Interesting chart. They say "trend", not 99% significant.

What I find interesting is that they say "Trend of stiffer bike requiring less effort". Then in the discussions on page 16, they write "Hypothesize there is an energy cost of stiff bikes" which is contrary to the not-significant trend they noted on the previous page.

I agree that they need a better variety of bikes, including classic Vitus Aluminum bikes which have a reputation for not being the stiffest on the block, as well as the Specialized Roubaix.

A single induced "bump" is hardly a good comparison when considering smooth pavement vs course pavement.

Anyway, it all seems like a pretty null study.

Frame material discussions are always entertaining. :thumb:

you were already in.

I would say that I was just marking my territory, but that brings up images which, although very appropriate for this thread, just don't seem to convey the right message. :)

On the other hand, I didn't think it counted as being in if you didn't show you knew where the thread was headed.

I think you may be hitting on a pet peeve of mine here. A "trend" is not something that you can see, but is statistically insignificant. Trends have to have a proven statistical significance to be meaningful. The "trend" they show here is consistent with a the trend they report, no trend, and an opposite trend, as far as I can see. If any trend exists, it's certainly not 99% significant, we'll agree on that!

You could not be more................RIGHT! Yes RIGHT! Well said.

o/\o

They certainly need more data, and could well have conducted the study for hours rather than 5 minutes and might have reached statistical significance (also switching bikes often so that there is no order & fatigue bias).

However, I'm doubting their study is giving any meaningful data for general rideability.

For a track setting (smooth concrete or wood), I would expect a benefit from the stiffest frame possible).
Smooth pavement with the periodic interruption... perhaps also tending towards a stiffer frame.
Rough pavement (chipseal) is annoying, and I could imagine a significant power loss for noncompliant tires/frames.

My guess that their study was like riding in the gutter, or on a sidewalk with a very smooth surface with a few thumps. It just doesn't seem like it would capture the effect of riding on chipseal, gravel, or cobbles. And the smooth nature of the treadmill may tend towards benefiting the stiff frames.

So we all agree this is bollocks then? Good. ;)

I honestly don't know why this is so hard for you. As you wrote above, quoting the paper, the objective was "to develop a system to characterize the effect of transmitted road vibration." Develop a system. Say it again, "the objective was to develop a system," NOT to prove a causal relationship between vibration and rider performance. One can characterize an effect as insignificant or zero, but again, the purpose was not establish an effect existed, but to develop a system...pause there for a moment to consider...to develop a system with which to characterize the effect of transmitted road vibration on rider performance. The results of which, by the way, they go on to characterize as precluding generalization *by design* and requiring further study.

Again, the purpose was not to establish causal relationships, but to develop a system to characterize the effects of transmitted road vibration.

Ok, so what did they do?
They developed a system.. YES.
Vibration.. Maybe
Rider Performance.. Null Results
They did use 3 different frames.. YES
Demonstrate Frame Material Differences... Not really. 1000 frames available, and they chose 3, with 1 in each category.
Some vibration response (of the 3 frames tested).
Cyclist Performance... Null

For testing a frame, a periodic bump on a treadmill may be good. However, that doesn't mean that it is the same as road vibration on rider performance, and thus one might not expect a significant or meaningful result.

So, they did develop a test. But the applicability is minimal, and certainly the results aren't generalizable.

And they failed to answer comfort or performance which is where the money is.

But they did not develop a system to do .... They don't know what was affecting performance. That is my point. They measured two different things and assumed one affected the other. But the many other aspects of the frame differences could be what was affecting the performance. For example power transmission, not vibration. To do what they wanted to do they would have had to start with one frame and a variable source of vibration. It is so obvious that your refusal to see it is bizarre.

Yes, they now have a test protocol, if that is what you mean by a system, but it is worthless. When they choose any frame to test in future, they won't know if the vibration transmission or something else is the cause of any performance effect they measure.

No, a condition of succes was not to prove the cause and effect relationship. WHY? Because the assumed it going in.

Wow. Knowing what was affecting performance was NOT the purpose of the study. I don't know how else to explain it to you, and whether a causal relationship was assumed doesn't matter, because they have a testing system to quantify transmitted vibration, which WAS the point of the study.

Your point is simply not germane to the study; it's a condition that you are reading into the study, because it was not part of the study's objectives, which makes it your problem, not one of the study.

April Fools' day was yesterday.

I read this as indicating the objective is "to characterize the effect of transmitted road vibration." Developing a system is merely the means to achieve that end. And if the study 'to characterize the effect of transmitted road vibration' is going to do so by measuring the rider performance with varying degrees of transmitted road vibration it's not much of a leap to conclude that they are looking for a cause and effect relationship with the cause being the level of transmitted road vibration and the effect being a change in rider performance.

Will they technically prove such a relationship? No, but by holding as many other factors as possible constant (same rider, same position/fit on bike, same wheels & tires, same saddle & pedals) their conclusions will almost undoubtedly be that any significant change in rider performance that correlates with variations in transmitted road vibration is in fact an effect of those variations. Otherwise they will not have achieved their objective to "characterize the effect of transmitted road variation."

I'm just reading what they wrote. Apparently you aren't.

Well said.

Within the context of the total published report, it's clear that development of system was the primary objective. You'd have to be an idiot to think any group university students would call observing one subject, and then commenting that the results of that observation preclude generalization by design, a study of the effects of road vibration on cyclists' performance. But you're not an idiot, are you?

Now that we're posting our C.V.s on a public forum, it would be wise to remember that even the best schools have graduated their share of numbnutz. My own alma mater claims John Kennedy Jr (actually a classmate of mine), who thought that if you're famous enough, the marine layer doesn't roll in on a summer evening, so it wouldn't be a problem to pilot a plane across Long Island sound on a July evening without being instrument rated. Sadly, he wasn't the only person on the plane.

Yes...
If in fact, the aluminum frame is stiffer than the CF or steel, that could account for the (not statistically significant) performance improvement.

However, simply attaching an electric vibrator to the bike would tell one absolutely nothing. Well, I suppose it would tell one if vibration alone is affecting the rider's performance.

The theory with high pressure hard tires vs low pressure soft tires is that bumps cause micro vertical accelerations and a corresponding energy loss. In theory, these accelerations could be dampened by either the tires or the frame. So your vibrator would not give one a good understanding of parasitic power losses of road induced vibrations.

Perhaps an option would be to use a full suspension MTB frame (or a similar custom "road" frame), then vary the suspension parameters between rides.

Just when I thought it couldn't get any richer...voilà.

Chaad...you seem to be one of the only guys here actually defending the article. To me, the study is rubbish. Lots of guys here with a science background that believe the article is fraught with improper boundary conditions to make any reasonable conclusions. Include me. The range of geometry for any of the materials will negate or promote if not expose the strengths and weakness of different materials...and yet 3 distinct geometries and 3 materials from a single manufacturer are used to judge the properties of three common bike materials. A steel bike can be made stiffer than Al or carbon...of course it will be boat anchor heavy. Easy to make a carbon bike stiffer than any of the materials because it is the strongest and stiffest material....or an Al bike even though it is the weakest material. The Vitus proves one can design a Al bike to ride like a trampoline. I have owned steel bikes that ride like a pogo stick over bumps, my latest Reynolds Bianchi was that way in fact and I could easily rub the front derailleur out of the saddle and I am no brute.. My current road bike mutes bumps better than any bike I have owned previous and it is 3 x's more stiff than the Bianchi laterally. There should be no debate as which material damps high frequency vibration better. Its non metallic carbon fiber. There is also further conflation of what constitutes ride quality. Is it attenuation of high frequency? Not necessarily. Specialized with their Zertz + carbon quells high frequency vibration probably better than any bike out there but there is a VAST difference in ride quality between a SL2 Roubaix and a SL4. In fact there has been an outcry from Roubaix loyalists that Specialized made the new SL4 too stiff. It has poorer ride quality than the SL2 which rides like a whippy steel bike only lighter and without the energy transfer of the SL4. Geometry matters a lot and perhaps even trumps material when it comes to ride characteristics. But no mistake, material is a BIG player when it comes to the performance and personality of a bike.

Lets take aluminum for example. Lets say that Cervelo makes a crappy aluminum bike. Most know the Soloist for example is a very stiff bike...has a VERY stiff ride. Btw, there is further conflation if not lack of differentiation between vertical stiffness normally considered important for ride quality and laterial stiffness important for energy transfer. This isn't even addressed in the article. The Soloist is VERY vertically stiff and not stiff laterally compared to many top racing frames. This is because of its aero tube sections. So the Soloist bike feels stiff but actually isn't when it comes to transferring power from the pedals to the rear wheel...the other aspect of the article woefully misrepresented. Also, how can it be that the softest material in the study aka Aluminum had the best energy transfer...even better than carbon? Many don't know that Aluminum is soft. And yet generally Aluminum bikes have a stiff ride. Aluminum has the lowest modulus of elasticity of either carbon fiber or steel. That is a fact. And yet, a Solist rides like a covered wagon. This is because of the geometry. The Vitus was mentioned which sometimes comes up in these types of discussions. And now the CAAD10 has arrived which many believe is the best race bike for the cash...although the Spesh Allez gives it a run for the money. They are different, in fact so radically different in ride quality, its almost hard to believe they are made from the same material and yet they are. Geometry matters a lot when is comes to vibration damping and ride quality and energy transfer from pedal to drive wheel and the article doesn't even address the root cause.
But make no mistake which material quells vibration better. Its the epoxy matrix in carbon fiber. It natively damps vibration. I mentioned the Allez which is considered one if not the best Al race bike on the market. Comparing it to its carbon brother...the Tarmac, there is no comparison in ride quality....the Tarmac as stiff as it is and it has world class stiffness as a premier race bike...it absorbs bumps and attenuates road shock better than the Al Allez.

Can I ask your science background?

I wonder how many guys racing this stuff for a paycheck give a hoot about this.

As they used to tell me..."Here's your bike. Shut up and ride or we will find somebody else."

Good lord...

A consumer has a choice of what to buy. A racer is paid to shut up and ride what they are given.

I also hope you aren't suggesting that this discussion doesn't matter. These considerations in fact are the underpinning of why bikes have improved so much...every frame material. A tremendous amount of technical analysis. Its just, the article is basically crap is the point.

I have a friend who lives in my complex and used to race for Trek. We ride together once in a while and he is still a good rider. His current bike is a carbon Pinarello.
He knows a lot about bikes and we have some interesting discussions about geometry, material, fit etc.
We share a similar view of fit for example in that he doesn't ride real slammed and loves to ride in the drops like I do.

He told me when the first carbon Madones came out and he was given one to race how much he hated the bike. He couldn't stand the BB. This guy is a beefy sprinter type. So he rode an Aluminum Trek when others were switching to the Madone because he hated the bottom bracket. Early Madones weren't exactly loved as many recall. Early carbon wasn't very good but that all has changed.