CB88

I am attempting to rebuild a Trek Mountain Bike with a triple chain ring

Installing the front derailer has proved tricky. I have a good understanding of high/low limit screws and the height and angle of the derailer, or at least I think I do

The problem is that when I attach the shift cable, I am having issues. I have adjusted the shifter to the 'slackest' position, pulled the cable relatively taut, then tightened the bolt to hold it in place. This seems to work for the first and second chain ring, but it appears that the cable is too tight to shift into the largest chain ring. If the cable is loosened any further, the derailer cage does not move far enough to cause a shift when it is shifted, even with high and low limit screws adjusted.

Please advise how to take care of this issue. Thanks.

HillRider

Did you route the cable to the clamp bolt properly? On Shimano derailleurs there is a small tab above and to the inside of the fd's clamp bolt. The cable must be routed outside and over this tab and then clamped into the groove under the bolt head. If you run the cable under this tab (between it and the bolt) the derailleur travel will be inadequate.

FBinNY 

First make sure to check the cable routing as Hillrider suggested. Changing the cable from inside the screw to outside changes the effective length of the cable arm on the FD and thereby changes the cable response ratio. The inside position increases FD travel compared to the outside.

Otherwise, you can join me with my pet peeve about modern bike FD systems, which is the lack of a barrel cable adjuster with which to fine tune FD trim.

Like a married couple arguing about who was supposed to check that the stove was off before a long trip, bike and component makers dropped the ball. Some bikes have adjusters in the lever and the D/T cable stops and others neither. Buy yourself an inline barrel adjuster if your bike is one of the neithers. It isn't absolutely necessary, but you'll be able to get more precise trim adjustments faster and with less effort if you do.

badamsjr

When you say 'rebuild', are you talking about using the original shifters? I had just this type of problem trying to make a Road shift/brake lever work with a MTB FD. Ended up going to bar end shifters and separate brake levers, and now have no issues. The brifters have a different pull ratio than MTB shifters, if I understand it right. All I know is I got tired of fighting with them, and switched. Now I wonder why I waited so long to do it!