Trek 5500 w/full Ultegra - a custom build. Front derailleur appears too high - about 1/2" above chainring and it's at the bottom end of the adjustment. Is there another braze-on mounting/adjustment plate I can purchase that will allow it to go lower or should I let it go? Bike appears to shift properly as-is.

55/Rad

What tooth chainring are you using?

Hey Rev - thanks for the info on the Powerlink...works like a charm.

Different bike, different issue. The crank is a standard 53/39.

55/Rad

Well, hmmm. There are only two braze on Ultegra der. FD-6500 a double and FD6503 for triples. And they travel a little different(The triple drops more when shifting down) but I wouldn't think this would cause your problem. You should be able to get the bottom of the cage with in 2mm of the chainring.
I would go to a Trek dealer and look at a 5500 on the floor, maybe you have the wrong braze on mount.

What's the problem if it's shifting properly? Not trying to be smartass, just wondering why would it needs to be fixed if it's working?

There isn't a problem, I don't think. I just purchased 2 used bikes and went through the process of learning about and changing derailleurs on one of them. The Park tool site was immensely helpful.

Then I took my new found knowledge and looked at the Trek. Although it works fine, the gap is substantial. Being obsessive compulsive, I want it perfect....if it's even possible.

55/Rad

The der can be pretty poorly adjusted and still work OK esp. with a double. But it is oh so crisp if you can get the bottom of the cage1-2mm from the top of the big ring teeth. Less chance of it hopping off to the outside on a bump as well.

After a trip to a Trek dealer to eyeball both the 52 and 5500's, and 30 minutes with a mechanic just shaking his head, I decide to strip the darn thing off the bike. Then I discover.....

The large chainring is a 50!

Did I say I feel stupid? I got the bike used from a good friend for Christmas and all the while I assumed it was a 53. Anyway, problem solved. Good thing too as I was beginning to go crazy.....

55/Rad

Very good. I was wondering myself. That was the only thing it could be (I was thinking)