Braze-On Derailleur Issues....
 

Forgive me, but I'm reposting this question due to lack of specific responses about this issue.

I'm have a difficult time narrowing the gap between the front dérailleur and the largest chain ring on my compact rank to the 1mm-3mm mark(it's a braze-on, so the lowest setting drops it to around 10mm away). Any suggestions on what to do here?

I believe the problem is with the crank being a compact, therefore having a smaller diameter chain ring. If it were bigger, I would not have this issue. I know there are tons of you out there with braze-on frames, so let's settle this once and for all:

Braze-on + Compact = trouble**********

Braze-on + Compact-compatible front derailleur + Compact crank = joy

What compact are you using. Shimano's compact is supposed to use the same dérailleur as the normal 53/39. If you want help give us enough information to help. If you just want to gripe than preface your post with that.

Are compact FDs capable of reaching further down? I was aware of these, but I posted a question about the differences between these dérailleurs, but many people said that my FD (a 6600 Ultegra, noncompact specific) should work fine.

Thanks

I have a Truvativ Rouleur Carbon Compact GXP Double.

Not the intended design/use of the compact F/D. The compact F/D has a cage that follows the curve of the smaller chainrings more closely. Therefore making it easier to throw the chain up onto the big ring.
It's not designed to reach further down from abraze-on.

The problem some folks are having is the fact that older frames have the braze-on welded too high for the current crop of compact cranksets. I just ran into this problem with a 10 year old Litespeed frame and Ultegra SL compact cranks. It shifts with the almost 1cm gap, but not well. Because the F/D is too high, it wants to throw the chain off the outside of the big ring.

The easier answer? Get a 52 big ring and run 52/36 and a 12/25 cassette...

I set up a friend's bike like this once. It was an older Trek. They apparently now make a braze-on tab with a longer/deeper slot, to accommodate moving the FD closer to the large ring. If you have a Trek, you might visit a local dealer and ask if they have a replacement braze-on tab that will accommodate a Compact (they're marked with a C on the tab; the tabs are held in place with a couple of 3mm bolts).

If you can't do that and you are handy with a Dremel (and there is sufficient room on the braze-on), you could just extend it yourself.

A 10mm gap is quite a lot; on my friend's bike we were able to get within about 6mm, and we just left it at that. I would just try it; it will probably work just fine even with the big gap. You want to make sure the high limit screw on the FD is adjusted right, because if you overshift going to the outer ring, the danger with that larger gap is that the chain will get caught under there and bend your FD cage.

if you're taking the time to repost. repost with a picture

Ah, I see. I was thinking about the current crop of Campy derailleurs, but I realize that doesn't apply here. And, for 2008, Campy went to a single FD for both compact and standard cranks.

I guess one other choice for the OP is to use a clamp on FD if he can get it in the correct position.

What bike are we talking about, anyway?

That's not likely to work, either. The clamp will interfere with the existing braze-on.

The realistic options are:

• extend the slot in the existing braze-on tab, if possible
• just leave it with a large gap (and pay close attention to the adjustment)
• ditch the compact and get at least a 52-tooth large chainring

Cheapest route would be to try a Compact specific FD. I bet your problem will be fixed. I nsay this from experience.

If it does, it's by accident more than by design. So-called compact-specific FDs have a different *curvature*, not necessarily a different depth from the mounting bolt to the bottom of the outer cage plate. That is the issue here.

Thank you for all of the helpful responses. I do not believe that a compact specific FD will work due to the nature of the problem.

I currently own a Trek Y-Foil 77 (year 1998) so it is an older model. I'll try to get in touch with Trek and see what they have (thanks for the suggestion).

Sorry about the fact that I didn't provide a pic. I'm at school now and about 200 miles away from my on-going bike build, which will be brought down to me this weekend. I'll get one ASAP.

Older Treks have this problem. I removed the tab, filed it open and it worked perfectly. Then I heard Trek had a replacement tab, so I ordered one for $20. When it arrived, it was nothing more that a regular one that had been filed...just like mine.

55/Rad

May I ask how you filed it (with a dremel as suggested before)? I don't have any power tools with me, but I guess I could "borrow" some from the University....... For a project of course.......

I used a round "rat tail" file and a vise. Pretty simple actually.

Thanks very much. Awesome Trek 5500 by the way.