Straight pull versus j-bend
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  1. #1
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    Straight pull versus j-bend

    Here's another one I have always wondered about: Conceptually I really like the idea of the straight-pull spoke. On the other hand, I also understand the unparalleled flexibility that the j-bend spoke afford the builder, by allowing a variety of lacing schemes even with the identical hub and rim. So my question really is: Do straight-pull spokes have tangible benefits? Other than perhaps saving five grams for a wheel? Are wheels built with them (ever so) slightly stronger? Stay true longer? Or are they just gimmicks? Serious question guys, not trying to start a flame war.

  2. #2
    A wheelist
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    Of course you're going to get opinions. IMO they're a solution looking for a problem. I can't remember a bend in a spoke causing me a problem ever since I figured out how to build wheels properly (which would be about 20 years ago after 30 years of building them not properly).
    .

  3. #3
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    I think Mike nailed it. Build it right, you will have a very low chance of failure. No need to worry about the bend.
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  4. #4
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    I had asked this question to a bunch of wheel builders off forum as we are developing some mtb hubs. Every single one said jbend due to the flexibility.

    Another good point t brought up by Dustin at Southern Wheelworks. He built up a straight pull hub with round spokes and said Never Again!!.

    The spokes just spin and it's hard to keep them in place without pliers. Bladed spokes are not as bad.
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  5. #5
    grizzly moderator
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    It seems to me that the case of the straight pull spokes was created by the majors to address issues resulting from the quest of continuously attempting to reduce the number of spokes. Issues like loss of lateral stiffness (hubs with straight pulls tend to have better bracing angles than j-bend hubs), higher tension values at the (less spokes = higher tension per spoke) and spokes made from other material other than steel (beefy bladed aluminum spokes used by Mavic, Fulcrum, etc).
    I think when looked at from that prospective the need of straight pulls may be easier to justify.
    The wheels I personally build don't use less than 28 conventional spokes at the rear (conventional in the sense of either thinner bladed spokes like the Cx-Rays or round double butted like the Race). For these kind of builds I don't see the benefits of the straight pulls justify the hassle of building using them.
    With bicycles in particular, you need to separate between what's merely true and what's important.

  6. #6
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    Quote Originally Posted by coachboyd View Post
    I had asked this question to a bunch of wheel builders off forum as we are developing some mtb hubs. Every single one said jbend due to the flexibility.

    Another good point t brought up by Dustin at Southern Wheelworks. He built up a straight pull hub with round spokes and said Never Again!!.

    The spokes just spin and it's hard to keep them in place without pliers. Bladed spokes are not as bad.
    Exactly what I concluded after building one wheel with straight pull spokes. They spin like crazy. It is bad design, spoke head and flange hole shouldn't be round on straight pull, but if they make it in some sort of shape which would sit firm it would probably add to the cost and make it less strength.
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  7. #7
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    I don't know but I suspect that with Shimano's engineering resources leading them to use straight pull and their ability to make low spoke wheels that actually do hold up probably indicates there is something to them.
    Maybe it's not straight pull per se but the bracing angle they allow for. I'm not trying to promote Shimano wheels as there are issues to consider but I think it's pretty clear they are stronger then a traditional set could be made with the same amount of spokes.

  8. #8
    changingleaf
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    I've seen both straigh-pull and j-bend spokes broken at the hub and I can't find any fatigue testing showing that one is stronger than the other.

    From the measurements that I've taken straight pull hubs do not necessarily have a better bracing angle then j-bend designed hubs.

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    Quote Originally Posted by changingleaf View Post
    I've seen both straigh-pull and j-bend spokes broken at the hub and I can't find any fatigue testing showing that one is stronger than the other.

    From the measurements that I've taken straight pull hubs do not necessarily have a better bracing angle then j-bend designed hubs.
    This.

    You can build a great wheel with either, but j-bend is a lot easier to work with and offers more flexibility.

    One nice thing about straight pull is it's easy to replace broken spokes, no need to remove the cassette if it's a drive-side, and no fishing it through all the other spokes like a heads-out spoke on a j-bend build. That's nice with Specialized's Roval MTB wheels, cause they break spokes a lot, so it's easy to fix them.

  10. #10
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    Quote Originally Posted by coachboyd View Post
    Another good point t brought up by Dustin at Southern Wheelworks. He built up a straight pull hub with round spokes and said Never Again!!.

    The spokes just spin and it's hard to keep them in place without pliers. Bladed spokes are not as bad.
    Seriously. NEVER AGAIN. I even bought a tool that's supposed to hold them, I just ended up with a cramping hand, you have to squeeze stupid hard and even then the spokes still spin sometimes. I don't ever build a new wheel with straight pull hubs, but that wheel I was lacing a replacement rim onto a Roval wheel. See my previous post...

  11. #11
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    As others have said, if you go straight-pull, save yourself a huge headache and get BLADED spokes and use the appropriate blade spoke holder to keep them from rotating during tensioning. CX-Ray or Aerolite if you are happy with thin spokes, Aero Comp if you want something thicker.

    As for tangible benefits, yes, absolutely. They remove the #1 failure point of bicycle spokes - the elbow. However, in doing that, they also inherently decrease the flange spacing and therefore the wheel's lateral stiffness by a small amount.

  12. #12
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    Quote Originally Posted by nhluhr View Post
    straight-pull...............They remove the #1 failure point of bicycle spokes - the elbow.
    I guess if a spoke is going to break, that's where it will be but I'll bet most of us that have built wheels for years can't remember the last spoke that broke on us. Hence my earlier comment - a solution looking for a problem.
    .

  13. #13
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    Quote Originally Posted by Mike T. View Post
    I guess if a spoke is going to break, that's where it will be but I'll bet most of us that have built wheels for years can't remember the last spoke that broke on us. Hence my earlier comment - a solution looking for a problem.
    That's the same questionable argument against spoke-prep or alpina ABS style nipples. Just because you CAN build a wheel that doesn't need the benefit doesn't mean you shouldn't also double-down on your approach to make it even more bombproof-reliable.

  14. #14
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    Quote Originally Posted by nhluhr View Post
    That's the same questionable argument against spoke-prep or alpina ABS style nipples. Just because you CAN build a wheel that doesn't need the benefit doesn't mean you shouldn't also double-down on your approach to make it even more bombproof-reliable.
    So you're saying that if I haven't built a wheel badly enough for a nipple to unscrew then I still should glue them in place? That's awesome logic. Maybe then I could do crap builds and still look like an expert!
    .

  15. #15
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    Quote Originally Posted by Mike T. View Post
    I guess if a spoke is going to break, that's where it will be but I'll bet most of us that have built wheels for years can't remember the last spoke that broke on us. Hence my earlier comment - a solution looking for a problem.
    It's not just about you and other people who have built wheels for years. You probably haven't built and used 16/20 wheels either.

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    Quote Originally Posted by Mike T. View Post
    So you're saying that if I haven't built a wheel badly enough for a nipple to unscrew then I still should glue them in place? That's awesome logic. Maybe then I could do crap builds and still look like an expert!
    That is exactly the opposite of what I said. Your implication that adding best-practices somehow mandates being sloppy elsewhere makes me hope to god you don't work in any kind of industry that affects me.

  17. #17
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    Quote Originally Posted by nhluhr View Post
    That is exactly the opposite of what I said. Your implication that adding best-practices somehow mandates being sloppy elsewhere makes me hope to god you don't work in any kind of industry that affects me.
    Ok then, I'm supposed to use a belt and suspenders to hold up my pants?
    .

  18. #18
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    DT's straight pull flange spacing is worse than their traditional flanged rear hub. It's a similar problem with all straight pull hubs. You need material all around the outer most spoke in order to make the spoke hole. A traditional flange has half the spokes on the outside of the flange improving the spacing. Average of the inner and outer spokes ends up being better.

    On to the spoke. Straight pull spokes are not immune to breaking at the head. Not by a long shot. Just ask people like me that have to service wheels on a regular basis. If you were to look at the percentage of straight pull spokes that break at the head to the millions of j-bend spokes Js are the winner.

    So to wrap things up. Straight pull spokes aren't less prone to breaking and the hubs aren't better designed. The final nail in their coffin for me is the fact that it's almost impossible to use round spokes with them.

    No thanks.

  19. #19
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    Quote Originally Posted by Mike T. View Post
    Ok then, I'm supposed to use a belt and suspenders to hold up my pants?
    Boy, I love this place.

    I didn't even know I was supposed to be wearing pants when I built wheels...

  20. #20
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    Straight pull look cooler. That should be the most important factor.

  21. #21
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    Quote Originally Posted by robt57 View Post
    I didn't even know I was supposed to be wearing pants when I built wheels...
    You should. Cheezies might be harmless but don't get that anti-seize anywhere it shouldn't be.
    .

  22. #22
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    Quote Originally Posted by changingleaf View Post
    From the measurements that I've taken straight pull hubs do not necessarily have a better bracing angle then j-bend designed hubs.
    Straight pull is definitely not better in that respect, and most designs are worse.

  23. #23
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    Quote Originally Posted by dcgriz View Post
    It seems to me that the case of the straight pull spokes was created by the majors to address issues resulting from the quest of continuously attempting to reduce the number of spokes.
    Not seeing any reason for it there.

    Issues like loss of lateral stiffness (hubs with straight pulls tend to have better bracing angles than j-bend hubs)
    What hub are you thinking of? It's possible, but usually the way the hub is made reduces the potential DS offset.

    spokes made from other material other than steel (beefy bladed aluminum spokes used by Mavic, Fulcrum, etc).
    I think you are getting warm. Manufacturers want their products to look different. Branding and marketing.

  24. #24
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    Quote Originally Posted by rruff View Post
    What hub are you thinking of? It's possible, but usually the way the hub is made reduces the potential DS offset.
    .
    When I compared the flange spacing of the Mavic Ksyrium SL to the j bend Durace I measured about 3 mm more on the Mavic, as I recall.
    (Approximate numbers; I don't have the Mavics where I am now)
    With bicycles in particular, you need to separate between what's merely true and what's important.

  25. #25
    wheelbuilder
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    To fairly measure a SP hub you have to take the average of the inner and outer spokes on each side. That's the equivalent of the j-bend spokes that have their elbows of both sides of the flange making the center to center of flange measurement an average of the two.

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