Physics 101

"MagillaGorilla" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

TO: All you dumbasses who think you go faster around a turn on a
velodrome than on the straightaways

You people need to go take take a physics class.

That's a double take. OK, some questions.....

1/ Where does PE go when a rider transfers from vertical to a 45 lean?
2/ If the rider practically rides the black line, does his center of
mass travel as far as the measured distance of the turn?
3/ What happens to rolling resistance in a turn?
4/ What affect does 1, 2 and 3 have on speed?

Phil H

Philip Holman said:

"MagillaGorilla" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

TO: All you dumbasses who think you go faster around a turn on a
velodrome than on the straightaways

You people need to go take take a physics class.

That's a double take. OK, some questions.....

1/ Where does PE go when a rider transfers from vertical to a 45 lean?
2/ If the rider practically rides the black line, does his center of
mass travel as far as the measured distance of the turn?
3/ What happens to rolling resistance in a turn?
4/ What affect does 1, 2 and 3 have on speed?

Phil H

Alright, listen and listen good.

1. The potential energy is NOT transfered to speed. It is transfered
to friction at a net loss BECAUSE when you leave the turn the rider has
to input energy to go from a 45 degree lean to upright again. Isn't
this obvious? You are also fighting against inertia and this cancels out
any temporary gains due to leaning.

2. No, but it is the speed of the bike that counts because that is the
rate-limiting factor, not the center of mass. Besides, this gain is
negligible and is offset by increased in friction and loss of energy due
to change in inertia.

3. Decreases slightly.

4. Decreases speed because the factors you cite are not the only things
going on in a turn.

You are failing to take into account the fact the biggest variables of
physics that occur in a turn on a velodrome or anywhere else that make
you go slower is that you are changing your inertia and your momentum
(your G's go up, not down). To actually think that you go faster around
a turn tells me you have no 'feel' or understanding for basic concepts
of physics.

According to you, everything goes slower in a turn except a bicycle.
This defies empirical logic. It's just bizarre to think that. Think
about what you are doing in a turn...you are taking all your momentum
(mV) - all your energy - and changing its vector 180 degrees! That act
requires a HUGE energy input (i.e. loss) that had you been going
straight would have been put into the pedals. How can that be more
efficient than NOT changing your vector or inertia at all (i.e. riding
straight)? ANSWER: it can't.

The things you cite above are simply moments where you gain a slight bit
of energy at certain instantaneous moments. But since energy cannot be
created or destroyed, we know that you have to "pay" for that somewhere
- like when you exit the turn and have to expend MORE energy to right
yourself (i.e. go from 45 degrees to upright). Even if you could build
a circular velodrome where you could perpetually ride around in a circle
leaning at 45 degrees, you would still not go faster than in a
straightaway because you are constantly fighting inertia.

If Lance wants to break the hour record, he should do it on a velodrome
with the LONGEST straightaways, and not by riding around in a circle
where most of his energy would be lost in friction to fight inertia.

Although this would be best demonstrated using quantifiable numbers, I
really don't think it's necessary given that it's just not logical to
think you go faster in a turn since nothing I know of goes faster in a turn.

And the reason why NASCARs go slower in turns isn't because of loss of
traction. It's because they are fighting inertia and the ennrgy is
dissipated into heat in the starboard tires. Same as a bike.

If you were to monitor the air pressure of your bike tires on a
velodrome, they would be highest in the turns because a rider's G's go
up in a turn. That means a loss of energy that does not occur on the
straightaways that can be put into the pedals.

I have office hours later today if you need to talk about this more.
Bring that cute sophomore who sits next to you in class.

Take care,

Magilla

Please don't feed the trolls. Thanks.

Bob Schwartz
[email hidden]

Bob Schwartz said:

Please don't feed the trolls. Thanks.

Bob Schwartz
[email hidden]

Ignorant people are always afraid of disagreement. So your post makes
sense when viewed in that context. How about going to college and then
coming back in here and posting?

See how far you get with that attitude in a university setting.

Physics Professor: ...so class, that's why a bike rider goes slower in a
turn on a velodrome then when he's going straight.

Bob Schwartz: Shut up...you're such a troll.

You're quite some intellect, Bob.

Take care,

Magilla

MagillaGorilla said:

See how far you get with that attitude in a university setting.

In my next life, I have resolved not to deal with either academics or
geeks. Unfortunately for the moment, I have to deal with both. And the
attitude you indicate is not the problem. The problem is the constant
hair-splitting and creation of alternate realities that "could" occur
and by some amazingly twisted logic, become reality for an academic. I
need a responsible adult to deal with the squabbling most days...

"Stewart Fleming" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

In my next life, I have resolved not to deal with either academics or
geeks. Unfortunately for the moment, I have to deal with both. And the
attitude you indicate is not the problem. The problem is the constant
hair-splitting and creation of alternate realities that "could" occur and
by some amazingly twisted logic, become reality for an academic. I need a
responsible adult to deal with the squabbling most days...

Thank you. Pay attention you putzes out there -- you know who you are. And
if you don't know who you are, ask me. I'll set you right up. And if
Lafferty doesn't know who you are, just remind him you might be the opposite
of you you are.

I think, therefore I wannabe.

"Jim Flom" <[email hidden]> wrote in message
news:MErRd.11862$%y.8705@clgrps12...

Quoted message said:

"Stewart Fleming" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

In my next life, I have resolved not to deal with either academics or
geeks. Unfortunately for the moment, I have to deal with both. And the
attitude you indicate is not the problem. The problem is the constant
hair-splitting and creation of alternate realities that "could" occur and
by some amazingly twisted logic, become reality for an academic. I need
a responsible adult to deal with the squabbling most days...

Thank you. Pay attention you putzes out there -- you know who you are.
And if you don't know who you are, ask me. I'll set you right up. And if
Lafferty doesn't know who you are, just remind him you might be the
opposite of you you are.

I think, therefore I wannabe.

Gödel just phoned to say that you may no be who you think you are. So, who
might you be?

"B Lafferty" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Gödel just phoned to say that you may no be who you think you are. So,
who might you be?

I might be... thee!

"Jim Flom" <[email hidden]> wrote in message
news:SatRd.8$0h.7@clgrps13...

Quoted message said:

"B Lafferty" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Gödel just phoned to say that you may no be who you think you are. So,
who might you be?

I might be... thee!

Then God help us both. ;-)

"MagillaGorilla" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Philip Holman said:

"MagillaGorilla" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

TO: All you dumbasses who think you go faster around a turn on a
velodrome than on the straightaways

You people need to go take take a physics class.

That's a double take. OK, some questions.....

1/ Where does PE go when a rider transfers from vertical to a 45
lean?
2/ If the rider practically rides the black line, does his center of
mass travel as far as the measured distance of the turn?
3/ What happens to rolling resistance in a turn?
4/ What affect does 1, 2 and 3 have on speed?

Alright, listen and listen good.

1. The potential energy is NOT transfered to speed. It is transfered
to friction at a net loss BECAUSE when you leave the turn the rider
has to input energy to go from a 45 degree lean to upright again.
Isn't this obvious? You are also fighting against inertia and this
cancels out any temporary gains due to leaning.

The reason you state supports an argument of going faster in a turn and
slower in the straight. Read your question again and revise it if it
wasn't what you meant to say.

Quoted message said:

2. No, but it is the speed of the bike that counts because that is the
rate-limiting factor, not the center of mass. Besides, this gain is
negligible and is offset by increased in friction and loss of energy
due to change in inertia.

3. Decreases slightly.

Take into account both weight and centripetal vectors. Does the
resultant force of the tire on the track increase, decrease or stay the
same?

Quoted message said:

4. Decreases speed because the factors you cite are not the only
things going on in a turn.

You are failing to take into account the fact the biggest variables of
physics that occur in a turn on a velodrome or anywhere else that make
you go slower is that you are changing your inertia and your momentum
(your G's go up, not down). To actually think that you go faster
around a turn tells me you have no 'feel' or understanding for basic
concepts of physics.

I haven't failed anything and where did I say I think you go faster.

Quoted message said:

According to you, everything goes slower in a turn except a bicycle.
This defies empirical logic. It's just bizarre to think that. Think
about what you are doing in a turn...you are taking all your momentum
(mV) - all your energy - and changing its vector 180 degrees! That act
requires a HUGE energy input (i.e. loss) that had you been going
straight would have been put into the pedals. How can that be more
efficient than NOT changing your vector or inertia at all (i.e. riding
straight)? ANSWER: it can't.

I asked simple questions, but from them you are unable to make a comment
"according to you everything goes slower" How do you determine that?

Quoted message said:

The things you cite above are simply moments where you gain a slight
bit of energy at certain instantaneous moments. But since energy
cannot be created or destroyed, we know that you have to "pay" for
that somewhere - like when you exit the turn and have to expend MORE
energy to right yourself (i.e. go from 45 degrees to upright). Even
if you could build a circular velodrome where you could perpetually
ride around in a circle leaning at 45 degrees, you would still not go
faster than in a straightaway because you are constantly fighting
inertia.

The question was, do you go faster in a turn. Whatever the reason, if
there is one, it's irelevant.

Quoted message said:

If Lance wants to break the hour record, he should do it on a
velodrome with the LONGEST straightaways, and not by riding around in
a circle where most of his energy would be lost in friction to fight
inertia.

Probably the right answer but the wrong reason.

Quoted message said:

Although this would be best demonstrated using quantifiable numbers, I
really don't think it's necessary given that it's just not logical to
think you go faster in a turn since nothing I know of goes faster in a
turn.

And the reason why NASCARs go slower in turns isn't because of loss of
traction. It's because they are fighting inertia and the ennrgy is
dissipated into heat in the starboard tires. Same as a bike.

If you were to monitor the air pressure of your bike tires on a
velodrome, they would be highest in the turns because a rider's G's go
up in a turn. That means a loss of energy that does not occur on the
straightaways that can be put into the pedals.

You said rolling resistance decreases in a turn (question 3). Which is
it?

Phil H

B Lafferty said:

Gödel just phoned to say that you may no be who you think you are. So, who
might you be?

Hey, if Godel just phoned you, do you have caller ID and if so, can you
tell us what his Number was?

Philip Holman said:

"MagillaGorilla" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Philip Holman said:

"MagillaGorilla" <[email hidden]> wrote in message
news:[email hidden]...

>TO: All you dumbasses who think you go faster around a turn on a
>velodrome than on the straightaways
>
>
>You people need to go take take a physics class.

That's a double take. OK, some questions.....

1/ Where does PE go when a rider transfers from vertical to a 45
lean?
2/ If the rider practically rides the black line, does his center of
mass travel as far as the measured distance of the turn?
3/ What happens to rolling resistance in a turn?
4/ What affect does 1, 2 and 3 have on speed?

Alright, listen and listen good.

1. The potential energy is NOT transfered to speed. It is transfered
to friction at a net loss BECAUSE when you leave the turn the rider
has to input energy to go from a 45 degree lean to upright again.
Isn't this obvious? You are also fighting against inertia and this
cancels out any temporary gains due to leaning.

The reason you state supports an argument of going faster in a turn and
slower in the straight. Read your question again and revise it if it
wasn't what you meant to say.

Quoted message said:

2. No, but it is the speed of the bike that counts because that is the
rate-limiting factor, not the center of mass. Besides, this gain is
negligible and is offset by increased in friction and loss of energy
due to change in inertia.

3. Decreases slightly.

Take into account both weight and centripetal vectors. Does the
resultant force of the tire on the track increase, decrease or stay the
same?

Quoted message said:

4. Decreases speed because the factors you cite are not the only
things going on in a turn.

You are failing to take into account the fact the biggest variables of
physics that occur in a turn on a velodrome or anywhere else that make
you go slower is that you are changing your inertia and your momentum
(your G's go up, not down). To actually think that you go faster
around a turn tells me you have no 'feel' or understanding for basic
concepts of physics.

I haven't failed anything and where did I say I think you go faster.

Quoted message said:

According to you, everything goes slower in a turn except a bicycle.
This defies empirical logic. It's just bizarre to think that. Think
about what you are doing in a turn...you are taking all your momentum
(mV) - all your energy - and changing its vector 180 degrees! That act
requires a HUGE energy input (i.e. loss) that had you been going
straight would have been put into the pedals. How can that be more
efficient than NOT changing your vector or inertia at all (i.e. riding
straight)? ANSWER: it can't.

I asked simple questions, but from them you are unable to make a comment
"according to you everything goes slower" How do you determine that?

Quoted message said:

The things you cite above are simply moments where you gain a slight
bit of energy at certain instantaneous moments. But since energy
cannot be created or destroyed, we know that you have to "pay" for
that somewhere - like when you exit the turn and have to expend MORE
energy to right yourself (i.e. go from 45 degrees to upright). Even
if you could build a circular velodrome where you could perpetually
ride around in a circle leaning at 45 degrees, you would still not go
faster than in a straightaway because you are constantly fighting
inertia.

The question was, do you go faster in a turn. Whatever the reason, if
there is one, it's irelevant.

Quoted message said:

If Lance wants to break the hour record, he should do it on a
velodrome with the LONGEST straightaways, and not by riding around in
a circle where most of his energy would be lost in friction to fight
inertia.

Probably the right answer but the wrong reason.

Quoted message said:

Although this would be best demonstrated using quantifiable numbers, I
really don't think it's necessary given that it's just not logical to
think you go faster in a turn since nothing I know of goes faster in a
turn.

And the reason why NASCARs go slower in turns isn't because of loss of
traction. It's because they are fighting inertia and the ennrgy is
dissipated into heat in the starboard tires. Same as a bike.

If you were to monitor the air pressure of your bike tires on a
velodrome, they would be highest in the turns because a rider's G's go
up in a turn. That means a loss of energy that does not occur on the
straightaways that can be put into the pedals.

You said rolling resistance decreases in a turn (question 3). Which is
it?

Phil H

You do not go faster in a turn because a 180 degree turn on a velodrome
is incredibly inefficient. The energy that goes into fighting inertia
outweighs any other negligible gains you are talking about that may
exist from leaning your bike or changing the angular momentum of a
spinning wheel, etc.

The actual rolling resistance on your tires increases in a turn because
your G's increase in a turn although changing the wheels angle to 45
degrees decreases it. I have never done a study on the net gain/loss in
a turn but I would imagine it would graph like a curve. But I am
confident that ANY turn is always going to be more inefficient than
going straight.

Basically, what I'm saying is you guys are focusing on all these trivial
physics variables and then not taking into account that the BIGGEST
subtraction in efficiancy in a turn on a velodrome is going to come from
changing your momentum and inertia 180 degrees.

Go ride your bike and take your hands off your handlebars. It will
always 'want' to go straight and take the path of least resistance (i.e.
most efficient). In order to turn the bike, you have to input energy
(i.e. here, you are already less efficient than had you continuued
straight). In a turn on a velodrome, the wheels and rider are
subjecting themselves to probably something like ~1.5 g's depending upon
the velocity. On the straightaway you are always at 1.0 g regardless of
the velocity.

There is NO WAY you can go faster at 1.5g's than at 1g. You are also
causing more friction on the wheels when you do that. Your aerodynamics
are also worse because the line the rider is taking exposes more surface
area of his lateral body to the vector of the wind.

I can't believe there are guys in here who ride the velodrome who think
they go faster in turns! It's just not in the cards of empirical
physics to think that is even possible.

If youc an get permissions, go take a road bike equipped with a
speedometer and SRM around a velodrome and you will see I'm right. The
goal of the rider would be to keep the watts constant. And at constant
watts, the speed would decrease in the turns.

I will bet $1,000 on this. Any takers?

Magilla

"MagillaGorilla" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

If youc an get permissions, go take a road bike equipped with a
speedometer and SRM around a velodrome and you will see I'm right. The
goal of the rider would be to keep the watts constant. And at constant
watts, the speed would decrease in the turns.

I will bet $1,000 on this. Any takers?

I'll take that bet.

Andy Coggan

Quoted message said:

Basically, what I'm saying is you guys are focusing on all these
trivial physics variables and then not taking into account that the
BIGGEST subtraction in efficiancy in a turn on a velodrome is going to
come from changing your momentum and inertia 180 degrees.

Momentum is conserved. Please explain the loss in momentum.
The biggest loss in a turn is increase in rolling resistance.

From F = mv^2/r
A 200lb rider + bike at 50ft/sec on a 77.64 ft radius will experience a
horizontal force of 200lb. At a lean angle of 45deg, the force on the
track will be Sqrt (200^2 + 200^2) = 282.8 lbf
Hence his rolling resistance will increase ~40%

Using a coeff. of RR of .004, the power requirement at 50ft/sec in the
straight will be .004*200*50*746/550 = 54 watts. In the turn this will
be 76 watts.

This will require an additional 22*77.64*pi/50 = 107 joules of energy

When leaning from vertical to 45deg, delta PE = mgh = 200/32.2*32.2*(4 -
4sin45deg)746/550
= 318 joules.

Of course the 45deg lean means the center of mass travels a shorter
distance and does less work. Assuming at 50 ft/sec the rider is putting
out 450 watts. The shorter distance will save 450*.074 = 33 joules.
So we are looking at 107 versus 351 joules. For the 4.88 seconds it
takes to go through the turn, it requires (351-107)/4.88 = 50 watts less
power.

Phil H

"MagillaGorilla" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Basically, what I'm saying is you guys are focusing on all these trivial
physics variables and then not taking into account that the BIGGEST
subtraction in efficiancy in a turn on a velodrome is going to come from
changing your momentum and inertia 180 degrees.

You mean the same way the Earth loses loads of energy changing its 'momentum
and inertia' 180 degrees as it goes round the Sun?

Or the same reason why if you spin a bike wheel it stops so quickly as its
momentum changes 180 degrees every revolution?

Or possibly the same reason you failed Physics 101?

Peter

Since it's unlikely monkey boy was serious about the bet, and since
I know some of you guys get boners over stuff like this, I decided
upload the data from my pursuit ride.

What I had was one of the Shimano compatible PowerTaps. I used one
of these http://sheldonbrown.com/harris/fixed-hubs.html#sub11 to
mount a cog.

This was in 2002. PowerTaps had (don't know if they still do this) a
feature where they auto-zero the torque. They way they did this was
to reset the torque minimum to zero. That meant that backpedaling
screwed everything up since it couldn't deal with negative torque.

But if you didn't backpedal you were OK. So what I did was reset it
before clipping in.

This was at Blaine, 250m, 43 degrees. What I discovered was that I
was backing off a lot in the turns, and punching it on the straights.
I had no clue I was doing this. You can see it's pretty pronounced.

With respect to monkey boy's tortured physics, you can see that there
are only very slight variations in speed in spite of the pretty wide
swings in power output.

The end result was a 4:07 3K pursuit. This was in the fall and I sold
the PowerTap over the winter, so there are no more data points.

OK, for the guys that get boners over stuff like this, here is a
screen snap of the graph and the data file.

http://my.execpc.com/~cvcc/boners/powertapscreen.jpg
http://my.execpc.com/~cvcc/boners/Pursuit407.csv

Bob Schwartz
[email hidden]