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Main
Date: 06 Oct 2007 23:48:13
From: Greens
Subject: Round tires not optimal for speed
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Bikes use round tires. It's assumed that this is the most efficient way to
interact with the road. Here are some drawbacks.
Large round tires result in the bike being pretty high up. This results in
less stability. Large diameter tires also results in a lot of extra weight.
A very small portion of the tire is in contact with the road at any time.
A more efficient way of contacting the road is through elliptical motion.
Think of tank tread, but then quickly stop thinking of tank treads. It's the
motion I want, but there's too much friction with the road with tanks. A
tank tread probably has 40 feet of contact with the road compareed to a
car's 4 feet of contact with the road. A bicycle with it's two wheels
probably only has a fool and a half of contact with the road. It's easy to
imagine the tremendous amount of friction in using tank type treads. The
idea of using this kind of elliptical motion then fails. It's only good for
rough ground where tremendous traction is required.
What if you could get elliptical motion without all that friction from many
feet of ground contact?
ENTER THE CENTIPEDE
It's legs move in elliptical motion. (page 22) It has lots of legs, but only
a few of them are contacting the ground at any time and the faster it moves,
the fewer of it's legs are in contact with the ground. (see page 23)
http://www.cgl.uwaterloo.ca/~vtluu/centipede/paper.pdf
A centipede in full sprint has only five legs touching the ground as opposed
to the slow centipede's 13 legs touching ground. Also note that it's almost
point contact on each leg. No doubt this reduces wasteful friction
tremendously. The tiny area of the centipede's legs that are in contact with
the ground are used to push it forward at high speeds. The relatively large
area of the bicycle tire that is in contact with the ground wastes a lot of
energy to friction. As a efficient as the common bicycle is, the centipede
is a model of efficiency.
Imagine if instead of very light legs, the centipede had 32 wheels with
heavy rubber tires. It would weigh much more and be much slower. The rubber
going around each rim would probably be three times as long as each
centipede leg if laid out straight. As a result, even if the rubber weighed
as much as the leg material, it would weigh three times as much and I've no
doubt that rubber weighs more than insect leg parts. I say without fear of
contradiction that the weight of the rubber for each rubber tire would
greatly outweigh each leg.
It would have fewer legs because the tires would rub against each other
unless they were staggered.
The Centipede Project - Build a pedal powered centipede that uses
elliptically moving legs with only point contact, segments and body
undulations for speed. Incredible speed, traction and stopping ability. It
will be the fastest moving human powered machine in the world. Segments will
allow you to go over the roughest ground smoothly. Put some gecko fingers on
it and you'll be able to go right up the walls of buildings or ride across
the ceiling. It will revolutionize pedal powered travel. Everyone will want
a pedal powered centipedal machine.
Who am I kidding? I can't even change a tire.
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Date: 10 Oct 2007 23:08:42
From: anth
Subject: Re: Round tires not optimal for speed
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On Sun, 2007-10-07 at 13:59 -0400, Greens wrote:
> I read somewhere that cockroaches if scaled up to human size, would be going
> 200 mph across a kitchen floor on their six legs, and while they can't go
> that fast over rough terrain, they can handle most any terrain at high
> speed. I think at cockroach scale wind resistance is minimized. The big
> roaches would probably start to get slowed down by the air.
Nah, they wouldn't move at all.
"The Biology of B-Movie Monsters" explains it pretty well:
http://fathom.lib.uchicago.edu/2/21701757/
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Date: 10 Oct 2007 20:51:27
From: Michael Press
Subject: Re: Round tires not optimal for speed
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In article
<1192010922.11029.8.camel@localhost.localdomain >,
anth <ajchapman@gmail.com > wrote:
> On Sun, 2007-10-07 at 13:59 -0400, Greens wrote:
> > I read somewhere that cockroaches if scaled up to human size, would be going
> > 200 mph across a kitchen floor on their six legs, and while they can't go
> > that fast over rough terrain, they can handle most any terrain at high
> > speed. I think at cockroach scale wind resistance is minimized. The big
> > roaches would probably start to get slowed down by the air.
> Nah, they wouldn't move at all.
>
> "The Biology of B-Movie Monsters" explains it pretty well:
> http://fathom.lib.uchicago.edu/2/21701757/
A great read. Thanks. And totally on topic,
as he obliquely addresses the squirrel menace.
--
Michael Press
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Date: 08 Oct 2007 14:37:32
From: datakoll
Subject: Re: Fool and a half (was Re: Round tires not optimal for speed)
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slime!
claws?
green spots?
velcro?
silica?
suction!!
magnetism
TOPOLOGICAL INDUCTION WITH DARK MATTER RUBBER
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Date: 08 Oct 2007 07:11:58
From: Colin Campbell
Subject: Fool and a half (was Re: Round tires not optimal for speed)
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Greens wrote:
snip
A bicycle with it's two wheels probably only has a fool and a half of
contact with the road.
snip
I would never share my bike with a "half fool" - no foolin'!
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Date: 07 Oct 2007 13:51:16
From: A Muzi
Subject: Re: Round tires not optimal for speed
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Greens wrote:
> Bikes use round tires. It's assumed that this is the most efficient way to
> interact with the road. Here are some drawbacks.
>
> Large round tires result in the bike being pretty high up. This results in
> less stability. Large diameter tires also results in a lot of extra weight.
> A very small portion of the tire is in contact with the road at any time.
>
> A more efficient way of contacting the road is through elliptical motion.
> Think of tank tread, but then quickly stop thinking of tank treads. It's the
> motion I want, but there's too much friction with the road with tanks. A
> tank tread probably has 40 feet of contact with the road compareed to a
> car's 4 feet of contact with the road. A bicycle with it's two wheels
> probably only has a fool and a half of contact with the road. It's easy to
> imagine the tremendous amount of friction in using tank type treads. The
> idea of using this kind of elliptical motion then fails. It's only good for
> rough ground where tremendous traction is required.
>
> What if you could get elliptical motion without all that friction from many
> feet of ground contact?
>
> ENTER THE CENTIPEDE
> It's legs move in elliptical motion. (page 22) It has lots of legs, but only
> a few of them are contacting the ground at any time and the faster it moves,
> the fewer of it's legs are in contact with the ground. (see page 23)
> http://www.cgl.uwaterloo.ca/~vtluu/centipede/paper.pdf
>
> A centipede in full sprint has only five legs touching the ground as opposed
> to the slow centipede's 13 legs touching ground. Also note that it's almost
> point contact on each leg. No doubt this reduces wasteful friction
> tremendously. The tiny area of the centipede's legs that are in contact with
> the ground are used to push it forward at high speeds. The relatively large
> area of the bicycle tire that is in contact with the ground wastes a lot of
> energy to friction. As a efficient as the common bicycle is, the centipede
> is a model of efficiency.
>
> Imagine if instead of very light legs, the centipede had 32 wheels with
> heavy rubber tires. It would weigh much more and be much slower. The rubber
> going around each rim would probably be three times as long as each
> centipede leg if laid out straight. As a result, even if the rubber weighed
> as much as the leg material, it would weigh three times as much and I've no
> doubt that rubber weighs more than insect leg parts. I say without fear of
> contradiction that the weight of the rubber for each rubber tire would
> greatly outweigh each leg.
>
> It would have fewer legs because the tires would rub against each other
> unless they were staggered.
>
> The Centipede Project - Build a pedal powered centipede that uses
> elliptically moving legs with only point contact, segments and body
> undulations for speed. Incredible speed, traction and stopping ability. It
> will be the fastest moving human powered machine in the world. Segments will
> allow you to go over the roughest ground smoothly. Put some gecko fingers on
> it and you'll be able to go right up the walls of buildings or ride across
> the ceiling. It will revolutionize pedal powered travel. Everyone will want
> a pedal powered centipedal machine.
>
> Who am I kidding? I can't even change a tire.
Build it and I, an over-the-hill Camel smoker on an ancient bike, will
race you. Even wager, name the stakes. Any paved course with less than
2" of snow and I'm on.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
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Date: 07 Oct 2007 15:35:12
From: Greens
Subject: Re: Round tires not optimal for speed
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"A Muzi" <am@yellowjersey.org > wrote in message
news:13giaj57q9kbbbf@corp.supernews.com...
> Greens wrote:
>> Bikes use round tires. It's assumed that this is the most efficient way
>> to interact with the road. Here are some drawbacks.
>>
>> Large round tires result in the bike being pretty high up. This results
>> in less stability. Large diameter tires also results in a lot of extra
>> weight. A very small portion of the tire is in contact with the road at
>> any time.
>>
>> A more efficient way of contacting the road is through elliptical motion.
>> Think of tank tread, but then quickly stop thinking of tank treads. It's
>> the motion I want, but there's too much friction with the road with
>> tanks. A tank tread probably has 40 feet of contact with the road
>> compareed to a car's 4 feet of contact with the road. A bicycle with it's
>> two wheels probably only has a fool and a half of contact with the road.
>> It's easy to imagine the tremendous amount of friction in using tank type
>> treads. The idea of using this kind of elliptical motion then fails. It's
>> only good for rough ground where tremendous traction is required.
>>
>> What if you could get elliptical motion without all that friction from
>> many feet of ground contact?
>>
>> ENTER THE CENTIPEDE
>> It's legs move in elliptical motion. (page 22) It has lots of legs, but
>> only a few of them are contacting the ground at any time and the faster
>> it moves, the fewer of it's legs are in contact with the ground. (see
>> page 23)
>> http://www.cgl.uwaterloo.ca/~vtluu/centipede/paper.pdf
>>
>> A centipede in full sprint has only five legs touching the ground as
>> opposed to the slow centipede's 13 legs touching ground. Also note that
>> it's almost point contact on each leg. No doubt this reduces wasteful
>> friction tremendously. The tiny area of the centipede's legs that are in
>> contact with the ground are used to push it forward at high speeds. The
>> relatively large area of the bicycle tire that is in contact with the
>> ground wastes a lot of energy to friction. As a efficient as the common
>> bicycle is, the centipede is a model of efficiency.
>>
>> Imagine if instead of very light legs, the centipede had 32 wheels with
>> heavy rubber tires. It would weigh much more and be much slower. The
>> rubber going around each rim would probably be three times as long as
>> each centipede leg if laid out straight. As a result, even if the rubber
>> weighed as much as the leg material, it would weigh three times as much
>> and I've no doubt that rubber weighs more than insect leg parts. I say
>> without fear of contradiction that the weight of the rubber for each
>> rubber tire would greatly outweigh each leg.
>>
>> It would have fewer legs because the tires would rub against each other
>> unless they were staggered.
>>
>> The Centipede Project - Build a pedal powered centipede that uses
>> elliptically moving legs with only point contact, segments and body
>> undulations for speed. Incredible speed, traction and stopping ability.
>> It will be the fastest moving human powered machine in the world.
>> Segments will allow you to go over the roughest ground smoothly. Put some
>> gecko fingers on it and you'll be able to go right up the walls of
>> buildings or ride across the ceiling. It will revolutionize pedal powered
>> travel. Everyone will want a pedal powered centipedal machine.
>>
>> Who am I kidding? I can't even change a tire.
>
> Build it and I, an over-the-hill Camel smoker on an ancient bike, will
> race you. Even wager, name the stakes. Any paved course with less than 2"
> of snow and I'm on.
> --
> Andrew Muzi
> www.yellowjersey.org
> Open every day since 1 April, 1971
I'm sure I could build it, but it would be expensive to get all those legs
and undulations working right. Centipede legs have several joints and each
joint rotates. They also have a feedback system to let them know when any of
their legs aren't touching ground. They have muscles to control their
segments.
I'll, uh, give you a call.
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Date: 07 Oct 2007 09:10:03
From: Ron Ruff
Subject: Re: Round tires not optimal for speed
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On Oct 7, 10:04 am, Ron Ruff <rruffrr...@yahoo.com > wrote:
> I think plenty of them would love to have wheels instead
On second thought, the main advantage of legs is the ability to
negotiate steep and rugged terrain. From a bug's perspective, pretty
much everything is steep and rugged.
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Date: 07 Oct 2007 09:04:16
From: Ron Ruff
Subject: Re: Round tires not optimal for speed
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On Oct 6, 9:48 pm, "Greens" <p...@adelphia.net > wrote:
> Imagine if instead of very light legs, the centipede had 32 wheels with
> heavy rubber tires. It would weigh much more and be much slower.
But if it only had 2 wheels it would be much faster... Name any animal
that can go 20mph on flat ground for 2 hrs, and do it more efficiently
than a human on a bike. .
Hasn't 6 legs won the evolutionary contest for the optimum number for
a bug? I think plenty of them would love to have wheels instead, but
that doesn't seem to be part of the biological possibility. I'd rather
have wings than wheels, though...
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Date: 07 Oct 2007 13:59:49
From: Greens
Subject: Re: Round tires not optimal for speed
|
"Ron Ruff" <rruffrruff@yahoo.com > wrote in message
news:1191773056.180647.285710@y42g2000hsy.googlegroups.com...
> On Oct 6, 9:48 pm, "Greens" <p...@adelphia.net> wrote:
>> Imagine if instead of very light legs, the centipede had 32 wheels with
>> heavy rubber tires. It would weigh much more and be much slower.
>
> But if it only had 2 wheels it would be much faster... Name any animal
> that can go 20mph on flat ground for 2 hrs, and do it more efficiently
> than a human on a bike. .
>
> Hasn't 6 legs won the evolutionary contest for the optimum number for
> a bug? I think plenty of them would love to have wheels instead, but
> that doesn't seem to be part of the biological possibility. I'd rather
> have wings than wheels, though...
>
Yea, but build a deer powered bicycle and you'll have a deer going sixty
miles an hour for 4 hours.
I read somewhere that cockroaches if scaled up to human size, would be going
200 mph across a kitchen floor on their six legs, and while they can't go
that fast over rough terrain, they can handle most any terrain at high
speed. I think at cockroach scale wind resistance is minimized. The big
roaches would probably start to get slowed down by the air.
Wings are definitly a blast, but of course a lot of people have worked on
that. What they don't have is the manuverability and precision of birds. I'd
like to be able to land on branches and telephone poles. That sort of air
machine doesn't exist. Far as I know no plane flares it's tail feathers and
pulls it's tail down like most every bird does to land, nor do planes change
their wing angle radically on landing. Human machines make small adjustments
and do it very slowly which leaves our landings and takeoffs to huge
runways. Helicopters are so slow compared to pigeons.
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Date: 07 Oct 2007 11:11:28
From: Ben C
Subject: Re: Round tires not optimal for speed
|
On 2007-10-07, Ron Ruff <rruffrruff@yahoo.com > wrote:
> On Oct 6, 9:48 pm, "Greens" <p...@adelphia.net> wrote:
>> Imagine if instead of very light legs, the centipede had 32 wheels with
>> heavy rubber tires. It would weigh much more and be much slower.
>
> But if it only had 2 wheels it would be much faster... Name any animal
> that can go 20mph on flat ground for 2 hrs, and do it more efficiently
> than a human on a bike. .
>
> Hasn't 6 legs won the evolutionary contest for the optimum number for
> a bug? I think plenty of them would love to have wheels instead, but
> that doesn't seem to be part of the biological possibility. I'd rather
> have wings than wheels, though...
Don't forget roads. Without roads you are nearly always better off with
legs than wheels, unless your habitat is the Bonneville Salt Flats
perhaps. Just try riding an MTB through a field of long grass.
I think this is a big reason why nature never evolved the wheel (unless
you count curling up into a ball and roll down hills).
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Date: 07 Oct 2007 16:02:42
From: Tim McNamara
Subject: Re: Round tires not optimal for speed
|
In article <slrnfgi1b0.5pl.spamspam@bowser.marioworld >,
Ben C <spamspam@spam.eggs > wrote:
> On 2007-10-07, Ron Ruff <rruffrruff@yahoo.com> wrote:
> > On Oct 6, 9:48 pm, "Greens" <p...@adelphia.net> wrote:
> >> Imagine if instead of very light legs, the centipede had 32 wheels
> >> with heavy rubber tires. It would weigh much more and be much
> >> slower.
> >
> > But if it only had 2 wheels it would be much faster... Name any
> > animal that can go 20mph on flat ground for 2 hrs, and do it more
> > efficiently than a human on a bike. .
> >
> > Hasn't 6 legs won the evolutionary contest for the optimum number
> > for a bug? I think plenty of them would love to have wheels
> > instead, but that doesn't seem to be part of the biological
> > possibility. I'd rather have wings than wheels, though...
>
> Don't forget roads. Without roads you are nearly always better off
> with legs than wheels, unless your habitat is the Bonneville Salt
> Flats perhaps. Just try riding an MTB through a field of long grass.
>
> I think this is a big reason why nature never evolved the wheel
> (unless you count curling up into a ball and roll down hills).
There's the problem of blood and nerve supply, too.
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| | | |
Date: 07 Oct 2007 13:51:01
From: Greens
Subject: Re: Round tires not optimal for speed
|
"Ben C" <spamspam@spam.eggs > wrote in message
news:slrnfgi1b0.5pl.spamspam@bowser.marioworld...
> On 2007-10-07, Ron Ruff <rruffrruff@yahoo.com> wrote:
>> On Oct 6, 9:48 pm, "Greens" <p...@adelphia.net> wrote:
>>> Imagine if instead of very light legs, the centipede had 32 wheels with
>>> heavy rubber tires. It would weigh much more and be much slower.
>>
>> But if it only had 2 wheels it would be much faster... Name any animal
>> that can go 20mph on flat ground for 2 hrs, and do it more efficiently
>> than a human on a bike. .
>>
>> Hasn't 6 legs won the evolutionary contest for the optimum number for
>> a bug? I think plenty of them would love to have wheels instead, but
>> that doesn't seem to be part of the biological possibility. I'd rather
>> have wings than wheels, though...
>
> Don't forget roads. Without roads you are nearly always better off with
> legs than wheels, unless your habitat is the Bonneville Salt Flats
> perhaps. Just try riding an MTB through a field of long grass.
>
> I think this is a big reason why nature never evolved the wheel (unless
> you count curling up into a ball and roll down hills).
I was walking some trails where there was grass 3 to 6 feet high. I spooked
some deer in the grass and they bounded out through that tall grass at
amazing speed, probably faster than any bear, wolf or mountain lion could
because they're pretty sleek and they jump high enough that they're at an
altitude the grass offers less resistance. A mountain bike would barely move
through grass like that. Human feet would get tripped up. Visibility down
low would be bad so you're right, the leg, or at least the bounding leg, is
better than the wheel in a lot of natural situations, even flat grassy
situations.
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Date: 07 Oct 2007 23:31:48
From: RF
Subject: Re: Round tires not optimal for speed
|
Greens wrote:
> "Ben C" <spamspam@spam.eggs> wrote in message
> news:slrnfgi1b0.5pl.spamspam@bowser.marioworld...
>> On 2007-10-07, Ron Ruff <rruffrruff@yahoo.com> wrote:
>>> On Oct 6, 9:48 pm, "Greens" <p...@adelphia.net> wrote:
>>>> Imagine if instead of very light legs, the centipede had 32 wheels with
>>>> heavy rubber tires. It would weigh much more and be much slower.
>>> But if it only had 2 wheels it would be much faster... Name any animal
>>> that can go 20mph on flat ground for 2 hrs, and do it more efficiently
>>> than a human on a bike. .
>>>
>>> Hasn't 6 legs won the evolutionary contest for the optimum number for
>>> a bug? I think plenty of them would love to have wheels instead, but
>>> that doesn't seem to be part of the biological possibility. I'd rather
>>> have wings than wheels, though...
>> Don't forget roads. Without roads you are nearly always better off with
>> legs than wheels, unless your habitat is the Bonneville Salt Flats
>> perhaps. Just try riding an MTB through a field of long grass.
>>
>> I think this is a big reason why nature never evolved the wheel (unless
>> you count curling up into a ball and roll down hills).
>
> I was walking some trails where there was grass 3 to 6 feet high. I spooked
> some deer in the grass and they bounded out through that tall grass at
> amazing speed, probably faster than any bear, wolf or mountain lion could
> because they're pretty sleek and they jump high enough that they're at an
> altitude the grass offers less resistance. A mountain bike would barely move
> through grass like that. Human feet would get tripped up. Visibility down
> low would be bad so you're right, the leg, or at least the bounding leg, is
> better than the wheel in a lot of natural situations, even flat grassy
> situations.
There it is! Congratulations! You found it Greens. What we need are
jumping bikes :-)
RF
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Date: 07 Oct 2007 02:51:24
From: bjw@mambo.ucolick.org
Subject: Re: Round tires not optimal for speed
|
On Oct 6, 8:48 pm, "Greens" <p...@adelphia.net > wrote:
> Bikes use round tires. It's assumed that this is the most efficient way to
> interact with the road. Here are some drawbacks.
>
> Large round tires result in the bike being pretty high up. This results in
> less stability. Large diameter tires also results in a lot of extra weight.
> A very small portion of the tire is in contact with the road at any time.
>
> A more efficient way of contacting the road is through elliptical motion.
http://www.stanwagon.com/HTMLFiles/index_1.gif
from http://www.stanwagon.com/
Ben
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Date: 06 Oct 2007 22:09:00
From: Donga
Subject: Re: Round tires not optimal for speed
|
On Oct 7, 2:35 pm, "Kerry Montgomery" <kamon...@teleport.com > wrote:
> "Greens" <p...@adelphia.net> wrote in message
>
> news:SMmdnbC9UrO6wZXanZ2dnUVZ_hmtnZ2d@adelphia.com...
>
> > Bikes use round tires. It's assumed that this is the most efficient way to
> > interact with the road. Here are some drawbacks.
>
> > Large round tires result in the bike being pretty high up. This results in
> > less stability. Large diameter tires also results in a lot of extra
> > weight. A very small portion of the tire is in contact with the road at
> > any time.
>
> > A more efficient way of contacting the road is through elliptical motion.
> > Think of tank tread, but then quickly stop thinking of tank treads. It's
> > the motion I want, but there's too much friction with the road with tanks.
> > A tank tread probably has 40 feet of contact with the road compareed to a
> > car's 4 feet of contact with the road. A bicycle with it's two wheels
> > probably only has a fool and a half of contact with the road. It's easy to
> > imagine the tremendous amount of friction in using tank type treads. The
> > idea of using this kind of elliptical motion then fails. It's only good
> > for rough ground where tremendous traction is required.
>
> > What if you could get elliptical motion without all that friction from
> > many feet of ground contact?
>
> > ENTER THE CENTIPEDE
> > It's legs move in elliptical motion. (page 22) It has lots of legs, but
> > only a few of them are contacting the ground at any time and the faster it
> > moves, the fewer of it's legs are in contact with the ground. (see page
> > 23)
> >http://www.cgl.uwaterloo.ca/~vtluu/centipede/paper.pdf
>
> > A centipede in full sprint has only five legs touching the ground as
> > opposed to the slow centipede's 13 legs touching ground. Also note that
> > it's almost point contact on each leg. No doubt this reduces wasteful
> > friction tremendously. The tiny area of the centipede's legs that are in
> > contact with the ground are used to push it forward at high speeds. The
> > relatively large area of the bicycle tire that is in contact with the
> > ground wastes a lot of energy to friction. As a efficient as the common
> > bicycle is, the centipede is a model of efficiency.
>
> > Imagine if instead of very light legs, the centipede had 32 wheels with
> > heavy rubber tires. It would weigh much more and be much slower. The
> > rubber going around each rim would probably be three times as long as each
> > centipede leg if laid out straight. As a result, even if the rubber
> > weighed as much as the leg material, it would weigh three times as much
> > and I've no doubt that rubber weighs more than insect leg parts. I say
> > without fear of contradiction that the weight of the rubber for each
> > rubber tire would greatly outweigh each leg.
>
> > It would have fewer legs because the tires would rub against each other
> > unless they were staggered.
>
> > The Centipede Project - Build a pedal powered centipede that uses
> > elliptically moving legs with only point contact, segments and body
> > undulations for speed. Incredible speed, traction and stopping ability. It
> > will be the fastest moving human powered machine in the world. Segments
> > will allow you to go over the roughest ground smoothly. Put some gecko
> > fingers on it and you'll be able to go right up the walls of buildings or
> > ride across the ceiling. It will revolutionize pedal powered travel.
> > Everyone will want a pedal powered centipedal machine.
>
> > Who am I kidding? I can't even change a tire.
>
> I particularly like the third paragraph, "...probably only has a fool and a
> half of contact with the road."
> Kerry
April 1st?
|
| |
Date: 06 Oct 2007 21:35:37
From: Kerry Montgomery
Subject: Re: Round tires not optimal for speed
|
"Greens" <prbj@adelphia.net > wrote in message
news:SMmdnbC9UrO6wZXanZ2dnUVZ_hmtnZ2d@adelphia.com...
> Bikes use round tires. It's assumed that this is the most efficient way to
> interact with the road. Here are some drawbacks.
>
> Large round tires result in the bike being pretty high up. This results in
> less stability. Large diameter tires also results in a lot of extra
> weight. A very small portion of the tire is in contact with the road at
> any time.
>
> A more efficient way of contacting the road is through elliptical motion.
> Think of tank tread, but then quickly stop thinking of tank treads. It's
> the motion I want, but there's too much friction with the road with tanks.
> A tank tread probably has 40 feet of contact with the road compareed to a
> car's 4 feet of contact with the road. A bicycle with it's two wheels
> probably only has a fool and a half of contact with the road. It's easy to
> imagine the tremendous amount of friction in using tank type treads. The
> idea of using this kind of elliptical motion then fails. It's only good
> for rough ground where tremendous traction is required.
>
> What if you could get elliptical motion without all that friction from
> many feet of ground contact?
>
> ENTER THE CENTIPEDE
> It's legs move in elliptical motion. (page 22) It has lots of legs, but
> only a few of them are contacting the ground at any time and the faster it
> moves, the fewer of it's legs are in contact with the ground. (see page
> 23)
> http://www.cgl.uwaterloo.ca/~vtluu/centipede/paper.pdf
>
> A centipede in full sprint has only five legs touching the ground as
> opposed to the slow centipede's 13 legs touching ground. Also note that
> it's almost point contact on each leg. No doubt this reduces wasteful
> friction tremendously. The tiny area of the centipede's legs that are in
> contact with the ground are used to push it forward at high speeds. The
> relatively large area of the bicycle tire that is in contact with the
> ground wastes a lot of energy to friction. As a efficient as the common
> bicycle is, the centipede is a model of efficiency.
>
> Imagine if instead of very light legs, the centipede had 32 wheels with
> heavy rubber tires. It would weigh much more and be much slower. The
> rubber going around each rim would probably be three times as long as each
> centipede leg if laid out straight. As a result, even if the rubber
> weighed as much as the leg material, it would weigh three times as much
> and I've no doubt that rubber weighs more than insect leg parts. I say
> without fear of contradiction that the weight of the rubber for each
> rubber tire would greatly outweigh each leg.
>
> It would have fewer legs because the tires would rub against each other
> unless they were staggered.
>
> The Centipede Project - Build a pedal powered centipede that uses
> elliptically moving legs with only point contact, segments and body
> undulations for speed. Incredible speed, traction and stopping ability. It
> will be the fastest moving human powered machine in the world. Segments
> will allow you to go over the roughest ground smoothly. Put some gecko
> fingers on it and you'll be able to go right up the walls of buildings or
> ride across the ceiling. It will revolutionize pedal powered travel.
> Everyone will want a pedal powered centipedal machine.
>
> Who am I kidding? I can't even change a tire.
>
>
>
I particularly like the third paragraph, "...probably only has a fool and a
half of contact with the road."
Kerry
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Date: 07 Oct 2007 01:18:38
From: Greens
Subject: Re: Round tires not optimal for speed
|
"Kerry Montgomery" <kamontgo@teleport.com > wrote in message
news:13ggogvpkv04b69@corp.supernews.com...
>
> "Greens" <prbj@adelphia.net> wrote in message
> news:SMmdnbC9UrO6wZXanZ2dnUVZ_hmtnZ2d@adelphia.com...
>> Bikes use round tires. It's assumed that this is the most efficient way
>> to interact with the road. Here are some drawbacks.
>>
>> Large round tires result in the bike being pretty high up. This results
>> in less stability. Large diameter tires also results in a lot of extra
>> weight. A very small portion of the tire is in contact with the road at
>> any time.
>>
>> A more efficient way of contacting the road is through elliptical motion.
>> Think of tank tread, but then quickly stop thinking of tank treads. It's
>> the motion I want, but there's too much friction with the road with
>> tanks. A tank tread probably has 40 feet of contact with the road
>> compareed to a car's 4 feet of contact with the road. A bicycle with it's
>> two wheels probably only has a fool and a half of contact with the road.
>> It's easy to imagine the tremendous amount of friction in using tank type
>> treads. The idea of using this kind of elliptical motion then fails. It's
>> only good for rough ground where tremendous traction is required.
>>
>> What if you could get elliptical motion without all that friction from
>> many feet of ground contact?
>>
>> ENTER THE CENTIPEDE
>> It's legs move in elliptical motion. (page 22) It has lots of legs, but
>> only a few of them are contacting the ground at any time and the faster
>> it moves, the fewer of it's legs are in contact with the ground. (see
>> page 23)
>> http://www.cgl.uwaterloo.ca/~vtluu/centipede/paper.pdf
>>
>> A centipede in full sprint has only five legs touching the ground as
>> opposed to the slow centipede's 13 legs touching ground. Also note that
>> it's almost point contact on each leg. No doubt this reduces wasteful
>> friction tremendously. The tiny area of the centipede's legs that are in
>> contact with the ground are used to push it forward at high speeds. The
>> relatively large area of the bicycle tire that is in contact with the
>> ground wastes a lot of energy to friction. As a efficient as the common
>> bicycle is, the centipede is a model of efficiency.
>>
>> Imagine if instead of very light legs, the centipede had 32 wheels with
>> heavy rubber tires. It would weigh much more and be much slower. The
>> rubber going around each rim would probably be three times as long as
>> each centipede leg if laid out straight. As a result, even if the rubber
>> weighed as much as the leg material, it would weigh three times as much
>> and I've no doubt that rubber weighs more than insect leg parts. I say
>> without fear of contradiction that the weight of the rubber for each
>> rubber tire would greatly outweigh each leg.
>>
>> It would have fewer legs because the tires would rub against each other
>> unless they were staggered.
>>
>> The Centipede Project - Build a pedal powered centipede that uses
>> elliptically moving legs with only point contact, segments and body
>> undulations for speed. Incredible speed, traction and stopping ability.
>> It will be the fastest moving human powered machine in the world.
>> Segments will allow you to go over the roughest ground smoothly. Put some
>> gecko fingers on it and you'll be able to go right up the walls of
>> buildings or ride across the ceiling. It will revolutionize pedal powered
>> travel. Everyone will want a pedal powered centipedal machine.
>>
>> Who am I kidding? I can't even change a tire.
>>
>>
>>
> I particularly like the third paragraph, "...probably only has a fool and
> a half of contact with the road."
> Kerry
LOL. That was totally an accident.
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