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  1. #1
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    2x9, or 2x10 on a Specialized Epic?

    Hey Gang,

    I am trying to put together a 2x10 drivetrain for 2007 Specialized Epic Carbon. I read this article that talked about putting together an FSA K-Force 2x9 crank, Ultegra front derailleur, Shimano flat-bar 10sp shifters (R770's), a Dura-Ace rear derailleur, and an IRD 11-34 cassette. It seems like it would be a great set up.

    But now that I am actually trying to do that I am running into all sorts of questions. Namely: The Epic Carbon seat tube is a 34.9mm tube (I believe) and I can't find an Ultegra F. derailleur for that size, even in a braze on adapter. I am wondering if a different derailleur would do it.

    Is the freehub body on a pair of 2008 Mavic crossmax wheels able to accept a 10sp cassette?

    Am I barking up the wrong tree trying to do this? It seems really cool but I don't know all the little details about what will work with what.

    Thanks!!!

  2. #2
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    If you want 2x10 with the SL-R770 shifters, the recommended front derailleur is the FD-R770, and here she is in 34.9mm: http://harriscyclery.net/page.cfm?Pa...ils&sku=FD7002

    For the rear derailleur, if you're planning on a 34-tooth cog, the Dura-Ace family may not be able to swing it without modifications. Probably best to stick with XTR unless you want to do some experimentation.

    Shimano 10sp cassettes fit into the same freehub-body space as an 8sp or 9sp, so the Crossmaxes should handle a 10sp. You will probably be using a ~1.5mm spacer behind the cassette.

    I guess the main questions I'd ask myself, before embarking on the project, are:

    1) "what do I actually need that tenth cog for?" In my case, if I ran a 9sp 11-34, I do know the answer: I'd like a 12 between the 11 and the 13, because I'm just crazy like that. Unfortunately, IRD's 11-34 ten-speed cassette doesn't have an 11-12-13, so there goes that motive. I'd be just as well off with a 9-speed.

    2) "do I actually like the SL-R770 shifters? Are they as good as my XTR SL-M970 shifters?" and the answers are "well, they're not awful, but they're not nearly as sweet as the XTRs." I'd have a tough time justifying 10sp if it meant giving up my preferred shifters.

    3) "will 10sp be more sensitive to ghost-shifting than 9sp, considering this is a full-suspension rig?" Hopefully some Epic owners with Shimano-based drivetrains will chime in with their experiences on that one.

  3. #3
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    Thanks for the reply. You raise some good questions. I guess the motivation to go this route stems from the fact that I rarely use my granny gear. This comes from a broken pawl in my left shifter that precluded me getting there but the realization was that I didn't use it much at all. Once I thought about a 2x9 I began reading that the possibility of a 2x10 drive train exists since all the components have been there for years in the road bike world. I read an article about it and they had suggested the aforementioned setup. But now that I am actually beginning to think about purchasing this stuff it seems like it may be a bit of a mis-mash of parts that would give me same troubles we all had in the early 90's with all the third-party stuff that was put out there but never really worked that well. (I need that reminder why I went back to one manufacturer's components throughout, I guess.)

    Of course upon further investigation I find that SRAM has their 2x10 group coming out soon, the "XX". Of course it is hush-hush and will most likely cost an arm and a leg.

    Some follow-up questions:
    What about a SRAM 10sp Double-tap? Has anyone used these shifters?

    Thanks for the link on the F. Derailleur. Why do you think I'd need the 1.5mm spacer in the rear? Is there an good article out there that covers chain alignment?

    I'm on the fence between just going XTR, for the reasons you mentioned mechBgon, and just going with the proven technology. But I do think the 2x10 would be sweet, I guess partly just for the uniqueness.

  4. #4
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    Some follow-up questions:
    What about a SRAM 10sp Double-tap? Has anyone used these shifters?
    If possible, try the road version, and see if you like the general concept. Personally, I don't, but it's your bike.

    Why do you think I'd need the 1.5mm spacer in the rear?
    Some Mavic wheelsets come with one. If your cassette goes on and snugs up without needing the spacer, and your derailleur and cassette spider are clear of the driveside spokes, then you're all set. Otherwise, use the spacer.

    I can understand bailing the granny gear, which I did myself. An 11-32 with a 32-44 works for my purposes. But I'd only switch to 10sp if there were a meaningful benefit, and IRD's 11-34 doesn't have one for me. Quite heavy, no 12-tooth cog, requires second-best shifters, expensive compared to XT... sorry, I'll pass.

  5. #5
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    Cool, thanks again for the reply. This is the type of info I was looking for. Now I just have to decide on where to get this stuff.

  6. #6
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    Quote Originally Posted by mechBgon
    ...3) "will 10sp be more sensitive to ghost-shifting than 9sp, considering this is a full-suspension rig?"...
    Heck yeah! IMO even 9-speed is too likely to ghost shift on sussy bikes, especially when things get dirty.

    I want to go back to wide spaced (lateral spacing and tooth count) 6-speed drivetrains. Close ratios and tight clearances just make little sense off road.
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  7. #7
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    Yeah, the more I talk with people that is the story I am hearing - stay away from narrow gearing when you're mixing mud into the scenario..

    So what are people saying about the SRAM XX?

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