CMC SanDiego

I'm trying to build an "All around" bike, using an older steel cromoly road frame, 700 wheels with larger tires, and what is essentially a compact triple crankset (46-36-24). My problem is getting a front derailleur that will shift properly (I am using a long cage rear derailler to make sure I take up enough chain slack).

I've attempted to use two different older Suntour Triple derailleurs, a Mountech and something else that no longer has it's name on it. What happens is when I mount either derailleur low enough (within about 1/8 to 1/16th of an inch from the top of the large ring) I get rubbing or actual interference between the bottom of the derailleur arm and the chainstay, and I can't shift into the small ring. If I move the derailleur up enough to clear the chainstay then I'm getting the chain caught/jammed on the derailleur when I try to shift from middle to large rings.

Do I need to just use a mountain derailleur or is there some other adjustment I could/should be considering? Any help would be greatly appreciated.

Yan 

I have a 48-38-24 crankset on my Surly Cross Check and use a Tiagra FD4403 without problems. The modern derailleur's shaped plates will solve the upshifting problem. The Tiagra is recommended by some on these forums because of more generous clearance between the plates for less chain rub. Whether or not this is true I have no idea, as I don't have another comparable derailleur. I suggest the FD4403 over the FD 4503 for two reasons. First it's probably cheaper. Second it's designed for a 10 teeth high and mid chainring difference (which you have), as opposed to an 11 teeth difference on the FD4503. I do not believe there is another Shimano road triple FD designed for a 10 teeth upper to middle chainring difference.

mike047

FD M413
https://techdocs.shimano.com/media/te...9830687361.pdf

LarDasse74

Are you using indexed MTN, indexed road, or friction shifting on the front?

If friction or mtn, then a Shimano mtn derailleur will work great - they are designed for smaller tooth-count cranksets. Entry level Shimano F ders are also vry reasonably priced and still good quality.

Garthr

Chainstay rub of the FD can be a problem on some frames with a low BB when using a smaller big ring. the guys at Rivendell use this Campy FD with success, as their frames have low BB's and usually sell with 46t big rings.
https://www.rivbike.com/products/show...railers/17-133

Metaluna

I've used the Campy triple FD's on 46-36-24 cranks and they work great with friction shifters.

The problem I had with the Shimano mountain FD's (LX and XT series mainly) I tried on my Cross-Check was that they took up a lot of room behind the seat tube (partially due to the top/bottom pull design), which ended up interfering with my rear fender. On some road frames they might even interfere with the rear wheel depending on the clearance behind the seat tube.

Garthr

I forgot to mention though ..... you may be able to use a double FD. I use a 105 double from 2000 with my 48/44/24 rings. I shift manual, it works flawlessly. There is plenty of travel in older FD's.
I'm not sure if it'll clear your 46/34/24 rings properly though, I've never tried it. Since you're experimenting, you may as well try one.

BTW, I'm assuming the OP is friction shifting.

davidad

You can mount it higher than the 1mm reccomended height and it will still work fine.

CMC SanDiego

Thanks for the advice/suggestions. I am using friction bar-end shifters.

I'll see if I can round up one of the suggestions made above, and will keep experimenting until I get something that works. I was just trying to get it finished late last night, and got frustrated after several failed attempts, then decided to throw it out there to see what I wasn't considering.

Al1943

I agree that a triple front derailleur designed for a 10 tooth drop from large to middle ring should be best. I would look for a 9-speed Shimano triple FD. With the exception of the D-A FD they are all designed for a 10 tooth drop, they are a little wider than a 10-speed FD, and should give you more clearance on the inside rail. A 9-speed FD will be more tolerant to compatibility issues.