Planing

[devlin]

What makes you think this energy is simply saved and not dissipated? Somehow it can't store energy forever and I don't see how a frame would have any mean of giving back that energy to propel the crank or wheel. I know that in magazines so called journalist try to make us think that this energy is stored then redelivered to the rear wheel at some point but it is simply not true or I can't think of a way it could be true. Did someone check the temperatures variations of a frame ? Could it really be measured ?

I would suggest the energy is transferred into heat but because the amount of energy is so small the amount of heat produced would be almost unmeasurable. IMHO.

[Too Tall]

(Cough) if Jan chimes in he might confirm that his fascination with planing has less to do wiith ultimate power output and more to do with the comfort and efficency when going long. Just like a sailboat, no one thing makes it fast rather it is the sum of many small things. pete Pennsyres and Lon Haldeman set an transcontinental tandem record on a nearly unrideable tandem that was very soft and flexy. Speed is relative to how you intend to survive the assault!!!

^^^ So many variables in that though. Change any one component in the chain from rider through to road surface and you are going to get a diiferent outcome. The cost, both time and money, would be huge for a few watts advantage, if any.

Other than sticking with a frame setup that feels good you are chasing something that IMO just does not matter.

[jclay]

(Cough) if Jan chimes in he might confirm that his fascination with planing has less to do wiith ultimate power output and more to do with the comfort and efficency when going long. Just like a sailboat, no one thing makes it fast rather it is the sum of many small things. pete Pennsyres and Lon Haldeman set an transcontinental tandem record on a nearly unrideable tandem that was very soft and flexy. Speed is relative to how you intend to survive the assault!!!

I applaud Jan’s efforts. Regardless of the true/false ratio of his work (which I think is pretty high) the cycling community has benefited from it. I know I have. Evgeniy’s contribution was refreshing and useful too. Regardless of the outcome I'd prefer to know it rather than take a position based on idealogy and table banging.

From a personal economic perspective I actually hope it proves to be a mirage. I make frames for pleasure, which means that I pay the freight! Relative to thinner walled pipes, conventional diameter 9/6 tubes, being generally non-heat treated, are less expensive and a little easier to cut, file & drill.

[EricKeller]

I think Jan has had a positive influence on cycling and certainly has changed the conversation.

[thollandpe]

I would suggest the energy is transferred into heat but because the amount of energy is so small the amount of heat produced would be almost unmeasurable. IMHO.

Immeasurable, likely. Heat, unlikely. That happens in systems with a relatively high hysteresis like tires. The frame will act like a spring and give back most of the energy stored as deflection. The question is how much of that return makes a significant contribution to forward motion.

Todd Holland

[Mark Kelly]

Which suggests a possible solution to the conundrum: if the energy is being returned to the system, there will be some combination of resilience (force and time) with pedalling mechanics which optimises the capture of the energy towards forward motion. The concept is relatively well understood for stride mechanics on a resilient surface (running tracks are routinely tuned to keep the track rebound in phase with the energy return from a runner's Achilles' tendon).

I think this gels with the OP's original contention that the effect was due to timing: as I understand the diagram, it is supposed to show equal impulse spread in two different patterns.

[devlin]

So... if you went along that train of thought you'd need a frame to suit your natural cadence. ie. someone who naturally pedals at 85-90 would need a slower returning frame than someone who pedals at 100-105.

[Craig Ryan]

So... if you went along that train of thought you'd need a frame to suit your natural cadence. ie. someone who naturally pedals at 85-90 would need a slower returning frame than someone who pedals at 100-105.

Which is why I think color is so important!

[Mark Kelly]

So... if you went along that train of thought you'd need a frame to suit your natural cadence. ie. someone who naturally pedals at 85-90 would need a slower returning frame than someone who pedals at 100-105.

Only if you pedal in perfect circles. Any variation in torque will create a series of extra terms in the transfer function, per Fourier's theorem.

[Andrew R Stewart]

Seems to me that the system is so sensitive that a full bladder or too tight a shoe will negate any planned planning. Andy.

[e-RICHIE]

I have a lot of questions (and a boatload of doubts, no pun intended) about the concept, but one is this: what do you do with the information? Oh and while I'm at it, are the results, the sensations, the visceral feelings, the data (datum?) repeatable? Are they repeatable on the same bicycle for the same person? Is the planing bicycle one that planes for the rider only, and not one where he can say to a pal - this fuckign rocks, and have him feel the same thing? Can you take the information from a bicycle that thrills you and say to someone, "copy this", and get another thriller? I can't debate the science and engineering that allows one to measure the small bits. I'm not even interested in them. But I make bicycles, and the head versus heart versus outside influences thing has always confounded me. Actually, it's rarely confounded me. I think many folks are unable to say simply, "I dunno. I just like it." and leave it at that.

[Mark Kelly]

Can't answer for anyone else, Richard, but here's my opinion: I think there is some validity to the concept that there are optima for cyclic inputs to the contact points. I think it's most likely to do with impedance matching. The data for human body mechanical input impedance, resonance and damping factors are well known and are indeed repeatable, including idiopathic variation. A lot of work has been done in this field because it's an important OHS issue.

As to taking the data and working with it, there's an easy shortcut which is to translate the mechanical terms into electrical equivalents: the concept has been around longer than you and I; see Olsen Dynamical Analogies Van Nostrand 1943 for an outline. The huge advantage these days is the sheer power of circuit simulation techniques using SPICE, even the freeware versions like LT-Spice are incredibly powerful.

A problem that would have taken hours to solve and challenged my mathematical skills back when I still had them* is now just a matter of arranging suitable analogies.

*much like my cycling the older I get the better I used to be.

[EricKeller]

I think it's pretty clear that the deflection of the frame does not store energy which is returned into the system as useful work. It swings back and forth and pretty much does nothing. The people that think it is returned into useful work should be able to describe a scenario where that might happen, and the truth is that they can't. This whole idea reached a pinnacle of ridiculousness for me when Mr. Heine recently posited that a flexible wheel stores energy which is somehow returned into the system as useful work. It's just not plausible.

[Mark Kelly]

I don't think the idea of the frame storing and releasing strain energy is any less plausible in principle than the idea of the Achilles' tendon storing strain energy. That's not the same as saying that I think it happenss, just that your reductio ad absurdam is insufficiently absurd.

Now all we need to do is teach a kangaroo to ride a bike.

[devlin]

I think we'll Skip that.

[Mike Mcdermid]

I think we'll Skip that.

ha see what you did there but this thread is useless without a nother picture

200px-Skippy-dvd.jpg

you australians slaps on the back all round ;-)

[devlin]

Nice pick up from the POM.

[jclay]

Let's please keep this civil and constructive; nothing is gained by turning it into the types of haranguing that must have accompanied the Flat Earth vs Round Earth "discussions" back in the century...which I'm glad someone had the strength of character to propose in the face of nasty consequences.

Strain energy provides useful work in boatloads of famaliar systems. A bicycle frame is a spring. Can this spring do the same, or do anything else that might benefit a riders performance?

That when the head tube is fixed and one stands on the pedals the frame flexes, and when one eases off that the frame restores to its unstressed state suggests that the frame has flexural modes that relate to power applied to the driveline. Thanks to this discussion and Evgeniy's suggestion we now have a rough idea of how to figure an upper energy bound. My spring test came up with quite a bit more strain energy, but the idea that it's small seems sound. But then again whole industries have sprung up to provide very expensive parts that save minor-league grams, so writing off this idea as a meaningless exercise seems contradictory.

So, apparently, small energy flows. Might something else be at play? Enough folks think they feel the phenomonia, and to my mind Jan has done a credible job of trying to correlate observed behavior with frame flexibility to support (if not prove) the notion. My electrical analog was not an unreasonable thought. Could a wee bit O'flex reduce maximum muscle fiber tension, just a tad? Just blunt a very short duration high stress spike? Doesn't seem heresy to ponder the question. There are lots of analogs for that too, and if it does, well that's a nice thing to do for the motor which ought to be reflected in performance.

What to do with the info? If it becomes a proven phenomonia, one might do little more than tend toward more flexible frames for, perhaps, smaller and less hammering riders.

Repeatable data? It won't come from getting shouted down but from folks seeing if they can get it. I think that for the money, and money always matters, Jan's start is fantastic.

Humans don't tend to say "dunno, I just like it", and leave it at that; its a two edged sword but on balance I'm glad. It got us The Reformation, a round Earth, penicillin, pneumatic tires and a whole bunch of other things most of us like. I'm not being a wise acre. It's what we do.

Applicable to other riders? Depends on the riders and the differences in the hardware. Give me two tennis racquets, strung differently and I'll still suck and not be able to differentiate. Give them to high level players and its a whole different ball game.

[Too Tall]

John,
Fact: Minnesota Fats will whip your @ss using a broomstick. A broomstick is no fun to play Billiards with. Jan's approach is to comfort over distance, long distance and for that application there is no question about it. Bikes that flex and reduce rider stress make you stay on the bike longer. Few of us doubt that and heck, I'm for one am very keen to see if you or anyone can resolve empirical data which measures frame flex on riders performance. Seeing that proved will help, not prove, to understand why we "feel" the way we do about bikes of differing build characteristics.

Is that what we are talking about? 'Cause if we are just talking about terms I'm out.

[Jonathan]

My own anecdotal experiences are that you can very much feel a difference in frames, but what you feel isn't driving you down the road any faster. I'm open to the idea there is some theoretical energy being harnessed, but there must be 1000 other variables that are in play too, so I'm suspect of this being anything more than an intellectual excercise. And that's ok too.