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  1. #1
    MADE IN HONG KONG
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    Wheel building - Bong! - TACO!

    I watched as this guy, almost finished with a wheel build, grabbed the rim like a steering wheel and pressed the axle firmly to the floor. There was a chatting bonging snapping sound, and the wheel became a shallow taco. It appears to be his first build.

    What exactly happened? was the spokes too tight or too loose? How do you avoid this?

    I would cry if it happened to me.

    btw: the rim was relatively low grade and you can see a seam at the joint.

    Thanks in advance for all your input
    If you are not having any fun, it's all your fault

  2. #2
    Senior Member juicemouse's Avatar
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    Too high spoke tension for that rim. If he was approaching that tension gradually, he could've just backed the tension off a bit, retrued, and been fine. Any idea how it ended up?
    It is my belief that every person in this world has something to teach, and everything to learn.

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  3. #3
    me have long head tube TallRider's Avatar
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    Btw, he was probably doing this to stress-relieve the spokes, and pressed too hard for the way that he'd tensioned it. I've had this happen to old wheels while stress-relieving after re-tensioning them, and have actually had good success with just pressing from the other side, popping them back into place, and re-tensioning.
    Was "this guy" you?

  4. #4
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    was not me, or I would be crying. I am trying to prevent that from ever happening to me, and this is a step I take during builds.

    So the verdict is too high tension? or too low tension? Does it happen with good quality rims?

    btw: when I left, the person had tried popping it the other way, but that wasn't working, so he was going to de-tension and start again.
    If you are not having any fun, it's all your fault

  5. #5
    B.C. to D.C.
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    that may have been me. at least I had a very similar thing happen. not my first build, though--just trying to true a new, crappy machine-made in Taiwan Weinmann S-23X alu wheel. The problem was a bent rim--spokes were loose in the pulled part of the bend when it tacoed. I don't think any amount of truing would have helped, actually, because it just kept on tacoing even after I'd re-trued it 4 times.

    last night I disassembled the wheel, bent the rim to about flat, and relaced that POS. It's still wobbly, but maybe more within the possibility of truing. We will see tomorrow when I launch the truing stand assault.

  6. #6
    Senior Member juicemouse's Avatar
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    Too high tension for that rim. It can happen to any quality rim, it just takes more tension to buckle a good-quality rim. Jobst Brandt, the author of the most widely respected book on wheelbuilding, actually says to slowly bring the wheel to the point that it buckles and then back off and retrue. I am skeptical that this produces the most durable wheel in all circumstances, but I don't really have any alternative advice to offer either.
    It is my belief that every person in this world has something to teach, and everything to learn.

    In memory of Jim Price (aka. sydney) ...

  7. #7
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    Thanks Juicemouse, May I propose that the idea of buckling a wheel and then returing seem more theory than practice. I'll just keep doing what I'm doing

    Now, off to put another 1/4 turn on the spokes.

    btw: Comrade, this happened last wed, so was it u?
    If you are not having any fun, it's all your fault

  8. #8
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    I kind of worry that it will buckle during a ride.... I really did not put a whole lot of lateral force on it when it initially tacoed. It really surprised me, actually. The rim was clearly bent when I took the spokes off.

    I thought over-tensioning resulted in tighter spokes on the outside of the rim bend/looser on the inside, and bent rims resulted in vice-versa. My wheel had the latter. Is that incorrect info regarding the loose/tight spokeage? I am totally ignorant about these things...

  9. #9
    B.C. to D.C.
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    snr. poop y vaca: yes.

  10. #10
    Senior Member juicemouse's Avatar
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    Quote Originally Posted by comradehoser
    I kind of worry that it will buckle during a ride.... I really did not put a whole lot of lateral force on it when it initially tacoed. It really surprised me, actually. The rim was clearly bent when I took the spokes off.

    I thought over-tensioning resulted in tighter spokes on the outside of the rim bend/looser on the inside, and bent rims resulted in vice-versa. My wheel had the latter. Is that incorrect info regarding the loose/tight spokeage? I am totally ignorant about these things...
    It doesn't take much lateral force at all to buckle a wheel if the tension is too high. The "tacoing" will not be horribly pronounced, it will be just enough to notice when the wheel is spun, like if your true all of a sudden goes out of whack after stress-relieving. The rim should not be permanently bent if the tension is brought back under the rim's limit from only slightly too high tension. It might become permanently bent if the tension were WAY too high. It takes a whole bunch of lateral force to taco a wheel if the tension is not too high.

    I don't know from what reference you're measuring inside/outside, but it sounds as though your wheel was under WAY too much tension.
    It is my belief that every person in this world has something to teach, and everything to learn.

    In memory of Jim Price (aka. sydney) ...

  11. #11
    Senior Member juicemouse's Avatar
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    Quote Originally Posted by poopncow
    Thanks Juicemouse, May I propose that the idea of buckling a wheel and then returing seem more theory than practice. I'll just keep doing what I'm doing
    Yeah, I think this method results in too-high tension for all but the absolute strongest rims, and shouldn't be a gauge for when you should stop adding tension (as Mr. Brandt asserts). I tried it on my Open Pro/Record wheels, and ended up having to push hard on the side of the rim (laterally) to release tension temporarilly so I could turn the spoke nipples! I never even got to the point of buckling the wheel. That's way too high tension, IMHO.

    The only reason I mentioned this theory is to point out that comradehoser (as it turns out) might just have been following protocol. It's now clear to me that that wasn't the case.
    It is my belief that every person in this world has something to teach, and everything to learn.

    In memory of Jim Price (aka. sydney) ...

  12. #12
    MADE IN HONG KONG
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    Comradehoser, no intention to bring light on your troubles, but it just happens to be a small world, good luck with the build. Boy would I like to be able to barrow the shop for the final tune on my builds. My cheapie home stand is ok, a pro stand shold make things a snap
    If you are not having any fun, it's all your fault

  13. #13
    Prefers Cicero cooker's Avatar
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    Confucius say: many people want taco after bong.

  14. #14
    B.C. to D.C.
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    --eh? several things I do not understand:

    1. the difference between home stand and pro stand--it's just a relational marker, no? You could use a couple zip ties on your rear stay and it would work just as good (at least for my non-anal race tolerances)

    2. not following protocol? there was no protocol to follow, my soppy murine friend. The wheel tacoed when I stress relieved it having just bought it brand new. poopncow was just witnessing my attempts to put it back into true and subsequent chronic tacoing--including after I had detensioned completely and retrued. All of which is what leads me to believe it was a bent rim to begin with. [edit: oh wait, you meant Brandt's protocol? never mind]

    On the inside/outside thing: if, looking at the wheel, it curves to the right from the centerline, the outside refers to the right-hand side; the inside refers to the left hand side. According to the hypothesis percolating around in my head from unknown sources, if waviness is due to spoke over-tension, the right hand side in our example will be tighter than the left. If due to a bent rim, the right hand side will be looser, and the left tighter. True hypothesis, or bunkum?

    poopncow--no probs shedding light on my probs. the more light, the better.

  15. #15
    Senior Member Chuckie J.'s Avatar
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    Quote Originally Posted by comradehoser

    poopncow--no probs shedding light on my probs. the more light, the better.
    You're a good man. Really!

    Chuckie

    (Unless, of course, you're a woman....)

  16. #16
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    Quote Originally Posted by poopncow

    What exactly happened? was the spokes too tight or too loose? How do you avoid this?

    Firstly, I'm a wheelbuilding newbie, so take what I say with a large grain of salt.

    I've built a few wheels which I think turned out fairly well (felt nice and tight, good and round), although only last weekend did I actually get a chance to ride on one (a long story).

    The first couple of wheels I put together using Gerd Schraner's book "The Art of Wheelbuilding". He recommend destressing by either pressing the wheel on a bench, or the technique I think you described.

    After the "long story" (note, spokes on the drive side of a rear wheel are slightly shorter than the otherside, and if you aren't aware of that, you'll waste a lot of time tensioning up a wheel twice and then having to pull it to bits to get the spokes right - I wish Gerd had put that in his book! It's in a table, just not in the text!), I went looking for one or two other books on wheelbuilding, and came across Roger Musson's, "Wheelbuilding, 3rd Edition". I think Gerd's book is pretty good, however Roger's is a lot more detailed, and I'd recommend Roger's over Gerd's. I personally don't mind having two different books on the same topic, you can compare what they say about the same topic, which will sometimes clarify it, or make you look further into it when they disagree. I haven't seen Jobst's book, that might be better than both of them. It's on my list of books to buy, although it's down the list - having 3 books on wheelbuilding is starting to get a bit obsessive I think

    http://www.wheelpro.co.uk/wheelbuilding/book.php

    He suggests that rather than pressing the wheel, to destress the spokes, grab a pair from opposite sides in the middle and squeeze them, using a set of heavy garden pruning gloves to protect your hands. Based on the lack of pinging I got when I used the "press the wheel technique" at the end of the build (just to compare the techniques), Roger's technique seems to work, and I'd be pretty sure there is no risk of taco'ing the wheel.

  17. #17
    Senior Member juicemouse's Avatar
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    Quote Originally Posted by comradehoser
    --eh? several things I do not understand:

    1. the difference between home stand and pro stand--it's just a relational marker, no? You could use a couple zip ties on your rear stay and it would work just as good (at least for my non-anal race tolerances)
    Yeah, that'll work just fine. A stand can just make it a little easier to see what's going on sometimes. I use one 'cause I'm "picky" about my front wheel's true.



    Quote Originally Posted by comradehoser
    2. not following protocol? there was no protocol to follow, my soppy murine friend. The wheel tacoed when I stress relieved it having just bought it brand new. poopncow was just witnessing my attempts to put it back into true and subsequent chronic tacoing--including after I had detensioned completely and retrued. All of which is what leads me to believe it was a bent rim to begin with. [edit: oh wait, you meant Brandt's protocol? never mind]
    Yeah, I was talking about Brandt's protocol. I think something was very wrong with the wheels you bought, but I'm not sure exactly what.



    Quote Originally Posted by comradehoser
    On the inside/outside thing: if, looking at the wheel, it curves to the right from the centerline, the outside refers to the right-hand side; the inside refers to the left hand side. According to the hypothesis percolating around in my head from unknown sources, if waviness is due to spoke over-tension, the right hand side in our example will be tighter than the left. If due to a bent rim, the right hand side will be looser, and the left tighter. True hypothesis, or bunkum?
    I don't think that's quite true. You're correct that a bent rim (that has not been re-trued) will have less tension on the "outside" (convex side) of the bend. But a wheel that's been over-tensioned to the point of buckling could conceivably have roughly even tension all the way around the wheel, or some completely random pattern of tension that would be hard to diagnose. I think the best course of action if you discover a tacoed wheel would be to slowly detension the wheel all the way around and see if it returns to normal or not. That should tell you whether it's salvageable.
    It is my belief that every person in this world has something to teach, and everything to learn.

    In memory of Jim Price (aka. sydney) ...

  18. #18
    The Red Lantern Rev.Chuck's Avatar
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    When stree relieving I prefer to hold the wheel like a steering wheel, with it in my lap and pull towards me with the rim against the backs of my forearms. Much, much better control.
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