Stiff front mech spring
09-16-08, 11:24 AM
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Stiff front mech spring
Hi,
Basically the problem is that the front mech spring is too strong for the friction shifter to hold it in place. I have a shimano 105 semi indexed friction shifter to change it but this isnt strong enough to hold it in place - it keeps moving back towards the inner chainring. Is there anything that I can do to reduce the strength of it?
Thanks,
Will
Basically the problem is that the front mech spring is too strong for the friction shifter to hold it in place. I have a shimano 105 semi indexed friction shifter to change it but this isnt strong enough to hold it in place - it keeps moving back towards the inner chainring. Is there anything that I can do to reduce the strength of it?
Thanks,
Will
09-16-08, 12:15 PM
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There are three possibilities i can think of...
Either the cable is routed wrong, or the shifter needs to be tightened, o the shifter is assembled or installed wrong.
When the front derailleur cable is installed it must go up over the little tab behind the pinch bolt (not between the tab and pinchbolt as seems correct sometimes when assembling). Putting the cable over the tab gives you alonger effective lever arm and you need less cable tension to move the derailleur, and the derailleur has less power to pull on your shifter. There should be a fairly small amount of force necessary at the shifter to move your front derailleur - if it feels stiff then cable routing is probably the problem.
The other possibility is that your friction shifter needs to be tightened (to have the friction increased).
Most friction shifters have a screw or wingnut or ring you can tighten if the shifter is slipping. Try tightening this part 1/4 turn and see if it makes any difference. You shouldn't have to crank the screw too tight to make it work. If you are tightening as much as you can and it still won't hold the derailleur in place then you have othr problems...
Lastly, it is possible that the shifter is installed incorrectly. If I recall correctly, shimano downtube shifters have multiple small parts and springs and whatnot... if these are installed in the wrong order then it is possibly it will not hold the derailleur in place.
Either the cable is routed wrong, or the shifter needs to be tightened, o the shifter is assembled or installed wrong.
When the front derailleur cable is installed it must go up over the little tab behind the pinch bolt (not between the tab and pinchbolt as seems correct sometimes when assembling). Putting the cable over the tab gives you alonger effective lever arm and you need less cable tension to move the derailleur, and the derailleur has less power to pull on your shifter. There should be a fairly small amount of force necessary at the shifter to move your front derailleur - if it feels stiff then cable routing is probably the problem.
The other possibility is that your friction shifter needs to be tightened (to have the friction increased).
Most friction shifters have a screw or wingnut or ring you can tighten if the shifter is slipping. Try tightening this part 1/4 turn and see if it makes any difference. You shouldn't have to crank the screw too tight to make it work. If you are tightening as much as you can and it still won't hold the derailleur in place then you have othr problems...
Lastly, it is possible that the shifter is installed incorrectly. If I recall correctly, shimano downtube shifters have multiple small parts and springs and whatnot... if these are installed in the wrong order then it is possibly it will not hold the derailleur in place.
