I have a 28X39X52 Specialized road crankset that I want to use on a newer Serrota Colorado with a braze-on front derailleur clamp-on)mount. That's a 24 tooth difference. I haven't been able to locate anything that can handle this spread in a braze-on (my current is Shimano bottom pull clamp-on. So, is there anyone that knows if there is a current or older front braze-on that can handle this? I use a 12-28 7 speed freewheel in back too.

What are you using for a shifter?

If you have a friction shifter for the front, I'd think most any road style front derailleur would work.

The problem sounds like a derailleur capacity issue, with the chain dragging on the bottom of the front derailleur.

I'm not sure if there is a stock derailleur that fixes the problem. However, apparently some people have made a modification to make it work.

front derailleur modification

What am I missing?

There's lots of stock bikes with 52/39/30 chainrings. I wouldn't think that a 2 tooth smaller granny would be enough difference to cause a problem.

Thanks Clifford and Retro Grouch. The derailleur modification link was most helpful. My concern is that most braze-on front derailleurs are designed for double chainwheels and finding a bottom pull front braze-on derailleur was the big concern for the triple. I will get as wide a capacity front derailleur as I can find and modify it if need be. Thanks.

I was looking at a few notes on the web.

I'm seeing the derailleurs:
FD-4403, FD-6503, & FD-6603 are rated for 52T max, and 22T capacity, with several people reporting a slightly wider range.

The A553 (RX100 Triple) seems to have ambiguous details, but probably is similar, although a couple of sites seem to be rating it as high as 26T.

I run 52-39-26 on two 9-speed bikes and one 10-speed bike using Ultegra FDs. One of the nine-speeds is a braze-on, which runs a 12-27 in back. The 10-speed runs an 11-25. The other 9-speed runs a 12-34. None of them have any problems. Of course one never runs the granny ring below the 4 largest cogs and the big ring above the 3rd largest cog, though the chain is always set to not break the RD plus 1 link at big-big.

Oh Braze on .. NMD get the Chainrings as far inboard as You can, Short BB spindles, so the FD swing outwards is not as Far.






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