# Helix shaped tubes?



## Walt (Jan 23, 2004)

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


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## zank (May 19, 2005)

yeah, that all goes against most of my engineering background and beliefs, especially my KISS philosophy.


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## smudge (Jan 12, 2004)

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.


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## playpunk (Apr 1, 2005)

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.


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## Yogii (Jun 5, 2008)

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


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## [email protected] (Oct 17, 2009)

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.
> ...


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## unterhausen (Sep 28, 2008)

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.


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## dbohemian (Mar 25, 2007)

Hey wait, I have seen that before:thumbsup:

Indian Larry (RIP) choppers.










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


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## byknuts (Aug 9, 2008)

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. :idea:


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## dr.welby (Jan 6, 2004)

Walt said:


> Thoughts?


Do they wind the helix in the opposite direction for customers in the southern hemisphere?


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## Climber999 (May 2, 2009)

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).


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## shiggy (Dec 19, 1998)

[email protected] said:


> 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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## shiggy (Dec 19, 1998)

Walt said:


> 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.
> 
> ...


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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## pvd (Jan 4, 2006)

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.


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## crux (Jan 10, 2004)

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


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## Vlad (Feb 7, 2004)

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


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## cannonballtrail (Sep 14, 2004)

*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...-helical-tube-gents-safety-bicycle-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.


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## Manicmtbr (Jan 26, 2004)

A helix seat tube would be pretty nice . . . .


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## dbohemian (Mar 25, 2007)

cannonballtrail said:


> Well, the idea is over 100 years in the making.
> 
> http://www.theoldbicycleshowroom.co...-helical-tube-gents-safety-bicycle-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.


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## 18bikes (Jan 15, 2007)

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

matt


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## dbohemian (Mar 25, 2007)

18bikes said:


> 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.


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## cannonballtrail (Sep 14, 2004)

*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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## cannonballtrail (Sep 14, 2004)

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


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## JohnnieA (Jan 20, 2004)

I think that if helix was stronger than round, tree limbs would be helix shaped. Trust mother nature.


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## Climber999 (May 2, 2009)

Manicmtbr said:


> A helix seat tube would be pretty nice . . . .


And what would you use as a seat post? A bottle opener?


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## [email protected] (Oct 17, 2009)

cannonballtrail said:


> 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...-helical-tube-gents-safety-bicycle-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.


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## Climber999 (May 2, 2009)

JohnnieA said:


> 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.


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## pvd (Jan 4, 2006)

Climber999 said:


> ...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.


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## unterhausen (Sep 28, 2008)

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.


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## coconinocycles (Sep 23, 2006)

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.


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## Schmitty (Sep 7, 2008)

cannonballtrail said:


> Well, the idea is over 100 years in the making.
> 
> http://www.theoldbicycleshowroom.co...-helical-tube-gents-safety-bicycle-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.


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## dbohemian (Mar 25, 2007)

*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....:thumbsup:


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## swift (Apr 3, 2007)

...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!


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## dbohemian (Mar 25, 2007)

swift said:


> ...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


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## Walt (Jan 23, 2004)

*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



dbohemian said:


> Just because I was curious.


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## aosty (Jan 7, 2004)

swift said:


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


Look at his pic again... it's actually pentagonal... 

@bohm - Nice job!


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## shiggy (Dec 19, 1998)

coconinocycles said:


> 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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## unterhausen (Sep 28, 2008)

coconinocycles said:


> 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.


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## dr.welby (Jan 6, 2004)

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

Meanwhile: Quantum Slacks


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## unterhausen (Sep 28, 2008)

dr.welby said:


> 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


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## cannonballtrail (Sep 14, 2004)

*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.


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## coconinocycles (Sep 23, 2006)

dr.welby said:


> 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.


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## surlytman (Nov 9, 2005)

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


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## cannonballtrail (Sep 14, 2004)

*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?layout=bikes&taxid=271


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## coconinocycles (Sep 23, 2006)

cannonballtrail said:


> . 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.


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## jcrew94123 (Aug 6, 2009)

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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## Schmitty (Sep 7, 2008)

cannonballtrail said:


> Do they know something we don't?
> 
> 
> 
> ...


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## [email protected] (Oct 17, 2009)

dr.welby said:


> I'm working on a prototype Shroedinger's Frame but I can't find anyone willing to test ride it.
> 
> Meanwhile: Quantum Slacks


Are you kidding? Huckin Kitty is both riding it and not riding it as we speak.


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## vulture (Jan 13, 2004)

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.


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## shovelon (Mar 16, 2006)

vulture said:


> 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.


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## Blaster1200 (Feb 20, 2004)

vulture said:


> 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.


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## dr.welby (Jan 6, 2004)

vulture said:


> 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).


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## dpugh5 (Oct 13, 2010)

dbohemian said:


> 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.
> 
> ...


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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