Getting Started on Rollers

William Asher said:

Besides, the light changed and I had to get around a recumbent, two
moms pushing double-wide strollers, a brace of nuns in wheelchairs, the
homeless man with all the cleaning supplies on his balloon-tire cruiser,
and five guys in local team colors stopped in the middle of the path to
discuss what gear to use for the upcoming hill

lol, you've just explained why i haven't been on the bgt for a year.
(especially after using the practically deserted green river trail and
interurban trail, i could never go back to that fun scene)

Quoted message said:

before the guy with the
katana in the back scabbard caught up with me.

for the non natives- this guy really exists...

heather

Alex Rodriguez says...

Quoted message said:

You must be guisness book of records material.

Correct.

Quoted message said:

Unless you kept pedaling after you came off the rollers, there is no way
you wet 15 feet forward.

Dammit, pay attention! And don't confuse threads from other newsgroups. The
15' horizontal [censored] claim was on rec.climbing.

[email hidden] says...

Quoted message said:

I'm not so sure. Because the tires instantly grab the floor
with perfect traction, it's effectively an inelastic collision
(like colliding bodies sticking together). KE is not conserved in
inelastic collisions.

I've always had to laugh when pseudoscience assumptions are linked to the real
world. The tires will not grab instantly, but we'll ignore that fact and
continue onwards with our fantasy... Amazing how many really cool hypotheses
are shot to [censored] by reality. I worked with a dude that had such a beautiful
treatment of gloss formation in pigmented systems - even 15 years of data that
refused to correlate was insufficient to sway his truth. Join the club, it's
everywhere.

Quoted message said:

Linear momentum is always conserved in the absence of an external force.

Like I said - I kept pedaling! How's that for some external force?

Quoted message said:

For there to be no skidding, the tires have to grab the floor with a
fair amount of friction.

Hey there, Mr. Rocket Scientist - design those tires and you'll make a pretty
penny. Oh, it's just an assumption to simplify your model? I see.

Quoted message said:

so unless I have grossly underestimated Mad Dog's
spin, it doesn't make a difference for the relative velocity.

I'll assume that was accidental humor but congratulate you nonetheless.

William Asher says...

Quoted message said:

It was a while back, you don't know me from Adam, or Eve for that matter,
so it was more like: "I wonder if that skater chick is h2? Looks kinda
like her picture but why is she beating the [censored] out of that guy wearing
the 'All Mad Dogs Go to Heaven' t-shirt? Best not get involved."

This would be a much better story if you'd replaced "the [censored] out of" with
"off". Regardless, couldn't be me because I've kicked tha ass of every skater
chick I've gone up against ever since Croce gave me the beta. And another thing
- mad dogs never die so they don't get to go anywhere.

Quoted message said:

Besides, the light changed and I had to get around a recumbent, two
moms pushing double-wide strollers, a brace of nuns in wheelchairs, the
homeless man with all the cleaning supplies on his balloon-tire cruiser,
and five guys in local team colors stopped in the middle of the path to
discuss what gear to use for the upcoming hill before the guy with the
katana in the back scabbard caught up with me.

Damn, either good drugs or an indigestive nap. Either way, it looks like you
survived, sorta.

Mad Dog said:

somehow, I couldn't let it go by.

well, at least bill's troll caught *someone*...

(yes, you begged me to write that. and that's enough petting for you
now, anyway, bye...)

heather

In article
<[email hidden]>,

Quoted post said:

Michael Press said:

Quoted message said:

Now I bunny hop off the rollers and onto the floor. Assume that
I stop pedaling, but my tires instantly grab the floor with perfect
traction, meaning no skidding, and convert that angular momentum
into linear momentum. This is unrealistic (there would surely be
skidding) but gives the maximum possible forward velocity.

Quoted message said:

Angular momentum is not the quantity to consider.
Kinetic energy is.

I'm not so sure. Because the tires instantly grab the floor
with perfect traction, it's effectively an inelastic collision
(like colliding bodies sticking together). KE is not conserved in
inelastic collisions. Linear momentum is always conserved
in the absence of an external force. One could argue about the
idea that the wheels' angular momentum is instantly converted
into linear momentum, but I thought that captured the putative
process we are talking about reasonably well. For there to be
no skidding, the tires have to grab the floor with a fair amount
of friction.

What I did omit to say was that the original linear momentum
of the total system (rider, bike and floor) was zero, so the
post-hop momentum is positive for the rider moving forward and
negative for the floor moving backward. Of course the earth is
very heavy, so unless I have grossly underestimated Mad Dog's
spin, it doesn't make a difference for the relative velocity.

Angular momentum is conserved.
Linear momentum is conserved.
Energy is conserved.

You are trying to argue that angular momentum converts to
linear momentum. In the world of physics it does not.

Look at the calculation I presented. I assume half the
energy of the turning wheels is converted into heating of
the floor and tires. The other half is converted into
kinetic energy of linear motion. I get a resultant speed
of ~ 5 km/hr for two 0.5 kg wheels. Angular momentum and
linear momentum are transferred to the motion of matter
associated with the earth to conserve these quantities.

--
Michael Press

Mad Dog said:

Kurgan Gringioni says...

Quoted message said:

So, how many grams saved on the rim translates to 2 minutes?

I'm not gonna take the time to go google out the sew-up discussion - do it
yourself. Look at it this way, though: many people that read here ride on wheel
sets that weigh over 2200g with tires - I see plenty of local people race on

Quoted message said:

2500g wheels. (All weights here without a cassette or skewers.) 2200g would

be like a Kycerium clincher with reasonably light tubes and tires. Swap to a
light set of climbing sew-up rims and tires and you could come in at about
1500g. I have a friend whose wheels plus tires weigh 1350g. So that 1500g
example is 700g less than 2200 and of that, the rim+tire weight loss is probably
on the order of 400 or more likely 500g. I'd have to go back and check, but
numerous people have ascribed a time penalty to static weight on long climbs,
but wheel weight is a greater penalty.

But you have to ask yourself a few questions about weight. First, is it dumb to
ride a superlight bike when you are carrying around a big wad of fat on your
gut? (Yes, if you want to go your fastest, it is.) Second, when guys like
Lance, Jan, Ivan, etc., go ride really light bikes, wheels etc., is it just to
advertise expensive items so dumbass racers will buy them? (That's not the only
reason - they ride them in part because there is a performance advantage to
weight reduction - and they see those advantages as being more important than
their potential disadvantages). And finally, do the guys and girls that diss
light weight bikes do it just because they are cheapscates? (And should they
therefore learn to steal wheels from Lance?)

Dumbass -

I can't really argue with any of that, but what I'd like to know is:
how many grams does it take to save 2 minutes?

just curious,

K. Gringioni.

Sure, quite simple. Not a physics major here, althought a few might be
lurking. The momentum of the wheels alone spinning at 40 mph is not nearly
enough to move a 155 lb rider on a 20lb bike forward. Of course I stopped
pedalling when I hopped of of the rollers. Like I said, I gave a
demonstration to the mall managers. Howabout anchovies ? They really stink.
OK, maybe I exageratted when I said "no forward motion whatsoever". What I
meant was no significant or perceptible forward motion. What that means is
that I did not travel.

Is the momentum of two lightweight wheels at 40 mph alone enough to move 175
lbs of bike a rider enough to crash into a wall.
If I am right then you can send me a six pack of the hoppiest beer that you
can buy.
Where is Jobst Brandt when you need him ?

Steve aka Joe Pro

Joe Pro was the name of a East Coast Cat2 in the early 1980s.
"Mad Dog" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Joe Pro says...

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Not that I do not believe you, but it is impossible. I once was involved

in

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Quoted message said:

setting up some roller races at a large regional mall. We had to

demonstrate

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Quoted message said:

to the mall manager that if someone fell off that he would not go

crashing

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Quoted message said:

into the crowd or a plate glass window. I did the demonstration and

hopped

Quoted message said:

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off of the rollers at speed. No forward motion whatsoever, and I did a

track

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stand.

Dunno what to say about that, Joe. I only know what I've seen. Not only

have I

Quoted message said:

seen forward motion when others rode off, I've ridden it myself into the
basement wall with boxes flying all over the place.

Your "no forward motion whatsoever" claim doesn't make physical sense. If
you're in a big gear and spinning, it's not unreasonable for the wheel to

be

Quoted message said:

going at the equivalent of 40 mph and most folks I know can easily

maintain 25

Quoted message said:

mph on rollers with no load unit strapped on. That's a fair bit of

angular

Quoted message said:

momentum on the average bike wheelset. Are you saying that the angular

momentum

Quoted message said:

of two spinning wheels just evaporates when you go off the rollers? It's

gotta

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go somewhere. Or did you develop a process to convert it into pizza? If

so,

Quoted message said:

send me a veggie deluxe, light on the cheeze, very heavy on the garlic and
jalapenos because it's gettin' deep here and I want to contribute to the

stench.

Quoted message said:

"Mad Dog" <[email hidden]> wrote in message

Quoted message said:

Quoted message said:

Quoted message said:

No, no no! I was using a resolution of 4 nanometers when we failed to
detect your brain!

Quoted message said:

Can't see the forest for the trees, eh?

No one taught you that you shouldn't think with your wood?

Hah! So sayeth the man who tried to power a 50x11 into a wall of boxes 15
feet away.

Thanks to your considerably significant and overdue bit of information about
pedaling after you came off the rollers, I'm ready to cede the *slight
possibility* that you had a long burnout, although I still find a 7 foot
burnout hard to believe.

As I mentioned in my original response about you wieghing about 30 pounds, I
couldn't imagine how you could spin a rear wheel for that distance. With
anything approaching normal weight and weight distribution, there's no way
the inertia of the wheels would overcome traction that far. (Remember,
initially _both_ wheels have driving force. How long was the front wheel
burnout?) I tried thinking of various scenarios where there would less
weight on the rear wheel, allowing it to spin longer and farther. I thought
about your weight distribution as the bike came off the rollers, but it
still didn't seem like a huge amount of your weight would be over the front
wheel for that long. I thought about you and your bike falling over to one
side, so the wheels would no longer be in the plane of gravity. I also
thought about weight transfer of an accelerating object shifting weight to
the _back_ of the vehicle, which would obviously work against loss of
traction.

However, as I said, the significant bit of information that you were still
pedaling hell-bent-for-leather (anyone know the origin of that saying?)
after you came off the rollers is the key. Not because you were able to
generate heretofore unseen amounts of wattage in your efforts to be a human
trash compactor, but because as anyone who has ridden a fixed gear knows,
the energy of your momentum via the drivetrain will damn near launch you
over the handlebars as the cranks push your legs (and the rest of you)
upwards on the crank upstroke. In your case, instead of being launched up
and forward by the upstroke of the crank (I'm assuming you were using a
freewheel (but it really doesn't matter; the drivetrain was not throwing you
up), what launched you up and forward, putting virtually all of your weight
over the front wheel, was the sudden, drastic change in crank rpm. Whereas
on the rollers you claim you were pedaling at 180 rpm (and at max effort,
I'd bet too), once you came off the rollers, your crank rpm dropped to
almost nothing in an instant. The inertia of the rotating wheels isn't that
great, but the inertia of your legs is much greater. Your legs, spinning at
180 rpm one moment, then having the resistive force of the cranks increase
dramatically, have to do something with that energy. The natural action is
to push your body up, and with your hands holding the bars, forward. That
changes your weight distribution enough that I can put the burnout within
the realm of possibility.

How's that for wood?

Kurgan Gringioni says...

Quoted message said:

Quoted message said:

I'm not gonna take the time to go google out the sew-up discussion - do it
yourself.

Quoted message said:

I can't really argue with any of that

You could, but you'd be wrong (again).

Quoted message said:

but what I'd like to know is:
how many grams does it take to save 2 minutes?

I already replied to that request. See above, feeble reader. Then get off your
lazy ass.

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

Quoted message said:

Sure, quite simple. Not a physics major here, althought a few might be
lurking. The momentum of the wheels alone spinning at 40 mph is not
nearly
enough to move a 155 lb rider on a 20lb bike forward. Of course I stopped
pedalling when I hopped of of the rollers. Like I said, I gave a
demonstration to the mall managers. Howabout anchovies ? They really
stink.
OK, maybe I exageratted when I said "no forward motion whatsoever". What I
meant was no significant or perceptible forward motion. What that means is
that I did not travel.

Is the momentum of two lightweight wheels at 40 mph alone enough to move
175
lbs of bike a rider enough to crash into a wall.
If I am right then you can send me a six pack of the hoppiest beer that
you
can buy.
Where is Jobst Brandt when you need him ?

Steve aka Joe Pro

Joe Pro was the name of a East Coast Cat2 in the early 1980s.
"Mad Dog" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Joe Pro says...

Quoted message said:

Not that I do not believe you, but it is impossible. I once was involved

in

Quoted message said:

Quoted message said:

setting up some roller races at a large regional mall. We had to

demonstrate

Quoted message said:

Quoted message said:

to the mall manager that if someone fell off that he would not go

crashing

Quoted message said:

Quoted message said:

into the crowd or a plate glass window. I did the demonstration and

hopped

Quoted message said:

Quoted message said:

off of the rollers at speed. No forward motion whatsoever, and I did a

track

Quoted message said:

Quoted message said:

stand.

Dunno what to say about that, Joe. I only know what I've seen. Not only

have I

Quoted message said:

seen forward motion when others rode off, I've ridden it myself into the
basement wall with boxes flying all over the place.

Your "no forward motion whatsoever" claim doesn't make physical sense.
If
you're in a big gear and spinning, it's not unreasonable for the wheel to

be

Quoted message said:

going at the equivalent of 40 mph and most folks I know can easily

maintain 25

Quoted message said:

mph on rollers with no load unit strapped on. That's a fair bit of

angular

Quoted message said:

momentum on the average bike wheelset. Are you saying that the angular

momentum

Quoted message said:

of two spinning wheels just evaporates when you go off the rollers? It's

gotta

Quoted message said:

go somewhere. Or did you develop a process to convert it into pizza? If

so,

Quoted message said:

send me a veggie deluxe, light on the cheeze, very heavy on the garlic
and
jalapenos because it's gettin' deep here and I want to contribute to the

stench.

Quoted message said:

When you ride off of rollers, you fall sideways like a trackstand gone amiss
where you can't unclip in time. . . learned first-hand on more than one
occasion. . . If you are really good and TRY really hard, you can hit the
ground, maintain your balance and CRANK to get your mass moving forward. . .
like getting started from a full-stop track stand. But the rotation of
wheels, regardless of "speed" shown on your cyclo-compuker, has virtually
zero potential to move the total mass of rider and bike forward when it hits
the floor. . .

Actually, the "no forward motion" statement makes perfect sense. Wheels
weigh something like 5-6 pounds with less than half of that actually moving
and carrying momentum while riding on rollers. And ONLY the wheels are in
motion while on rollers . . . Rider plus bike weigh 175-200 lbs. (in my
case, more like 300 lbs. for the total package). 6 pounds cannot easily
cause 175 lbs. to be propelled forward. . . . An object at rest will stay
at rest unless acted upon by an external force. 6 lbs. doesn't pack
sufficient external force to alter the static physical condition of
175-200lbs. of rider and bike. . .

Carl Sundquist says...

Quoted message said:

As I mentioned in my original response about you wieghing about 30 pounds, I
couldn't imagine how you could spin a rear wheel for that distance.

Considering the antics I witnessed at the mall fund raiser, I concluded that the
paint on the basement floor was a key component. It was slick. The cement
surface on the mall floor was relatively smooth but still considerably coarser
than the painted basement floor. The typical skid mark at the mall was in the
1' range. We got to clean them up so I got to know roller-dismount skid marks
real well. Some mall managers have even less sense of humor than the typical
rbr'er.

Quoted message said:

With
anything approaching normal weight and weight distribution, there's no way
the inertia of the wheels would overcome traction that far. (Remember,
initially _both_ wheels have driving force. How long was the front wheel
burnout?)

I don't recall any significant rubber being laid down by the front tire. You
could see an effect, like a short polish mark.

Quoted message said:

I thought about your weight distribution as the bike came off the rollers,
but it still didn't seem like a huge amount of your weight would be over
the front wheel for that long.

That's logical - I didn't have extended bars at that time.

Quoted message said:

However, as I said, the significant bit of information that you were still
pedaling hell-bent-for-leather (anyone know the origin of that saying?)

You mean before Judas Priest?

Quoted message said:

Whereas on the rollers you claim you were pedaling at 180 rpm (and at
max effort, I'd bet too), once you came off the rollers, your crank rpm
dropped to almost nothing in an instant.

I was not able to observe the change in cadence upon dismount. I was busy doing
other [censored] at the time, like watching my life go by. I never got to where I
could ride smoothly at 180, but I could achieve it for a very brief peak. Ever
try that exercise?

Quoted message said:

The inertia of the rotating wheels isn't that
great, but the inertia of your legs is much greater.

Bingo!

Quoted message said:

Your legs, spinning at
180 rpm one moment, then having the resistive force of the cranks increase
dramatically, have to do something with that energy. The natural action is
to push your body up, and with your hands holding the bars, forward.

I don't remember any sensation of being pushed significantly up or back. But
with the couple or three accidental roller dismounts I did plus the quite a few
intentional dismounts I did and those I witnessed of my team mates, what I do
remember is that you can't expect to get off parallel to the path you were on.
You can have the back tire get off the rollers first and the front can even move
backwards as the bike rotates. Thus the high side I mentioned that you should
avoid. But I do remeber one sensation from the 7' skid dismount (other than
mass laughter) and that was the out of control feeling of sliding sidewards.
After a few feet, I straightened out slightly, but it was too late because by
then I was about to hit the wall of boxes.

Quoted message said:

That changes your weight distribution enough that I can put the burnout
within the realm of possibility.

Potential X Games event? Naah, too boring unless you're intoxicated.

Quoted message said:

How's that for wood?

I wood say that you have knots in your head but you've instead shown an
impressively open mind. Balsa? Hopefully not rot?

"Joe Pro" wrote

Quoted message said:

Sure, quite simple. Not a physics major here, althought a few might be
lurking. The momentum of the wheels alone spinning at 40 mph is not

nearly

Quoted message said:

enough to move a 155 lb rider on a 20lb bike forward. Of course I stopped
pedalling when I hopped of of the rollers. Like I said, I gave a
demonstration to the mall managers. Howabout anchovies ? They really

stink.

Quoted message said:

OK, maybe I exageratted when I said "no forward motion whatsoever". What I
meant was no significant or perceptible forward motion. What that means is
that I did not travel.

Is the momentum of two lightweight wheels at 40 mph alone enough to move

175

Quoted message said:

lbs of bike a rider enough to crash into a wall.
If I am right then you can send me a six pack of the hoppiest beer that

you

Quoted message said:

can buy.
Where is Jobst Brandt when you need him ?

Steve aka Joe Pro

Interesting problem. Here is what I came up with:

1884g Shimano R500 wheels without cassette or skewer

440 two Michelin Pro2 Race tires 23mm

200 two Continental tubes

50 two Zefal rim tapes

2574 TOTAL weight

453.6 grams is one pound.

5.67 pounds is total weight of wheels.

Assume the total energy of the wheels rotating at 40 mph is converted into
forward motion of the rider and bike. Assume the entire mass of the wheels
is at the tires. Assume the bike is 20 pounds and the rider is 155 pounds
giving a total of 175 pounds.

Kinetic energy is one half mass times velocity squared, if I remember my
grade school physics,

The velocity of the rider and bike after coming off of the rollers is V in
the following equation.

E=5.67x40x40/2=175xVxV/2

This gives V=7.2 mph

Actually 20 mph is more reasonable for a fairly fast ride on rollers. This
brings the exit speed down to 3.6 mph. And since not all of the mass of the
wheels is at the periphery as assumed above, recalculate taking the weight
of the rims instead of the wheels. Mavic Open Pro rims are 425g each so that
the rotating mass drops from 2574 to 1540 g. This drops the exit speed from
3.6 mph down to 2.8. This is 4.1 feet per second, which is much faster than
I would have guessed. But if you put on the brakes fairly quickly, you will
not have gone very far.

It seems to me that forgetting to stop peddling is far more important than
the energy in the rotating wheels.

Mark Fennell says...

Quoted message said:

MadDog, I know you wouldn't BS me, so I'm sincerely interested in knowing
what kind of cluster you had in the early 80s that had an 11-tooth cog.

Brand name? Good god I don't know. The hubs were Shimano and the dude that
owned Dyke's Bikes in Ft Collins not only got me an 11/19 freewheel but also 38,
39, 49 and 50 tooth chainrings. It wasn't trivial to get a 39 back then. He
got them at a distributer in Denver not far off of I-25 a little ways south of
Mile High Stadium. Actually, I went along and pulled them off the shelf. We
assembled the freewheel from a body and loose cogs and the inside diameter of
the 11 was smaller than the rest of the cogs. anyone out there remember
anything like this from that era? Who out there has seen an early 80's era 38
tooth chainring that fit a Dura Ace crank? I broke 2 before bailing out on
them. They told me they were made locally but I can't remember if they named
the machinist. Somewhere in the 80s, Shimano came out with cassette hubs and
you could get an 11 tooth as a spare part. That might have even been in the
very early 80s. I've seen a 10 tooth cog before, so an 11 is relatively huge,
right?

Quoted message said:

ps. I just couldn't resist so, like a dumbass, I went out in the garage and
hopped off the rollers at ~15 mph and went absolutely nowhere.

I'm sorry. Maybe you just don't have what it takes.

h squared says...

Quoted message said:

(yes, you begged me to write that.

Me?

Quoted message said:

and that's enough petting for you
now, anyway, bye...)

Yo, H2 petted me! Match that [censored], dudes.

Quoted message said:

Where is Jobst Brandt when you need him ?

He's probably riding to the beach, like I did today. Californians
don't need no steenking rollers... . Predicted 75F tomorrow. See you
in San Gregorio!

Mad Dog said:

Kurgan Gringioni says...

Quoted message said:

Quoted message said:

I'm not gonna take the time to go google out the sew-up discussion - do it
yourself.

Quoted message said:

I can't really argue with any of that

You could, but you'd be wrong (again).

Quoted message said:

but what I'd like to know is:
how many grams does it take to save 2 minutes?

I already replied to that request. See above, feeble reader. Then get off your
lazy ass.

Dumbass -

You said that one could easily save 500g off a pair of wheels. You
didn't say that would translate to 2minutes over a 1 hour climb.

Is that what you're saying? 500gram lighter on the wheel=2minutes?

just asking,

K. Gringioni.

Alfred Ryder said:

Actually 20 mph is more reasonable for a fairly fast ride on rollers. This
brings the exit speed down to 3.6 mph. And since not all of the mass of the
wheels is at the periphery as assumed above, recalculate taking the weight
of the rims instead of the wheels. Mavic Open Pro rims are 425g each so that
the rotating mass drops from 2574 to 1540 g. This drops the exit speed from
3.6 mph down to 2.8. This is 4.1 feet per second, which is much faster than
I would have guessed. But if you put on the brakes fairly quickly, you will
not have gone very far.

I think you did a good job of showing what we are looking at here. To
simplify your equation a bit:

V= v*(m/M)^.5

... where large letters are the total bike and rider and small letters
are the wheels only. If you wanted to get picky I suppose you could put
the kinetic energy of all the rotating parts in the equation (including
the riders feet and legs), and also include the rotational energy after
the rider jumps off...

But, there is a bigger problem... how much energy gets dissipated by
the rear tire skidding on the floor? Could be a lot...

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

Quoted message said:

"Joe Pro" wrote

Quoted message said:

Sure, quite simple. Not a physics major here, althought a few might be
lurking. The momentum of the wheels alone spinning at 40 mph is not

nearly

Quoted message said:

enough to move a 155 lb rider on a 20lb bike forward. Of course I

stopped

Quoted message said:

Quoted message said:

pedalling when I hopped of of the rollers. Like I said, I gave a
demonstration to the mall managers. Howabout anchovies ? They really

stink.

Quoted message said:

OK, maybe I exageratted when I said "no forward motion whatsoever". What

I

Quoted message said:

Quoted message said:

meant was no significant or perceptible forward motion. What that means

is

Quoted message said:

Quoted message said:

that I did not travel.

Is the momentum of two lightweight wheels at 40 mph alone enough to move

175

Quoted message said:

lbs of bike a rider enough to crash into a wall.
If I am right then you can send me a six pack of the hoppiest beer that

you

Quoted message said:

can buy.
Where is Jobst Brandt when you need him ?

Steve aka Joe Pro

Interesting problem. Here is what I came up with:

1884g Shimano R500 wheels without cassette or skewer

440 two Michelin Pro2 Race tires 23mm

200 two Continental tubes

50 two Zefal rim tapes

2574 TOTAL weight

453.6 grams is one pound.

5.67 pounds is total weight of wheels.

Assume the total energy of the wheels rotating at 40 mph is converted into
forward motion of the rider and bike. Assume the entire mass of the wheels
is at the tires. Assume the bike is 20 pounds and the rider is 155 pounds
giving a total of 175 pounds.

Kinetic energy is one half mass times velocity squared, if I remember my
grade school physics,

The velocity of the rider and bike after coming off of the rollers is V in
the following equation.

E=5.67x40x40/2=175xVxV/2

This gives V=7.2 mph

Actually 20 mph is more reasonable for a fairly fast ride on rollers. This
brings the exit speed down to 3.6 mph. And since not all of the mass of

the

Quoted message said:

wheels is at the periphery as assumed above, recalculate taking the weight
of the rims instead of the wheels. Mavic Open Pro rims are 425g each so

that

Quoted message said:

the rotating mass drops from 2574 to 1540 g. This drops the exit speed

from

Quoted message said:

3.6 mph down to 2.8. This is 4.1 feet per second, which is much faster

than

Quoted message said:

I would have guessed. But if you put on the brakes fairly quickly, you

will

Quoted message said:

not have gone very far.

It seems to me that forgetting to stop peddling is far more important than
the energy in the rotating wheels.

Science rules !!!!

Laz

Mad Dog said:

Bob Schwartz says...

Quoted message said:

If I told you that riders at constant power on a
velodrome accelerate in the corners, what would
you tell me?

I'd tell you to get out your chalk board & calculator and prove it.

http://anonymous.coward.free.fr/rbr/schwartzpursuit.png