If Straight Pull is so great...
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  1. #1
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    If Straight Pull is so great...

    Why is it when someone calls and ask me to replace a spoke on the Straight Pull wheel, it comes in with the Head blown off? I thought this was supposed to be the cure for that?

    I just don't see where straight pull spokes are really any better... Rant Over.


  2. #2
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    Would the same spoke on the same wheel, built exactly the same way and ridden the same exact way, break at the bend sooner if the spokes were j-bends?
    With bicycles in particular, you need to separate between what's merely true and what's important.

  3. #3
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    Quote Originally Posted by dcgriz View Post
    Would the same spoke on the same wheel, built exactly the same way and ridden the same exact way, brake at the bend sooner if the spokes were j-bends?
    Hard to say...

    I get the theroy of straight pull, it might b lighter, there may even be some geometric advantages of hub design. I'm just not sold on it. All the force is still going to each end of the spoke wether it is straight or J bend

    I did have a ENVE wheel come by the other day that broke a straight pull at the rim (internal nipplels). I still see more headless straight pull ones.

  4. #4
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    I am not a fan of straight pulls either but mostly for the reason of being a royal pain in the arse to build with.
    The theory on the advantage of the straight ends vs. the bended ends relative to strain etc. sounds reasonable but I dont have j-bends breaking often enough to justify dealing with the hassle of keeping the straight-bends steady so they dont wind-up during tensioning. I dont see j-bends being an underlying problem on a properly built wheel.
    With bicycles in particular, you need to separate between what's merely true and what's important.

  5. #5
    A wheelist
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    If spoke heads are the achilles' heel of spokes then wouldn't it make sense to have no heads? Enter, the Velomax hub with not a spoke head anywhere!

    I have one of these rear hubs, gifted to me by the late great tool-maker Paul Morningstar. He sent it to me with the comment "If you can figure out the formula for spoke length, let me know as I have a few of these hubs and don't have the time or ambition to do it myself".

    As I could foresee a whole load of issues that made the problem of the occasional j-bend head popping off seem irrelevant, I never did figure it out for Paul. Here the hub sits! IMO it was a solution looking for a problem.

    velomax.jpg
    .

  6. #6
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    That hub is what got me started in wheel building! This is sort of a funny one. It was my first Cat 4 race, a flat fast crit in a parking lot (RFK Crit for anyone who's raced in DC) and a guy put his front skewer into my rear wheel two turns from the finish. Broke several spokes. Two of them were broken off like right at the hub flange, and try though I might - and I'm generally wicked resourceful about figuring stuff like this out - the spokes would not come out of the flange for anything. I bought a hub second hand from a guy on the team who'd destroyed his rim, and was on my way.

    The guy whose front wheel did the damage wound up building like 100 wheels for us when we were just starting out. Excellent wheel builder. Alas, he got a real job and moved to China to work for Oracle, as I recall.

    I find most straight pull hubs actually have worse geometry than j-bend, but like most things there are good and bad examples of each. Waiting for a set of rims to build these up, by customer request. carbonti.jpg

  7. #7
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    My first reaction to seeing this hub in my hand was "How the hell do you get a broken (flush) spoke end out of the hub? I did research that as I couldn't imagine having to chuck a hub away that had one broken spoke. The info it out there and it suggests, hair dryer for heat, needle nose vise-grips for the threaded part (that sticks down through the flange) and a boat load of patience. It make a snapped-off j-bend head seem like a walk in the park.
    .

  8. #8
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    Well hopefully the next guy to Google search that topic will find this thread and learn that the answer to a spoke broken off close to the flange is to save your time and spend your money on a new one. My next step would have been to drill out the broken spokes and every other drive side hole and replace the threaded-on-both-ends spokes with normal straight pulls, but I got sane before that happened.

  9. #9
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    I guess the good thing about Straight pull is if your lucky enough to break a spoke at the nipple, you can easily remove it even with disc brakes. You just push it thru the hub with no cssette or disc removal, unlike those pesky j bends

  10. #10
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    Quote Originally Posted by November Dave View Post
    Well hopefully the next guy to Google search that topic will find this thread and learn that the answer to a spoke broken off close to the flange is to save your time and spend your money on a new one. My next step would have been to drill out the broken spokes and every other drive side hole and replace the threaded-on-both-ends spokes with normal straight pulls, but I got sane before that happened.
    This is why I don't get into oddball (aka dumb-ass) hub ideas. I can't say a j-bent spoke has ever caused me a problem (based solely on its bend over a non-bent spoke).
    .

  11. #11
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    Quote Originally Posted by dcgriz View Post
    I am not a fan of straight pulls either but mostly for the reason of being a royal pain in the arse to build with.
    The theory on the advantage of the straight ends vs. the bended ends relative to strain etc. sounds reasonable but I dont have j-bends breaking often enough to justify dealing with the hassle of keeping the straight-bends steady so they dont wind-up during tensioning. I dont see j-bends being an underlying problem on a properly built wheel.
    This. Especially trying to true a bladed spoke wheel without turning the hub end of the spoke.
    "COMPLACENCY IS LETHAL - VOTE in November." - System Shock.

    "With
    bicycles in particular, you need to separate between what's merely true and what's important."
    -- DCGriz, RBR.





  12. #12
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    Bladed spokes actually give you your best chance, as you can use a holder. I won't build a straight pull wheel with round spokes (at lest for what anyone would pay).

  13. #13
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    Quote Originally Posted by dcgriz View Post
    Would the same spoke on the same wheel, built exactly the same way and ridden the same exact way, break at the bend sooner if the spokes were j-bends?
    J bends tend to bread due to flexing, not overall tension. Threaded ends represent a stress riser. You takes your choice. We're well over 100 years into J bend spokes. Something must be working OK.

  14. #14
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    Quote Originally Posted by Enoch562 View Post
    Why is it when someone calls and ask me to replace a spoke on the Straight Pull wheel, it comes in with the Head blown off? I thought this was supposed to be the cure for that?

    I just don't see where straight pull spokes are really any better... Rant Over.
    The straight pull spoke is not a better design.

    A straight pull spoke has its head forged on which disrupts the grain structure making it weaker in that area. When the spoke is used, all the tension is taken directly on the already weakened head area, so failure is more likely.

    A J bend design is much better, since the forces at the hub end are taken by a stronger part of the spoke and not taken directly on the spoke head. Okay, they may fail (due to poor building technique), but saying a straight pull design will prevent this is false.

    Edited for clarity. Word "mashed" replaced by "forged".
    Last edited by roger-m; 06-02-2017 at 04:50 AM. Reason: Clarity

  15. #15
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    Quote Originally Posted by roger-m View Post
    A straight pull spoke has its head mashed on
    Just to clarify, exactly how do u know this?

    Your statement implies that there is a box of spokes and a box of heads on the assembly line, I find that highly implausible and therefore the remainder of your post is also highly suspect.
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  16. #16
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    Quote Originally Posted by duriel View Post
    J
    Your statement implies that there is a box of spokes and a box of heads on the assembly line, I find that highly implausible and therefore the remainder of your post is also highly suspect.
    The end of the spoke blank is forged to make the spoke head.

  17. #17
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    Quote Originally Posted by Enoch562 View Post
    Why is it when someone calls and ask me to replace a spoke on the Straight Pull wheel, it comes in with the Head blown off? I thought this was supposed to be the cure for that?

    I just don't see where straight pull spokes are really any better... Rant Over.

    Only a couple of weeks ago.

    My straight pull Shimano Rs31 spoke on the NDS snapped at the thread/nipple.

    Btw: The wheel was only slightly tacoed and only when at home did I notice it. However, the ****ing **** was there was only one online dealer in the entire UK who just happened to have on in stock (all the local bike shops wouldn't have been able to source it before August 2017 as the main UK supplier is just lazy).

    I don't know why the **** snapped at the nipple and why it broke at all.

    Edit: it was impossible to use the old nipple because the spoke broke at exactly the edge level where the nipple ends. Local bike shop had no way to remove the remaining broken spoke. I was lucky not just to source a spoke but also a new Shimano RS31 nipple.

  18. #18
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    Quote Originally Posted by November Dave View Post
    Bladed spokes actually give you your best chance, as you can use a holder. I won't build a straight pull wheel with round spokes (at lest for what anyone would pay).
    Do straight pull round spokes actually exists?

    I always thought every straight pull spoke is ,,bladed" in a way or another.

  19. #19
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    Quote Originally Posted by roger-m View Post
    The straight pull spoke is not a better design.

    A straight pull spoke has its head forged on which disrupts the grain structure making it weaker in that area. When the spoke is used, all the tension is taken directly on the already weakened head area, so failure is more likely.

    A J bend design is much better, since the forces at the hub end are taken by a stronger part of the spoke and not taken directly on the spoke head. Okay, they may fail (due to poor building technique), but saying a straight pull design will prevent this is false.

    Edited for clarity. Word "mashed" replaced by "forged".
    This is questionable argument in my view. Proper building requires that the j-bend elbows are bent to lay properly on the hub flange for support. If they are not, their fatigue life usually decreases and the spoke breaks prematurely. Setting the right spoke angle on j-bend spokes takes a bit of time and knowledge as its affected by location of spoke (inside or outside) and hub design. Often is not done or done half-arse and spokes break.

    The straight-pull spokes, on the other hand, appear to overcome this "custom" fitting necessary with the j-bends as their design makes their placement standard for all hubs and spoke locations. So from that prospective are they more forgiving (decreased fatigue cycle life wise) when compared to a j-bend spoke where the builder did not take the time to bend the elbows right?

    Straight-pulls also come with their own baggage of problems and wind-up is one that made me look elsewhere as I will not do them again unless they are bladed.

    Which is the worst between the two evils? Do the straight-pulls better guard the average consumer against premature spoke breakage from poor quality builds? I find answers will vary.
    With bicycles in particular, you need to separate between what's merely true and what's important.

  20. #20
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    I rebuilt my Eastons with straight pull DT swiss spokes, haven't had a problem. The original build spokes were a disaster, IMO.

    Calling this design an error is just ridiculous, sounds like they all have problems if not installed with care.
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  21. #21
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    Quote Originally Posted by duriel View Post

    Calling this design an error is just ridiculous, sounds like they all have problems if not installed with care.
    I am not certain if you are referring to my post but if you are I suggest you go back and read it again because your understanding of what you think I said is dead wrong.
    With bicycles in particular, you need to separate between what's merely true and what's important.

  22. #22
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    File under "no good deed goes unpunished." On last night's Thursday night worlds, I notice that the guy who doesn't have the finest hand built wheels in Rhode Island has a wobble in his rear wheel that could seriously make you throw up if you looked at it long enough. Disc bike, no chance the wheel would have fit through rim brakes - reduct the error by half and they still wouldn't have. The wheels came with the bike, the bike is a major brand bike and these are their high end house brand wheels. So I say "hey bring that wheel in tomorrow, I don't want you riding around on that and it's so out I want to check for damage."

    So he brings it in.

    Straight pull, round spokes, internal nipples. It's like the devil had a menage a trois with himself and this is the offspring. Of course I could see none of this as we were riding, otherwise I'd have told him to take it to the shop where he bought it (which is down the street) and they need to make it right. This is a $7000 bike that's almost a year old. Gets ridden maybe 80 miles/week, and none in the winter.

    So I take the whole thing down to zero tension because it's totally messed up, and then a non drive straight pull head comes off at somewhere around 60 kgf (they're 2:1 laced, so nds has fairly good tension). So now I'm an hour into this total b of a job, having just yesterday said there's no way I'd build straight pull round spokes, only since I offered this I'm doing it for free. Shoot me now.

    No good deed goes unpunished.

    I hate straight pull spokes.

  23. #23
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    Never volunteer to work on a disaster, of course it is sometimes difficult to determine from outside.

    my other comment was in response to roger-m. If you don't like them, ok, I'm good with one not using them. But to say the whole design is messed up cause somebody somewhere broke a factory made wheel is just wrong. Plenty of J bend spokes have been broken in this world.
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  24. #24
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    Quote Originally Posted by dcgriz View Post
    This is questionable argument in my view.
    Nope.

    If a j-bend spoke breaks at the elbow, then taking away the elbow with a straight pull spoke solves the problem. This logic is wrong, the straight pull spoke will still fail, but for a different reason, and the explanation I gave is why the OP was seeing many such failures in straight pull spokes.

    The mode of failure in straight pull spokes has been discussed many times before (including contributions from Jobst Brandt), although today's better quality steel reduces the number of straight pull failures (and also J-bend failures).

  25. #25
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    Quote Originally Posted by duriel View Post
    my other comment was in response to roger-m. If you don't like them, ok, I'm good with one not using them. But to say the whole design is messed up cause somebody somewhere broke a factory made wheel is just wrong. Plenty of J bend spokes have been broken in this world.
    Hey, all I was doing was giving an explanation why the OP was seeing straight pull heads popping off. It's not a wrong explanation, it's based on metallurgy and engineering. Your one pair of sp wheels that are so far working fine proves nothing.

    There's a greater proportion of J bends breaking for the simple reason that there are many times more wheels built with them, and a larger proportion of low cost wheels with poor quality spokes and questionable building.

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