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PostPosted: Wed Oct 04, 2017 2:28 am 
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Title says it all. There is no argument. Do everything the pros do /end


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Posted: Wed Oct 04, 2017 2:28 am 


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PostPosted: Wed Oct 04, 2017 7:52 am 
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This is nice to see that we can ride what the pro ride! In other sports this is quite difficult as it is much more expensive (racing cars, racing motorcycles) or impossible (i.e. Formula One)


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PostPosted: Wed Oct 04, 2017 9:05 am 
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"The pro's ride it, therefore it must be good"

I don't think all equipment pro's use is necessarily good, however given how often their bikes are serviced any parts not performing well just get replaced - so you can't really tell based what you see on TV. For instance I'm sure the majority of the people here like BSA bottom brackets over BB30/PF30 etc. Also quite often you'll see pro's use blacked out logo equipment instead of what is provided by their sponsors, so for specific purposes their equipment isn't good for that specific purpose. Some examples: stiffer stems for sprinters, specific saddles, wheels etc.

In terms of pro's riding it, therefore it must be good enough for me: I don't think I need any of the more marginal upgrades from a performance point of view to make me ride faster. I ride most of the stuff I own because I like the way it looks or feels, not specifically because it makes me ride faster. I'm sure I'd be equally fast on a 105 equipped bike compared to my DI2 fleet. Honestly the only thing I believe will truly impact my performance are good wheels, good tires and a well maintained bike.


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PostPosted: Wed Nov 01, 2017 4:54 pm 
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waltthizzney wrote:
rossjm11 wrote:
waltthizzney wrote:
rossjm11 wrote:

Respectfully, I believe that just isn't true. A super stiff set of bars and a stem definitely helps in a sprint. Lightweight wheels, specifically carbon wish depth, save a ton of energy in races over 105 level wheels, because you freewheel way more. Equipment will not win you a race, but little to no difference?

To OP;
I think in certain situations you can say pros riding it proves something. If pros are racing it, banging out 1900 watt sprints and such, it isn't shit. It shows the company is actually testing the stuff very heavily and theoretically improving it as time goes on.

With that said, you're not wrong that the pros ride it isn't a great argument.


You clearly do not race at a high level..... and if you are a master racer, lusting for gear to get faster is even more stupid. Its fine to have nice stuff, but the concept that PROS are riding gear inferior to yours is insane.

There is a split second decision in every race where you have to decide if you are going to put down the power or not, that is what makes a difference, a functioning bike with an aggressive position is all you need.

Working on your flexibility will get you faster than any set of wheels ever will.


Well first, I clearly am not saying equipment makes up for fitness. Second, I am a high level racer, don't try to be rude to those who may be faster than you :lol:

Finally, I'd say the higher I personally get, the more I notice little fitness gains and little gear gains. Not just in bikes but also shoes etc.

One example of pros riding the best was when SRAM was not yet electric and only ONE worldtour team ran SRAM. All else went for Di2 or EPS


lol you are a shill to cycling marketing you will not meet anyone with any talent or fitness who shares this insane opinion as you


I'm a fairly high level racer as well and I agree with him. Races are won and lost by fitness and by decisions, and they're won and lost by feet and inches. Equipment choices matter, just like fitness and tactics matter. They may not matter equally or to the same extent, but obviously it makes no sense to say that your wheels or tires or equipment has no role in anything.

Having to resort to vacuous insults and the like because someone has a different perspective than you does nothing for your argument except make it look both juvenile and uninformed.

After all, if your argument had merit, you could just logic and facts to back it up. If it doesn't, then we're left with increasingly aggressive name-calling.

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PostPosted: Fri Nov 03, 2017 3:02 am 
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I feel we are missing some data. This is because pros can't publicly complain about their equipment or recommend favourite equipment if it's different from their sponsors. I'm sure that pros would have totally different equipment if they had the choice and that this would vary to each individual.

I'd like to think that looking closely at what recent ex-pros buy and ride would give you more insight to what's good.


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PostPosted: Sat Nov 04, 2017 8:22 pm 
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And it's also an insight on what brand/companies are willing to lend them stuff to use.

One example; notice how many ex pro retired even from ages ago when taking part at cycling events do appear on public by using gear of their old teams (I have seen many).
Another example; an ex Lampre told me that if he had to buy a bike he would go for the De Rosa King because during his career it was the one he liked the most. When he heard how much it cost, he said "no thanks".

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PostPosted: Sun Nov 05, 2017 5:54 pm 
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I haven't read all the prior responses, so this is just my raw opinion:
Pros ride what they are paid to ride. Period. End of that side of the story.

That being said, companies that sponsor pros are generally interested in having "good" equipment and it would be bad publicity to have parts failing or too heavy or have too much friction to win, etc. So "What the pros ride" is probably "not too bad". It is all probably "pro-level quality.
But consider that they also have full-time professional mechanics and can get free replacements whenever they need them. Without naming any specific pieces of equipment, I have had a few products that "the pros ride" that IMO were really poorly designed pieces of crap.

A consumer has a lot of other concerns: price and long-term reliability being most obvious.

Now noticing that there is some prior discussion of "power loss from flexing components": NO power is "lost" from flexing components, as long as they flex BACK to the original shape and don't remain permanently bent. They might inhibit or bother you personal technique, but they don't actually cause and "power loss". One could probably even theorize that a certain amount of flex could optimize power delivery by having the components flex back at the proper synchronization to your physiological details. But that power would be is pretty minuscule and speculative. On the other hand, excessively stiff components can be very fatiguing during any significantly long ride.


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PostPosted: Thu Nov 09, 2017 12:57 am 
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You're close about the power loss, but there's more to it.

Power is absolutely lost through strain; it's just a very small amount. Laminar composites dissipate more power than steel or aluminum...they damp better, and damping is energy dissipation. Things that don't spring back as fast as they're deformed are said to exhibit hysteresis. Tires have a lot of hysteresis, relatively speaking, which is why some tires have much less rolling resistance than others. (N.B.: tires are also laminar composites).

Even if deformations are perfectly elastic, it's not clear that the energy absorbed in bending is all returned as useful work. This is a hard thing to test, and there's been a fair amount of debate about it. For example, cranks deform torsionally quite a bit at the 3:00 position. The crank "unwinds" as you go through the rest of your pedal stroke, but there's no obvious way for that unwinding to be converted to forward motion.

Finally, no, you can't "optimize" power delivery on a bike via tuned flex (AKA driving at resonance). Think about it: you just said that no power was lost to flex, and then you wondered whether you could gain efficiency with tuned flex. If you weren't losing any energy to flex to begin with, how can you get anything back with tuned flex?

I'm not trying to come down too hard on you here: you're right that energy losses to deformation aren't worth worrying about because they're so low. Also, other sports equipment like tennis rackets and golf clubs do deliver more energy via tuned flex. (Notice a theme here? It has to do with impulse...) These are reasonable questions to ask. I've done a fair amount of work on this question, so I'm skipping right to the answer (insofar as we have one).

Finally, what you're suggesting about resonance is essentially the same idea as Jan Heine's "planing" concept, which (in Heine's case) is straight-up cargo cult science*. People who like Heine tend to accept the "planing" idea as true, or at least plausible, which it isn't. As a federally licensed boffin, I feel obligated to explain this. ;)




*Just today, I ran across a post on Heine's web site wherein he makes it clear that he has no idea how vectors work. That would be fine, except his post is primarily a rumination on how vectors work. This was pointed out to him in the comments, but he still didn't get it.


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PostPosted: Thu Nov 09, 2017 3:35 pm 
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^ further to this, excessive flex in the drive train may cause rear wheel tracking issues, which most certainly will cause losses through a) hysteresis b) force vectors not aligned with the direction of travel. In any case, excessive flex will also lower confidence in handling. That said, I think you'd be hard pressed to find a reputable/pro quality bike with "excessive" flex.

I do think impulse has some bearing on sprinting - the pedal force vectors when out of the saddle are far from consistent, and flex may reduce work done during particular phases of the pedal stroke. A stiff bike seems to sprint better.


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PostPosted: Thu Nov 09, 2017 6:29 pm 
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youngs_modulus wrote:
I'm not trying to come down too hard on you here: you're right that energy losses to deformation aren't worth worrying about because they're so low.

So....no power is "lost" if it is so small that it is insignificant and unmeasureable (by any cycling power meter).
(I happen to be a thermodynamicist and using common language on a cycling forum, not impressing people with vacuous theoretical subtleties. Yes, I am acutely aware that flexing actually does dissipate a miniscule amount of energy. I depend on that phenomenon every day in my job. :) )
)

Quote:
If you weren't losing any energy to flex to begin with, how can you get anything back with tuned flex?

"Mechanical Impedance". Look it up. It is not that you are "getting it back", it is that it is transferred more efficiently.
Here again, it is only VERY theoretical, and that's why I only mentioned it in passing, it is about as useful as worrying about how much your losing through flexing.
For those not familiar with the concept: If you push a spring at certain frequencies, the energy is transferred to the spring more efficiently than at other frequencies. If you try to push a swing "out of synch" with the swinger, very little energy is transferred to the swing, even though it is not "lost" and you don't "get anything back".

The point of all this is that "No, you are not losing any power through crank or frame flex. It might bother you, but you are not actually losing any power."

Quote:
The crank "unwinds" as you go through the rest of your pedal stroke, but there's no obvious way for that unwinding to be converted to forward motion.

Simply resist it, by keep force on the pedal. Force (resisting) *velocity = power, just exactly the same as when you are deliberately stepping down on the pedal. (Admittedly, AGAIN, it is a miniscule amount. But very real. )

Quote:
Finally, what you're suggesting about resonance is essentially the same idea as Jan Heine's "planing" concept, which (in Heine's case) is straight-up cargo cult science*. People who like Heine tend to accept the "planing" idea as true, or at least plausible, which it isn't. As a federally licensed boffin, I feel obligated to explain this

I had never heard of Heine's "planing" so I went out and read some stuff, an I think it is at least plausible that it would have a much greater effect on power out put than any "dissipation" in the materials.
But I also have a much simpler and I think more believable explanation that most cyclists would probably identify with: When you are tired and at your limits, a stiff frame that transfers every minute road contour and pebble strike directly into your perineum is like a Chinese water torture to the psyche. A certain amount of flex is simply more comfortable and pleasant and you therefore feel better and more willing and eager to try to put out more power. :)


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PostPosted: Thu Nov 09, 2017 11:08 pm 
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Rick wrote:
youngs_modulus wrote:
I'm not trying to come down too hard on you here: you're right that energy losses to deformation aren't worth worrying about because they're so low.

So....no power is "lost" if it is so small that it is insignificant and unmeasureable (by any cycling power meter).
(I happen to be a thermodynamicist and using common language on a cycling forum, not impressing people with vacuous theoretical subtleties. Yes, I am acutely aware that flexing actually does dissipate a miniscule amount of energy. I depend on that phenomenon every day in my job. :) )

Hey; awesome! I didn't mean to patronize you, but I also couldn't have guessed what you do for a living. (I still can't, quite...is your last name "Carnot" by any chance?) ;)

"Vacuous" is an interesting way to describe theoretical subtleties. Maybe you mean to say that the losses are so small as to be of no concern? If so, we totally agree on that point.

Rick wrote:
Quote:
If you weren't losing any energy to flex to begin with, how can you get anything back with tuned flex?

"Mechanical Impedance". Look it up.

Hey, you caught me! I was using common language on a cycling forum. Why so testy?

As far as I can tell, we fundamentally agree with each other, so I don't get the snark. Henry Kissinger once (supposedly) observed that the arguments in academia get so vicious because the stakes are so low. These are pretty low stakes.

Rick wrote:
It is not that you are "getting it back", it is that it is transferred more efficiently.

These are the same thing. If there are no losses, then efficiency is already at 100%. A golf club with stiffness "tuned" the wrong way isn't 100% efficient, at least not the way I'm using the term.

Rick wrote:
Here again, it is only VERY theoretical, and that's why I only mentioned it in passing, it is about as useful as worrying about how much your losing through flexing.

Here again, we agree. And I understand that when you mentioned driving the bike/rider system at resonance, you were only saying, "hey, it's possible," rather than trying to argue that it's happening and measurable. And that's fine, but you just sneered at "vacuous theoretical subtleties," so I'm not sure why this is different.

Besides, your initial post said that no energy is lost to "flex". If that's true, there is no hysteresis and no mechanical impedance. So my question still stands: if there's no mechanical impedance, what would it mean to reduce (via "tuned flex") what's already zero?

For mechanical impedance to matter, the bike/rider system would have to have a mode near 1.67 Hz to be excited by the forcing frequency (the rider's pedaling). A cadence of 100 RPM works out to about 1.67 Hz. What part of a bike/rider system do you think has a mode near 1.67 Hz?

Again, I realize that you don't genuinely think this is happening. But Jan Heine sure does, which is why I went out of my way to discuss it.

Rick wrote:
The point of all this is that "No, you are not losing any power through crank or frame flex. It might bother you, but you are not actually losing any power."

Yep; we basically agree. You are losing a small-but-nontrivial amount of power, but there's nothing you can do about it. There's not a measurable amount of difference in power absorption between, say, two different cranks. (Or, if there is, no one has yet measured it).

Rick wrote:
Quote:
The crank "unwinds" as you go through the rest of your pedal stroke, but there's no obvious way for that unwinding to be converted to forward motion.

Simply resist it, by keep force on the pedal. Force (resisting) *velocity = power, just exactly the same as when you are deliberately stepping down on the pedal. (Admittedly, AGAIN, it is a miniscule amount. But very real. )


Well, there are three problems with that:
  • Pedal float and foot/shoe compliance makes it impossible to resist the small torsional unwinding of the crank near BDC.
  • There are many strains that, even when resisted, don't get turned into forward motion. For example, at BDC, it doesn't matter how hard you push down--you're not going to move the bike forward. You're bending the crank and the pedal spindle when you push down, but even when they spring back, they don't create forward motion.
  • The biggest problem is that resisting the spring is physiologically the same thing as pedaling harder. Resisting the spring force does no work in the physical sense, but it requires muscular effort. A rider's muscular effort is stored as strain energy within the crank, and then the rider must exert additional effort to resist the "spring-back" of the crank. Yes, energy is stored, but the spring needs something to push against in order to turn the stored energy into forward motion. The only spring-resisting force comes from the rider's legs. So the rider can recover the stored energy, but must exert more energy to do so. On balance, it's a losing proposition.

I'm not saying that none of the energy stored in the spring gets turned into forward motion; I'm just saying that it's not clear how much of it, if any, gets returned without further effort/calories from the rider.

Rick wrote:
I had never heard of Heine's "planing" so I went out and read some stuff, an I think it is at least plausible that it would have a much greater effect on power out put than any "dissipation" in the materials.

Heine is trained as a paleoclimatologist, but his command of mechanics is about as good as my understanding of paleoclimatology. He hypothesizes that riders produce more measureable power on a flexible bike than they do on a slightly stiffer one. He claims to have found that a rider on a more-flexible bike produced 12% more power than on a slightly stiffer bike. In the words of Wolfgang Pauli, Heine isn't right; he's not even wrong. His "experiment" doesn't test his hypothesis and he won't publish his data.

If a flexible frame were 12% more efficient than a stiffer frame, I promise you that the engineers at Cervelo, Trek and other manufacturers would bend over backwards to equip their teams with bendy frames. 12% more watts is an enormous (and imaginary) advantage. In reality, pedaling inputs are well below any relevant natural frequencies. It's not that flexible bikes are inefficient; they're just not more or less efficient to pedal than stiff bikes.

Even more damning is that his "planing" theory predicts that bicycle efficiency should be exquisitely sensitive to cadence, and it's not. If his flexible, more efficient frame is resonating ("planing") at the rider's chosen cadence, then the stiffer bike would resonate at a higher cadence. You and I agree, Rick, that bicycles are high-Q systems, so the "planing" response should exist over a narrow cadence range, maybe 10 RPM. In other words, if Heine's bike "planes" best at 100 RPM, it should be drastically less efficient below 95 RPM and above 105 RPM. But Heine has a strange aversion to testable hypotheses, so he hasn't addressed this. And if the peak efficiency range is broader than this, there's necessarily a lot of damping/energy dissipation happening, but we just agreed that wasn't the case.

(I'm not kidding about this aversion. He has rejected the Chung method for his rolling resistance tests, even though it's objectively much better than his own poorly-designed experiment. If he knew what he was doing, he'd be excited about getting better data with an improved experiment).


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PostPosted: Fri Nov 10, 2017 12:21 am 
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I am just generally a grouchy, snarky guy! :oops:

We agree substantially. Just a little different emphasis maybe.

On the subject of mechanical impedance
Quote:
What part of a bike/rider system do you think has a mode near 1.67 Hz?

In power transfer calculations, it is not just the frequency response of the driven element that is important, but also the frequency response of the driving element that comes into play: the rider's body.
It would not be just the mechanical impedance of the bike, but also the mechanical impedance of the rider's legs that would be relevant.
And more complicated than that, the rider's legs (and torso, and arms) are an "biochemical and mechanical impedance" dependent upon blood delivery cycles, chemical diffusion and reaction rates, and muscle contraction rates. So, I don't pretend to know exactly what the "resonant frequency" of such a system is, but that is why I said it sounds at least plausible that it all has an effect that Heine would interpret as "planing". I agree his explanation is probably wrong, but that doesn't make the phenomenon of "flexy bikes producing more power" wrong. Many times throughout the history of science an effect is noticed long before the correct explanation is really arrived at. I am just giving him the benefit of the doubt.


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PostPosted: Fri Nov 10, 2017 1:19 am 
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Where can I purchase Peter Sagan's legs?

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PostPosted: Fri Nov 10, 2017 3:57 am 
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Rick wrote:
I am just generally a grouchy, snarky guy! :oops:

We agree substantially. Just a little different emphasis maybe.
If I had never been grouchy or snarky in my life, I could really let you have it. But I'm a little grouchy and snarky myself, so we're square. :beerchug:

Rick wrote:
On the subject of mechanical impedance
Quote:
What part of a bike/rider system do you think has a mode near 1.67 Hz?

In power transfer calculations, it is not just the frequency response of the driven element that is important, but also the frequency response of the driving element that comes into play: the rider's body.

And that's why I was careful to mention the bike/rider system. But your point is well taken, and the frequency of interest may not be 1.67 Hz.

Rick wrote:
It would not be just the mechanical impedance of the bike, but also the mechanical impedance of the rider's legs that would be relevant.
And more complicated than that, the rider's legs (and torso, and arms) are an "biochemical and mechanical impedance" dependent upon blood delivery cycles, chemical diffusion and reaction rates, and muscle contraction rates. So, I don't pretend to know exactly what the "resonant frequency" of such a system is, but that is why I said it sounds at least plausible that it all has an effect that Heine would interpret as "planing".

Yes, I agree that Heine's idea is plausible in principle.


Rick wrote:
I agree his explanation is probably wrong, but that doesn't make the phenomenon of "flexy bikes producing more power" wrong. Many times throughout the history of science an effect is noticed long before the correct explanation is really arrived at. I am just giving him the benefit of the doubt.

I don't yet have enough information to make a call on whether flexible bikes might be more efficient than stiff bikes. But I do have enough information to say that if a difference exists, it isn't nearly the 12% that Heine breezily claims. If that were true, a stiff bike would be a huge disadvantage:

If you need 300 watts to go 25 miles per hour on a stiff bike, switching to Heine' bike would get you an extra 12%. Now you're making 336 watts. Woot! Your 40K time drops nearly 2.5 minutes: from 60 minutes to 57:33.* 12% is obviously wrong, but Heine is untroubled.

I'd be willing to give him the benefit of the doubt if he expressed a little more doubt himself. He's not thinking critically and he's certainly not sciencing. That wouldn't be a problem, except he explicitly claims he's sciencing like a boss. (I'm paraphrasing here). He has the training to know better, which is why I can't give him the benefit of the doubt myself.

As I mentioned before, if a small decrease in stiffness is enough to achieve a useful resonance, then efficiency depends on pedaling at a fairly narrow range of cadences. The flexy bike should be slower at 120 RPM than it is at 95. This is a testable prediction made by Heine's theory. If he can show it's true, then it strengthens his case considerably. If he can't, then he doesn't get the (scientific) benefit of the doubt. At some point, declining to prove something and being unable to do it become indistinguishable.


* Numbers via analyticcycling.com


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Posted: Fri Nov 10, 2017 3:57 am 


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PostPosted: Sat Nov 11, 2017 12:19 am 
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to the physicists above: if crank arm, BB flex etc in todays bikes are minimal, would you say that when new bikes come out with claims that the bb or cranks are X% stiffer, that these are inconsequential, even for pros?


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