With all the talk of superior design and obsolete technology, wouldn't real world performance be both relevant and testable in the environment the bikes are designed for - that being road racing?

No.

Cool.

Yes.

Also road riding.

Towards the end of this podcast...they reach a bit of a similar conclusion. To sum up...their overall assessment of frame stiffness is it doesn't really matter that much, BUT some frames, for seemingly inexplicable reasons, ARE faster. And they were the more flexible frames. But only for certain people. They ran a test, where the only thing different between different runs was a different frame with a different level of flexibility. The bikes were indistinguishable from each other...they even swapped wheels.

They came to the conclusion that frame stiffness can have a similar effect to fit. It doesn't affect power transfer per se, but it DOES have an impact on the ability of some riders to generate power. Different people are suited to different levels of frame stiffness for maximal power generation.

My own takeaway from this? Nobody knows for sure what's going on, but it's something interesting. And if someone says they DO know exactly how stiffness affects power transfer and speed, they just don't know what they're talking about.


Specifically regarding control and stiffness....I'll defer to you. Don't have enough info to speak intelligently .

Abe, how many watts do you put out at full sprint?

I havent the slightest idea lol. If I guessed, it would probably be 200% of actual...

e-wangs out.

I don't think they do, or at least not very broadly and holistically. Cycling research budgets just aren't all that huge; optimizing particular components for particular properties is a thing, and characterizing what's optimal is done for a few things where there's an efficient and repeatable way to measure effects with fast turnaround. Less so with things that are messy and take time to measure... even things that have demonstrably significant effects. For instance, suspension is the entire reason that we use pneumatic tires, but it's only been the last decade or so that anyone has gotten around to actually characterizing that effect on road bikes.

Maybe. Or maybe not. Probably not much, if that talk Abe_Froman linked is anything to go by.

This is the first time I've ever seen this concept mentioned anywhere. Could you recommend any sources where I could read more about this?

What is the fastest you have ridden a bicycle on flat land without wind? We can perform a basic watt equivalence.

Also, you seem hyper focused on power transfer being the sole reason for the stiffness of race bike frames today. What do you think maybe other reasons a frame is made stiff? I mentioned control...the rider's ability to control the bike when putting a lot of power into it. Why else may a manufacture place a priority on a stiff frame? Hint: your watt output relative top amateurs and pros that buy a given race bike is relevant.

Was joking. There are reasons as discussed why bicycle technology can't be isolated as the difference in average speed at the TdF over the years.

Why should the link Abe posted be valid compared to all the race and test data teams amass? Is testing performed in auto racing against the clock?...or do they just show up at the track and just race too? Maybe I should buy a F1 car and try that?

So you don't think they test....broadly or holistically? They just show up and race?...lol. No wind tunnel testing?
Aerodynamics don't matter or at least they would rather not study it? No FEA to optimize weight and understand stiffness?
I wonder why bicycles are set up so much differently at the Classics compared to the TdF? Why wheelbases are longer, head tube angles generally less, chainstays longer, tires wider and run much less pressure? Or why specific gearing is chosen for particular venues? What's available in the parts bin that day? Or why they wear those pointy helmets some days and other days more conventional looking helmets? Fashion? Divine intervention? Or...why do TT bikes exist compared to conventional race bikes? Aren't TT bikes a little hard on the boys? That wasn't wrought by testing and determining a specific bike is faster at a particular venue?
Can't make this stuff up.

Do you think stiffness matters in a bicycle frame? Do you think stiffness matters more or less comparing a 12 year girl to Marcel Kittel?

Not at all. I am a slow sprinter. Probably not compared to Abe but in general.
Its related to frame stiffness.

I'm not saying it's more or less valid than anything else. I'm saying it offers insight as to what people within the bicycle industry are willing/able to test, and in particular the lack thereof.

No, they definitely do test. I'm saying that the testing probably isn't as broad and holistic as you think.

For instance, I would expect that it's rare or nonexistent for racing teams to have a bunch of otherwise-equal copies of a frame made with varying stiffnesse in order to quantify the impacts. That's in the realm of things that are messy and where you can't tweak things for rapid turnaround. And that's the sort of thing that would have to be done to make a useful judgement on the effect of frame stiffness.

Yes.

Stiffness should matter to how a frame behaves as suspension. Plenty of modern frames try to smooth the ride by allowing considerable vertical flex to occur, sometimes adding an explicit damping mechanism to prevent ringing.
That's one area where CF may have an advantage over the metals; it seems like it tends to be a more imperfect spring on its own. Titaniums and steels can often be allowed to flex by a huge amount without durability concerns, although being very undamped, that could cause excessive rebound in some circumstances.

As far as pedaling...
I recently changed the cranks on my gravel bike to test how it would feel if I made the pedal position closely match my road bikes. Not a big change, but slightly narrower Q and slightly shorter arms. However, the new cranks are a bit on the cheap side and doubtless much stiffer than the old ones; both use solid aluminum arms, but the old ones are decent spindly vintage arms while the new ones are very fat. Since that change, which I will soon revert, it's been nigh-impossible for me to stress my cardio on that bike; I simply can't get my lungs to work hard even at very high RPMs, except while climbing. The speeds I can maintain on flat ground are noticeably slower, and my quads fatigue extremely quickly if I try to go fast. It is exactly in line with the sorts of differences described in the results of the BQ frame flex study for when someone's legs weren't liking the characteristics of the bike.
I find the argument that flex about the bottom bracket can be significant in terms of the biomechanical side of the pedal stroke to be pretty convincing, even if the mechanism isn't well-understood.

Hard to say. I'd say that needs further study. Intuitively it seems that increased rider power should play nicely with increased stiffness, although without the effects of frame stiffness being characterized across demographics, and without the mechanisms behind its effects being well-understood, I hesitate to make a particular judgement. Sean Kelly seems to have enjoyed riding a screw-and-glue wet noodle, at any rate.

How is this state-of-the-art design relevant work for a casual rider who doesn't produce the same watts a professional racer does?

To me and to use your word, I don't believe most who think of frame stiffness, they don't think of it holistically enough. They think of stiffness in the context of energy transfer only. To me, this is a big mistake. There are many more reasons top manufacturers make their frames stiff.

Do you put out big watts? Ever broken a frame while sprinting? Ever caused your brake pads to rub while sprinting? How about pretzeled a frame so much it shifted a gear? Top racers have this problem. Bicycles aren't just manufactured for you or for me...or a tall skinny boy who can only put out 300 watts in a sprint...but for everybody and top racing frames have to be able to stand 220 lb guys that can put out 2000 watts or almost 3 hp. The world of design isn't an even playing field. Its made up of a broad demographic for different riders even specific to a given frame size.

Hurricanes have been frequent of late and I just lived through one...my first in Florida. If you watch the news maybe you have seen a palm tree that has snapped in two...one with a deep root structure. Many of these trees have been around for decades and even withstood tropical winds in the 50-60 mph range. What happens when a Cat 4 wind comes to these trees that typically bend due to their evolution? They snap. So do frames. Stiffness matters on many levels. There is a reason why some pro's need reinforced frames which makes them stiffer. They can snap with the force they can apply to the pedals that the average guy can only think about.

Control is another big factor as I discussed in a previous post. A rider's ability to control the frame in space while powering the bike matters. Heck...me a guy who can't push even 1000 watts on a bike can sprint faster on a stiff bike versus a noodly bike I am all over the road on because the bike is twisting all over the place which affects the handling and even the chainline. There are guys out there that the same bikes are sold to that put out twice the power I have. I can't even imagine how much a noodly frame would twist with the kind of power they can lay down.

In summary, there are many reasons why top race bikes are made stiff. There is a precarious balance for example between stiffness aka force/deflection, weight and yield strength. Weight is a priority in road bikes of course because lighter tends to be faster...certainly for acceleration and climbing. But if a bike is made too light and relatively stiff, it can crack like a pane of glass. The UCI weight limit in fact came about as a safeguard to bicycle safety...because a stiff 10 lb bike may crack in half made out of modern material with a 2000 watt sprinter on board.

Testing isn't momentary. Data bases aren't instantaneous....or can be but buttressed with years of data. Riders known anecdotally what kind of frame works best for them as they experiment throughout their riding lives until they come across a bike they are faster on. Race bikes are stiffer because they are faster. A broken bike isn't fast. A bike that is twisting all over the place a rider can't control isn't fast. A bike where the brakes rub isn't fast. A bike that unintentionally shifts gears in the middle of a sprint isn't fast. Stiffness is about control, safety, durability and arguably more efficient energy transfer. But there is a reason why many doubt that stiffness matters. Because they don't put out much power and riding a bike to them and me is like a grasshopper versus a sumo wrestler jumping on a swimming pool diving board.

Not as relevant. How does Giant know if you are shopping for a new TCR or Peter Sagan's twin brother?

So there is an advantage there for the custom builder who does know what the expectations are for each individual frame they produce?

Customer expectations are one thing. Meeting them is another. Perhaps you have read accounts where a buyer worked closely with a custom bike builder only to be disappointed with the outcome. Qualitative metrics are one thing. Creating a bicycle is not qualitative but rather a quantitative process based upon physics. Every time, a single dimension is changed on a bike frame, its mechanical properties change. A custom bike is a swag. A guess.
This nexus isn't easy. Schwinn for example after making many bicycles for many years got it wrong and went out of business.

Your Roubaix has an endurance frame.

The Specialized Secteur(used market only) has been mentioned..AL version of the Roubaix, if that frame works for you, then a used Secteur is a short punt. You even know how to set it up..duplicate what you have now.

Anytime the combo of "long legs, shorter torso" comes up, a women's specific design (WSD) is an option. You may want to look into a WSD model of some of the bikes you're considering.

27 at a reasonably comfortable effort, where I check the speedometer withkut feeling like i'm going to crash lol.. Totally all out, on a good day, no concern about being able to finish a long ride fresh...say 29-30. I should probably mention it's on a big steel touring bike in a t-shirt. I'm ~6 ft 190 lbs, and brunette,if it matters, though I'm still not sure where this is going...

Better design can make riding more fun. I went from a 2007 aluminum Trek Pilot to a 2017 CAAD12 and the frame design improvements made bike riding more fun. The subjective sensations of control, comfort, responsiveness all improved. I feel more confident and relaxed on the new bike. The few watts I produce are more efficiently transferred to forward movement.

Good post.

Stiffness doesn't matter to you as much as a pro or top amateur who may walk into bike shop and point to the new Venge VIAS or Tarmac or Evo. You see the top race bikes aren't really for you, but rather guys serious about racing or training hard. A strong guy can flex a top frame and you can't.
Golf is a good analogy. An average pro who can generate 115mph clubhead speed with driver and can hit the ball 300 yards. There are pros even stronger...but that average pro...if he plays with a regular stiffness shaft in his clubs, he will hit the ball all over the golf course. Most pros play with XS shafts to control the power they can impart to the golf ball. Stiffness is many things. If you can't flex a bike frame than greater stiffness doesn't matter. But to say stiffness doesn't matter is wrong and for some strong riders, more stiffness is better.