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#32
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Is body weight equivalent to bicycle weight?
On Mon, 25 Jul 2005 09:38:19 -0700, Terry Morse
wrote: In article , wrote: When we walk, weight on our back moves along at a steady pace, much like our bicycle frames doing the same thing when we ride. But weight on our feet must be swung forward by our legs, somewhat like the wheels on our bikes, which must spin as well as move forward. With every step, the foot hits the ground, comes to a halt, trails behind and provides a forward push, and is then whipped forward (and upward) again at roughly twice the walker's speed for the next step. Add a pound or two on the end of your hind leg and the repeated violent acceleration and raising becomes much more difficult. Weight added to the hands would be just as obnoxious, since the hands are constantly waving back and forth during walking and running. Walking is not as horrid as your description portrays. Legs are approximate pendulums which require little effort to keep them swinging. The same goes for arms. Adding mass to the feet reduces the natural frequency of the pendulum, though, which naturally slows down the walking speed. The only efficient way to go faster in this situation is to lengthen the stride, which of course is limited. Dear Terry, If you add ten pounds to your back, I think that you'll find it a burden when you walk, but nothing horrid. If you add five pounds to each shoe, I think that you'll find it horrid to walk--slow and difficult. This is why boots caked with heavy, wet mud remain annoying even after you get out of the foot-sucking bog. Legs and feet may be approximate pendulums, but the approximation goes to hell uphill, which for some reason is the favored path in the original poster's army. There's a reason why children prefer to play barefoot. Carl Fogel |
#33
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Is body weight equivalent to bicycle weight?
wrote:
If you add ten pounds to your back, I think that you'll find it a burden when you walk, but nothing horrid. If you add five pounds to each shoe, I think that you'll find it horrid to walk--slow and difficult. This is why boots caked with heavy, wet mud remain annoying even after you get out of the foot-sucking bog. Legs and feet may be approximate pendulums, but the approximation goes to hell uphill, which for some reason is the favored path in the original poster's army. Just try walking with and without ankle weights. It changes your gait, but walking on level ground is no more difficult. I agree it may slow you down, but you can make up for this by lengthening your stride. Unless you're already at your maximum stride. Uphill is another matter. I experience the effect of heavy feet every time I go ski touring. I can skin up a hill faster than most people, even though I have a heavy alpine touring set-up. But my little hip flexor muscles tire from having to lift skis, boots, and binding on every step. They're just not used to that much work. -- terry morse Palo Alto, CA http://bike.terrymorse.com/ |
#34
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Is body weight equivalent to bicycle weight?
On Fri, 22 Jul 2005 19:43:48 GMT "Bruce W.1"
wrote: Is body weight equivalent to bicycle weight? In other words, would riding a bicycle that's five pounds lighter be the same as losing five pounds off of your body weight? There is a greater penalty for unsprung weight than for "sprung" weight. Most of the rider's weight can be sprung weight, and if the bike has a suspension then some of the bike's weight is also sprung, but you pay an overall weight penalty for a suspension. Sprung vs. unsprung doesn't matter, however, if the road is smooth. - ----------------------------------------------- Jim Adney Madison, WI 53711 USA ----------------------------------------------- |
#35
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Is body weight equivalent to bicycle weight?
On Fri, 22 Jul 2005 19:43:48 GMT "Bruce W.1" wrote: Is body weight equivalent to bicycle weight? In other words, would riding a bicycle that's five pounds lighter be the same as losing five pounds off of your body weight? Reducing body weight reduces also air resistance, and body weight loss may even give possibility to achieve more aerodynamic position without thighs smashing against stomach on every stroke. Five pound effects might not yet be so concrete, but there are examples where reater reductions might be possible to achieve... Antti |
#36
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Is body weight equivalent to bicycle weight?
"Philip Holman" wrote in message ... "41" wrote in message oups.com... Jim Smith wrote: writes: (If you're not sure about the odd business of the foot coming to a halt with every step, even at Olympic sprinting speeds, step through a puddle and then look back at your wet footprint s. They show that your foot never slipped when it was touching the ground, If one is interested in the dynamics of the system it makes a lot more sense to use a reference frame centered on the body. The foot does not stop. Imagine you have a (let's say small) bicycle wheel which you can hold up in the air by a handle attached to the axle on the left, and which has a handle on the right attached to the rim which you can use to crank the wheel up to speed. You then crank in uniform circular motion. Now, start running forward at the same time: even more motion. Finally, at the same time as all this, slowly lower the wheel down so that the tire touches ground. If you get the timing right, it will roll along the ground with no slippage. You can think of this as one reason why, in problems with systems that both rotate and translate- like the leg system while running, or a bicycle wheel, or for that matter, a person leaning over- neither the ground coordinate system NOR one attached to the body is adequate. One uses both: one attached to the ground, and one attached to the center of mass of every rotating system. I agree but I think your description is too broad to be useful for a specific sport. Now, "get back to your oar 41"....bonus points for the movie and actor quoted. "Does that interest you 41" I can see that it doesn't. Ben Hur and Jack Hawkins. Wot, no movie buffs on rbt. Phil H |
#37
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is boot weight equivalent to body weight?
Bruce, Carl, and Terry wrote:
There's an old Army saying; one pound on your foot (boot weight) is equivalent to five pounds on your back. If you add ten pounds to your back, I think that you'll find it a burden when you walk, but nothing horrid. Just try walking with and without ankle weights. It changes your gait, but walking on level ground is no more difficult. I've walked quite a large accumulated amount with and without ankle weights [up to 40 ounces each], and you can believe me when I tell you it's significantly more difficult with weights than without. The reason is easy to analyse: you lift the trailing foot [off which you're stepping] a few inches each half-pace, along with about half the weight of the lower leg — the other half being supported at the knee. Even with a big foot and ankle like mine, another 40 ounces adds considerably to the work done. On the other hand, carrying another 80 ounces on my back is insignificant compared with the other 3700 ounces, because its elevation hardly changes with each pace. -- "Bicycling is a healthy and manly pursuit with much to recommend it, and, unlike other foolish crazes, it has not died out." -- The Daily Telegraph (1877) |
#38
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is boot weight equivalent to body weight?
How 'bout merely F=ma? Ya ain't 'a-ing' anything above yur hips anywhere
near as much as your boot. "LioNiNoiL_a t_Y a h 0 0_d 0 t_c 0 m" wrote in message news:O6zFe.23560$bp.11918@fed1read03... Bruce, Carl, and Terry wrote: There's an old Army saying; one pound on your foot (boot weight) is equivalent to five pounds on your back. If you add ten pounds to your back, I think that you'll find it a burden when you walk, but nothing horrid. Just try walking with and without ankle weights. It changes your gait, but walking on level ground is no more difficult. I've walked quite a large accumulated amount with and without ankle weights [up to 40 ounces each], and you can believe me when I tell you it's significantly more difficult with weights than without. The reason is easy to analyse: you lift the trailing foot [off which you're stepping] a few inches each half-pace, along with about half the weight of the lower leg - the other half being supported at the knee. Even with a big foot and ankle like mine, another 40 ounces adds considerably to the work done. On the other hand, carrying another 80 ounces on my back is insignificant compared with the other 3700 ounces, because its elevation hardly changes with each pace. -- "Bicycling is a healthy and manly pursuit with much to recommend it, and, unlike other foolish crazes, it has not died out." -- The Daily Telegraph (1877) |
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