Helix shaped tubes?- Mtbr.com
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  1. #1
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    Helix shaped tubes?

    Check it: http://forums.mtbr.com/showthread.php?t=577959

    There's a link to a badly-written page on the Lynskey site about halfway through the thread. Reads like marketing drivel, though - there's not much there in the way of actual info.

    Anyone think this is anything but a gimmick? I don't see any reason to try to fold a perfectly good round tube into a helix shape, myself, but then again I've never even heard of such a thing, so who knows?

    Thoughts?

    Edit: Here's the Lynskey link: http://lynskeyperformance.com/morespeed/ Warning: their grammar is atrocious.

    -Walt

  2. #2
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    yeah, that all goes against most of my engineering background and beliefs, especially my KISS philosophy.
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  3. #3
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    Marketing. I wonder about all the stresses along the corner of that tube caused by the shaping process. I highly doubt it does anything beneficial or even perceptible by the rider. But I don't know for sure, I've never ridden anything like that.
    Sean Chaney :: Owner/Builder :: Vertigo Cycles

  4. #4
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    Even if it doesn't do anything, it LOOKS cool, which is what matters in high end bikes - especially high end road bikes. (See Pinarello, etc.)

    I like it. Something different.

  5. #5
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    Would be cool to watch your sweat drip off those tubes.....LOL

  6. #6
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    Best article I found so far. (I didn't know Lynskey was Litespeed) ...

    BIKE TESTS: LYNSKEY HELIX
    THE FRAME
    Looking at tubing cross-sections in CAD drawings, it became apparent that the compound shape of the Helix tubes were best able to simultaneously deal with the torsion and bending forces normally exacted on the front triangle. Mark says their data showed that where diamond-shaped tubes are about 30 percent stiffer than standard round tubes, the Helix-shaped tubes provide close to an additional 30 percent increase in stiffness.

    The Helix is also the first titanium bike we’ve tested that runs with such super small diameter seat stays. Twisted too as they are, Lynskey contends that along with the asymmetrical chainstays, the seat stays help resist vertical forces to enhance sprinting and climbing. Besides the seat tube, only the tapered chainstays aren’t twisted because Lynskey has yet to figure out a way to add twist and a taper to any tube.
    ...
    THE VERDICT
    In the bigger picture, what the Helix represents is a titanium stab at the performance (and shaping) market that has been so dominated by carbon fiber. The Helix hits the mark with its wild tube profiles and has the handling and performance to back it up—and comes within less than a pound of its carbon rivals. Where the Helix package steps ahead of its molded competitors is (like most titanium bikes) the promise of lifetime durability.

  7. #7
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    asymmetry just doesn't appeal to me in a bike frame. It's really hard to beat a round tube in a complex bending/torsion application like a bike frame. 30% stiffer than a round tube sounds bogus, I would like to know which two tubes they are comparing there.

  8. #8
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    Hey wait, I have seen that before

    Indian Larry (RIP) choppers.



    He said you have waaayyy more torsional rigidity.....

  9. #9
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    he was right!! they DO....




    when you use a solid hexagonal bar with the same diameter/cross section that weighs 4x as much as the tube it replaced

    personally I LOVE the cross twists he did, but that's OT.
    always wondered if maybe he chain drilled the bar out after making the twists... heard he didn't.
    If steel is real then aluminium is supercallafragiliniun!

  10. #10
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    Quote Originally Posted by Walt
    Thoughts?
    Do they wind the helix in the opposite direction for customers in the southern hemisphere?

  11. #11
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    Got their Pro29. Can't compare to any other Ti (my first...).
    However a great frame both stiff and forgiving (a bit paradoxical, but that's how it feels).

  12. #12
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    Quote Originally Posted by [email protected]
    Best article I found so far. (I didn't know Lynskey was Litespeed) ...

    BIKE TESTS: LYNSKEY HELIX
    Lynskey was Litespeed. They sold LS, waited a few years and started again.
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  13. #13
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    Quote Originally Posted by Walt
    Check it: http://forums.mtbr.com/showthread.php?t=577959

    There's a link to a badly-written page on the Lynskey site about halfway through the thread. Reads like marketing drivel, though - there's not much there in the way of actual info.

    Anyone think this is anything but a gimmick? I don't see any reason to try to fold a perfectly good round tube into a helix shape, myself, but then again I've never even heard of such a thing, so who knows?

    Thoughts?

    Edit: Here's the Lynskey link: http://lynskeyperformance.com/morespeed/ Warning: their grammar is atrocious.

    -Walt
    It looks cool, but for the main tubes it does not make any sense to me. Maybe--MAYBE-- there could be an advantage for helix stays if they twisted in opposite directions.
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  14. #14
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    Complete and utter marketing driven garbage.

    I'm a firm beleiver in shaped tubing and hydroforming, but the helix tube is an obvious joke. Basically, the framebuilding equivialant of twisted spokes on wheels.

  15. #15
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    An example of where form does not really add to the function.

  16. #16
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    Looks as gimmicky as anything else that Litespeed put out. Lame, lame, lame.

  17. #17
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    They weren't the first

    My Pro 29er cracked along the helix and they fixed it under warranty. Great customer service and this is by far the best bike I have ever owned or ridden, but yes, even I must ask, what's the point? Well, the idea is over 100 years in the making.

    http://www.theoldbicycleshowroom.co....cle-1510-p.asp

    On a more serious note, I don't understand "Looking at tubing cross-sections in CAD drawings, it became apparent." This was determined by "looking at" just as Einstein "looked at" a clock tower and came up with relativity, I guess. A giant leap for mankind from the boys at Lynskey? What happened to a finite element analysis of bending moments, torsional rigidity, compression, and tension? Test results? Their write up either doesn't want to give away trade secrets and RD or they're just spewing hot ti. Whatever the case might be, the design looks cool and the bike is a blast to ride.
    Last edited by cannonballtrail; 12-12-2009 at 12:44 AM.
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  18. #18
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    A helix seat tube would be pretty nice . . . .
    Thanks to www.weavercycleworks.com for my awesome bike frames!

  19. #19
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    Quote Originally Posted by cannonballtrail
    Well, the idea is over 100 years in the making.

    http://www.theoldbicycleshowroom.co....cle-1510-p.asp

    On a more serious note,
    Actually that is not a helical tube. That is how they used to make tubes. They would take a strip of steel about 5'' wide and at a angle roll it into tubes. The joint all along the tube would be soldered/brazed. They actually used to market that as stronger than a tube made in the traditional manner. The tube still turned out to be round though.

  20. #20
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    like a toilet roll tube? i'd love to watch someone doing it that way, that's a skill!

    matt

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    Quote Originally Posted by 18bikes
    like a toilet roll tube? i'd love to watch someone doing it that way, that's a skill!

    matt
    Excellent analogy! Just like a toilet paper roll.

    Oh crap! New idea, just now.......No need for bamboo. I will make bicycles from recycled paper towel and toilet paper rolls! So green.

    Call it S-H-A-T. Spiral High Density Ass Paper Technologies.

    Which getting to the point is about as good as the helix tube we have been discussing.

  22. #22
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    S.h.a.t

    Yes, they are rolled like toliet paper tubing but they also had the option of using standard round tubing. S.H.A.T would actually be a great technology for AZ. Trail side emergencies get ugly fast when you only have the option of Cholla or Prickly Pear. Unroll the top tube and leave with dignity. Got my vote
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  23. #23
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    Excuse the double post, but I'm waiting for it to warm up so that I can ride my helix.


    An UG materials book lists helical twisting up to 22 degrees under methods of strain hardening. No other explanations or references to a helical shape throughout the 800 page book. Interesting, but insignificant and irrelevant to the discussion. S.H.A.T still may be the future.

    Op, 61 degrees.. ride time
    Last edited by cannonballtrail; 12-12-2009 at 11:03 AM.
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  24. #24
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    I think that if helix was stronger than round, tree limbs would be helix shaped. Trust mother nature.

  25. #25
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    Quote Originally Posted by Manicmtbr
    A helix seat tube would be pretty nice . . . .
    And what would you use as a seat post? A bottle opener?

  26. #26
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    Quote Originally Posted by cannonballtrail
    My Pro 29er cracked along the helix and they fixed it under warranty. Great customer service and this is by far the best bike I have ever owned or ridden, but yes, even I must ask, what's the point? Well, the idea is over 100 years in the making.

    http://www.theoldbicycleshowroom.co....cle-1510-p.asp

    On a more serious note, I don't understand "Looking at tubing cross-sections in CAD drawings, it became apparent." This was determined by "looking at" just as Einstein "looked at" a clock tower and came up with relativity, I guess. A giant leap for mankind from the boys at Lynskey? What happened to a finite element analysis of bending moments, torsional rigidity, compression, and tension? Test results? Their write up either doesn't want to give away trade secrets and RD or they're just spewing hot ti. Whatever the case might be, the design looks cool and the bike is a blast to ride.
    I am contemplating a Ti Lynskey or Vassago this next summer. I am open to new tech and will wait to hear more reviews from people who know what they are talking about before I make a decision on this. Owner reviews (such as yours) and technical analysis basically.

  27. #27
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    Quote Originally Posted by JohnnieA
    I think that if helix was stronger than round, tree limbs would be helix shaped. Trust mother nature.
    I am afraid you rely incorrectly on the principle of natural selection. Mother nature improves things when there is pressure to change; utmost rigidity and resistance to torsional pressures have not been trees top priorities.

    Anyways, Lynskey has an identical model--dimension wise--which Ted Guitar tested and pointed out to flex in the frame. From personal experience, the Pro29 2010 does not show a hint of flex whatsoever. Now, I may not be as heavy or strong and Ted, so it would be interesting to have him test that bike as well.

  28. #28
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    Quote Originally Posted by Climber999
    ...Mother nature improves things when there is pressure to change; utmost rigidity and resistance to torsional pressures have not been trees top priorities. ...the Pro29 2010 does not show a hint of flex whatsoever.
    That sounds like a really bad bike.

    Any road or mountain bike needs to be designed to have just the right amount of flex in just the right ways. A mountain bike that doesn't flex will not track well in corners at speed. A road bike won't hug the road quite as well without some flex. The only bike that really shouldn't be flexing is a velodrome bike.

    Motorcycle companies put massive amounts of time and energy into making sure their chassis flex properly. They stopped making hyper-rigid chassis about 20 years ago.

    Basically, bicycles ARE just like trees. They flex to survive.

  29. #29
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    even if the objective was to avoid flex, given the same amount of material and any choice of shape possible, a helix really seems unlikely as a shape that would win out as the stiffest tube. I think our intuition incorrectly takes work hardening into account into our mental calculations of stiffness. Anyone that has bent a paperclip to failure feels the clip becoming harder to bend as it becomes work hardened. But that is outside the elastic limit of the material, something you don't experience with a bike that is going to last until the next ride.

  30. #30
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    i'm working on the "moebius" frame - it's all mine & it's going to be 15263% stiffer then anything you guys have ever seen. heads up. Steve Garro, Coconino Cycles.
    steve garro el jefe/el solo. coconino cycles www.coconinocycles.com www.coconinocycles.blogspot.com

  31. #31
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    Quote Originally Posted by cannonballtrail
    Well, the idea is over 100 years in the making.

    http://www.theoldbicycleshowroom.co....cle-1510-p.asp
    You got the translation wrong on this. Should read: "Very few 'new' marketing gimics are new. Most have been tried, and few have stood the test of time".

    All those tubes will break b/c forming them into that shape has already broken them most of the way. Out of S3? What a joke.

    -Schmitty-

    Actually, the bike in that link has round tubes with helical seams ala cardboard toilet paper roll. Different deal.
    Last edited by Schmitty; 12-14-2009 at 01:24 PM.

  32. #32
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    FEA analysis

    Just because I was curious.

    I modeled two tubes. Made it real simple and FEA is only as good as the info in and this is a simple beam bending example. Not very fancy.

    One was a .6 wall 1.5 tube round and the other was a helix tube same size, same thickness.

    I applied a 100lb load in one direction while fixing one end. Tubes weigh the same within a few grams.

    Bottom line as far as displacement is concerned. Round tube flexes 12.35mm and helical tube flexes 15.08mm. Helical tube is not as stiff as a round tube. At least in pure sideways loading. I also ran some torsional scenarios. Round tube is stiffer again by a fair amount and overall peak stresses are less for the round tube.

    The helix tube began to show points of failure at 1.5 times a factor of safety and the round at 1.75. The round tube is superior here also.

    I would say though, taking a queue from Mythbusters........This myth is BUSTED....

    Last edited by dbohemian; 12-14-2009 at 02:58 PM.

  33. #33
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    ...But you're modelling a hexagon tube vs. the original square.

    The stress concentrated on the apex of the corner is what I would have expected. Good illustration.

    The springer fork on that Indian Larry chopper is sweet!

  34. #34
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    Quote Originally Posted by swift
    ...But you're modelling a hexagon tube vs. the original square.

    The stress concentrated on the apex of the corner is what I would have expected. Good illustration.

    The springer fork on that Indian Larry chopper is sweet!
    Opps. Well, I changed it to a square of equal weight. The deflection got even higher and stresses are greater still. Really busted.

    One of use should make a springer with chain

  35. #35
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    Say "what" again!

    Look at the big brain on Brad! Er, I mean Dave.

    BTW, we will see you in like 3 weeks. Be ready for some mountain biking and beers...

    -W

    Quote Originally Posted by dbohemian
    Just because I was curious.

  36. #36
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    Quote Originally Posted by swift
    ...But you're modelling a hexagon tube vs. the original square.
    Look at his pic again... it's actually pentagonal...


    @bohm - Nice job!

  37. #37
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    Quote Originally Posted by coconinocycles
    i'm working on the "moebius" frame - it's all mine & it's going to be 15263% stiffer then anything you guys have ever seen. heads up. Steve Garro, Coconino Cycles.
    That will be the perfect bike for my "Escher" trail! An all downhill loop.
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  38. #38
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    Quote Originally Posted by coconinocycles
    i'm working on the "moebius" frame - it's all mine & it's going to be 15263% stiffer then anything you guys have ever seen. heads up. Steve Garro, Coconino Cycles.
    my lawyers tell me it's safe to reveal that I have applied for a patent for bicycle tubes based on the Klein bottle and all other higher dimensional manifolds with a non-intersecting surface. The only problem is that they are really hard to miter and sometimes fatigue cracks start in the higher dimensions and you can't see them until it's too late. The advantage is that they are optimally horizontally stiff and vertically compliant ... as far as you know.

  39. #39
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    I'm working on a prototype Shroedinger's Frame but I can't find anyone willing to test ride it.

    Meanwhile: <a href="http://www.theonion.com/content/node/28385">Quantum Slacks</a>

  40. #40
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    Quote Originally Posted by dr.welby
    I'm working on a prototype Shroedinger's Frame but I can't find anyone willing to test ride it.
    I dunno, that should be a real hit at Critical Mass

  41. #41
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    FEA Analysis

    The thread that doesn't die. Thanks for posting the FEA. I think Lynskey varied the wall thickness, however the point is a Helix has more flex than a round tube regardless. Second, as my materials prof used to say "garbage in garbage out" when it comes computer models vs. in-situ tests, so I think a lab test is in order. Anyone want to sacrifice a Pro 29er?

    Well, I just got back from 3 days on the road with my Helix. Tucson Mnt Park, Trail 100, and Coast to Coast on National in PHX + the hill climb and Mormon. The bike is actually quite flexy, but some flex=comfort and control IMHO. At 140 lbs with gear, I might not be the best tester.

    Still on a level of strangeness the Pro 29er pales in comparison to the black sheep.
    Attached Thumbnails Attached Thumbnails Helix shaped tubes?-bs.jpg  

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  42. #42
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    Quote Originally Posted by dr.welby
    I'm working on a prototype Shroedinger's Frame but I can't find anyone willing to test ride it.
    i bet it kills you like a cat in a box............maybe. + the klein jar comment made me bust up & i feel like crap, so thanks, Ut! Steve Garro, Coconino Cycles.
    steve garro el jefe/el solo. coconino cycles www.coconinocycles.com www.coconinocycles.blogspot.com

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    I'm surprised Gary Fisher didn't come up with that marketing drivel!

  44. #44
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    Niner goes hexagonal

    Just received a mail from Niner with a preview of their Air 9 carbon and what are they advertising? A hexagonal downtube for better "stiffness." Now this is not the same as twisting a tube or plastically deforming a tube and calling it stiffer, but it is interesting that they have departed from the round tube concept. Do they know something we don't?

    http://www.ninerbikes.com/fly.aspx?l...ikes&taxid=271
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  45. #45
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    Quote Originally Posted by cannonballtrail
    . Do they know something we don't?
    nope. it's just that with production units if you don't have a new offering every model year people loose interest. in custom every bike is it's own model...........just sayin - not bagging on niner........... Steve Garro, Coconino Cycles.
    steve garro el jefe/el solo. coconino cycles www.coconinocycles.com www.coconinocycles.blogspot.com

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    While they mention hexagonal, Niner doesn't mention that they twist the downtube - it looks pretty straightforward/symmetrical to me in the pics on their site.
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  47. #47
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    [QUOTE=cannonballtrail] Do they know something we don't?

    [QUOTE]

    They can barely make a frame that doesn't break....

    I'd insert a youtube of Steely Dan doing Asia here, but I'm lazy.....

    -Schmitty-

  48. #48
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    Quote Originally Posted by dr.welby
    I'm working on a prototype Shroedinger's Frame but I can't find anyone willing to test ride it.

    Meanwhile: <a href="http://www.theonion.com/content/node/28385">Quantum Slacks</a>
    Are you kidding? Huckin Kitty is both riding it and not riding it as we speak.

  49. #49
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    I wonder if the direction of the twist is specific to the northern hemisphere? I mean whats that thing gonna ride like if it conflicts with the Coriolis force when it is in say, New Zealand or some other southern hemisphere location? I love the bike industry.

  50. #50
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    Quote Originally Posted by vulture
    I wonder if the direction of the twist is specific to the northern hemisphere? I mean whats that thing gonna ride like if it conflicts with the Coriolis force when it is in say, New Zealand or some other southern hemisphere location? I love the bike industry.
    My Karma hates your Voodoo.

  51. #51
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    Quote Originally Posted by vulture
    I wonder if the direction of the twist is specific to the northern hemisphere? I mean whats that thing gonna ride like if it conflicts with the Coriolis force when it is in say, New Zealand or some other southern hemisphere location? I love the bike industry.
    I believe they offer two versions: One for the northern hemisphere and one for the southern hemisphere. However, in the southern hemisphere both versions are available and marketed a bit different. The NH version is actually designed for right handed people who are presumably stronger with their right leg. As a result, the twist is designed to counteract the forces applied by the stronger right pedal. The SH version is actually designed for left handers who are stronger with their left foot, and it is designed to counteract the forces applied by the stronger left pedal. If the wrong application is use, the rider risks turning the frame into a pretzel.
    May the air be filled with tires!

  52. #52
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    Quote Originally Posted by vulture
    I wonder if the direction of the twist is specific to the northern hemisphere? I mean whats that thing gonna ride like if it conflicts with the Coriolis force when it is in say, New Zealand or some other southern hemisphere location? I love the bike industry.
    You have to twist the head tube and the down tube in opposite directions so they cancel out (of course accounting for the different outside diameters with the amount of twist angle).

  53. #53
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    Quote Originally Posted by dbohemian
    Just because I was curious.

    I modeled two tubes. Made it real simple and FEA is only as good as the info in and this is a simple beam bending example. Not very fancy.

    One was a .6 wall 1.5 tube round and the other was a helix tube same size, same thickness.

    I applied a 100lb load in one direction while fixing one end. Tubes weigh the same within a few grams.

    Bottom line as far as displacement is concerned. Round tube flexes 12.35mm and helical tube flexes 15.08mm. Helical tube is not as stiff as a round tube. At least in pure sideways loading. I also ran some torsional scenarios. Round tube is stiffer again by a fair amount and overall peak stresses are less for the round tube.

    The helix tube began to show points of failure at 1.5 times a factor of safety and the round at 1.75. The round tube is superior here also.

    I would say though, taking a queue from Mythbusters........This myth is BUSTED....

    I do not believe your model is accurate to the shape of the tubing that lynskey uses in the pro 29. if you look closely you can see within each segment of the helix there are large radii . So what your looking at is a regular round tube twisted and then in between each twist the tube being pushed inward ... creating a strong inner radius. i may be wrong but it seems like your model is a square tube twisted ?

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