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Has anyone heard or experienced Titanium bikes having a tendency to high speed shutter or wobble. I talked to a guy that rides a high end Ti bike. He said he loves his bike except that he got a dangerously bad high speed wobble 50mph (once). He said it only happened once out of many miles but it scared him very bad. He said he has heard of other people having the same problem.

I hadn't heard this before and was curious if there was an explanation or if he was just wrong about the tendency.
 

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High speed wobble

tortoise said:
Has anyone heard or experienced Titanium bikes having a tendency to high speed shutter or wobble. I talked to a guy that rides a high end Ti bike. He said he loves his bike except that he got a dangerously bad high speed wobble 50mph (once). He said it only happened once out of many miles but it scared him very bad. He said he has heard of other people having the same problem.

I hadn't heard this before and was curious if there was an explanation or if he was just wrong about the tendency.
Do a search and you'll find that there has been much posted about high speed wobble (shimmy) on bicycles. It is a function of many variables, and has been experienced with frames of all materials; steel frames, aluminum frames, carbon frames, and yes, ti frames, have been known to experience high speed wobble.

Although many variables come into play, in general the larger and flexier the frame, the more the tendency to develop high speed wobble.
 

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Juanmoretime
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Two Litespeeds.

Both size 59 and rock solid at over 50 MPH. The guy either has a poorly made frame, a mis-aligned frame, loose or incorrectly adjusted headset, wheel issues, bad fork or he could even be positioned wrong.

Large size are not necessarily less stable when designed and made correctly. I don't think bike manufactures want to be sued when someone looses control at high speed due to the before mentioned factors. Heck even wheels not properly balanced can cause serious high speed issues.
 

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Juanmoretime said:
Both size 59 and rock solid at over 50 MPH. The guy either has a poorly made frame, a mis-aligned frame, loose or incorrectly adjusted headset, wheel issues, bad fork or he could even be positioned wrong.
Maybe you should do a search as well. Shimmy is a resonance, and is not caused by frame mis-alignment or a loose headset, or a wheel imbalance, or a "bad fork". In fact, a perfectly aligned frame with a correctly adjusted headset is more likely, not less likely to shimmy (all other things being equal).

Shimmy article

[/QUOTE]Large size are not necessarily less stable when designed and made correctly. I don't think bike manufactures want to be sued when someone looses control at high speed due to the before mentioned factors. Heck even wheels not properly balanced can cause serious high speed issues.[/QUOTE]

Large bicycles can be made that are not more prone to shimmy, but that usually is done by increasing their rigidity. Also it is an old wive's tale that unbalanced wheels can cause shimmy. Firstly, a shimmy is a lateral and torsional (out of plane) resonance of the bike, while the forces generated by a wheel imbalance are in plane with the bike. And besides which, the amount of imbalance is relatively small compared to the "unspung mass", so to little of the energy from the imbalance can be stored by the bike.
 

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Juanmoretime
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It would be nice....

Mark McM said:
Maybe you should do a search as well. Shimmy is a resonance, and is not caused by frame mis-alignment or a loose headset, or a wheel imbalance, or a "bad fork". In fact, a perfectly aligned frame with a correctly adjusted headset is more likely, not less likely to shimmy (all other things being equal).

Shimmy article
Large size are not necessarily less stable when designed and made correctly. I don't think bike manufactures want to be sued when someone looses control at high speed due to the before mentioned factors. Heck even wheels not properly balanced can cause serious high speed issues.[/QUOTE]

Large bicycles can be made that are not more prone to shimmy, but that usually is done by increasing their rigidity. Also it is an old wive's tale that unbalanced wheels can cause shimmy. Firstly, a shimmy is a lateral and torsional (out of plane) resonance of the bike, while the forces generated by a wheel imbalance are in plane with the bike. And besides which, the amount of imbalance is relatively small compared to the "unspung mass", so to little of the energy from the imbalance can be stored by the bike.[/QUOTE]


If he had backed it up with some data via actual testing. Yes I do know who Mr Brandt is. That's funny how I have a front wheel that gets very unstable, shimmy, over 50 mph, it's a Rolf Prima Elan Aero, but can put another wheel on and have zero shimmy over 50 mph on the same bike, same tire and same air pressure, every time. Bicyling is very subject to many opinions on everything including frame materials. I tend to believe in real life exprience or actual scientific data that is repeatable verses an article that doesn't reference on how the information was obtained including the method used, how many test cycles, and where they able to duplicate the experiment every time it was conducted with the same results.

Right or wrong,,.. I don't win a prize or a medal. My .02 centavos.
 

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Juanmoretime said:
Both size 59 and rock solid at over 50 MPH. The guy either has a poorly made frame, a mis-aligned frame, loose or incorrectly adjusted headset, wheel issues, bad fork or he could even be positioned wrong.

Large size are not necessarily less stable when designed and made correctly. I don't think bike manufactures want to be sued when someone looses control at high speed due to the before mentioned factors. Heck even wheels not properly balanced can cause serious high speed issues.

It would be hard to prove that a frame manfu was responsible for a high speed accident
due to a low frequency cycle wobble after the bike is trashed and the cyclist is probably wasted.
 

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Juanmoretime said:
Large size are not necessarily less stable when designed and made correctly. I don't think bike manufactures want to be sued when someone looses control at high speed due to the before mentioned factors. Heck even wheels not properly balanced can cause serious high speed issues.
Large bicycles can be made that are not more prone to shimmy, but that usually is done by increasing their rigidity. Also it is an old wive's tale that unbalanced wheels can cause shimmy. Firstly, a shimmy is a lateral and torsional (out of plane) resonance of the bike, while the forces generated by a wheel imbalance are in plane with the bike. And besides which, the amount of imbalance is relatively small compared to the "unspung mass", so to little of the energy from the imbalance can be stored by the bike.[/QUOTE]


If he had backed it up with some data via actual testing. Yes I do know who Mr Brandt is. That's funny how I have a front wheel that gets very unstable, shimmy, over 50 mph, it's a Rolf Prima Elan Aero, but can put another wheel on and have zero shimmy over 50 mph on the same bike, same tire and same air pressure, every time. Bicyling is very subject to many opinions on everything including frame materials. I tend to believe in real life exprience or actual scientific data that is repeatable verses an article that doesn't reference on how the information was obtained including the method used, how many test cycles, and where they able to duplicate the experiment every time it was conducted with the same results.

Right or wrong,,.. I don't win a prize or a medal. My .02 centavos.[/QUOTE]

Sounds like a wheel issue, not shimmy.
 

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Alignment, adjustment, size, flex, steering trail and shimmy

Troy16 said:
If he had backed it up with some data via actual testing. Yes I do know who Mr Brandt is. That's funny how I have a front wheel that gets very unstable, shimmy, over 50 mph, it's a Rolf Prima Elan Aero, but can put another wheel on and have zero shimmy over 50 mph on the same bike, same tire and same air pressure, every time. Bicyling is very subject to many opinions on everything including frame materials. I tend to believe in real life exprience or actual scientific data that is repeatable verses an article that doesn't reference on how the information was obtained including the method used, how many test cycles, and where they able to duplicate the experiment every time it was conducted with the same results.
If you've read Brandt's postings over the years on the rec.bicycles.tech newsgroup, you'll know that he has done testing on shimmy, including initiation speeds and damping, with repeatable results.

As far as believing that shimmy is not caused by misaligned frames or misadjusted components, and that larger or more flexible frames are more prone to shimmy, that view is shared by many noted frame designers. Here are a few:

Article on frame design (including shimmy) by Dan Empfield, founder of Quintano Roo

Discussion of frame properties, including shimmy, by Mark Hickey, proprietor of Habenaro Cycles

Discussion of shimmy by Tom Kellog, designer of Spectrum and Merlin frames

Note: Tom Kellog has the relationship between fork rake/steering trail and shimmy backwards; increasing rake, and thus decreasing trail, makes a frame less prone to shimmy, not more prone. This is also noted in a Lennard Zinn article on shimmy.
 

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Road cyclist said:
It would be hard to prove that a frame manfu was responsible for a high speed accident
due to a low frequency cycle wobble after the bike is trashed and the cyclist is probably wasted.
Actually these types of movements are usually broken down into two subsets: weave and wobble. Weave is a low frequency phenomenon, and I don't know if it manifests in bicycles. Wobble, or as used here, shimmy, is a high frequency oscillation. 'ts a tank slapper.

Mark McM is right: every bike can shimmy. In fact every bike will have a harmonic or many harmonics where the shimmy occurs. A bike designer cannot design something that is shimmy proof. A designer can try to design so that the harmonic occurs outside the range of normal riding conditions, but even this would be difficult since there are so many variables the designer can't control: rider weight, rider position, components on the bike, road conditions, atmospheric (i.e., wind) conditions, condition of bike, whether or not Mila Javovavich will ever date Gweneth Paltrow and make a video of said date, and etc.
 

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Would this be effective?

I am having the same problem with a Merlin Proteus 35+ mph and woah look out. Now I current have the stock fork on the front. Understanding that the wobble comes from a resonance in the frame, would going to a stiffer or more compliant Fork help at least delay the onset of the shimmy? Since its the fork that transfers any gyroscopic and road vibrations to the rest of the bike its just an idea. I am trying to avoid tossing my bike.
 

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badge118 said:
I am having the same problem with a Merlin Proteus 35+ mph and woah look out. Now I current have the stock fork on the front. Understanding that the wobble comes from a resonance in the frame, would going to a stiffer or more compliant Fork help at least delay the onset of the shimmy? Since its the fork that transfers any gyroscopic and road vibrations to the rest of the bike its just an idea. I am trying to avoid tossing my bike.
Might or might not. You can try it and see. You can also make sure your headset is properly preloaded, skewers are tight, yada yada yada.
 

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sorry if this is too obvious...try resting a thigh on your top tube when the bike starts to wobble. it will help your stability. granted, i don't know how bad your wobble is, but this has helped me out at speeds greater than 40 mph...good luck!
 
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