Is body weight equivalent to bicycle weight?

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.
--
terry morse Palo Alto, CA http://bike.terrymorse.com/

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

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/

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
-----------------------------------------------

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

"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

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)

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)