BMX crank compatibility- Mtbr.com
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  1. #1
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    BMX crank compatibility

    Hi all

    I know a bunch of you use BMX cranks on your SS's. I have a couple of questions for you.

    How do I know if my ss mtb will accept BMX cranks? I have a 1994 Spacialized Stumpjumper, steel frame. At the moment it has an LX square taper bettom bracket in it fitted at a shop so I dont know if it an American or European BB or what.

    Also I am running a flip flop hub at the mo. I have a shimano freewheel on it that I am told will work with 1/8 or 3/32 chain but can you also get fixed cogs that will work with a 1/8 chain if I go with the BMX crank?

    Sorry for the newby questions but I dont want to buy something on ebay I cant use.

    Thanks a lot.

  2. #2
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    Euro BB will fit.
    1/8" Chain will work with any Cog/Freewheel/Chainring, 3/32" or 1/8"
    wanted: Cannondale Lefty w/ V-brake studs

  3. #3
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    cool, thanks. So how do I know if I have a Euro BB?

  4. #4
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    Euro BB = BSA BB, 68mm (on some bikes 73mm) wide and 1,37"x24tpi

    almost all MTB, and most roadbike frames have BSA BB shells
    wanted: Cannondale Lefty w/ V-brake studs

  5. #5
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    Quote Originally Posted by rusty_ss
    So how do I know if I have a Euro BB?
    American BB shells are huge and the BB itself is press-fit into it. Your Specialized has a Euro, thread-in BB.

    Quote Originally Posted by rusty_ss
    can you also get fixed cogs that will work with a 1/8 chain if I go with the BMX crank
    Yes, you can buy fixed gear cogs in either 3/32 or 1/8. As noted elsewhere, the 3/32 size will work with either a 3/32 or a 1/8 chain; the 1/8 will only work with a 1/8 chain.
    "America is the greatest country in the world, but that's a lot like being the prettiest waitress at Denny's."

  6. #6
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    Not to insult your intelligence but in case you did not know, you can also run BMX chainrings. You do not have to use a spider, which gives you a lot of cool options on chainrings.

  7. #7
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    Quote Originally Posted by rusty_ss
    Hi all

    I know a bunch of you use BMX cranks on your SS's. I have a couple of questions for you.

    How do I know if my ss mtb will accept BMX cranks? I have a 1994 Spacialized Stumpjumper, steel frame. At the moment it has an LX square taper bettom bracket in it fitted at a shop so I dont know if it an American or European BB or what.

    Also I am running a flip flop hub at the mo. I have a shimano freewheel on it that I am told will work with 1/8 or 3/32 chain but can you also get fixed cogs that will work with a 1/8 chain if I go with the BMX crank?

    Sorry for the newby questions but I dont want to buy something on ebay I cant use.

    Thanks a lot.
    I would forget ebay and have your LBS order a set of FSA Nasty Boy cranks with the euro BB. Cheaper than Profile Racing with a MUCH better BB. Available in 175 and 180mm lengths.

    You need to buy the chainwheel or spider/chainring separately. BMX chainwheels are available in every size from 25t to 48t. If you are using a chain tensioner (like a Singelator) you can not use an 1/8" chain so be sure the chainwheels are 3/32".
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  8. #8
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    I second the FSA route. Nice BB with super stiff crank arms. I think I paid like $90 or so for the FSA's.

  9. #9
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    The only thing you really lose out on with BMX cranks is the outrageous weight penalty.

  10. #10
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    If you use a Ti spindle the weight is about the same.

    Of you could get the new Eastern Bikes Ti Cranks. Only 1.35 lbs
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  11. #11
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    Quote Originally Posted by Matty H
    The only thing you really lose out on with BMX cranks is the outrageous weight penalty.
    If you consider 200 grams to be an outrageous weight penalty then you're probably not strong enough to ride a single speed anyway.

  12. #12
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    I'm running 180mm Primo Powerbites. I've had FSAs before, but I had problems with them loosening too often, since you can't crank down the bolts too tight of you'll tighten the bearings. Not to mention the weight. The Powerrbites are aluminum, and have pinch bolts that hold the cranks to the spindle. Only had them about 3 weeks, maybe 200 miles, so I can't report on the long-term durability, but I'm happy so far!

  13. #13
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    Quote Originally Posted by Vermont29er
    The Powerrbites are aluminum, and have pinch bolts that hold the cranks to the spindle.
    Mmmmm.. pinch bolts....
    "America is the greatest country in the world, but that's a lot like being the prettiest waitress at Denny's."

  14. #14
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    Quote Originally Posted by Vermont29er
    I'm running 180mm Primo Powerbites. I've had FSAs before, but I had problems with them loosening too often, since you can't crank down the bolts too tight of you'll tighten the bearings...
    Then you had the wrong BB. The euro FSA X-Drive BB has an adjustable cup which lets you set it so you can tighten the crank bolts as hard as you want without affecting the bearing. That is why I recommend it.

    The FSA Euro Pro BB (and most other BMX euro BBs) does NOT have an adjustable cup and can suffer from binding bearings.
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  15. #15
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    I supposedly had the X-Drive. But it came with no directions, and their web site had no directions either. Maybe I had it setup wrong, but I played with it a lot, could never get it quite right. Caused me a lot of grief and a long walk.

    How is the adjustable cup setup? I just dont see how I could have ever tightened the bolts fully with the setup I had. Mine had a lot of spacers. I even got some really thin washers to try to fine tune it. There were some cup shaped parts, but they only rested on parts that needed to move, or else they would leave a gap for mud to get in.

    I just dont see why more manufacturers dont use pinch bolts, it makes it all a lot easier.

    Jeez, Im getting pissed off just thinking about the whole experience. I hate FSA.
    Last edited by Vermont29er; 08-26-2006 at 10:21 PM.

  16. #16
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    Pinch bolt arms can slide off. I have seen it happen and it was a chronic problem.

    X-Drive

    Adjusts like any other ("old school") non-cartridge BB except the splined cups require the left arm to be removed.

    Euro Pro
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  17. #17
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    Mine was similar to the X-Drive you have pictured, but it dind't have the lock ring. And the cups were not splined. Weird.

    The Primos have a bolt on the end, cranks can't slide off unless that falls out as well as having the pinch bolts loosen.

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