Getting Started on Rollers

When I rode off the side of the rollers that were on the tile floor of Ansel
John's shop in West Carrollton OH in 1968, it left two (yes, two) black skid
marks on the tile, each two or three inches long. The bike didn't progress
much, if at all.

Al Williams

Kurgan Gringioni said:

Mad Dog said:

Kurgan Gringioni says...

Quoted message said:

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

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. ...

Quoted message said:

Dumbass -

Quoted message said:

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?

Dumbass,

About 30 milligrams of methamphetamine hydrochloride USP.
You're welcome.

Ben
Disclaimer: not a USAC certified coach

John Forrest Tomlinson said:

Quoted message said:

They wear tires rapidly if not set up correctly. The tire has to be
tight on the roller, so it doesn't slip. It it slips, the tire will
wear out fast.

Curtis L. Russell said:

And now someone is selling 'trainer tires' (I think that's what they
call them) to use in the winter on rollers and resistance trainers.
'Specially formulated and all that.

Specially formulated to produce 7' rubber streak during an involuntary
dismount.
PS: The fact that I mentioned the word dismount does NOT mean I'm trolling
heather.

Kurgan Gringioni said:

Quoted message said:

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?

Quoted message said:

About 30 milligrams of methamphetamine hydrochloride USP.
You're welcome.

I always thought the [censored] that will kill them was more sophisticated.

PS Thanks for bringing us back on topic.

Mad Dog said:

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?

http://brainyhistory.com/events/1961/november_24_1961_124681.html

--
E. Dronkert

Al Williams said:

When I rode off the side of the rollers that were on the tile floor of Ansel
John's shop in West Carrollton OH in 1968, it left two (yes, two) black skid
marks on the tile, each two or three inches long.

Of course! There would be two; not just the rear... doh!

Kurgan Gringioni said:

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

If he weighs 30 lbs, why not?

Jenko

Ewoud Dronkert said:

Mad Dog said:

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?

http://brainyhistory.com/events/1961/november_24_1961_124681.html

That entry has a link to India.

Alfred Ryder 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.

Quoted message said:

Interesting problem. Here is what I came up with:

Quoted message said:

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

Quoted message said:

453.6 grams is one pound.

Quoted message said:

5.67 pounds is total weight of wheels.

Kinetic energy for linear motion is (mv^2)/2. For rotational energy, as
in the wheels spinning, the energy is (Iw^2)/2, where I is the
rotational inertia and w is the angular velocity.

First I'll assume that the spokes and hub don't contribute much to the
rotational inertia. Then I'll estimate the distance from axis of
rotation to the center of mass for the rim/tire/tube/tape combination to
be 622 mm. Finally, I'll use 500g as an estimate of the rim mass. Then

I = m r^2
= (500 + 220 + 100 + 25) g * (622 mm)^2
= 0.33 kg m^2

The rotational speed (w) is 2 pi * linear velocity / circumference, or

w = 2 * pi * 40 mph / (2 * pi * (622+46) mm)
= 27 rad/sec

(note the mixed units; conversion factors required!)

So the kinetic energy of one rolling wheel is

KE = (I w^2)/2
= 0.33 kg m^2 * (27 rad/sec)^2 / 2
= 117 J

Now translate that into forward velocity of the rider. Assuming the 175
lb total for bike and rider, and assuming that all of the KE of the
wheels is conserved (none lost to skid marks, brakes, etc)...

KE = (m v^2)/2
v = sqrt(2 * KE / m)
= sqrt(2 * (2*117J) / 175 lb)
= 2.4 m/s (5.4 mph)

(note the extra 2 in the equation for the KE of two wheels, and the
mixed units requiring conversion factors that I have left out)

Summary: I disagree with your physics, but my conclusion is the same.
The rotational inertia of the wheels *alone* won't propel the rider very
far or very fast. A little energy lost to skidding wheels, maybe a
slight touch of the brakes, and the rider might move a few feet before
stopping.

By the way, I have tested this experimentally, but at less than 40 mph.
The experiment was unintended 🙂.

--
Dave
dvt at psu dot edu

Michael Press said:

Kinetic energy in two wheels:
2 * I * w^2 / 2 = 450 J

Does the front wheel spin as fast as the rear wheel?

Jenko, never used a roller

Mad Dog says...

Quoted message said:

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?

Oops, my mistake. Went into the archive and looked at a few photos and they
jogged my memory. The bike with the custom freewheel was stolen in '80 and I
replaced it with a Dura ace bike. My guess is that was late '80 or early '81
and it was the first DA cassette hub I'd seen. It had an 11 tooth lock cog - I
think it came with a 12 or 13 in the box and if memory serves correctly, I
picked up the 11 from Bike Nashbar. I still have that wheel hanging on the
basement wall. What jogged my memory was a photo taken of the gang riding up to
Estes Park to watch a Coors Classic stage and I had put on the "sombrero"
gearset for the hill above Glen Haven. It was an 11/12/13/15/24 or something
close to that (actually, those early cassettes were 6 speed weren't they?). If
I could find my training log from those years, I could be more exact with dates
and such, but it's buried down in the basement chaos and it simply ain't worth
the effort.

Alfred Ryder says...

Quoted message said:

Actually 20 mph is more reasonable for a fairly fast ride on rollers.

Not for me, especially back at the age I was at the time. My rollers had no
load fan or mag and they were large diameter rollers. I could ride top gear at
a decent cadence for quite a long time. That's way above 20 mph. BUT, you
missed the details - the 7' skid mark came after a dismount at my max spin, and
I kept pedaling. You'll need a significantly different treatment to be in the
ballpark.

Quoted message said:

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

You got that right, especially when there was no intent to stop pedaling for a
couple of seconds.

Wheels by BFWG 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.

Congratulations on enough forward motion to get the rear wheel to
clear the front roller(s). Might be easier to do on the old small
single front roller folding Cinellis, but would defintiely be a
control issue on any larger roller, single or double. I'm guessing a
cyclocrosser with really quick reflexes to do it, accident or
otherwise. Me, I'd probably hit the roller with a pedal, then fold the
rear wheel...

Curtis L. Russell
Odenton, MD (USA)
Just someone on two wheels...

Ewoud Dronkert says...

Quoted message said:

http://brainyhistory.com/events/1961/november_24_1961_124681.html

Yep, Carl's still a young pup.

On Tue, 15 Nov 2005 05:17:10 GMT, "Alfred Ryder" <[email hidden]>

Quoted message said:

Quoted message said:

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
and other stuff...

Are you guys riding with rollers with platforms between the front and
rear rollers that is keeping the rear wheel up and off of both the
ground and smacking the [censored] out of the front roller in all this front
motion stuff? Seems like you have to figure the effort to do the hop
to clear all this stuff.

OTOH, I've never had enough spin to actually generate lift, so what do
I know?

Curtis L. Russell
Odenton, MD (USA)
Just someone on two wheels...

Curtis L. Russell says...

Quoted message said:

Are you guys riding with rollers with platforms between the front and
rear rollers that is keeping the rear wheel up and off of both the
ground and smacking the [censored] out of the front roller in all this front
motion stuff? Seems like you have to figure the effort to do the hop
to clear all this stuff.

The rear wheel often goes off first. At that point, the outcome depends in part
on whether the front is coming off the side or if it's going backwards and
dropping in behind the front roller.

Quoted message said:

OTOH, I've never had enough spin to actually generate lift, so what do
I know?

You have to learn to time your farts.

Robert Chung says...

Quoted message said:

Mad Dog wrote:

Quoted message said:

Quoted message said:

Bob Schwartz says...

Quoted message said:

Quoted message said:

Quoted message said:

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

Quoted message said:

Quoted message said:

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

Quoted message said:

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

So, Robert, are you calling that power output constant?

Mad Dog said:

Robert Chung says...

Quoted message said:

Mad Dog wrote:

Quoted message said:

Quoted message said:

Bob Schwartz says...

Quoted message said:

Quoted message said:

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

Quoted message said:

Quoted message said:

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

Quoted message said:

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

So, Robert, are you calling that power output constant?

Nope. I'd say, however, that if riders can accelerate in the corners of a
velodrome with decreasing power, they can also accelerate with constant
power.

George Mueller said:

Quoted message said:

Where is Jobst Brandt when you need him?

Quoted message said:

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!

Well that was last week via Big Basin redwoods and Gazos Creek in
wonderful fall weather. This Sunday it was Mt. Hamilton where
beautiful fall foliage was augmented by a herd of a dozen adult wild
pigs (shoot then varmints) in Grant Park and scores of turkeys from
the San Jose hills to Livermore. Among other wildlife, on two
occasions, a Roadrunner crossed in front of us and stood there long
enough for us to appreciate its beautiful plumage. They did not say
"mbeep beep". A flock of about 100 migrating Canada Geese were
waiting for sunset to continue their trek as they ate grass on the
lawns of the large office center with the geyser like fountain at the
west end of Livermore.

As for riding rollers, I haven't, but I have enough friends who did
and reported crashes in which some bent forks when hitting the wall
when the bicycle came off at speed. Jumping off the bicycle while at
speed, holding onto the saddle so it doesn't launch itself, also
works, but the rotating energy of the wheels must dissipate somewhere
so they coast down for a while.

Jobst Brandt

In rec.bicycles.tech Curtis L. Russell said:

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.

Quoted message said:

Congratulations on enough forward motion to get the rear wheel to
clear the front roller(s). Might be easier to do on the old small
single front roller folding Cinellis, but would definitely be a
control issue on any larger roller, single or double. I'm guessing a
cyclocrosser with really quick reflexes to do it, accident or
otherwise. Me, I'd probably hit the roller with a pedal, then fold
the rear wheel...

Coming off the rollers is generally a riding-off-the-side event and
that doesn't require riding over the forward roller.

Jobst Brandt