BMX cranks on a Mountin bike?- Mtbr.com
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  1. #1
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    BMX cranks on a Mountin bike?

    Does anybody have any experience with BMX cranks on a MTB bike? I am thinking about trying to put on a set of Primo cranks/euro bottom bracket with a BMX bash guard on a Yeti ASX.

  2. #2
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    I have Profiles on both of mine and they work good! They are a little harder to set up but once in never need anything!

  3. #3
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    almost everyone in my crew runs bmx cranks on our bikes, i've been doing it for many years because i used to destroy the old square tapers in a matter of weeks. made the switch to bmx cranks on my mtb back in the early 90's and have never looked back...


  4. #4
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    Sounds great- what sprokets are you guys running, how many teeth?
    thanks

  5. #5
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    36 for the former HT and 38 for the DH ride both are PROFILES I have their 5 ring adapter on there to run an EVIL giude!!

  6. #6
    conjoinicorned
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    i run a true BMX chainwheel/sprocket, at 36t. many BMX cranks have a spider so you can use a normal MTB chainring.

    chainwheels are sexy...
    what would rainbow unicorn do?

  7. #7
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    what about the chain any problems with a 9speed moutian bike chain on a BMX sproket?

    I dont know why people dont run this type of set-up instead of weak, creaky moutain bike scranks & sporkets

  8. #8
    dirt rules
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    25T guardsprocket in front and a 12 in the back.

  9. #9
    conjoinicorned
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    Quote Originally Posted by nikodj01
    what about the chain any problems with a 9speed moutian bike chain on a BMX sproket?

    I dont know why people dont run this type of set-up instead of weak, creaky moutain bike scranks & sporkets
    can't use a 9spd chain on a sprocket, gotta use at least a 1/8" chain (mtb or bmx). even better a 1/4" BMX chain, it'll outlast your frame...
    what would rainbow unicorn do?

  10. #10
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    What are you running as far as the rear end goes cassette / or single spees
    Yeah I have a moped type chain on my BMX bike - not breaking it

  11. #11
    conjoinicorned
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    i'm running a 1x9 with FSA 3-piece on my DH bike, using a regular chainring and an 8spd chain. on my FR HT, azonic 3-piece singlespeed with a massive BMX cog (running 36x18) and a 1/4" BMX chain.
    what would rainbow unicorn do?

  12. #12
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    i use a 30/15 ss with 7mm thick bmx chainwheels and a half-link chain with no basher. smash it all the time on copings and ledges and never had any problems....


  13. #13
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    I have a good idea of the crank, sproket and chain set up. Now I just have to figure out what rear single speed and chain tensor.

    thanks for the help.

  14. #14
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    the Rennen is the most solid ss tensioner around. here is a pic of one, but i run my chain under it instead of over it....

    www.rennendesigngroup.com



  15. #15
    All 26.5" all the time!
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    Quote Originally Posted by nikodj01
    what about the chain any problems with a 9speed moutian bike chain on a BMX sproket?

    I dont know why people dont run this type of set-up instead of weak, creaky moutain bike scranks & sporkets
    Quite a few of the Profile chainwheels are compatable with 3/32" chains (8 and 9 speed).

    Like this one -- note the SRAM eight speed chain.


  16. #16
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    alright hey,
    nikodj01 - what bike are you putting this on? will you be running a chainguide? What is your bb shell width, and how much space will you need between the arm and the bb? Most BMX cranks come with a short 5.5" spindle which is too skinny for most MTB set-ups with a 73mm bb shell.
    I've been wondering these same things as you lately too. I currently run an old FSA X-drive extreme bmx style crankset with a long 6.5" chromo spindle on my FR rig (as well as a wethepeople Royal setup with an FSA ti spindle on my ss street bike), but I want to upgrade to something else, such as the Odyssey Wombolts, but I'm just apprehensive if it will work with a chainguide on my Splinter.... confusing stuff, and expensive to go through trial and error... damn, nobody's got straightforward answers on this stuff either.
    Schralp it Heavy.

  17. #17
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    I bought Primo Power bite 175mm BMX cranks along with an S&M sproket/bashguard.
    The cranks and sproket are on the bike right now (Yeti ASX) standard Euro bottom bracket. I bought a surely chain tensor and single speed kit. 16t in the rear 33t up front.
    I'm also running a standard BMX chain. I should be getting these remaining parts Friday.
    (The cracks and Sprocket look sick)
    nikodj

  18. #18
    tuck-n-roll master
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    I've run both and the one thing I don't like about BMX cranks is they don't have pedal inserts. I've ended up with two stripped cranks before and that was a pain, but I like 'em better in general. Some are flexy too. Strong but flexy. It really depends on what kind of setup you want to run. Big and burly bikes where weight doesn't matter too much would be better off with a solid set of DH cranks. Street and DJ bikes run BMX cranks a large portion of the time.
    Quote Originally Posted by Cru Jones
    Yikes. :nono: We need to add about 10 years onto that age. Unless she's a smokin hottie, then maybe 5...

  19. #19
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    Quote Originally Posted by pavement_hurts
    I've run both and the one thing I don't like about BMX cranks is they don't have pedal inserts. I've ended up with two stripped cranks before and that was a pain, but I like 'em better in general. Some are flexy too. Strong but flexy. It really depends on what kind of setup you want to run. Big and burly bikes where weight doesn't matter too much would be better off with a solid set of DH cranks. Street and DJ bikes run BMX cranks a large portion of the time.
    why would a chromoly crank need pedal inserts? it's for aluminum arms, and I believe primo powerbites and hollowbites (aluminum) have inserts and they are bmx cranks.
    and you think 3pc chromo cranks are flexy?!?! were you running them without a bottom bracket or something? yeah, it does depend on the set-up to an extent, but I wouldn't say flexy. I'm just slightly confused by this post... has that new trials rig of yours twisted your mind? haha, j/k, looks very trick! I just sold my echo trials bike over the summer to finish other projects, and now after seeing yours, I kinda want it back....
    Schralp it Heavy.

  20. #20
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    Quote Originally Posted by BikeSATORI
    why would a chromoly crank need pedal inserts? it's for aluminum arms, and I believe primo powerbites and hollowbites (aluminum) have inserts and they are bmx cranks.
    and you think 3pc chromo cranks are flexy?!?! were you running them without a bottom bracket or something? yeah, it does depend on the set-up to an extent, but I wouldn't say flexy. I'm just slightly confused by this post... has that new trials rig of yours twisted your mind? haha, j/k, looks very trick! I just sold my echo trials bike over the summer to finish other projects, and now after seeing yours, I kinda want it back....
    I've never had a problem with cranks that had pedal inserts. True about the aluminum part, I didn't think about that . I dunno about aluminum bmx cranks, sounds like they would be eaten by concrete very quickly. They're about the same weight as chromo too... weird. Maybe I've just had a bad string of breaking parts.
    Quote Originally Posted by Cru Jones
    Yikes. :nono: We need to add about 10 years onto that age. Unless she's a smokin hottie, then maybe 5...

  21. #21
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    The Primo BMX cranks I am running have peddled inserts. I like BMX parts because of strength plus simplicity. My friend bought a mountain bike with Race face DH cranks recently. There is so much bull crap with those cranks (plastic parts, complexity) He is already having problems with them, defective from the factory. We'll see how the Primos work out in the long run.
    To each his own.

  22. #22
    local trails rider
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    Quote Originally Posted by nikodj01
    ... (Yeti ASX) ... I bought a surely chain tensor and single speed kit. 16t in the rear 33t up front.
    Are you sure the Surly tensioner has enough range? I recently estimated that the AS-X BB-to-rear hub distance varies over an inch through the suspension stroke. I think that means the tensioner needs to handle something like 2.5" of loose chain to allow the suspension to work through its range, without breaking the chain or worse..

  23. #23
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    I hope it is able to handle the chain slack - well see.
    what tensior do you recommend?
    Last edited by nikodj01; 11-16-2006 at 11:42 AM.

  24. #24
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    Quote Originally Posted by nikodj01
    ....what tensior do you recommend?
    for bikes with a lot of CS growth, a cheap short cage derraileur fixed into place, is the most common SS tensioner.


  25. #25
    local trails rider
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    I have no experience with SS tensioners, yet, but I know that Rohloff makes a tensioner that can take up a lot of chain (it has two of the pulley things). I have seen some others that are similar but cannot remember the brand names.

    I guess these are much like deraileurs, except they do not have all the joints and knuckles that a deraileur needs to put the chain where it should be.

  26. #26
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    Quote Originally Posted by nikodj01
    I hope it is able to handle the chain slack - well see.
    what tensior do you recommend?

    I really have no clue how much chain-growth there is with the AS-X... never seen one run SS before either, so good luck...

    but this one here should take up quite a bit of chain slack, as it was originally designed to run dual rings up front, but a single cog in the rear...
    called the Paul Components Melvin


    And show some respect to the man himself: Paul Melvin from point park university
    Schralp it Heavy.

  27. #27
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    Looks like the Shurley tensor doesn’t work (As predicted by some of you guys) not enough wrap around on the rear cog
    The Paul and Rohloff look good and should be able to handle the full suspension. I just have to make sure these tensors are able to handle a BMX chain 1/8 size. I believe these tensors are around the same price? I kind of leaning more towards the Paul right now.

  28. #28
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    Quote Originally Posted by nikodj01
    Looks like the Shurley tensor doesn’t work (As predicted by some of you guys) not enough wrap around on the rear cog
    The Paul and Rohloff look good and should be able to handle the full suspension. I just have to make sure these tensors are able to handle a BMX chain 1/8 size. I believe these tensors are around the same price? I kind of leaning more towards the Paul right now.

    The Paul is expensive as hell....
    Schralp it Heavy.

  29. #29
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    Yeah I think they are both around $73.00 or so

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