Shimano 105 FD Adjustment

[cbjesseeNH]

In an effort to overcome some front derailleur noise, I was going to adjust my Shimano FD-5503 Triple Clamp-On and came to an immediate halt. All mechanic books I look at say to adjust the outside edge of the cage relative to the outside (big) chainring so that the cage rides about 1mm above the teeth.

Mine rides 4mm (at the front) and 6mm (at the rear) above the teeth.

The Shimano instructions refer to installing it with a "Pro-Set Alignment Block" in place 1-3mm above the teeth (using a "Pro-Set Gauge" that apparently comes stuck to the FD cage). Subsequent Low/High Limit adjustments are made with the "Pro-Set Alignment Block" removed.

I'm guessing the "Pro-Set Alignment Block" holds the cage open against the spring until the FD is mounted. Perhaps once Low/High Limit screws are set, the 1-3mm distance maintains?

Bottom Line: Should I adjust my FD so I can fit a penny (1-2mm) between the outside cage and big ring, like all the books seem to say, or just leave it as is and adjust from there? The bike was assembled by a very reputable custom shop, so I'd hate to 2nd guess a professional mechanic - but I'll consider it if given good reason.

 

[John M]

In an effort to overcome some front derailleur noise, I was going to adjust my Shimano FD-5503 Triple Clamp-On and came to an immediate halt. All mechanic books I look at say to adjust the outside edge of the cage relative to the outside (big) chainring so that the cage rides about 1mm above the teeth.

Mine rides 4mm (at the front) and 6mm (at the rear) above the teeth.

The Shimano instructions refer to installing it with a "Pro-Set Alignment Block" in place 1-3mm above the teeth (using a "Pro-Set Gauge" that apparently comes stuck to the FD cage). Subsequent Low/High Limit adjustments are made with the "Pro-Set Alignment Block" removed.

I'm guessing the "Pro-Set Alignment Block" holds the cage open against the spring until the FD is mounted. Perhaps once Low/High Limit screws are set, the 1-3mm distance maintains?

Bottom Line: Should I adjust my FD so I can fit a penny (1-2mm) between the outside cage and big ring, like all the books seem to say, or just leave it as is and adjust from there? The bike was assembled by a very reputable custom shop, so I'd hate to 2nd guess a professional mechanic - but I'll consider it if given good reason.

I suppose I could speculate on the reasons why the derailleur was initially installed as it was, but front derailleurs installed and adjusted as you read in the manuals and in the shimano instructions shift perfectly well. That being said, they can also shift well when installed a little higher. I would go with the standard 1-2mm above the chainring. If it doesn't work as well, maybe try raising it up a bit.

 

[Retro Grouch]

Many mechanics have trouble getting triple front derailleurs to function well when using STI shifters. In most cases I think that it's because they jump into the middle of the adjustment and pile one misadjustment onto another trying to correct a more basic problem. It isn't that difficult to do.

Goto the Park Tool website. Find the front derailleur installation and adjustment section. Disconnect your front shift cable and start at the very beginning with the position of the derailleur on the seatpost. It's easier with Shimano's block in place but you can work around it. Follow all of the instructions in order (that's important).

You'll do fine!