Can't be "accurately" correlated because the subjective part is the flaw here. That's what the OP has proposed to eliminate with his DOE.

No, the real problem, should anyone do this, is the meltdown on BF as everyone desperately and angrily fights to hold on to their subjective notions...and eventually convince themselves that no matter what the data says, their subjectivity is actually more accurate.

Then one would have to tackle the marketers...and the ridiculous James Huang of Cyclingplus.

It might be less work to not do this, and just let people believe whatever they want.

Bicycle Quarterly has been doing double blind tests with identically built bikes with identical components, tires, tire pressure etc and a group of testers that ride the same size bikes. The differences are in the tube diameters and tube wall thicknesses. It's expensive and labor intensive testing. Preliminary indications are that for some riders a more flexible frame is faster. Why that is is a matter of conjecture.

tire compounds are one of the biggest secrets kept by tire companies.
really big R&D money in this field.
on race cars, the biggest improvement is from a better tire.

You're kidding, right?

so what is the spring rate of a typical 23c tire vs psi? easy as Pi?

This thread was meant to point out the lack of factual information in current arguments about bike frame material. It sounds like you want everyone "to take your word for it" and you dont want to provide the data that was the basis for this thread. In the end... you want this to end up like every other thread

"tires make a big difference and carbon reduces road vibration".... ugh, thanks for the update. I'll go bang my head on the wall for trying to step out of the status quo.

I will say in the automotive world, you are much more correct as tires run at much higher slip angles. In the biking world, its primarily the tradeoff of rolling resistance to grip, not alot of technology in bike tires comparively.

In about 15 minutes I could, it's all ideal gas you know. Introducing slip angle means either you're trying to throw up smokescreens or you just wandering all over the place. In either case, that's where I stop reading.

The original post raised the question of effects of frame material on ride quality, but showed no thought on how to separate design effects from material ones. There is plenty of factual information on material properties of common bicycle materials. The problem is interpreting them in light of the infinite possible design space.

Unfortunately, there just isn't a lot of data out there. Or at least, there isn't some sort of established methodology to which a manufacturer or 3rd party adheres. I.e. it seems that the scientific data just isn't there.


1) Precise, repeatable, credible, consistent methods -- particularly ones that work in the field, rather than in a testing environment -- are not particularly easy or cheap.
2) You'd have to test specific framesets, not frame materials. A given frame material can be stiff or compliant -- especially CF, which has a huge possible range of characteristics, which will be determined in actual use by the designer's goals (and skill with the material).
3) You'd have to test a pretty large sample of frames. Again, not easy or cheap.

So in the absence of published scientific tests, unfortunately it seems like your only options are to a) trust the manufacturer's descriptions and/or b) trust the expertise of anyone who has time to review the specific bike you're interested in and/or c) hope your subjective judgments aren't overwhelmed by your expectations.

And then that would only tell you how that frame performed, not a measure of "goodness." That's because there is no single standard of performance for frames. Some designers are trying for a very "soft" or "compliant" frame others want "stiffness" above all else. For the vast majority, the goal is some balance in the middle. To that end, they will specify frame geometry, tube geometry, thickness, material, gussetting, and the list goes on and on. All these factors will influence the performance of the final product. As consumers, the best we can do is find the frame which most closely matches out personal preferences and not worry about how the designer accomplished that result.

thats fine if you dont care, there are plenty of other threads to discuss the subjective nature.

How does the "designer" accomplish his final result? he knows the influence of the design parameters, precisely what we are trying to discuss here. The designer is truly an engineer because he understands the objective factors to create the final 'subjective' feel.

Or - and I know that this is crazy - we could get people to actually listen to materials scientists/engineers (and no, not just any old engineer... too many engineers out there think that their fancy degree means that their intuitions are correct) when they describe the actual effects that material has on structural design. There's no need to do some complicated and probably utterly confounded test when:

a) the properties of the materials in question are known. That is to say, if an appropriately qualified engineer were to design a frame with X material in Y dimensions and Z geometry, the exact flex, stiffness, etc of any given frame can be determined strictly by application of theory. There are little details that are difficult to account for that contribute to feel, but those are not much easier to measure than they are to design. C'mon. Do you think that the engineers who design those fancy pants carbon bike are able to make them stiffer each year through guesswork? No, it's the specific application of a material with known properties. The same thing can be done with steel, aluminum and titanium, in principle, though frame design need not be done in such detail.

b) No one will care or pay any attention to the results. People's prejudices and preconceived notions are far more powerful than mere data. See a), above: the information needed to demonstrate that frame materials only change the parameters of design rather than having some essentialist effect on the ride of a given frame is already out there. The problem is that no one pays it any attention, they just cling to their beliefs. Collecting yet data on this would only be a colossal waste of time. There is no shortage of fact out there. There is also no shortage of credulous people.

Actually, no. Let's go to the text:
You say this is easy, but you have not presented any test which would separate out the influence of design from material. A simple example shows why this is not only difficult but unrealistic. Compare and contrast the ride characteristics of a Vitus 929 and a Cannondale CAAD 3 with special attention to the role of frame material.

ah the joys of BF...

so how do you suppose they design automobiles? or are bicycles that much more complex? Yes that is a rhetorical question. Ah! too many variables

So you're claiming there's an inherent difference in the ride quality between steel, aluminum, and fiberglass bodied automobiles?

Ride quality depends on flex at least as much as material damping. Steel for example, doesn't damp very well but many people laud the ride quality because the typical steel frame, made with small diameter tubes, flexes in response to road inputs. Aluminum on the other hand, is a more flexible material than steel but because of fatigue related concerns, the typical Al frame is designed to reduce flexing in order to preserve frame life. Bottom line is that trying to measure frame characteristics would be relatively meaningless unless the testers are prepared to measure many many variables to quantify the various differences between all the frames given both design and material considerations. Good luck with that.

no... i was just making fun of you and your negative comments. (just being honest)

and you completely missed the point of my post...

So to stay away from the ad hominem, why should there be an inherent difference in ride characteristics of a bicycle based on material of construction?

well actually the material that vehicles are made of does play a role in ride quality. The chassis stiffness both beam and torsional rigidity plays a role which is a function of geometry and material properties. However, vehicles have suspension and the % influence on ride quality from chassis material is minor.

On a bicycle, there is no suspension, thus the chassis(frame) stiffness will be a much larger portion of the overall ride quality.

did you really need me to explain that for you?

O.K. If you want to play, you're really going to have to pay attention. When I wrote, "why should there be an inherent difference in ride characteristics of a bicycle based on material of construction?" That's what I meant; I used the word inherent for a reason. So do you believe a car with a steel body would have ride characteristics resulting purely from the body being made of steel which could not be replicated with a body made of another material?

I do like the way you shift back and forth between automobiles and bicycles in your examples depending on which you think you can better twist to suit your argument.

I dont have an argument.... you have an argument. I dont understand what you are trying to prove by nit picking wording on an internet forum. Yes materials have different properties? is that what you want to hear?

I really could care less what you think, my post was intended to inspire a slightly higer level of thinking on BF compared to the typical "carbon rides better" comments. If you think we should go back to that, by all means, feel free.

If you could refrain from posting again in this thread, it would be greatly appreciated.

No, he isn't.

F1 tyre guys - back when they had multiple brands - would engineer their tyres so the rubber left on the road was sticky to their brand but slippery to the other brand.

You can overcome anything except being on the wrong tyre.

DG

Except the subject was not road-tire interaction but tire deformation, and the application was bicycles not cars. For bicycles, this is purely a function of the inflation pressure not the construction of the casing (or the gas used to fill the tire, within reason). So to introduce tread compounds into the discussion is either a joke or a total misreading of the governing physics.

Alright mister king of the world, it is your internet.

But it might be in your own interest to stop and think about what you're writing. You began this thread by proposing an easy, simple experiment to demonstrate how material of construction alone controls ride characteristics. I, and others, have repeatedly tried to point out that this is a fools errand since ride quality depends on design and construction and these two cannot be separated. Even if identical frames were made of different materials, this would not prove the point you are searching for since the design could be optimized for only one material, at best.

So let me end with the following question - since I seem to be too simple to follow your experimental plan, explain how the data you gather from measuring accelerations on frames leads to correlation of comfort level to material of construction?

Hi,

Would you do a standard DOE or a Taguchi DOE? You need to determine the relative sensitivities of the output, vibration, against you variables at different levels. It would be interesting to see if frame geometry is a greater influence on ride comfort than material.

Also for a given geometry, how much influence does bottom bracket and chainstay stiffness have on comfort? Are seat stays the primary influence on comfort as Cervélo would have you believe with their R3 design?

Wounds like a challenging analysis even with a relatively simple system.

no doubt a challenging analysis to do properly

but even if it is just a simple analyisis it would provide some data for better (more interesting) discussion.