horizontal seat position

While in a university biomechanics course, I looked into horizontal
seat position. The study I did looked at oxygen uptake for a given work
load at three positions, (normal, forward and aft). Not surprisingly,
the normal position took less o2 for a given work load. The change of
position was quite extreme, and inch or so, so not much enlightenment
there for anyone serious about adjusting their position.

But I wondered if this was all about training and habituation, or
whether there is something more efficient about a given position. I
did an analysis of the movement of the centres of gravity of each leg.
It seemed that the path of the c of g's of each leg (ie. one on each
side) described an alternating pendulum movement almost exactly equal
fore and aft of a line dropped from whole body c of g.

So, I wondered if this might be a formula for finding an efficient
position? Aerodynamics and power output are different questions.
Certainly the internal of work of moving each leg c of g back and forth
would be small relative to outside work, but could it be minimized by
centering the body c of g between the two leg c's of g?

mtb Dad wrote:
While in a university biomechanics course, I looked into horizontal
seat position. The study I did looked at oxygen uptake for a given work
load at three positions, (normal, forward and aft). Not surprisingly,
the normal position took less o2 for a given work load. The change of
position was quite extreme, and inch or so, so not much enlightenment
there for anyone serious about adjusting their position.

But I wondered if this was all about training and habituation, or
whether there is something more efficient about a given position. I
did an analysis of the movement of the centres of gravity of each leg.
It seemed that the path of the c of g's of each leg (ie. one on each
side) described an alternating pendulum movement almost exactly equal
fore and aft of a line dropped from whole body c of g.

So, I wondered if this might be a formula for finding an efficient
position? Aerodynamics and power output are different questions.
Certainly the internal of work of moving each leg c of g back and forth
would be small relative to outside work, but could it be minimized by
centering the body c of g between the two leg c's of g?

That last line should read "centreing the body c of g between the
extremes of the arc of the leg c of g movement"

I really am frustrated not knowing the percents on expensive tires
versus basic ones impact wise on rolling resistance. Or even by what
factor a cush mountain ride is more taxing then a sticker slain carbon
road butterfly.

I mean is it fractional, or multiples?

Schwin has come out with powerassisted road bikes for adults. THat's
interesting, and the quality might be there as they are about two
grand, but PA for me means you can have better durability AND SAFETY
ETC. without having to accept lesser range. Only on the kids model not
yet out are they promissing that.

Biomechanically generator effficiency might be so great that pedalling
to charge all the time and running the wheels from motors not
mechancally connected to our bodies at all is concievable. Pedal by
wire technology I've never seen implimented though. Using more of our
muscles across our bodies to convert glucose into electricity buffered
much more effictively chemically outside our bodies then we can train
ourselves to actually seems reasonable to me. It is after all what
hybrid does for the internal combustion car. It allows the gas to not
spin the wheels, to not waste so as to have adequate acceleration
power, to not have to have the bulk that highway power requires either.

Being able to respond to cognitively taxing circumstances, collision
avoidance, without losing power, is a huge safety boon. Comparing
lighweight vehicles to motorcycles loses that benefit. Nothing is
nimbler then a vehicle that weigh less, not much more, then us alone.
But it's not about grams. A few dozen pounds here or there matters
squat if those pounds can contribute much more then we can. IS there a
motorised bike list beyond the tidal force one anyone can recommend?
THe 'need' seems to be being met as a disservice by novel,. amazing,
but not production mature offerings.

IT should cost much less to distribute a miracolously powered vehicle
then bike fanatics routinely pay for there works of art with little
(relatively) practical value. A few thousand bucks these days can buy
peace if widely invested into flying carpet like contraptions almost
everyone who can walk would pony up for. WHy is this not happening?


mtb Dad wrote:
While in a university biomechanics course, I looked into horizontal
seat position. The study I did looked at oxygen uptake for a given work
load at three positions, (normal, forward and aft). Not surprisingly,
the normal position took less o2 for a given work load. The change of
position was quite extreme, and inch or so, so not much enlightenment
there for anyone serious about adjusting their position.

But I wondered if this was all about training and habituation, or
whether there is something more efficient about a given position. I
did an analysis of the movement of the centres of gravity of each leg.
It seemed that the path of the c of g's of each leg (ie. one on each
side) described an alternating pendulum movement almost exactly equal
fore and aft of a line dropped from whole body c of g.

So, I wondered if this might be a formula for finding an efficient
position? Aerodynamics and power output are different questions.
Certainly the internal of work of moving each leg c of g back and forth
would be small relative to outside work, but could it be minimized by
centering the body c of g between the two leg c's of g?

mtb Dad wrote:
While in a university biomechanics course, I looked into horizontal
seat position. The study I did looked at oxygen uptake for a given work
load at three positions, (normal, forward and aft). Not surprisingly,
the normal position took less o2 for a given work load. The change of
position was quite extreme, and inch or so, so not much enlightenment
there for anyone serious about adjusting their position.

But I wondered if this was all about training and habituation, or
whether there is something more efficient about a given position. I
did an analysis of the movement of the centres of gravity of each leg.
It seemed that the path of the c of g's of each leg (ie. one on each
side) described an alternating pendulum movement almost exactly equal
fore and aft of a line dropped from whole body c of g.

So, I wondered if this might be a formula for finding an efficient
position? Aerodynamics and power output are different questions.
Certainly the internal of work of moving each leg c of g back and forth
would be small relative to outside work, but could it be minimized by
centering the body c of g between the two leg c's of g?

I suspect this is entirely training and habituation. Were these
fore-aft changes accompanied by corresponding height changes to keep
the effective height the same? Were bar positions changed to maintain
torso-thigh angles?

Joseph

"meeklyornot" wrote:

I really am frustrated not knowing the percents on expensive tires
versus basic ones impact wise on rolling resistance.

I am frustrated by gibberish masquerading as English. Are you Gene
Daniels?

Or even by what factor a cush mountain ride is more taxing then a sticker slain carbon
road butterfly.

Hmm. Slain butterflies?

I mean is it fractional, or multiples?

Two sides of the same coin.

Schwin has come out with powerassisted road bikes for adults. THat's
interesting, and the quality might be there as they are about two
grand, but PA for me means you can have better durability AND SAFETY
ETC. without having to accept lesser range. Only on the kids model not
yet out are they promissing that.

Biomechanically generator effficiency might be so great that pedalling
to charge all the time and running the wheels from motors not
mechancally connected to our bodies at all is concievable. Pedal by
wire technology I've never seen implimented though. Using more of our
muscles across our bodies to convert glucose into electricity buffered
much more effictively chemically outside our bodies then we can train
ourselves to actually seems reasonable to me. It is after all what
hybrid does for the internal combustion car. It allows the gas to not
spin the wheels, to not waste so as to have adequate acceleration
power, to not have to have the bulk that highway power requires either.

Gene Daniels for sure.

Being able to respond to cognitively taxing circumstances, collision
avoidance, without losing power, is a huge safety boon. Comparing
lighweight vehicles to motorcycles loses that benefit. Nothing is
nimbler then a vehicle that weigh less, not much more, then us alone.
But it's not about grams. A few dozen pounds here or there matters
squat if those pounds can contribute much more then we can. IS there a
motorised bike list beyond the tidal force one anyone can recommend?
THe 'need' seems to be being met as a disservice by novel,. amazing,
but not production mature offerings.

IT should cost much less to distribute a miracolously powered vehicle
then bike fanatics routinely pay for there works of art with little
(relatively) practical value. A few thousand bucks these days can buy
peace if widely invested into flying carpet like contraptions almost
everyone who can walk would pony up for. WHy is this not happening?

WHy is what not happening? Miraculously powered vehicles? Do you mean
by cyclists after having eaten of the loaves and fishes?


Welcome back, Gene.

--
Ted Bennett

Efficiency is measured through time measures using about 12 different
disciplines and allowances that increase normal rest periods from
repetition, posture, fatigue, ergomonics, environment, anthropometrics,
complex thinking, or strain for example. Biomechanics contributes to
the primary allowance tables but is useless alone in practice.
Sometimes background reaseach for unique allowances is required which
it suports, and those are generally from a table or footnote. You
usually don't have time to make 1000 sensitivity range samples for
every question ($$$); so without valid historical data, statistical
measures are worthless with widely variable human beings.

Bicycling, because of natural cooling and ultra efficiency on your
joint impacts is incredibly efficient. Biomechanics will tell you sit
up straight for breathing efficiency and at 45 degree angle for output
efficiency. Otherwise, its good to have as many comfortable positions
on bars as possible for differnet situations, and shifting on seat
possibly to reduce chances of repetitive trauman disorders. Biking is
highly repetitious though, so alternate riding positions is significant
in any kind of riding, even racing longer distance. For each individual
and every interface, your ultimate thermometer is how does it feel:
your body rarely lies. And its best to keep joints at near 90 degree
angles at any position, except straight wrists/ankles, and an ALWAYS an
arch in your neck which is natural on bikes.


mtb Dad wrote:
While in a university biomechanics course, I looked into horizontal
seat position. The study I did looked at oxygen uptake for a given work
load at three positions, (normal, forward and aft). Not surprisingly,
the normal position took less o2 for a given work load. The change of
position was quite extreme, and inch or so, so not much enlightenment
there for anyone serious about adjusting their position.

But I wondered if this was all about training and habituation, or
whether there is something more efficient about a given position. I
did an analysis of the movement of the centres of gravity of each leg.
It seemed that the path of the c of g's of each leg (ie. one on each
side) described an alternating pendulum movement almost exactly equal
fore and aft of a line dropped from whole body c of g.

So, I wondered if this might be a formula for finding an efficient
position? Aerodynamics and power output are different questions.
Certainly the internal of work of moving each leg c of g back and forth
would be small relative to outside work, but could it be minimized by
centering the body c of g between the two leg c's of g?

mtb Dad wrote:
While in a university biomechanics course, I looked into horizontal
seat position. The study I did looked at oxygen uptake for a given work
load at three positions, (normal, forward and aft). Not surprisingly,
the normal position took less o2 for a given work load. The change of
position was quite extreme, and inch or so, so not much enlightenment
there for anyone serious about adjusting their position.

But I wondered if this was all about training and habituation, or
whether there is something more efficient about a given position. I
did an analysis of the movement of the centres of gravity of each leg.
It seemed that the path of the c of g's of each leg (ie. one on each
side) described an alternating pendulum movement almost exactly equal
fore and aft of a line dropped from whole body c of g.

So, I wondered if this might be a formula for finding an efficient
position? Aerodynamics and power output are different questions.
Certainly the internal of work of moving each leg c of g back and forth
would be small relative to outside work, but could it be minimized by
centering the body c of g between the two leg c's of g?

ddog wrote:
Efficiency is measured through time measures using about 12 different
disciplines and allowances that increase normal rest periods from
repetition, posture, fatigue, ergomonics, environment, anthropometrics,
complex thinking, or strain for example. Biomechanics contributes to
the primary allowance tables but is useless alone in practice.
Sometimes background reaseach for unique allowances is required which
it suports, and those are generally from a table or footnote. You
usually don't have time to make 1000 sensitivity range samples for
every question ($$$); so without valid historical data, statistical
measures are worthless with widely variable human beings.

Bicycling, because of natural cooling and ultra efficiency on your
joint impacts is incredibly efficient. Biomechanics will tell you sit
up straight for breathing efficiency and at 45 degree angle for output
efficiency. Otherwise, its good to have as many comfortable positions
on bars as possible for differnet situations, and shifting on seat
possibly to reduce chances of repetitive trauman disorders. Biking is
highly repetitious though, so alternate riding positions is significant
in any kind of riding, even racing longer distance. For each individual
and every interface, your ultimate thermometer is how does it feel:
your body rarely lies. And its best to keep joints at near 90 degree
angles at any position, except straight wrists/ankles, and an ALWAYS an
arch in your neck which is natural on bikes.


Gene?? Is that you?

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

PUSHERBOT wrote:
Wow!! - such a large vocabulary, so little sense. It's like William
Burroughs has been reborn as bike geek.

What/who are you talking about/to?

On 18 Jan 2007 18:55:41 -0800, "meeklyornot"
may have said:

I really am frustrated not knowing the percents on expensive tires
versus basic ones impact wise on rolling resistance. Or even by what
factor a cush mountain ride is more taxing then a sticker slain carbon
road butterfly.

I mean is it fractional, or multiples?

The range of weights of the riders will produce a greater amount of
variation than any differences in the bikes.

If you're looking to build a power-assist system with general
applicability and ready acceptance by the largest market share, then
design around a 250 lb rider, on a knobby-tire mountain bike, in
Denver, commuting 14 miles each way with no charger hookup at work.
Minimum parameters: 1000 charge-discharge cycles before the batteries
will fail to make the trip unassisted in 28F weather, total conversion
weight under 35 lbs, cruise speed of 14mph average, price without bike
under $350. I figure that we're effectively about 30 years away from
meeting that spec.

Schwin has come out with powerassisted road bikes for adults. THat's
interesting, and the quality might be there as they are about two
grand, but PA for me means you can have better durability AND SAFETY
ETC. without having to accept lesser range. Only on the kids model not
yet out are they promissing that.

Power assist will have a much smaller market than power conversion.
This is a nation of couch potatoes. At $2000, Pacific will be selling
those bikes to the boutiques only; it's in the same market as a
Segway. (How many of *those* do you see?).

Biomechanically generator effficiency might be so great that pedalling
to charge all the time and running the wheels from motors not
mechancally connected to our bodies at all is concievable.

Not a stinking chance. Read some EE books. Thsi Will Not Work.
Period, full stop, no kidding, don't go there.

Pedal by
wire technology I've never seen implimented though. Using more of our
muscles across our bodies to convert glucose into electricity buffered
much more effictively chemically outside our bodies then we can train
ourselves to actually seems reasonable to me. It is after all what
hybrid does for the internal combustion car. It allows the gas to not
spin the wheels, to not waste so as to have adequate acceleration
power, to not have to have the bulk that highway power requires either.

It sounds to me like you've been reading way too many issues of
Popular Science or Popular Mechanics. The blue-sky crap they publish
is just that; crap.

Being able to respond to cognitively taxing circumstances, collision
avoidance, without losing power, is a huge safety boon. Comparing
lighweight vehicles to motorcycles loses that benefit. Nothing is
nimbler then a vehicle that weigh less, not much more, then us alone.
But it's not about grams. A few dozen pounds here or there matters
squat if those pounds can contribute much more then we can. IS there a
motorised bike list beyond the tidal force one anyone can recommend?
THe 'need' seems to be being met as a disservice by novel,. amazing,
but not production mature offerings.

IT should cost much less to distribute a miracolously powered vehicle
then bike fanatics routinely pay for there works of art with little
(relatively) practical value. A few thousand bucks these days can buy
peace if widely invested into flying carpet like contraptions almost
everyone who can walk would pony up for. WHy is this not happening?

You are hereby invited, even encouraged, to go find an investor and
try to develop your dream. Be sure to report back with progress
often. The cynics among us could use a better source of amusement
than Washington. (Either one.)





--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

On Sat, 20 Jan 2007 14:33:32 -0800, "Bill Sornson" may
have said:

PUSHERBOT wrote:
Wow!! - such a large vocabulary, so little sense. It's like William
Burroughs has been reborn as bike geek.

What/who are you talking about/to?

You didn't miss anything. It was another "why hasn't anyone marketed
a practical and cheap version of something for which we don't even
have the basic research done that would describe the actual magnitude
of the technical problems that must be overcome in order to build the
first rude prototype?", mixed with a generous portion of "I don't
think we need to pay any attention to those confusing and inconvenient
Laws of Thermodynamics."

Nothing to see, move along.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.