Help with front mech
 

ok no one flame me, this is a dead easy question if you know what your doing. I have just gotten hold of an old basic MTB frame and have put all the components on it from scratch. Everything is working(suprise suprise!) except for my front mech. it seems that it wont stretch as far as the third chainring with the shhifter. However, if i push it with my fingers it will go as far as I want it. The instructions that come with the parts are next to useless. Can anyone please help as I have spent a week building this bike and cant wait to take her out on her maiden voyage! Maybe if you can just talk me through right from the startof setting the front gears it would be best!

Cheers

MArk in Scotland

What kind of shifter? Is it had to move the shifter to the high gear position? If so:
-check cable friction, and routing beneath bb shell

Can the shifter move easily to the 3rd gear position, but the derailleur won't follow?
-Tighten the cable with a 4th hand tool

The other thing I'd suggest would be BB length, but if you got everything from a build kit, the spindle should be the proper size.

If it will more outward far enough when you push it with your finger, I'd suspect one of two things.

The first is that you didn't have your shifter all of the way in it's lowest gear position when you anchored the shift cable. If that's the case, you'll get a significant amount of cable slack when you shift into the grannie chainring position.

The second is that your front derailleur might not be compatable with your shifter. If you are using a Rapid Fire shifter, you have to have a front derailleur that is designed for indexed shifter use.

Sram and Shimano uses different cable pull ratio, if I remember correct.

Not on the front. Sram/shimano/ shifters/FD are compatible.

Are you using SIS housing or Coil wound? Some lesser brands of coil wound can have a lot of spring and cause that. Rare but it happens. I only use SIS for that. It costs more but it is way better.

Thanks guys. It should all be compatible i am using deore everything. I am going to try and tighten the cable with a 4th hand as suggested.

D'oh? All I ever had to do was give the cable a bit of a pull with one hand and tighten the retainer bolt with the other. No rocket science here,but it's possible to get it too tight.Make sure the adjuster has travel both ways so you can make final adjustments for tension with it.

I usually pull the der over a little off the limit screw then pull the cable. Not a lot, but it tends to make things easier. Then, if any adjustments are needed its a matter of releasing the barrel adjuster.