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I'm putting together a drop bar hybrid conversion for a gravel bike and want to run a 1x10 drivetrain. So far the only shifting component I have is a pair of Shimano Dura-Ace sl-bs79 10 speed bar end shifters. I'm planning to just use the rear one, obviously.

Before I go ahead and buy a RD and cassette, I though I would check for any compatibility issues. I guess that the shifters are intended to work with road RDs, whereas I guess that I'll be wanting a MTB RD to deal with whatever wide range cassette I end up getting.

Any suggestions?

Edit: Although I'm committed to the idea of 1x10 with bar end shifters, I'm not particularly wedded to these particular shifters - they just happen to be the ones that I have in the parts bin. So if what I'm proposing is going to be a big ordeal, please say!

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One thing you could do is use a Microshift Advent 9 rear derailleur. You could even get the clutch one. They're 9-speed Shimano compatible, which means they use the same actuation ratio expected by a 10-speed road shifter - there are many questions here about this. The Microshift mountain compatible bar ends are another path, but having worked on tons of bikes with them, I just don't like them all that much - the lever motion is sloppy and indeterminate, especially compared to the Shimano one you've got, plus you're buying an RD anyway.

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Not without some fooling around.

The shifter doesn't really care what cassette you're using, but in between the shifter and cassette is the rear derailleur, and that will be specific to the kind of cassette you're using and the kind of shifter.

More specifically, the problem is what's called the cable pull ratio: for every millimeter of cable the shifter takes up, how far does the derailleur move horizontally? And unfortunately, Shimano's road shifters are designed for a completely different pull ratio than their mountain derailleurs.

What you want (road in front, MTB in back) is often referred to as a mullet drivetrain. The linked page describes some workable configurations, but none of them seem to work with Shimano 10-speed.

Although we try to avoid specific product recommendations here, I can think of only one solution. Jtek makes a line of special pulleys that translate cable-pull ratios between the shifter and derailleur, and it looks like their Shiftmate 6 in conjunction with a Shimano 10-speed shifter and SRAM 1:1 derailleur would work with a 10-speed cassette.

The alternative is to get a long-cage road derailleur and live with the range you can get out of a compatible cassette.

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  • Thanks for the advice. If it's allowed to add another question, would something like this: microshift.com/en/product/bs-m10 make life a lot easier?
    – mojones
    Apr 29 '20 at 14:56
  • I don't think so. My understanding is that Microshift parts are interchangeable with equivalent Shimano parts, so this wouldn't be any different.
    – Adam Rice
    Apr 29 '20 at 15:37
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    The BS-M10 exist to do this exact thing, being a Shimano mountain 10 pull shifter. Apr 29 '20 at 15:46
  • I stand corrected! Thanks @NathanKnutson
    – Adam Rice
    Apr 29 '20 at 16:35

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