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  1. #1
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    Metallurgist-twisting a 3/2 ti tube like Lynskey helix. Salesmanship or practically?

    Doing what they do with the tubes at Lynskey on the helix, is it good for us or marketing for him?
    I spoke with another Ti Co. And they say twisting the tube weakens the tube.
    Thank you.
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  2. #2
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    Not a metallurgist or an engineer, but if it was structurally sensible, it wouldn't similar designs have been made years ago by companies with far more $$$ to spend on R&D?

    I'd also expect that any functional downtube shaping should to be bilaterally symmetrical, instead of just choosing an arbitrary clockwise or counter-clockwise corkscrew.

    It's got 'gimmick' written all over it.

  3. #3
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    Having a spiral reinforcement on bicycle tubing is not new - Columbus TSX was rifled internally 25 years ago. The idea is that bike tubes are torque tubes, and you can resist twisting with a spiral reinforcement. True, not true? No idea.

    As for the other ti company's opinion, keep in mind that there are two completely different schools of thought when it comes to ti bikes - leave the tubes alone (Merlin, Spectrum, Seven, etc.) vs. the cold work places like Serotta, Lynskey, Litespeed. The round tube guys don't like to bend the ti more than they have to and grind the tubing to butt it for both strength and ride qualities. The other school of thought is that the ti becomes stronger and works better when you bend, form or swage it; "cold working". I think both schools have a point, but neither are building bikes that break any more often than the other, so who cares if one is theoretically "weaker" than the other?

    I think ALL bike design is marketing, to some extent. That includes the companies that won't cold work the tubing. The Helix is showy and it's hard to define what the twist does - but the frames are light and ride great, so what's the downside to owning one of these unique looking bikes? It isn't going to break.

    I think the Helix is no more marketing than super stiff BB frame designs like BBright and BB386. I'd rather have my Koolaid be pretty rather than a pain to find parts for.
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  4. #4
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    I can't imagine any benefit from twisting a tube like that. Usually if you cold work something you do it to get material properties in a particular direction. Of course, there are benefits and drawbacks to cold working, but I think for a frame you would generally NOT want it cold-worked. Other applications you definitely want it.

  5. #5
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    Such a shape wouldn't help torsionally or for flexion.

    If the wall thicknesses were very thin, it might help make the tube a bit harder to dent/ding.

    But the real answer is that it looks distinctive. Nothing wrong with that, if you happen to like the look.
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  6. #6
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    Quote Originally Posted by enzo24 View Post
    I can't imagine any benefit from twisting a tube like that. Usually if you cold work something you do it to get material properties in a particular direction. Of course, there are benefits and drawbacks to cold working, but I think for a frame you would generally NOT want it cold-worked. Other applications you definitely want it.
    The Lynskey's have been cold working titanium for close to 20 years. Why is it a bad idea, exactly?


    I don't think the Helix is a miracle bike or anything, but the proof is in the pudding. Either the bike weighs right and rides right, or it doesn't. I have read or heard zero real criticisms of these bikes. Every armchair engineer seems to have a well rehearsed opinion about the Helix, but 90% of the tube shape dogma from other manufactures goes unquestioned.

    I would say the Helix is little different than the silly shape of a Pinarello fork or "Squoval" Cervelos. You can debate whether it works or not until you're blue in the face, but NO ONE has any definite engineering data to say otherwise.
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  7. #7
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    One of my friends has one of the spiral-tubed Lynskeys. He likes it a lot. He thinks (and I agree) that the stuff about twisting it imparting special ride characteristics is marketing mumbo-jumbo. But he thinks it looks cool, which it does, he likes the way the bike rides, and he's comfortable with the idea that there's some silly ad copy out there. Basically, it's a cool-looking, unique bike that rides well.

    I'm partway through an engineering master's, for whatever that's worth. (And he's a nuclear engineer, actually.)

  8. #8
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    Mumbo jumbo indeed. A twisted tube is a helical spring, and will behave differently when 'wound' one way vs the other (torsional elasticity, Mr. Engineer?)

    Will you notice it when riding? Unlikely. Does it matter? Unlikely. Look cool? For sure.

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    ^^^
    If it's got residual stress, it might fail more easily. That's about it.

    If they heat-treated it after twisting it, there's no residual stress. Any odd behavior would be due to the geometry.

    No reason for a twisted tube to behave more or less like a spring than a circular tube, which already behaves like a spring. Because everything does. Springs just have a geometry that subjects them to a crazy amount of shear, so we can actually see them deform but don't have to deform them all that much to get a big effect.

  10. #10
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    I don't think they are twisting a square tube to achieve that appearance. I believe that are forming the tube into the shape that appears twisted.
    Don't mind me, it's just the online disinhibition effect typing.

  11. #11
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    Quote Originally Posted by ericTheHalf View Post
    I don't think they are twisting a square tube to achieve that appearance. I believe that are forming the tube into the shape that appears twisted.
    No, they are actually twisting them. I've talked to guys who've done it at the plant.
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  12. #12
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    Quote Originally Posted by Kontact View Post
    The Lynskey's have been cold working titanium for close to 20 years. Why is it a bad idea, exactly?


    I don't think the Helix is a miracle bike or anything, but the proof is in the pudding. Either the bike weighs right and rides right, or it doesn't. I have read or heard zero real criticisms of these bikes. Every armchair engineer seems to have a well rehearsed opinion about the Helix, but 90% of the tube shape dogma from other manufactures goes unquestioned.

    I would say the Helix is little different than the silly shape of a Pinarello fork or "Squoval" Cervelos. You can debate whether it works or not until you're blue in the face, but NO ONE has any definite engineering data to say otherwise.
    Well said. From a strictly subjective perspective I've owned both a non-Helix Lynksey L3 with manipulated butted tubes as well as my current Helix. Both with Campy Record and utilizing the same wheels and saddles. I can say with experience that there is a subtle difference in the ride of the Helix tubed bike. Both are smooth (with a slight nod to the L3) but the Helix is slightly stiffer in the BB and HT. Both have oversized down tubes but cold worked/manipulated differently. Both were/are the best Ti frame I've ever owned (much preferred over my IF and Moots).
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  13. #13
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    Quote Originally Posted by Kontact View Post
    No, they are actually twisting them. I've talked to guys who've done it at the plant.
    Not that it matters much to this conversation, but they aren't really 'twisting' them as such - the action is more like 'rifling.'

    As I understand it, David came across the shape by accident, when trying to make a diamond-shaped tube. A mis-alignment of the die in a new-to-them tube-drawing machine created a spiral instead, and an idea was born.

    So rather than take each end of a tube and twisting, it's more like taking a tube and pulling it through a square-shaped hole while twisting it. The difference? if you marked a reference line down the tube before starting, with "your" method it would follow the ridges, appearing as a spiral, while with "mine" it would appear (nearly) straight, crossing over the ridges.

    A pre-formed tube can't be "twisted" like that - it just buckles into itself.
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  14. #14
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    Quote Originally Posted by Kontact View Post
    No, they are actually twisting them. I've talked to guys who've done it at the plant.
    Thanks for straightening me out.
    Don't mind me, it's just the online disinhibition effect typing.

  15. #15
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    Quote Originally Posted by danl1 View Post
    Not that it matters much to this conversation, but they aren't really 'twisting' them as such - the action is more like 'rifling.'

    As I understand it, David came across the shape by accident, when trying to make a diamond-shaped tube. A mis-alignment of the die in a new-to-them tube-drawing machine created a spiral instead, and an idea was born.

    So rather than take each end of a tube and twisting, it's more like taking a tube and pulling it through a square-shaped hole while twisting it. The difference? if you marked a reference line down the tube before starting, with "your" method it would follow the ridges, appearing as a spiral, while with "mine" it would appear (nearly) straight, crossing over the ridges.

    A pre-formed tube can't be "twisted" like that - it just buckles into itself.
    Just repeating what I was told by guys who worked there then started their own bike company making helix steel bikes.
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  16. #16
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    Quote Originally Posted by Kontact View Post
    Just repeating what I was told by guys who worked there then started their own bike company making helix steel bikes.
    Hearsay is hearsay either way, since neither of us has watched it happen, so no worries.

    My 'heard it from' is Mark Lynskey, so I'll take it from there - plus it makes sense in terms of what materials can really do.

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    Not trying to argue - I'm sure it's just lost in translation.
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  17. #17
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    Quote Originally Posted by Kontact View Post
    Just repeating what I was told by guys who worked there then started their own bike company making helix steel bikes.
    Sounds ool. Whats the name of the company?
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  18. #18
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    Quote Originally Posted by mtnbikerva1 View Post
    Doing what they do with the tubes at Lynskey on the helix, is it good for us or marketing for him?
    I spoke with another Ti Co. And they say twisting the tube weakens the tube.
    Thank you.

    From what I understand; When said tube is twisted or bent it stretches the material at the bend/twist making said area thinner. Thinner=weaker.



    FWIW: That's why NASCAR uses welded frames and not bent-tube frames.
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  19. #19
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    Quote Originally Posted by danl1 View Post
    Not that it matters much to this conversation, but they aren't really 'twisting' them as such - the action is more like 'rifling.'

    As I understand it, David came across the shape by accident, when trying to make a diamond-shaped tube. A mis-alignment of the die in a new-to-them tube-drawing machine created a spiral instead, and an idea was born.

    So rather than take each end of a tube and twisting, it's more like taking a tube and pulling it through a square-shaped hole while twisting it. The difference? if you marked a reference line down the tube before starting, with "your" method it would follow the ridges, appearing as a spiral, while with "mine" it would appear (nearly) straight, crossing over the ridges.

    A pre-formed tube can't be "twisted" like that - it just buckles into itself.

    Does that have a similar effect of twisting?


    Stretching the tube?
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  20. #20
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    Richie Moore used to work there and started Cysco Cycles, which offers twisted steel and titanium.

    Story | cyscocycles.com

  21. #21
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    Quote Originally Posted by skepticman View Post
    Richie Moore used to work there and started Cysco Cycles, which offers twisted steel and titanium.

    Story | cyscocycles.com

    Interesting.

    Looks like a Lynskey.
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  22. #22
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    Makes me wonder if he's licensed the design or buys the tubesets from Lynskey. I also find it kinda intresting that his biggest dealer is Harpath Cycles in Nashville where I bought my first inaugural year Lynskey...wonder if he built my old L3.
    Last edited by Ramjm_2000; 07-31-2012 at 01:05 PM.
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  23. #23
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    Quote Originally Posted by mtnbikerva1 View Post
    Doing what they do with the tubes at Lynskey on the helix, is it good for us or marketing for him?I spoke with another Ti Co. And they say twisting the tube weakens the tube.
    Thank you.
    The two aren't necessarily mutually exclusive.

    Regardless of the reason by all reports it's a great bike and that's all that matters anyway.

  24. #24
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    Quote Originally Posted by Ramjm_2000 View Post
    ...much preferred over my IF and Moots...
    May I ask why? I have a Merlin, which I love. If I were ever going to get a custom Ti frame made, IF and Moots would be on my long list.

  25. #25
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    Quote Originally Posted by Ramjm_2000 View Post
    Makes me wonder if he's licensed the design or buys the tubesets from Lynskey. I also find it kinda intresting that his biggest dealer is Harpath Cycles in Nashville where I bought my first inaugural year Lynskey...wonder if he built my old L3.
    Those are the guys I spoke to. They twist the tubes themselves.
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