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  1. #1
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    Shims to run a 34.9 front derailleur on a 31.8 seatpost?

    Does anyone have any "homemade remedies" for this or know where to find these shims for cheap? My LBS wanted $15 for the part...I'd rather wrap a piece of Coke can and electrical tape around my frame than pay $15 for a piece of plastic. The kid acted like he was doing me a favor as well by pulling that "cheap" price out of thin air. Maybe I'll just wait until I can find a good 31.8 XT or LX on eBay. They seem to be going for around $15 anyways.
    Last edited by BMRisko; 04-15-2007 at 04:27 PM.

  2. #2
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    I think you have the numbers backwards, right? The derailluer is too big for the frame - correct? The coke can idea would probably work if that's the case. If the frame is in fact bigger than the derailluer, you are SOL.

  3. #3
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    Quote Originally Posted by kdiddy
    I think you have the numbers backwards, right? The derailluer is too big for the frame - correct? The coke can idea would probably work if that's the case. If the frame is in fact bigger than the derailluer, you are SOL.


    Yea, thanks for catching that. I meant that the der. clamp is too big for the seatpost. Universal Cycles sells the Shimano bulk part for $5. Maybe the LBS will match that or maybe they weren't aware how much they really cost. $5 is about the max. I'm going to pay for a little piece of plastic. I plan on checking the other 3 LBS' this week and maybe one of them will come through w/o trying to rip me off.

  4. #4
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    not clear on your question but doesn't a 31.8 seatpost

    use a 34.9 front derailleur because the seatpost is measured on the outside of the post or the inside of the seat tube and the derailleur measured on the inside of the clamp or the outside of the seat tube. I am not sure, but just wanted to ask the question.

  5. #5
    Meh.
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    Quote Originally Posted by ol-crank
    use a 34.9 front derailleur because the seatpost is measured on the outside of the post or the inside of the seat tube and the derailleur measured on the inside of the clamp or the outside of the seat tube. I am not sure, but just wanted to ask the question.
    Not neccesarily. The gauge of the tubing can influence what size derailleur or seatpost clamp you need.

  6. #6
    'aua e te fati
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    shimming 34.9 to work w/31.8

    I had a similar problem with my Sram X Gen on my Jamis Dakar Expert. I had a 34.9 fd laying around and when I built up my frame i discovered that it was 31.8mm. I couldn't even find a shop or anywhere online that carried a shim. So I improvised. I'm not so sure that the coke can/electrical tape would be a good idea because it would have too much slop in the electrical tape. I used an old piece of tube cut to match the fd footprint first, but I found that it was too loose and slipped around after only about a week.

    My fix: I took several (3) zip ties and cut them for length (so that they wouldn't overlap) and then mounted the fd on top of those. It took some patience to get it all lined up, but it is working fine for a 1 cent backyard mechanic job.

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