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It appears that there are similar threads, so I'll reformulate it with more specific questions and taking the cue from comments.

I am assembling my brand-new touring bike on a LHT frame, and I'd like to make STI shifters work on it. My setup at the moment is

  • shifters shimano 105 STI
  • crankset shimano LX 48-36-26
  • cassette+chain 10 speeds shimano XT

Apparently to make STI work with rear MTB derailleurs, one needs to take the 9 speed RD, since new 10 speeds have different pull ratio. What concerns me most, at the moment, is the dirtiness that comes from the choice:

  • using a 10s chain on a 9s rear derailleur, due to different thickness
  • using a road FD (e.g. shimano 105 triple) with a MTB RD and with a 48-36-26 crank
  • other issues that you will suggest

do you think it would affect shifting smoothness and durability of the setup to use this kind of melting-pot solution?

bonus question: on this compatibility reference, are you aware of any difference between shimano SHADOW XT RD and normal XT RD?

bonus solution: I am not a STI religious, so if issues are real I might shift to barends to make a fast and long lasting fix. Anyway, I'd like to stay on brifters if problems are not that significant.

thanks a lot!

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    The difference between brifters and bar-end shifters is pretty significant, I wouldn't make the change just because of a minor hassle getting the right components. Better to buy an RD that works IMO
    – Móż
    Jul 17, 2016 at 23:27
  • sure, I actually have no experience with any of the two (always toured with a MTB) so that would be a major change in any case. Let's say there is also barends-vs-sti pros and cons hidden question :)
    – LorenzoP
    Jul 17, 2016 at 23:35
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    Possible duplicate of Shimano Compatibility and many others.
    – mattnz
    Jul 18, 2016 at 2:12
  • Sorry, have you not worked out that the speed parts are designed for is pretty important, even from the same manufacturer? It's just that you've managed to work out that you need 9-speed components, yet you're still proposing to buy a 10-speed front derailleur. I'd be tempted to take the bike to a shop and ask them to help.
    – PeteH
    Jul 18, 2016 at 6:56
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    My guess as to why he wants a mountain derailleur... more gear range. Most 10-speed road shifters claim to max out at 28 or 30 tooth max cog size. MTB can go to 36t max in rear and deal better with a triple front.
    – Benzo
    Jul 27, 2016 at 19:32

1 Answer 1

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10 speed brifters with a shadow Deore XT rear derailleur will work fine. Tested.

Your front derailleur will work great with mountain bike crankset - in fact, some new touring bikes use this exact setup!

All 9 speed, high end derailleurs like Deore XT is "Shadow", but not "Shadow Plus". (Shadow plus have clutch, but no 9 speed derailleur has clutch). Shadow is a fancy word for a heavier spring and more streamlined derailleur, that does not expose itself too much, hence lesser risk of breaking it due to hitting something, like a rock.

In your setup, there is no risk of incompatibility, UNLESS your frame is a road bike frame, which the front derailleur you have is designed for - MTB and road seatposts have different angles, so with an MTB frame, road derailleur compatibility can be a bit sketchy.

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