? How can I tell if its too tight? I just fed it down to the mech, tensioned it and tightened up the cable screw.

 

[Andy B]

I take it you mean when in the smallest chainring & you shift up wanting the middle ring it over shifts to the outer ring?

Either too much cable tension

Or

Cable is not correctly attached to mech. If the cable is the wrong side of the cable clamp bolt it can mis shift too. Look for the groove (if it has one) behind the bolt, which indicates which side of the bolt the cable goes.

Limit screws are only there to stop the chain from dropping off either side of the (inner & outer) chainrings, nothing to do with the indexing

 

[Andy B]

Have a look at this website for more help

http://www.parktool.com/blog/repair-help

 

[eightiesman]

http://www.youtube.com/watch?v=EDFl4xCS8FU

This might help.

 

[jimo746]

what shifters are you using?

 

[Ian W]

what shifters are you using?

I've tried my XT m737 pods and some old STi's, both the same problem.

Has anyone got a pic of how the cable is routed from the bottom bracket area upto the cable clamp on an XTR m900 on a zaskar?