Boost crankset with non boost rear hub?- Mtbr.com
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  1. #1
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    Boost crankset with non boost rear hub?

    When I purchaed my Yeti I received an extra Shimano M7000 SLX boost crankset as part of the deal. I already have the XT crankset on my Yeti and the SLX crankset is only 170mm, so it is of no use to me. I am upgrading my wifes Giant Trance to the full SLX groupset (1x11) and was wondering if I could use a boost crankset on a non boost bike?
    2016 Yeti SB4.5c
    2007 Specialized Stumpjumper FSR Expert
    2013 Giant Trance X3

  2. #2
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    Your chainline would be horrible, maybe unusable in the lowest (climbing) gears. I'd sell it and get the right one.
    I brake for stinkbugs

  3. #3
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    That's what I figured, but what if a chainring with 2mm spacers were used? Would the difference only be 1mm at that point? Is that enough to make a big difference? I am still learning how all of this works
    In my reading up on the topic, I have found where non boost crank arms can be used on a boost rear hub. If that is the case, wouldn't the opposite be true?
    2016 Yeti SB4.5c
    2007 Specialized Stumpjumper FSR Expert
    2013 Giant Trance X3

  4. #4
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    Will it work, yes. Although based on the bike's BB shell width, you might have very few threads engaged. I'd be very reluctant to use it on a 68mm wide BB shell. As mentioned, it will probably mess up the chainline, but I don't think it will be horrible. A couple mm off, but still off. If you're in a area with a lot of mountain biking, I think you could easily find someone willing to trade you cranksets.
    "a hundred travel books isn't worth one real trip"

  5. #5
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    This should explain it for you...

    Tech Talk: Boost 148 explained - Mtbr.com

  6. #6
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    Quote Originally Posted by 2AllBeef View Post
    That's what I figured, but what if a chainring with 2mm spacers were used? Would the difference only be 1mm at that point? Is that enough to make a big difference? I am still learning how all of this works
    In my reading up on the topic, I have found where non boost crank arms can be used on a boost rear hub. If that is the case, wouldn't the opposite be true?

    Non-boost cranks stock cranksets usually don't have the best chainline due to clearance issues and there are tons of threads about people spacing them inboard to improve it. If you "boost" it out 3mm it's obviously going to make the situation even worse.

    Non-boost crankarms can sometimes be used successfully with boost hubs because it can actually improve the chainline. The center of your cassette is @~45mm and boost chainring is 53mm.
    I brake for stinkbugs

  7. #7
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    Quote Originally Posted by J.B. Weld View Post
    Non-boost cranks stock cranksets usually don't have the best chainline due to clearance issues and there are tons of threads about people spacing them inboard to improve it. If you "boost" it out 3mm it's obviously going to make the situation even worse.

    Non-boost crankarms can sometimes be used successfully with boost hubs because it can actually improve the chainline. The center of your cassette is @~45mm and boost chainring is 53mm.
    That makes sense. Thank you for clearing that up.

    It probably will not work, but it will not cost me anything to try since I need to buy a new chainring anyway for the Yeti which I could also use as a test on the Trance. If it doesn't work I can just reuse the stock Shimano M542 crankset or sell the SLX and get the proper one.
    2016 Yeti SB4.5c
    2007 Specialized Stumpjumper FSR Expert
    2013 Giant Trance X3

  8. #8
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    I put a 2x boost crank on my 135mm spaced Surly troll and yeah the chainline ain't great, but not horrible (from my understanding a 49mm chainline is ideal for 135mm spacing). However, it was a necessary evil to clear a 26x3.0 knard without chain rub

    With 26x2.8 tire options now available, I was thinking of using 3mm spacers to bring the chainline back inboard from 52mm to 49mm. My question is then won't I need longer nuts/bolts? I can find the 3mm spacers, but not sure which nuts/bolts to get. Help?

  9. #9
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    M7000 to replace a 9 speed crank? I think I wouldn't unless it's the 10 speed (3x) version.

    I don't fully understand your statement about testing/switching chainrings, but they aren't compatible with each other as the M542 has 64/104 mm BCD and the M7000 uses a new 96/64 non-square setup.

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