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  1. #1
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    Need some advice on a crankset for kids bike....

    I recently pickep up a xsmall Giant Anthem to build up for my 10 year old son. I've got a good parts list coming together, but the cranks are stumping me. I've found some 155MM square taper arms (Origin 8) on eBay and am considering using these and building it as a 1x9. Would this be a good option or is there an option out there (that doesn't break the bank) that I could get shorter arms set up with 3x9 or 2x10?

  2. #2
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    For short crank info see
    Short Triple Chainring Cranks
    and
    Highpath Engineering : Crank shortening
    There have also been a few other threads recently.

    Some people also use Sinz BMX cranks.

  3. #3
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    Sinz Expert Crank Arms at Danscomp

    Got 'em down to 130mm for $45.
    5 bolt though, but you can get rings at the same site.

  4. #4
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    I use Sinz or for a little lighter AC mini LE. Both work well and have a wide range of sizes.

  5. #5
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    Quote Originally Posted by Otter View Post
    I recently pickep up a xsmall Giant Anthem to build up for my 10 year old son. I've got a good parts list coming together, but the cranks are stumping me. I've found some 155MM square taper arms (Origin 8) on eBay and am considering using these and building it as a 1x9. Would this be a good option or is there an option out there (that doesn't break the bank) that I could get shorter arms set up with 3x9 or 2x10?

  6. #6
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    Quote Originally Posted by Otter View Post
    I recently pickep up a xsmall Giant Anthem to build up for my 10 year old son. I've got a good parts list coming together, but the cranks are stumping me. I've found some 155MM square taper arms (Origin 8) on eBay and am considering using these and building it as a 1x9. Would this be a good option or is there an option out there (that doesn't break the bank) that I could get shorter arms set up with 3x9 or 2x10?
    Quote Originally Posted by bme107 View Post
    For short crank info see
    Short Triple Chainring Cranks
    and
    Highpath Engineering : Crank shortening
    There have also been a few other threads recently.

    Some people also use Sinz BMX cranks.
    I got cranks from him, really quality work. I wanted 2x9 for my son since we have some pretty steep hills here for a kid.
    13 Lenz Lunchbox punkass

  7. #7
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    I've also used the Sinz cranks on a few bikes. They work great.
    I like turtles

  8. #8
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    +1 for the Sinz, I have those on my kids bike. They are only 1 ring though.

  9. #9
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    I built my son's first two bikes as a 1x8 and a 1x10. Keeps it simple.
    I like turtles

  10. #10
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    Thanks for all the replies...looks like I'll go with the Sinz and 1x10. Any suggestions on the chainring to go with? Thinking 34T, but not sure if I just go with a regular BMX chainring (does the thickness matter) or if I should look for one that's made for 10spd?

  11. #11
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    Need some advice on a crankset for kids bike....

    Go with a 10spd Chainring. What size cassette are you going with. 34t chainring is the smallest
    You can go with a 110 bcd. I would recommend
    A 11-36 cassette.

  12. #12
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    Yep. I used a Salsa 34 tooth and an 11-36 cassette.
    I like turtles

  13. #13
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    I agree with the 34T Sprocket and 11-36 rear. Here is a gear chart to help understand the differences. The far right 3 columns was my old 2001 Stumpjumper Pro with a typical 3X front. You can compare that to modern 2X setups (24/38 or 26/39 fronts) and 1X setups (34T, 35T, 36T).



    The 34T 11-36 provides the bulk usable range he would need. A 32T would be a little more ideal but it's not possible with a 110BCD. Let us know how it works out.

    Also, don't forget that you will need a chain guide. Check out Paul's Components or use the stock front derailleur with the adjustment screws accordingly.

  14. #14
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    Need some advice on a crankset for kids bike....

    If you find a 104bcd crank you can go as low as a 30t and use a narrow wide chainring like wolftooth or raceface and ditch the chain guide all together.

  15. #15
    turtles make me hot
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    I used a Salsa chain ring guard and a N Gear Jumpstop. My son hasn't dropped a chain yet.
    I like turtles

  16. #16
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    one more thing you can try...

    I think eveyone's got you on the right track. BMX cranks (Sinz, AC, Crupi, etc.) are lighter and have more lengths to choose from, but you are then limited to 110 BCD, which means 34t is the smallest ring you can run. My son wanted a lower gear on his XS FIsher Cake (we have some steep climbs here), so I mounted an IRD tripleizer (not cheap @ $60) so I could mount an inner ring so he has a 2x setup. Works great. Hard to see, but this is the setup before I put the IRD ring on (155mm Crupi cranks I got off ebay).
    Attached Thumbnails Attached Thumbnails Need some advice on a crankset for kids bike....-evan_trestle.jpg  


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