TSUNAMIBAY

Look, I can provide links to the website and data showing the results of testing, but my point was not to post here to convince anyone of this design. My friend Mark has been working on this concept for over twenty years and has slowly convinced some hardcore skeptics, myself included, that this design works. The point of this thread is to express my amazement at how few people are even curious enough to find out more. It reminds me of the quote "The only barrier to truth is the presupposition of already having it".

gl98115

Alt explanation:

On the downstoke, the curved downtube and top tube flex vertically , so the center of mass of the rider goes down while the rear wheel moved back and the front wheel forward, effectively lengthening the wheelbase. At the bottom of the down stroke, the energy is released allowing the wheels to come back together and raising the center of mass of the rider.

Basically a pogo stick with a horizontal spring.

gl98115

The Slingshot (1992):

Maelochs

If after 20 years your friend has not been able to conclusively prove his case .....

nycphotography

Getting people to change is based on a very fragile assumption that they even want to change.

This broken assumption is usually a defect in the person thinking other people should want to change, which explains why they waste all their time and energy on

nycphotography

At this point, everything else you say is irrelevant, as you can safely be assumed to be clueless.

dougphoto

I always wanted a Slingshot frame

wphamilton

People always say this, but it still doesn't add up.

You know, you could lose energy by opposing the flexing with your leg muscles. You could lose energy bouncing your body up and down, again the leg and back muscles. That's not heat or friction in the frame. Tire deflection increases every time that frame flexes - you lose energy there, that isn't heat or friction in the frame. There are lots of ways to use that flex energy that aren't returned to forward motion. The whole argument, which essentially asks "where else would it go" always seems to boil down to faulty reasoning.

That doesn't say that the conclusion is wrong. But it probably is.

WhyFi

Curiosity gap shilling - the worst kind.


BTW, YOU WON'T BELIEVE WHAT HAPPENED NEXT!

scuzzo

thats a neat idea, but if you are going custom down tube.. why not get a clear plexi glass one and fill it with gold fish... it would be a bout the same in ride characteristics and you could have a cool conversation piece.. or make one with a lava lamp in it.... there is a reason this idea never caught on... i cant think of any time i road my bike where i thought.... "you know if i could only tune my bike by swapping out the down tube..." most often i would just change out tire size to affect ride feel.

rpenmanparker 

I don't know what puts out more watts means. I guess you mean the same rider is capable of putting out more watts on one frame than another. But that is not how frame efficiency is measured. The only sensible measure is the comparison of power at the crank to power at the rear wheel. Doesn't matter what the rider thinks about their power output on the bike. How much of the power at the pedals reaches the rear wheel? Easy enough to do with today's commercially available do-dads. The only difficulty is making sure both power meters are correlated, that they measure power the same or at least in a know relationship to each other. Probably an absolutely rigid trainer type device could be used to standardize the relative power detection of the two meters. Either a lot of steel or reinforced concrete shaped to accept a saddle, crank, rear wheel, and handlebar. Once the two meters are correlated, then the power loss to a real frame is easy to determine. Talking about this without such data is just useless.

So OP, do you have that kind of data for this cockamamie frame. What fraction of the power at the crank makes it to the rear wheel? And on other popular frames.

Jakedatc

More watts at the same speed is worse not better

the Tri/ TT folk aren't going to look twice at that thing because the rest of it is not as aero as even a basic TT bike.

ingo

So many fails here:
1. Anecdote + Anecdote + ... does not equal DATA.
2. Flexible cranks, handle, seatpost, wheels are not faster, why would a flexible frame?
3. So easy to get data to confirm, OP prefers to provide personal qualitative observation without verification.
4. Less aero is not faster.
5. Contrary thinking against proven designs does not equal better.

wphamilton

That's admirable out of the box thinking. Being more staid and practical, all I come up with is it would be convenient to swap out motors and batteries installed in the replaceable downtube. I could go for something like that.

Carbonfiberboy 

My mind keeps coming back to this thesis: FTP is FTP. If power is measured at the rear hub, it's safe to say that, other than losses in the wheels and tires, the measured power at the hub is the power moving the bike forward. So can one's FTP be different when measured on different bikes? Of course it can! Fit is critical to power production and includes many subtleties like trail, saddle model, cranks, and pedals as well as the obvious things like saddle height, reach and stack, and bar width. It's normal to have a lower FTP on a TT bike than on a road bike, just because of the position.

The OP is essentially alleging that his FTP is higher on his flexible frame than his more rigid frame. This could very well be the case and yet have nothing to do with frame stiffness. Or it could be due to a physical peculiarity of the OP and another rider would not get the same result. Or his FTP could be even higher on a stiff frame with a different fit which he as yet has never ridden.

Basically I'm saying that we have no reason to question his results, though we do have reason to question the means. What with the tremendous amount of research and testing that goes into the production of modern racing frames, I'm quite confident that if there were something this huge out there, it would already be dominating the peloton. History is filled with dedicated inventors whose inventions actually never performed as touted. As it is said, one can tell the pioneers by the arrows in their backs. My experience leads me to prefer following to leading in the tech field.

That latter paragraph thus answers the OP's question. It's not a question of change, just the desire to move forward when adopting new technology rather than to move backward.

HTupolev

It's something that definitely merits looking into, though. The results of Heine's double-blind study on the matter were extremely interesting, namely that it seemed that there were biomechanical factors with the stiffer bike preventing high aerobic efforts. Even if it turns out to just be user adaptation, it's compelling stuff.

(Also, flip-side skepticism: if stiff frames offer any real efficiency/power/whatever benefits, why have major manufacturers never provided any evidence of this despite pushing it as a big sales point for several decades?)

Wileyone 

Kinda fits in with most "modern" Bikes. At least it's not flat Black.

That said I do admire people who are willing to try something different.

jamesdak 

LOL, you beat me too it. There's been two of them for sale locally and they appear to be in great shape. Yet they aren't selling....

Carbonfiberboy 

IMO the majors don't need to provide any evidence. Riders do that for them. I'm sure there are fast and stiff steel frames out there, but my carbon bike felt like a rocket ship after riding steel all my life and it wasn't just the weight. I was such an ass about it that I got this nickname. Carbon is so easy to tune that a few name riders have custom layups done for them to tune the stiffness just right.

The builder of this new bike should be able to place it with some outstanding competitors and start raking in the money. If it works as advertised. I used to ride with a fellow who used a relatively unknown sponsor bike as one of his RAAM bikes. The bike was no better than all right though. He gave it back and uses major builder bikes now.

shelbyfv

That bike is ugly. If he wants to sell them locally, he should give some to winning racers. If they were under $500 for frame and fork, someone might give it a try.

rpenmanparker 

That is totally fallacious thinking. Totally unscientific. Subjective opinions even from pro riders carries absolutely no weight among folks who understand how science and technology works. And like it or not, we are talking science and technology.

But most important is this: if the effect were real, you wouldn't need to rely on riders' opinions. It could be measured in a controlled experiment. That is true whether the effect we are talking about says frame stiffness is a positive or a negative. I described above how it could be done. So why hasn't it been?

Carbonfiberboy 

Not fallacious thinking at all. That's what races are all about, be it auto, MC, or bike. The human/machine interface is too complicated for another method of testing. How do you pick a bike? Don't you get on one and test ride it? Or would you rather buy an unridden but "scientifically" validated bike? That's how modern bikes are designed. They get the parameters approximately right, then someone goes out and rides the crap out of the prototype. They keep modifying it until riders in the the prospective users' class say it's right. There are GT bikes, classics bikes, crit bikes, many specialized bikes developed for specific types of events and even specific events. Their designers are not idiots.

In today's race bike market, the carbon bikes are all tuned so similarly that there's not an obvious advantage to any one manufacturer's bikes. You are saying that they're doing it wrong. Many, many thousands of riders disagree.

Inpd

I find this bike weirdly exciting, must be time for a break!

rpenmanparker 

Keep believing it. We are talking about a specific relationship: frame stiffness to power transfer. Not how much someone likes a bike or how fast they feel on it. Very simple: the relationship of frame stiffness to power transfer. You can either show it and it's real, you can't and it's not.

smarkinson

You'd have better luck if you were showing off your bike at a triathlon rather than a time trial.

Triathletes love crazy bikes.