1. The most important thing about buying a new bike is to make sure it fits. The only way you'll know if the bike is right for you is to size up the bike and make sure that the bike's geometry matches your body's geometry. Ask questions and do some research.
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  1. #1
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    mtb - road chainrings

    Do mtb rings fit on road cranks and the other way round? Thanks

  2. #2
    Just Ride
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    I' would think they would. Though you'd probably have to move the front derailleur to accommodate. Also the rear der might not be able to handle it. Where on earth are you gonna pedal a 52t front ring on a mtb trail? Or are you super human???
    SS ==> Nut up or Shut up!

  3. #3
    Flow like water
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    The same cranksets can be used on both MTB and road bikes. If they have the same bolt circle diameter and number of bolts, they would work.

    What are you up to anyway?

    Edit: Better information in later posts.
    Last edited by DavyRay; 07-30-2012 at 02:33 AM. Reason: reconsidered

  4. #4
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    As long as the ring fits, it works. You will have trouble finding a dirth of rings smaller than 39 teeth, though.

  5. #5
    What could go wrong ...
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    Quote Originally Posted by wschruba View Post
    You will have trouble finding a dirth of rings smaller than 39 teeth, though.
    and anything bigger than a 44 might rub on the chainstay
    I used to ride to Win ... Now I ride to Grin

    While my guitar gently weeps, my bike sits there mocking me

  6. #6
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    Most road chain rings are 5 bolt in my experience and most MTB are 4 bolt - so they won't fit.
    There are some road triples around such as the 105 50/39/29 - which I use - even the 29T ring has 5 bolts. My 105 Crank will not fit on my Epic, I sometimes use the 44/32/22 XT crank on my road bike for touring and just pushed the 105 into the BB out of interest - the 50T ring won't clear the chainstay

  7. #7
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    not likely.

    the reasons have already been mentioned. road rings are 5 bolt, mtb are 4 bolt more often than not. with a 4 bolt mtb crankset, you can buy big chainrings, but they can taco easier because the bolts are closer to the center of the ring, so there's a better chance of folding the ring. If you go 50t or bigger, you should just use a 5 bolt road crankset, really.

    clearance at the chainstay is another potential problem with putting big rings on a mtb. it depends on the frame in question, but this is often a problem where a belt drive is fitted to a bike not designed to clear the wide pulleys used for a belt drive. many frames will never be able to accept a belt drive system because many frames designed for it have design specifications to handle the wider pulley. A similar problem occurs with trying to put bigger rings on a mtb frame. a mtb frame is often designed with a max of 48t on the big ring in mind. I have seen some frames with mm of clearance for the ring. no way possible to put a bigger ring on there.

    a road frame, in contrast, can take smaller mtb rings with no problem because they're designed to take bigger ones.

  8. #8
    Fat-tired Roadie
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    Quote Originally Posted by NateHawk View Post
    not likely.

    the reasons have already been mentioned. road rings are 5 bolt, mtb are 4 bolt more often than not. with a 4 bolt mtb crankset, you can buy big chainrings, but they can taco easier because the bolts are closer to the center of the ring, so there's a better chance of folding the ring. If you go 50t or bigger, you should just use a 5 bolt road crankset, really.
    Quoted as a voice of actually knowing something about what's usually spec'd on a road vs. a mountain bike.

    I'd add that the circle described by the bolts on a crank comes in a few different diameters. Mountain bikes, for example, have a 104mm and 64mm circle on almost all cranks, although a few other patterns are still out there. Road cranks mostly have 110 or 130mm circles, with a 74mm circle added on a triple, and a few other patterns out there.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  9. #9
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    What if I were to put 3 spacers on my bottom bracket - all on the crank chain-ring side; would there be clearance for the roadie crank-set from my bike frame chain-stay.

  10. #10
    Fat-tired Roadie
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    It would be simpler just to use a three-piece crank. Then you get some choice about your spindle length and still get symmetrically placed pedals.

    If it were my project, I'd test-fit a road crank installed according to the manufacturer's instructions before trying anything different. The thread contains a number of reasons this sort of thing might not work, but it's certainly possible that your frame will allow a road crank to bolt right on.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

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