How do you know when your wheels aren't stiff enough

[daveornee]

Next time you're out on a fast ride with the boys, see if you ever overhear anyone saying, "Gee, my new wheels are flexy! It's REALLY cool! They're great! I wish they were just a bit flexier though. Maybe I should get out my spoke wrench and loosen them up a bit more to get that ultra-plush ride I've be so desiring! After all...I 'only' need stiffness when I enter and exit a corner...and when sprinting...and when climbing...and maybe fast descending...and possibly while just plain going at it hard.".

Yeah...you let me know when that happens, willya?

I'll go with my experience over the **** I read here every day.

http://www.sheldonbrown.com/rinard/wheel/index.htm

Damon Rinard seems to agree with your conclusion: "Is it possible for wheels to be too stiff?
Never! How could infinite lateral stiffness be bad?

Is it possible for wheels to be too too flexible?
Maybe. Control issues? Contribute to speed wobble?"

Damon is talking about and measuring lateral stiffness. 140 wheels measured in his efforts. See:

http://www.sheldonbrown.com/rinard/wheel/data.htm


Lateral stiffness is great and more of it is good too: along as methods chosen to attain it don't compromise durability and other aspects of the wheel that make them desirable. As an example, I would accept 5% less lateral stiffness to attain 25% more durability. I didn't make up this example; it comes from tests and measurements done by reputable sources: Jobst Brandt (author of "The Bicycle Wheel") and Sapim (a manufacturer of high quality stainless steel spokes).
My experience and limited testing agrees with Damon Rinard, Jobst Brandt, and Sapim. I have built over 1,000 wheels and repaired a like number + I have ridden over 250,000 miles in my 50+ years of riding.
The OP seemed to be talking about radial stiffness. Most things done to get more stiffness radially also effect lateral stiffness.

 

[artemidorus]

http://www.sheldonbrown.com/rinard/wheel/index.htm

Damon Rinard seems to agree with your conclusion: "Is it possible for wheels to be too stiff?
Never! How could infinite lateral stiffness be bad?

Dave, I would make two responses to this point.

Firstly, noone is saying flexibility is good, just that stiffness may not be worth pursuing as far as the marketers would have us go, particularly if it is at the expense of durability, weight, affordability or aerodynamics.

Secondly, Rinard at no point makes any effort to prove that stiffness delivers anything in terms of efficiency, stability or improved cornering. He is just measuring stiffness. He's gone to great lengths to do so, yet this is all he had to say about the consequences of his research:

"Is it possible for wheels to be too stiff?

Never! How could infinite lateral stiffness be bad?

Is it possible for wheels to be too too flexible?

Maybe. Control issues? Contribute to speed wobble?"

Not a very enlightened discussion. Makes you wonder why he bothered.

I am not aware of Brand publishing anything proving that stiffness beyond a reasonable average provides any performance gains.

 

[CAMPYBOB]

Damon Rinard seems to agree with your conclusion: "Is it possible for wheels to be too stiff?
Never! How could infinite lateral stiffness be bad?

Dave, thanks for the info.

I really don't give a rat's ass what science or study agrees or disagrees with me though. Data can (and most often IS!) twisted to 'prove' any case under the sun...from global warming to Smart cars save lives.

Just the shear idiocy that someone with half a brain...and claiming to have ridden a bicycle from more than to market and back...can sit there and try to tell me flexy wheel is 'good' is just beyond comprehension. Then, to top the cake off, they have the lack of common sense to tell me that people can not tell a flimsy wheel from a stiff wheel is just pure, unadulterated horseshit.

Remember folks...you only need a stiff wheel for...uh...what was that?...oh yes...for entering a corner...and for exiting a corner...and uh, for...sprinting...and um...for climbing...and maybe just for frickin' riding harder than going from your day job as a mad scientist to to the front of the local pack of weekend warriors. But, don't worry. The rest of the time you won't be noticing how bendy those 12-spoke, low tension aluminum spoke wonders are...trust me. Why, no one can tell that sort of stuff! Only guys with pocket protectors and fancy jigs and fixtures can tell us...what anyone with an I.Q. over room temperature already knows.

Like I said, let's all listen up next spring for the huge crowd of folks begging for more flimsy wheels. Those guys will be lining up right behind the crowd that's standing ready to throw their Cervelos in the incinerator.

 

[artemidorus]

Just the shear idiocy that someone with half a brain...and claiming to have ridden a bicycle from more than to market and back...can sit there and try to tell me flexy wheel is 'good' is just beyond comprehension.

Just who said this?

You have a pretty amazing line in wilful, or more likely rhetorical, misunderstanding.

 

[ScienceIsCool]

So there's *no* possibility that you could ever learn something new about bikes? You already have it all figured out because your IQ is a shade over room temperature (was that celsius or fahrenheit)?

Good luck with that.

It would have been more interesting if you'd work with me on one of the experiments I suggested. We could have both learned something in the process. As it is, I'm a bit weary of your shrill proclamations and personal attacks. They really don't add much to the conversation.

I'm outta here.

John Swanson
www.bikephysics.com

 

[CAMPYBOB]

Not a very enlightened discussion. Makes you wonder why he bothered.

You know, art, even a broken clock is correct twice a day...

These two times are when the wheel experiences the greatest lateral loads when cornering, and the stiffness at these points improves stability and control.

When it comes to wheels on a bicycle used for anything other than a grocery getter...stiff wheels are better.

Sometimes it really is...just...that...simple.

...as far as the marketers...

Here we go again... It's all a vast conspiracy by those eeeevil 'marketers'. Always trying to get our money. First it's "Buy our stiff wheels!". Now it must be those uber clever French Mavic marketers have the scientists convinced that less stiff is better and you really need to 'upgrade' to flexy wheelsets this year!! Well, I'm convinced. I'm running right out and buying a pair of Kysrium ES tomorrow.

Yuppers. Nothing matters and no one call tell the difference anyways. That's the real jist of it, ain't it?

 

[artemidorus]

When it comes to wheels on a bicycle used for anything other than a grocery getter...stiff wheels are better.

Sometimes it really is...just...that...simple.

OK, you've obviously got a pair of wheels on your favourite bike that you consider pretty stiff. You're telling me that they would clearly be better if they were twice as stiff?

Sure thing, say the wheelmakers, here's another pair that are twice as stiff. So you put these on and after a while, you think to yourself, "wouldn't it be good if these wheels were twice as stiff!", so you go to the wheelmakers and....

Where do you stop? Is there such a thing as adequate stiffness?
What I am saying is that I think that most wheels are over the line of adequacy already, and that further bleats about stiffness are a waste of breath.

 

[daveornee]

Dave, I would make two responses to this point.

Firstly, noone is saying flexibility is good, just that stiffness may not be worth pursuing as far as the marketers would have us go, particularly if it is at the expense of durability, weight, affordability or aerodynamics.

Secondly, Rinard at no point makes any effort to prove that stiffness delivers anything in terms of efficiency, stability or improved cornering. He is just measuring stiffness. He's gone to great lengths to do so, yet this is all he had to say about the consequences of his research:

"Is it possible for wheels to be too stiff?

Never! How could infinite lateral stiffness be bad?

Is it possible for wheels to be too too flexible?

Maybe. Control issues? Contribute to speed wobble?"

Not a very enlightened discussion. Makes you wonder why he bothered.

I am not aware of Brand publishing anything proving that stiffness beyond a reasonable average provides any performance gains.

I guess I wasn't clear!

 

[CAMPYBOB]

OK, you've obviously got a pair of wheels on your favourite bike that you consider pretty stiff.

They could be stiffer.

You're telling me that they would clearly be better if they were twice as stiff?

Yup. That, I am. At the risk of repeating myself for the twentieth time...stiffer is better.

Sure thing, say the wheelmakers, here's another pair that are twice as stiff. So you put these on and after a while, you think to yourself, "wouldn't it be good if these wheels were twice as stiff!", so you go to the wheelmakers and....

No. Not really. You see, I 'AM' the wheelmaker (well, i do ride a couple pair that Colorado Cyclist built up...pretty good builders there, if I say so myself!). "Marketing", as it were, doesn't mean squat to me. They, like John and Alienator, could cite all manor of spiel and it doesn't mean **** **** to me. I build 'em. I ride 'em. I'm no Jobst brandt (although I've read his book I could care less what he says either), but I know enough to know stiffer is better. I ain't seen the 'too stiff' wheelset yet.

But hell, this is America and those guys can believe whatever the hell their damn calculators tell them. My Hewlitt-Packards don't do wheel calcs.

Where do you stop? Is there such a thing as adequate stiffness?

Well, obviously, 'some' folks stop when the marketers' at Mavic tell them to...and that well, after all these years...guess what? Yup. We geniuses were wrong. What you folks really need is thissy here merely adequately stiff wheelset...and a steal it is at only $499 per end of the bike!

Hell, just go back and read the genius post that tells us all exactly when we 'need' stiffness in a wheel...but, not in any quantifiable amount mind you. It's only needed for that thar turning...and maybe sprinting...possibly climbing...perhaps hard braking...eh. I give up. Flimsy is fine. Merely adequate is even better...as long as it isn't pleasing some eeeevil marketer out there...somewhere.


What I am saying is that I think that most wheels are over the line of adequacy already

And I think you need to tell that to the OP...hopping and boppin' all over god's earth. Tell it to the Mavic buyers *****ing about heir wobble-matics. And the kid trying to bomb into that corner with the big dogs on his cheap Trek as he hunts for a line his eyes saw but his flimsy wheels, flexy head tube and maybe his 2mm travel rear triangle helped him miss.

I will agree with you in that adequacy is norm in more than just wheel building skills and the ability of some folks to walk and chew gum at the same time though.

Regards,
Campy(the wishing the world a merry flexy wheelmas)bob

 

[artemidorus]

Well, OP, you've got the facts and can conclude that infinite stiffness is to be pursued at all cost.

I can't afford that attitude and will continue to ride my positively quaking Cosmic Carbones and my homebuilts.

For what it's worth, I doubt that your original problem has anything to do with the wheels, as all wheels are pretty stiff radially. Maybe the fork. Maybe an undulating road surface.

 

[alienator]

Well, OP, you've got the facts and can conclude that infinite stiffness is to be pursued at all cost.

I can't afford that attitude and will continue to ride my positively quaking Cosmic Carbones and my homebuilts.

For what it's worth, I doubt that your original problem has anything to do with the wheels, as all wheels are pretty stiff radially. Maybe the fork. Maybe an undulating road surface.

Yup. Wheels deflect in plane all of a few parts of a millimeter.
As for the rest of this discourse....well, assometer readings are worth just about nothing when it comes to quanitfying physical behavior or phenomena. Likewise, many times intuition has been proved to be lacking when it comes to accurately describing the physical reality of something. To some, it might seem intuitive that stiffer is better. The reality just might be something else. The fact that test riders judgement about the stiffness of wheels in blind tests in no way correlated with the actual stiffness of the wheels raises the question about whether stiffness is really godliness.

There is nothing to indicate that ultimate stiffness is best. There is no data that correlates stiffness with improved performance. Further, it's not even known what amount of stiffness is best.

As is usually the case in science and engineering, blind statements about a given property are often wrong or at least misinformed and inaccurate. That some folks can't even rationally argue their point only points to just how weak their arguments are. It's patently obvious that the functional dependence of wheel performance on wheel stiffness--take your pick, in plane or lateral stiffness--is not a rect function that is either one or zero. That people even make arguments about grocery trips and the like only points out the poor grasp those folks have on the fundamentals involved.

That there has been no definitive work, research, publications, or developments re: bicycle wheel performance is very telling: for the slow learners, it means things ain't cut and dry like you paint them. If it were that cut and dry, there would be a universally accepted truth about wheels and their performance. Alas, no such thing exists.

Someone should take John Swanson up on his idea re: creative experimentation.