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| *Vultures Knob>>>Cycling |
Rotary motion Vrs pumping action? |
A thought occurred to me in one of those mad moments. The human body is all set up and conditioned from an early age for a walking style that is more of a pumping action than a purely even rotary motion that we use on cycles.Has any research been done on alternative power input mechanisms on bicycles. By this I mean a more natural power input being mechanically translated to rotational energy It is not as a easy question. First. As natural is to push and pump as to go round. Just tickle a baby that is laying down, face up, and watch his legs go round! The running stride, even though it pushes, it is most effective when done in a rotary motion as you move your legs forward and back. (a lot of the training has to do with mastering that kind of motion). Second: Linear movement is as natural as circular movement. Inertia law says that an objetc will remain in its (state) course unless a force chanches its motion. Planets, satelites, stars, etc. revolve, they have a "circular" motion. So does the atom particles (spin), and so on. So, it is not that simple to say linear motion is the natural motion. That is over simplifing things a bit. Third: In cycling the "circular" motion has been, so far, the most effective way of deliver power to the wheel. But it is not perfect. The most upward position and the lowest postion of the foot are called death points, because the produce no power at all and tend to make the rotary motion a kind of "square" one. This is less effective (push, pump, pull). Is is like the motion we use when climibng a steep hill. It can deliver more power, but with a high cost and for a short period of time. We are on the limits of our pedaling power or capacity. A lot of the cycling training is aimed a soft round motion while pedaling. Biopace was an idea in that direction and in protecting the knee from strain in a not so perfect pedaling motion of push and pull ("square pedalling". Although the idea was good it did not do to well in practice. The motion was "funny" , it felt more like sliding than pedaling, the knee did not get the relief it was suposed to, and it was not so efficient, specialy climbing hills or while sprinting. The latest idea (at least that I kmow of) is called "Rotor". It is pedal cranks that are not stiff. The pedals crancks are aloud some motion precisely on the two dead points of pedaling, so you are never in a feet position of 12 and 6 o 麓clock at the same time. Never at the dead spots with both feet, so there is always one of them that can still deliver power to the wheel, and thus, help set the other feet in a better position to do the same. This cranks has been tested for over 10.000 kilometers and with good results. Also in challenging road races and mountain trails and competitions. (Yes, models are made for road and mountain bikes). Look under ROTOR in your search engine. (The brand name of this contraption). While not totaly popular (at least yet) it seems to be a improvement over the fixed pedal cranks and their round, circular motion. (Because the dead points ae eliminated or diminished). Time will tell if they are really up to par and are a real "revolution" in the way motion is turned into wheel power. Hope I have help some. Yes, over many, many decades there have been numerous attempts to modify the pedaling motion. A simple and relatively recent (actually, probably a very old) idea : Bio-Pace with elliptical chain rings. I read a couple articles many years ago on this subject, don't recall details though. That's mild but there's wild too. Ratcheting mechanisms etc. I don't know a single good place to find this info aside Googling the web. Apparently, even though circles don't seem as natural as a pumping motion it sure seems to be the best so far. It's called Linear Drive. There were a few built, but they were built one-at-a-time. The Linear Drive has never been produced on an assembly line. The first time I saw this invention, it was a prop in the original Star Trek series, with William Shatner and Leonard Nemoy and produced by Gene Rodenbury. When anyone was in sick-bay aboard the USS Enterprise, they would be pumping the pedals while lying on the examination table , with "Bones" McCoy, played by Deforest Kelly, taking notes. http://www.speed101.com http://www.ihpva.org A rotary action is more efficient but you do have to train for it! Your correct in saying thats its not a natural movement, because it isn't! But the whole concept of using machines isn't really natural either. Research has been done in other forms of propulsion, often producing some interesting looking contraptions, usually by guys in their garden sheds ! Yes M R ,eliptical chain rings have been around for a long time, I have seen a number of the Shimano Biopace chainsets, you mentioned but alas never riden one, I would like to try one though! Team Honda on the World Cup Mountain Biking circuit has probably the most innovative crank mechanism to date. Check it out at the link below. The picture is of Greg Minnaar, who has one a few World Cup Season Titles over the past few years. Honda has to be one of the most innovative companies in the world. http://world.honda.com/mtb/2005/u06usa/r... |
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