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  1. #1
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    CX Build Question

    Hey Guys,

    I am in the process of brainstorming a wheel set build. The hubs that I want to use are the Shimano CX75. This hub only comes in a 28H version. I weigh 180 pounds. The wheels will be used for CX racing, gravel, and road. Does anybody see any issues with wheel strength if I use a nice strong spoke like DT Comps, etc?

    The wheel that I want to use is the ZTR Ironcross. Does anybody see any issues running latex tubes when there is a need to surpass the 45 psi limit (road riding, etc.)?

    Thanks in Advance!
    G

  2. #2
    turtles make me hot
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    The wheel itself will be fine.
    I can't help you with the tube question.
    I like turtles

  3. #3
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    I just rebuilt a 36h stock wheel for my girlfriend. Its a noodle. Its not going to hold up to her road riding it, and shes light. Its getting replaced by a much stronger, stiffer, more durable 24h rear wheel. The 36h uses straight 2.0 spokes, the 24h uses lasers, 2.0/1.5. Its really not about spoke count!

    The iron cross is really, really lightweight. You may have problems with the build, flex, and keeping true. I would use a heavier, sturdier rim.

  4. #4
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    Quote Originally Posted by One Pivot View Post
    I just rebuilt a 36h stock wheel for my girlfriend. Its a noodle. Its not going to hold up to her road riding it, and shes light. Its getting replaced by a much stronger, stiffer, more durable 24h rear wheel. The 36h uses straight 2.0 spokes, the 24h uses lasers, 2.0/1.5. Its really not about spoke count!

    The iron cross is really, really lightweight. You may have problems with the build, flex, and keeping true. I would use a heavier, sturdier rim.
    Thanks Pivot. The Iron Cross gets many recommendations. What would you recommend in its place?

    G

  5. #5
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    Ill flat out admit im biased against stans, so take that with a grain of salt. I havent had luck with them at all, except flows and arches (which are weight comparable to other rims and seem to hold up as such). I steer away from any non carbon 29/700c rim thats under 400g. If you dont mind the extra weight, id look at kinlins.

    I like A23's too, but again its a big jump in weight.

  6. #6
    Positively negative
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    The Iron Cross still has a 65psi limit with tubes.

  7. #7
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    As another data point... I'm 235-240lbs running Light Bicycle carbon rims with DT 350 hubs, 28 holes front/32 rear, with DT Comp spokes on my cross bike. You'll be fine.

  8. #8
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    Quote Originally Posted by One Pivot View Post
    I just rebuilt a 36h stock wheel for my girlfriend. Its a noodle. Its not going to hold up to her road riding it, and shes light. Its getting replaced by a much stronger, stiffer, more durable 24h rear wheel. The 36h uses straight 2.0 spokes, the 24h uses lasers, 2.0/1.5.
    What problems do you envisage with this 36 hole wheel?

    Its really not about spoke count!
    Wheel Building Philosophy Nox Composites

    Taken from the above page...

    As we said above, number of spokes is the 2nd most important factor when building a set of stiff wheels. Therefore, we use 32 spokes by default. It may not be "trendy," or "look cool" but it's the right thing to do from an engineering standpoint. Many people assume that with super-stiff carbon rims you can "get away" with very few spokes. Perhaps you can depending on what level of stiffness you are happy with, but there is more to the story, and that's opposite load deflection.

  9. #9
    mtbpete
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    That wheelset should be fine for your intended use. I've built similar for others and they're fine.

    There's no reason that you can't use latex tubes at 45psi, though I recommend going tubeless.

  10. #10
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    Quote Originally Posted by roger-m View Post
    What problems do you envisage with this 36 hole wheel?



    Wheel Building Philosophy Nox Composites

    Taken from the above page...

    As we said above, number of spokes is the 2nd most important factor when building a set of stiff wheels. Therefore, we use 32 spokes by default. It may not be "trendy," or "look cool" but it's the right thing to do from an engineering standpoint. Many people assume that with super-stiff carbon rims you can "get away" with very few spokes. Perhaps you can depending on what level of stiffness you are happy with, but there is more to the story, and that's opposite load deflection.
    Not that im all that great at mechanical engineering, but from an engineering standpoint spoke count still has nothing to do with stiffness.

    If you push with 5kg of force, no matter how many spokes you have, the rim is moving in the direction you push, the total tension loss and gain is 5kg. The more spokes you have, the more the 5kg is spread across spokes.

    Less spokes means more stress at the rim, yes, and its less durable. It is not more or less stiff though.

    I can bend this 36h rim, by hand, until its out of true. Its so flimsy that I can knock it completely out of true doing the regular destressing process. Its a noodle. The rim is not quality. I can taco it by hand. My 24h rim is very high quality and incredibly stiff.

    I like 32h rims because they're more durable, but I have a 24h wheel hanging around thats great quality so im using it. Shes light, so im not worried about stress at the rim holes.

    Im not saying to ditch spokes and go to low spoke counts, but you gotta look at the whole picture. You cant use a noodle rim and then use 36 spokes to counter it. You cant use a stiff rim and low spokes and expect it to be as durable as a 32 spoke wheel either.

  11. #11
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    Quote Originally Posted by One Pivot View Post
    Not that im all that great at mechanical engineering, but from an engineering standpoint spoke count still has nothing to do with stiffness.
    See the NOX link in my previous post. This analysis is proven in other sources as well.

    If you push with 5kg of force, no matter how many spokes you have, the rim is moving in the direction you push
    You are exerting a force in the direction you push which is resisted by the spokes. More spokes (or stiffer spokes) gives a stiffer resistance and the rim doesn't move as much.

    I can bend this 36h rim, by hand, until its out of true. Its so flimsy that I can knock it completely out of true doing the regular destressing process. Its a noodle.
    The spokes are too tight and the rim has reached its compressive limit, easily obtained with a flimsy rim and 36 spokes. Pushing by hand exerts a lot of force on the spokes the same as the 'destressing process' which overloads the rim and it goes out of true.

  12. #12
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    Its not resisted by the spokes though. Theres opposite spokes helping to pull the rim the way you push equaling the resistance of the opposite spokes.

    The rim isnt overloaded. I tested it at all tensions from slack to the 110 kgf i settled on. Its flimsy at all tensions.

    At 130 kgf, the 24h rim will not bend. Itll bruise your hands before giving.

    Stiff rims will be stiff regardless of spoke count. You cant bandaid weak rims with more spokes.

  13. #13
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    Quote Originally Posted by One Pivot View Post
    Its not resisted by the spokes though. Theres opposite spokes helping to pull the rim the way you push equaling the resistance of the opposite spokes.

    The rim isnt overloaded. I tested it at all tensions from slack to the 110 kgf i settled on. Its flimsy at all tensions.

    At 130 kgf, the 24h rim will not bend. Itll bruise your hands before giving.

    Stiff rims will be stiff regardless of spoke count. You cant bandaid weak rims with more spokes.
    WTB frequency cx?

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