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  1. #1
    RoadBikeReview Member
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    Bottom bracket mount XTR front deraileur on road bike?

    Hi,

    My frame has a bent front deraileur hanger. In taking it off to investigate, I've found the tube is cracked where it mounts. I also found my front deraileur off ebay is beyond repair. So, I'm looking for a replacement front deraileur, but even once i mount it, the braze on mount could be too flexible. My options are:

    1) fit a 42 ring I've got sitting around and go 1 x 9.
    2) maybe use an XTR bottom bracket mounted deraileur?
    3) new frame ... which given the prices of frames, it seems I'd end up buying a new bike ... which I really don't want to do right now.

    Has anyone seen 2) done before?
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  2. #2
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    The derailleur pictured is called an e-type and is available in LX and XT specs too. It is held in position by the set screw in the centre of the photo which threads into a lug which is part of the frame. It may be possible to bodge an alternative but there are other consideations too.
    There is no adjustment of the dreailleur up or down and it is designed to be used with a 44 tooth big ring. I know you can get a 48 tooth ring for a MTB but looking at mine I don't think it would fit.
    Also the cable pull ratio is different to road bikes and it would not index with Sti shifters.
    Good luck if you can make it work but I dont think this is an easy fix.
    I'd go with 1x9 and maybe a MTB cassette if I needed lower gears, or investigate getting the frame fixed, if necessary removing the braze-on tab and going with a band on FD.

  3. #3
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    If you can find a BB mount FD compatible with your preferred chainring size, that's one approach to the problem.

    Another, maybe simpler approach is to remove the braze-on mount (unscrew, or carefully saw, and file) and use a clamp on derailleur. If you're fairly skilled you can make an even nicer repair by using a clamp 1/8" bigger than your seat tube, and using 1/16" shim stock to make a sleeve wide enough to shore up the damaged tube.

    Having a 1" wide aluminum band under your FD clamp may not be beautiful, but it's cheaper than replacing a frame.
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    Solving any problem requires understanding the underlying cause

  4. #4
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    That derailleur is also designed for top mount cables, while yours come from the bottom.

    If I wanted to keep riding the frame, I'd grind the mount off, then sand and wrap the tube with epoxy and fiberglass until it is the next size up, so your shim actually makes the tube stronger and stops the cracking.

    However, you can replace the frame for cheap:
    http://www.nashbar.com/bikes/Product...0_10000_202337
    New for $100, if it is compatible with your fork.

    Ebay has a ton of framesets with forks for $80 and up in the buy it now.

  5. #5
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    Quote Originally Posted by rx-79g
    That derailleur is also designed for top mount cables, while yours come from the bottom.
    I don't think that's correct. My LX e-type is set up bottom pull, which is pretty normal for full suspension MTBs which tend not to have a conventional top tube. Certainly my FD will allow top or bottom pull. I wonder why road bike FDs aren't so flexible?

  6. #6
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    Quote Originally Posted by baker921
    I don't think that's correct. My LX e-type is set up bottom pull, which is pretty normal for full suspension MTBs which tend not to have a conventional top tube. Certainly my FD will allow top or bottom pull. I wonder why road bike FDs aren't so flexible?
    Because they don't need to be, and flexibility costs in weight and complexity.

    Thank you for the correction, though. Either way, that derailleur is not a solution for the OP's problem.

  7. #7
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    Thanks for the info. I'd read about these derailleurs before, but as I never had a bike that needed one I didnt actually look into them.

    I am going to look for a new front derailleur to replace the one I bought (the one I bought has a helicoil in the mounting bolt and the adjustment screws are seized ... there is a fair bit of salt damage to the whole thing).

    I have been thinking about a new frame, but 1) I really like the ride of this Look, 2) I like having a frame that is just as out of date now as it'll be in five years time, 3) it owes me little, so I'm more inclined to take it traveling and not be worried ..

    I have however been looking at options such as these Ribble frames which are cheapish in the UK. I'm not inclined to go chinese ebay frame right now, as the UK sting you for import duties etc.

    Thanks
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