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  1. #1
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    Any hubs built for higher spoke tension?

    With FR and even DH bikes starting to head down the big wheel path, I was wondering if anyone was building a hub strong enough to stand up to higher spoke tension. To me one of the biggest hurdles in using 650 or 29er for hardcore gravity riding is building a wheelset that won't be overly flexy. I would think higher spoke tension will go a long way toward fixing that problem. I'm pretty sure the current rims and spokes will work fine but the hub flanges seem to be the weak link here.
    Any ideas?
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  2. #2
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    Dt straight pull.

  3. #3
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    Tension is unrelated to stiffness. Its been very well proven. Stiffness is irrelevant to tension until one side goes slack.

    All hubs will take whatever tension you want, you're rim limited. The hubs are by far the strong link in the system. Rims start to collapse well before you reach the hubs limit.

  4. #4
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    Quote Originally Posted by One Pivot View Post
    Tension is unrelated to stiffness. Its been very well proven. Stiffness is irrelevant to tension until one side goes slack.

    All hubs will take whatever tension you want, you're rim limited. The hubs are by far the strong link in the system. Rims start to collapse well before you reach the hubs limit.
    What he said^ . I've built wheels at 130kgf and rebuilt same weight wheel with stan's rims at 105kgf (95kgf was recommended). The new wheels felt stiffer with thinner spokes, my conclusion; stiffness has a lot to do with the rims. About the only time hub spoke hole strength came into play was back in rim brake days and we were building radial laced wheels. Even Chris King gave a warning about such builds back then.

  5. #5
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    Yup, what OnePivot said, hubs are not the weak link here. I've tried going super high on tension and the hub had nothing to say, the rim however went all out of whack.
    Quote Originally Posted by One Pivot View Post
    Tension is unrelated to stiffness. Its been very well proven. Stiffness is irrelevant to tension until one side goes slack.

    All hubs will take whatever tension you want, you're rim limited. The hubs are by far the strong link in the system. Rims start to collapse well before you reach the hubs limit.
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  6. #6
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    What the posters above said.

    Wheel stiffness is going to be determined by spoke thickness, spoke count, and the rim that you choose to use.

    Spoke tension won't do much for you, stiffness-wise.

  7. #7
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    OK, I'm not arguing, I'm merely trying to get this through my own head.
    How can tension not effect stiffness? A spoked wheel is basically a triangle with the two long sides holding the rim in place. How can the tension on those two sides not effect how easily the center point (rim) moves?
    In real life, if I have too little spoke tension, the wheel is a wet noodle; the rim easily deflecting when side stresses are applied. This problem goes away as the tension is brought up correctly. This would seem to support the idea that more tension gives the rim additional side support against deflection.

    Ratt, I agree with your example of the lower tension on a better quality rim being stiffer than higher tension an a lower quality rim, however, don't you think the same rim/hub/spoke combo would be stiffer at 130kgf than at 95kgf?

    What am I missing?
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  8. #8
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    Rims can only take "so much" tension before they start to go the opposite way as in my example and start to buckle/warp. Yes, if you chose a very hefty and strong rim it could handle higher tensions, however you have to chose just how stiff you want and at what expense to weight. From my experience the rims most people are willing to accept weight wise, will not take tensions over 130kgf well.

    Quote Originally Posted by roxtar View Post
    OK, I'm not arguing, I'm merely trying to get this through my own head.
    How can tension not effect stiffness? A spoked wheel is basically a triangle with the two long sides holding the rim in place. How can the tension on those two sides not effect how easily the center point (rim) moves?
    In real life, if I have too little spoke tension, the wheel is a wet noodle; the rim easily deflecting when side stresses are applied. This problem goes away as the tension is brought up correctly. This would seem to support the idea that more tension gives the rim additional side support against deflection.

    Ratt, I agree with your example of the lower tension on a better quality rim being stiffer than higher tension an a lower quality rim, however, don't you think the same rim/hub/spoke combo would be stiffer at 130kgf than at 95kgf?

    What am I missing?
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  9. #9
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    The only case where a hub flange would fail is radial lacing, but that's probably not what you're doing anyways.

    Roxtar, if the rim is not stiff, flex of the wheel comes from the rim momentarily becoming the shape of a waveform, because the spokes pull it to alternate sides. Adding tension will do little if anything to compensate for a flexy rim, and increasing the tension too far makes the rim constantly waveform-shaped. With a stiff rim the spokes hold it centered, round and true, and at a reasonable tension the wheel will be much more rigid than a wheel with a flexy rim at any tension.

    Moral of the story: for a bombproof wheel use bombproof rims. You'll notice it's a strong piece even at regular spoke tension.

    EDIT: Another point crossed my mind. Making the rim flex is more difficult when the spokes are closer together, because they have less leverage on the rim before another spoke pulls the rim to the opposite side. So if you think your wheel was too flexy, consider building one with more spokes. Even with the same components (apart from hole count) an increased spoke count makes a very noticeable and significant difference.

  10. #10
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    Quote Originally Posted by roxtar View Post
    OK, I'm not arguing, I'm merely trying to get this through my own head.
    How can tension not effect stiffness? A spoked wheel is basically a triangle with the two long sides holding the rim in place. How can the tension on those two sides not effect how easily the center point (rim) moves?
    In real life, if I have too little spoke tension, the wheel is a wet noodle; the rim easily deflecting when side stresses are applied. This problem goes away as the tension is brought up correctly. This would seem to support the idea that more tension gives the rim additional side support against deflection.

    Ratt, I agree with your example of the lower tension on a better quality rim being stiffer than higher tension an a lower quality rim, however, don't you think the same rim/hub/spoke combo would be stiffer at 130kgf than at 95kgf?

    What am I missing?
    This is not a case where more is better. You just need enough.

    I do not think that 95kgf is "enough" for most dished wheels if you use that as the high limit. I use 115-125 as my normal "high" tension (mostly because the wheel is more durable IME). More makes no difference in the feel of the wheels, even compared to 95kgf.

    A good rim, not too thin spokes and at least 32 spokes matters MUCH more. Hubs with wider flange spacing also helps but there is little difference between models.
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  11. #11
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    The hub is sometimes the weak link. A buddy of mine who likes to take that "extra step" brought his wheels up to 160 kgf. DT comps, brass nips, Rhynolite rims and Chris King hubs. He stretched the hub shell to the point where the bearings would just flop out. CK put some oversize bearings in to make up for it.
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  12. #12
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    So we basically just need seriously bomp-proof 29" & 650 rims before they can be seriously considered for DH and heavy duty FR use.
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  13. #13
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    Any hubs built for higher spoke tension?

    Quote Originally Posted by roxtar View Post
    So we basically just need seriously bomp-proof 29" & 650 rims before they can be seriously considered for DH and heavy duty FR use.
    No more so than 26" rims.

    If you are an abusive rider you need beefy rims, no matter their diameter.
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  14. #14
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    Quote Originally Posted by tedsti View Post
    The hub is sometimes the weak link. A buddy of mine who likes to take that "extra step" brought his wheels up to 160 kgf. DT comps, brass nips, Rhynolite rims and Chris King hubs. He stretched the hub shell to the point where the bearings would just flop out. CK put some oversize bearings in to make up for it.
    Are you saying he pulled the hub flange out of spec before the spokes stretched, or the rim failed? That is pretty hard to imagine. I can see elongating the flange spoke holes over time, but what you describe seems crazy!

  15. #15
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    Quote Originally Posted by ghettocop View Post
    Are you saying he pulled the hub flange out of spec before the spokes stretched, or the rim failed? That is pretty hard to imagine. I can see elongating the flange spoke holes over time, but what you describe seems crazy!
    Yup, the hub flange was deformed. CK was nice enough to find some bearings on the large side to fix it up for him. We don't call him Broke-Bike-Bob for nuthin'.
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  16. #16
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    Quote Originally Posted by tedsti View Post
    Yup, the hub flange was deformed. CK was nice enough to find some bearings on the large side to fix it up for him. We don't call him Broke-Bike-Bob for nuthin'.
    This story seems highly unlikely to me. Not only because the chances of a hub shell "stretching" like you describe are like one in a billion, but it would be very out of character for Chris king to jerry rig one of their hubs. They make their own bearings - there's no way they'd take the time to program the machine to make a few one off oversize bearings vs. telling the customer to just buy a new hub shell. Or they would have given him a hub shell with a cosmetic defect or something if he was short on money.

  17. #17
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    Broke-Bike-Bob here. (I'm not normally following this forum)

    What Tedsti said is true. At the time, I was running 36-hole Rhyno Lites with straight gauge 2.0 spokes trued nicely so that the Park tension meter said 26.5 on the drive side (close enough that the min was > 26 and max was < 27). I laced them using standard 3-cross pattern as I've been doing for the last 35 years. I'm a big guy, and tend to flex my wheels so hard that the tires will rub holes in the chainstay. (even with shop-build wheels) So, stiffness is as big of an issue as strength. At the time, I was running Rhynos because they are cheap, wide, and reasonably strong. Plus, they have the inserts in the spoke holes, to keep the nipples from pulling through.

    Like other posts here, my understanding was always that maximum spoke tension was limited by the rim. If the rim can handle it, the hub will be fine.

    I had never run into this problem with Shimano, Hope, Surly, and Phil Wood hubs. But that tension was too much for the Chris King. Pull off the cassette, and the entire ring drive plus bearing are in your lap. So, I sent my wheel into Chris King for service. (I have the CK tool and normally rebuild my own) They told me what happened.

    The spokes stretched the hub so badly that there was slop on the drive-side bearing. They rebuilt it with an over-sized bearing, and put in their largest oversize at no-extra charge. They also told me what was the maximum tension that their hubs could handle. I lowered my spokes to that amount, but it was too late. Even the oversized bearing flops out without any tools.

    Since then, I've switched over to Halo Freedom rims. They seem to be much stiffer, so I can run them at a lower tension (about 120kgf = 25 on the Park gauge). I haven't had any problems since then, but I now have an expensive hub that is used only for spare parts. One of these years, I'll probably replace the shell and bearing and scavenged parts, and try to get it working again.

  18. #18
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    Quote Originally Posted by roxtar View Post
    I would think higher spoke tension will go a long way toward fixing that problem.
    It will not.
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  19. #19
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    Quote Originally Posted by 92gli View Post
    This story seems highly unlikely to me. Not only because the chances of a hub shell "stretching" like you describe are like one in a billion, but it would be very out of character for Chris king to jerry rig one of their hubs. They make their own bearings - there's no way they'd take the time to program the machine to make a few one off oversize bearings vs. telling the customer to just buy a new hub shell. Or they would have given him a hub shell with a cosmetic defect or something if he was short on money.
    He is correct.
    That's why CK does not recommend less than 3x lacing and has a max spoke tension of 120kgf.
    160kgf, however, is not a well-informed thing to do.
    On page 14 of the Technical Service Manual they describe how spoke tension affects the bearing preload adjustment:
    "Spoke tension pulling out on the flanges can slightly loosen the preload adjustment on the bearings. The hub(s) come pre-adjusted from the factory anticipating both spoke tension and skewer compression. However, because of variations in wheel-building practices, a minor adjustment should always be performed upon completion of the wheel build. Please see the appropriate “adjustment” section and check the hub before using."
    Quote Originally Posted by pvd
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  20. #20
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    (Some?) hub flanges from 'tune' are limited to spoke tension of max. 1.000N.

  21. #21
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    (Dang it Ted. I don't want to get into another techie argument on another forum!)

    Regarding spoke tension vs "stiffness". I understand that lateral stiffness won't change very much as spoke tension is increased. That isn't my problem.

    Any big guy will know that when you hit a rock at enough speed, there is a point where the wheel deforms. You'll know this when you hear the spokes go "Sproing!" when you exit the rock and the wheel pops back into shape. Cheaper rims will do this sooner, but any rim will deform if you hit a rock/log/hole/bump at enough speed and your suspension doesn't suck it up.

    During the time while the rim is deformed, the down-facing spokes go slack. Therefore, the rim is free to move whatever way it wants. The point of tight spokes is to prevent this from happening as often. Otherwise, there would be no reason to ever go higher than 10 kgf spoke tension on any wheel.

  22. #22
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    When you're building a wheel and you have the spokes laced it is easy to see how spoke tension affects lateral stiffness. Tension to 65 DS 40 NDS.
    Put the hub on a magazine on the floor. Put the rim on another at the 6'clock position with the mag wrapped over the top of the rim so you can kneel on it. Push the rim down toward the floor at the 11 and 1 o'clock positions with your hands and body weight. It flexes easily. Continue to tension the wheel for another stage at 85-90 and 60 or so NDS. Repeat the procedure and the wheel will need more weight to flex. Rotate it to stress all the spokes and flip it for the other side. Go up to115-125 and 90 or so NDS. It's not going to flex laterally much at all when you put reasonable weight on it. The correct amount of spoke tension will give you a laterally stiffer wheel than the same wheel built with less optimum spoke tension.
    You just felt it yourself.

  23. #23
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    Quote Originally Posted by eb1888 View Post
    The correct amount of spoke tension will give you a laterally stiffer wheel than the same wheel built with less optimum spoke tension.
    You just felt it yourself.
    Wrong
    I've done this any many similar experiments (where actual measurements were taken).
    This "argument" also has no logical basis if you want to get technical. The elasticity of spokes (the force-deflection response) is linear up to the yield point, meaning that an additional 10kgf will stretch a spoke the same amount whether you start at 40kgf of 150kgf. If you have not stress-relieved spokes (poor wheel building) you will see some effects that are not strictly tension related.
    Last edited by meltingfeather; 06-28-2013 at 04:11 PM.
    Quote Originally Posted by pvd
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  24. #24
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    Quote Originally Posted by B.S. View Post
    Otherwise, there would be no reason to ever go higher than 10 kgf spoke tension on any wheel.
    Except that a wheel at 10kgf would go slack as soon as you sit on the bike. There would also not be enough tension in the spokes to be able to bed them in.
    Quote Originally Posted by pvd
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  25. #25
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    Traditionally, higher spoke cross counts were used to make a more compliant wheel (less radially stiff). the individual spoke tensions would be significantly lower for a properly built wheel with 4 (crossed) spokes as opposed to 3.
    especially with suspension, spoke tension is a smaller factor in wheel stiffness than the rim construction.
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