physics of bicycle rollers information?

[[email protected]]

Can anyone point me towards some information about the physics of
bicycle rollers. By rollers I mean:

http://www.kreitler.com/product.php?section=product&item=rollers_4_5

I have been reading about the physics of a bike in motion, and why it
"stays up," but i was wondering if these same principles explain why
you can ride on cycling rollers and not fall over. A simple
explanation would be fine as well, with some keywords that I can
further research. Thanks.

 

[Tim McNamara]

In article <[email protected]>,
[email protected] wrote:

> Can anyone point me towards some information about the physics of
> bicycle rollers. By rollers I mean:
>
> http://www.kreitler.com/product.php?section=product&item=rollers_4_5
>
> I have been reading about the physics of a bike in motion, and why it
> "stays up," but i was wondering if these same principles explain why
> you can ride on cycling rollers and not fall over.

Yes, since there's nothing else to keep a bike upright unless you
mechanically prop it up. It doesn't make any difference whether the
bike is on pavement or on rollers.

Learning to ride rollers takes practice, though, because of the effects
of the front roller as the front wheel turns from side to side. As the
tire turns to the side, it wants to slide down the slope but the motion
of the roller tends to pull the tire forward. It makes for a nervous
rider who tends to overcorrect initially. I have seen photos of people
riding rollers no-handed, even taking off jerseys, arm or leg warmers,
etc.- even playing guitar! I've never gotten anywhere near that good at
riding rollers...

 

[[email protected]]

[email protected] writes:

> Can anyone point me toward some information about the physics of
> bicycle rollers. By rollers I mean:

http://www.kreitler.com/product.php?section=product&item=rollers_4_5

> I have been reading about the physics of a bike in motion, and why
> it "stays up," but I was wondering if these same principles explain
> why you can ride on cycling rollers and not fall over. A simple
> explanation would be fine as well, with some keywords that I can
> further research.

Its the same effect except you must visually keep track of position on
the rollers. See:

http://www.sheldonbrown.com/brandt/gyro.html

Jobst Brandt

 

[Chocobot]

>
> Its the same effect except you must visually keep track of position on
> the rollers. See:
>
> http://www.sheldonbrown.com/brandt/gyro.html
>
> Jobst Brandt

Thanks, I had read this previously, but it didn't seem to answer my
question. If I am reading this write, the act of moving forward has
nothing to do with the riders ability to balance the bike, that is why
one can ride on a set of rollers and still stay upright? However,
moving forward does help to keep the front wheel straight?

On another note, here is a video of someone people attempting
ridiculous tricks on rollers. At one point someone tries to do a skid
(as in on a track bike) on the rollers, i think this proves the point
that there is a little to zero forward momentum, and "rolling off"
these things pretty much not possible.

Also, one last question. I had my headphones plugged into my computer
while riding on the rollers and I was given a very startling
electrical shock, where is that energy coming from? my bike is
totally aluminum.

 

[[email protected]]

Chris Allick writes:

>> Its the same effect except you must visually keep track of position on
>> the rollers. See:

http://www.sheldonbrown.com/brandt/gyro.html

> Thanks, I had read this previously, but it didn't seem to answer my
> question. If I am reading this write, the act of moving forward has
> nothing to do with the riders ability to balance the bike, that is
> why one can ride on a set of rollers and still stay upright?
> However, moving forward does help to keep the front wheel straight?

It doesn't matter whether the bicycle moves forward or the road moves
backward for staying upright from steering. The inertia of rider
velocity makes road riding more stable but riding slowly is much like
balancing on rollers at any speed, there being no forward momentum and
inertia of the bicycle.

> On another note, there is a video of someone people attempting
> ridiculous tricks on rollers. At one point someone tries to do a skid
> (as in on a track bike) on the rollers, I think this proves the point
> that there is a little to zero forward momentum, and "rolling off"
> these things pretty much not possible.

But you can roll of them to either side and therein lies the skill. I
have seen 150mm diameter rollers about as wide on which a skilled
rider rides with little effort.

> Also, one last question. I had my headphones plugged into my computer
> while riding on the rollers and I was given a very startling
> electrical shock, where is that energy coming from? My bike is
> totally aluminum.

Static electricity is on the surface of insulators and most likely
generated like a Van de Graaff generator in dry air by the tires.

http://amasci.com/emotor/vdg.html
http://en.wikipedia.org/wiki/Van_de_Graaff_generator

Jobst Brandt

 

[Jim Behning]

On Mon, 03 Sep 2007 08:21:27 -0700, Chocobot <[email protected]>
wrote:

>
>>
>> Its the same effect except you must visually keep track of position on
>> the rollers. See:
>>
>> http://www.sheldonbrown.com/brandt/gyro.html
>>
>> Jobst Brandt
>
>Thanks, I had read this previously, but it didn't seem to answer my
>question. If I am reading this write, the act of moving forward has
>nothing to do with the riders ability to balance the bike, that is why
>one can ride on a set of rollers and still stay upright? However,
>moving forward does help to keep the front wheel straight?
>
>On another note, here is a video of someone people attempting
>ridiculous tricks on rollers. At one point someone tries to do a skid
>(as in on a track bike) on the rollers, i think this proves the point
>that there is a little to zero forward momentum, and "rolling off"
>these things pretty much not possible.
>
>Also, one last question. I had my headphones plugged into my computer
>while riding on the rollers and I was given a very startling
>electrical shock, where is that energy coming from? my bike is
>totally aluminum.
Your bike is not totally aluminum. There is steel and other materials
in it. The power lines in the US that service most houses is aluminum.
Aluminum has nothing to do with you question about static. You can
create a static charge getting in and out of your car seat. That is
why they recommend you discharge yourself of static before you start
fueling your car and do not resfresh that static by sitting in the car
while the pump is running.

 

[A Muzi]

>> Its the same effect except you must visually keep track of position on
>> the rollers. See:
>> http://www.sheldonbrown.com/brandt/gyro.html
>> Jobst Brandt

Chocobot wrote:
> Thanks, I had read this previously, but it didn't seem to answer my
> question. If I am reading this write, the act of moving forward has
> nothing to do with the riders ability to balance the bike, that is why
> one can ride on a set of rollers and still stay upright? However,
> moving forward does help to keep the front wheel straight?
>
> On another note, here is a video of someone people attempting
> ridiculous tricks on rollers. At one point someone tries to do a skid
> (as in on a track bike) on the rollers, i think this proves the point
> that there is a little to zero forward momentum, and "rolling off"
> these things pretty much not possible.
>
> Also, one last question. I had my headphones plugged into my computer
> while riding on the rollers and I was given a very startling
> electrical shock, where is that energy coming from? my bike is
> totally aluminum.

Even I can ride no-hands, change a jersey and do a jump-to-floor to
finish, these are not difficult things to learn. I'd even say that after
you've ridden rollers for twenty minutes _anything_ to break the boredom
is a good adventure.

Yes static electricity can build up while riding. Like rubbing a nylon
comb across a sweater.

I think the way a bike rides on rollers is perhaps different from actual
pavement cycling. I suspect the gyroscopic effect, minimal on the road,
becomes the primary effect on rollers. Riding rollers teaches good
riding habits quickly and subliminally. Spinning smoothly, not keeping a
death grip on the handlebars, being relaxed on the bike all keep the
bike upright and smooth.

Those unfamiliar with rollers expect that riding off will shoot the bike
through the plaster at 25mph. Since only the rims and tires are moving,
you merely get a small skid on the floor as the bike falls over. (proper
jumps require a burst of muscle to move the bike across the room instead
of falling on the floor)

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

 

[Tom Nakashima]

"A Muzi" <[email protected]> wrote in message
news:[email protected]...
I suspect the gyroscopic effect, minimal on the road,
> becomes the primary effect on rollers. Andrew Muzi
> www.yellowjersey.org
> Open every day since 1 April, 1971

I've watched a gyroscope, why is it that it has great leaning capabilities,
while
riding a bicycle does not and riding on rollers even less of a lean angle?
Is it because the gyroscope is pivoting on one point rather than two?
-tom

 

[Paul Myron Hobson]

Tom Nakashima wrote:
> "A Muzi" <[email protected]> wrote in message
> news:[email protected]...
> I suspect the gyroscopic effect, minimal on the road,
>> becomes the primary effect on rollers. Andrew Muzi
>> www.yellowjersey.org
>> Open every day since 1 April, 1971
>
> I've watched a gyroscope, why is it that it has great leaning capabilities,
> while
> riding a bicycle does not and riding on rollers even less of a lean angle?
> Is it because the gyroscope is pivoting on one point rather than two?
> -tom
>
>

The gyroscopic moments of a rotating bicycle wheel are very small
compared to the moment of the weight of the cyclist while leaning.

\\paul

 

[zencycle]

On Sep 4, 10:42 am, Paul Myron Hobson <[email protected]> wrote:
> Tom Nakashima wrote:
> > "A Muzi" <[email protected]> wrote in message
> >news:[email protected]...
> > I suspect the gyroscopic effect, minimal on the road,
> >> becomes the primary effect on rollers. Andrew Muzi
> >>www.yellowjersey.org
> >> Open every day since 1 April, 1971
>
> > I've watched a gyroscope, why is it that it has great leaning capabilities,
> > while
> > riding a bicycle does not and riding on rollers even less of a lean angle?
> > Is it because the gyroscope is pivoting on one point rather than two?
> > -tom
>
> The gyroscopic moments of a rotating bicycle wheel are very small
> compared to the moment of the weight of the cyclist while leaning.
>
> \\paul

Besides, the gyro has a fixed point of resistance. A bike on rollers
will 'slide' since the vector force of the leaning tire against the
smooth drum will push it away from the direction of the lean. The
extremely low rolling resistance of the smooth drum against the tire
doesn't provide enough opposing force to counter the force of gravity.
If you lean on rollers, you have to slightly turn the front wheel in
the _same_ direction as the lean, which is not only counter intuitive
to normal bicycle handling technique, but also exceptionally difficult
to perform - try to lean a bike to the right while turning left.
Outside, the resistance of the rubber against the earth or pavement
provides enough opposing force that it's easy to compensate will small
steering motions. You'd have the same problem if you were to ride on a
polished aluminum floor, and also why it's nearly impossible to ride
on ice - you lean, you slide. FWIW, get a mag loader for your rollers.
The added resistance makes it much easier to learn to stay up.

 

[[email protected]]

On Sep 4, 8:51 am, A Muzi <[email protected]> wrote:
> >> Its the same effect except you must visually keep track of position on
> >> the rollers. See:
> >>http://www.sheldonbrown.com/brandt/gyro.html
> >> Jobst Brandt
> Chocobot wrote:
> > Thanks, I had read this previously, but it didn't seem to answer my
> > question. If I am reading this write, the act of moving forward has
> > nothing to do with the riders ability to balance the bike, that is why
> > one can ride on a set of rollers and still stay upright? However,
> > moving forward does help to keep the front wheel straight?
>
> > On another note, here is a video of someone people attempting
> > ridiculous tricks on rollers. At one point someone tries to do a skid
> > (as in on a track bike) on the rollers, i think this proves the point
> > that there is a little to zero forward momentum, and "rolling off"
> > these things pretty much not possible.
>
> > Also, one last question. I had my headphones plugged into my computer
> > while riding on the rollers and I was given a very startling
> > electrical shock, where is that energy coming from? my bike is
> > totally aluminum.
>
> Even I can ride no-hands, change a jersey and do a jump-to-floor to
> finish, these are not difficult things to learn. I'd even say that after
> you've ridden rollers for twenty minutes _anything_ to break the boredom
> is a good adventure.

Jump to floor sounds like fun! As far as stability for no-handed goes,
it is important to have rollers that are adjusted to the wheelbase of
the bike. As most rollers are not infinitely adjustable, some bike/
roller combos may be more stable than others. As for boredome
breakers, I like lane-changes on my rollers. I try to ride as close to
one edge as I can and randomly zig over to the other side as fast as I
dare. I try to zoom all the way over so I end up exactly at the
opposite edge without having to do any adjustments. Another fun thing
is to have peices of tape making lanes you can try to ride in and on.

> Yes static electricity can build up while riding. Like rubbing a nylon
> comb across a sweater.
>
> I think the way a bike rides on rollers is perhaps different from actual
> pavement cycling. I suspect the gyroscopic effect, minimal on the road,
> becomes the primary effect on rollers. Riding rollers teaches good
> riding habits quickly and subliminally. Spinning smoothly, not keeping a
> death grip on the handlebars, being relaxed on the bike all keep the
> bike upright and smooth.

I think there is some geometric differences with the 2 contact patches
in tha back and their relative distance to each other that affects how
rollers feel differnt as well. I think this is one of the reasons
standing is so difficult; the rear steers in an unusual way when the
bike leans by any significant degree. When I stand on the road I can
rock the bike quite a bit still keeping a very straight line. Standing
on the rollers I need to keep the bike much more upright if I want to
not crash.

> Those unfamiliar with rollers expect that riding off will shoot the bike
> through the plaster at 25mph. Since only the rims and tires are moving,
> you merely get a small skid on the floor as the bike falls over. (proper
> jumps require a burst of muscle to move the bike across the room instead
> of falling on the floor)
>

I think I'll try that one in the grass first...

Joseph

 

[A Muzi]

> "A Muzi" <[email protected]> wrote
> I suspect the gyroscopic effect, minimal on the road,
>> becomes the primary effect on rollers.

Tom Nakashima wrote:
> I've watched a gyroscope, why is it that it has great leaning capabilities,
> while
> riding a bicycle does not and riding on rollers even less of a lean angle?
> Is it because the gyroscope is pivoting on one point rather than two?

I suspect the normal steering behavior of a bicycle is limited on
rollers. Look over the excellent 'Building An Unrideable Bicycle' for
background on 'normal'.

The motion of the rims/tires, which is trivial to a moving bicycle,
probably has some effect on the rollers where our arcs across the
pavement are absent. You can tell I'm speculating. Any other roller
riders care to comment? The bike definitely handles differently on
rollers and I'm grasping at why exactly. The net effect though is that
style which would be merely sloppy or inefficient on the road will dump
you off the rollers.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[[email protected]]

On Wed, 05 Sep 2007 01:25:53 -0500, A Muzi <[email protected]>
wrote:

>> "A Muzi" <[email protected]> wrote
>> I suspect the gyroscopic effect, minimal on the road,
>>> becomes the primary effect on rollers.
>
>Tom Nakashima wrote:
>> I've watched a gyroscope, why is it that it has great leaning capabilities,
>> while
>> riding a bicycle does not and riding on rollers even less of a lean angle?
>> Is it because the gyroscope is pivoting on one point rather than two?
>
>I suspect the normal steering behavior of a bicycle is limited on
>rollers. Look over the excellent 'Building An Unrideable Bicycle' for
>background on 'normal'.
>
>The motion of the rims/tires, which is trivial to a moving bicycle,
>probably has some effect on the rollers where our arcs across the
>pavement are absent. You can tell I'm speculating. Any other roller
>riders care to comment? The bike definitely handles differently on
>rollers and I'm grasping at why exactly. The net effect though is that
>style which would be merely sloppy or inefficient on the road will dump
>you off the rollers.

Dear Andrew,

Here's a theory.

On pavement, you can do two things: lean into turns and steer the
contact patch under your center of gravity.

On rollers, you can't lean. If you do, you either fall down or else
stop leaning and steer the contact patch back under your center of
gravity as quick as you can.

There's just no centripetal force, no actual turn on rollers, to allow
the normal leaning that pavement provides.

Cheers,

Carl Fogel

 

[sergio]

On Sep 4, 4:12 pm, "Tom Nakashima" <[email protected]> wrote:
> Is it because the gyroscope is pivoting on one point rather than two?

I have never tried rollers and have no feeling, nor any good idea
either, of what you are alking about. But one thing I surely know.
Any rigid body has one, and oinly can it have, instantaneous axis of
rotation.
So, no two simultaneous pivoting points, unless both on that very
axis.

Sergio
Pisa

 

[[email protected]]

On Sep 5, 9:19 am, [email protected] wrote:
> On Wed, 05 Sep 2007 01:25:53 -0500, A Muzi <[email protected]>
> wrote:
>
>
>
> >> "A Muzi" <[email protected]> wrote
> >> I suspect the gyroscopic effect, minimal on the road,
> >>> becomes the primary effect on rollers.
>
> >Tom Nakashima wrote:
> >> I've watched a gyroscope, why is it that it has great leaning capabilities,
> >> while
> >> riding a bicycle does not and riding on rollers even less of a lean angle?
> >> Is it because the gyroscope is pivoting on one point rather than two?
>
> >I suspect the normal steering behavior of a bicycle is limited on
> >rollers. Look over the excellent 'Building An Unrideable Bicycle' for
> >background on 'normal'.
>
> >The motion of the rims/tires, which is trivial to a moving bicycle,
> >probably has some effect on the rollers where our arcs across the
> >pavement are absent. You can tell I'm speculating. Any other roller
> >riders care to comment? The bike definitely handles differently on
> >rollers and I'm grasping at why exactly. The net effect though is that
> >style which would be merely sloppy or inefficient on the road will dump
> >you off the rollers.
>
> Dear Andrew,
>
> Here's a theory.
>
> On pavement, you can do two things: lean into turns and steer the
> contact patch under your center of gravity.
>
> On rollers, you can't lean. If you do, you either fall down or else
> stop leaning and steer the contact patch back under your center of
> gravity as quick as you can.
>
> There's just no centripetal force, no actual turn on rollers, to allow
> the normal leaning that pavement provides.
>
> Cheers,
>
> Carl Fogel

There certainly is centripetal force, and you can lean for an actual
turn. It's just that these turns are limited in arc and duration by
the width of the rollers. But it does feel weird.

My rollers are heavy and thus keep spinning even after I stop pedaling
so I have had the chance to notice some odd things. When I pull one
foot out, and stand on that one foot like I were stopped with th ebike
leaned to one side, if the wheels are still turing the rear wheel has
a tendency to move away from the side the bike is leaning to. This
leads me to belive there is some weirdness with the 2 contact patches
in the back and their combined responses to leaning.

Joseph

 

[Tim McNamara]

In article <[email protected]>,
A Muzi <[email protected]> wrote:

> > "A Muzi" <[email protected]> wrote
> > I suspect the gyroscopic effect, minimal on the road,
> >> becomes the primary effect on rollers.
>
> Tom Nakashima wrote:
> > I've watched a gyroscope, why is it that it has great leaning
> > capabilities, while riding a bicycle does not and riding on rollers
> > even less of a lean angle? Is it because the gyroscope is pivoting
> > on one point rather than two?
>
> I suspect the normal steering behavior of a bicycle is limited on
> rollers. Look over the excellent 'Building An Unrideable Bicycle'
> for background on 'normal'.
>
> The motion of the rims/tires, which is trivial to a moving bicycle,
> probably has some effect on the rollers where our arcs across the
> pavement are absent. You can tell I'm speculating. Any other roller
> riders care to comment? The bike definitely handles differently on
> rollers and I'm grasping at why exactly. The net effect though is
> that style which would be merely sloppy or inefficient on the road
> will dump you off the rollers.

I think that bikes handle different on rollers for at least a couple of
reasons. One of them is that the rear wheel has two contact patches
rather than one which restrains the bike from moving fore and aft under
the rider's center of gravity (which is maybe the root of one of the
benefits of roller riding- developing a smoother style). The other is
the slope of the front roller- as the wheel turns from side to side, it
slips downhill because the rake of the fork pulls the contact patch
backwards. At the same time the rotation of the roller is trying to
drag the wheel forwards and uphill.

 

[Tom Nakashima]

<[email protected]> wrote in message
news:[email protected]...
> On Wed, 05 Sep 2007 01:25:53 -0500, A Muzi <[email protected]>
> wrote:
>
>>> "A Muzi" <[email protected]> wrote
>>> I suspect the gyroscopic effect, minimal on the road,
>>>> becomes the primary effect on rollers.
>>
>>Tom Nakashima wrote:
>>> I've watched a gyroscope, why is it that it has great leaning
>>> capabilities,
>>> while
>>> riding a bicycle does not and riding on rollers even less of a lean
>>> angle?
>>> Is it because the gyroscope is pivoting on one point rather than two?
>>
>>I suspect the normal steering behavior of a bicycle is limited on
>>rollers. Look over the excellent 'Building An Unrideable Bicycle' for
>>background on 'normal'.
>>
>>The motion of the rims/tires, which is trivial to a moving bicycle,
>>probably has some effect on the rollers where our arcs across the
>>pavement are absent. You can tell I'm speculating. Any other roller
>>riders care to comment? The bike definitely handles differently on
>>rollers and I'm grasping at why exactly. The net effect though is that
>>style which would be merely sloppy or inefficient on the road will dump
>>you off the rollers.
>
> Dear Andrew,
>
> Here's a theory.
>
> On pavement, you can do two things: lean into turns and steer the
> contact patch under your center of gravity.
>
> On rollers, you can't lean. If you do, you either fall down or else
> stop leaning and steer the contact patch back under your center of
> gravity as quick as you can.
>
> There's just no centripetal force, no actual turn on rollers, to allow
> the normal leaning that pavement provides.
>
> Cheers,
>
> Carl Fogel

But what if you're "not" leaning into a "turn" on pavement, but instead
just leaning the bike on a straight where there is no centrifugal force?
One still manages to stay upright on pavement while leaning the bike,
rather on rollers where you'll topple over.

The more I think about the science of riding on rollers, the more
confusing it becomes. It sort of defies the gyroscope theory.
-tom

 

[Tom Nakashima]

"sergio" <[email protected]> wrote in message
news:[email protected]...
> On Sep 4, 4:12 pm, "Tom Nakashima" <[email protected]> wrote:
>> Is it because the gyroscope is pivoting on one point rather than two?
>
> I have never tried rollers and have no feeling, nor any good idea
> either, of what you are alking about. But one thing I surely know.
> Any rigid body has one, and oinly can it have, instantaneous axis of
> rotation.
> So, no two simultaneous pivoting points, unless both on that very
> axis.
>
> Sergio
> Pisa
>

Sorry, actually when riding rollers, it's 3 points contact.
Two contact points on the rear, and one on the front.
Take away the belt that rotates the front rollers, and you're in trouble.
Very interesting.
-tom

 

[A Muzi]

>>> "A Muzi" <[email protected]> wrote
>>> I suspect the gyroscopic effect, minimal on the road,
>>>> becomes the primary effect on rollers.

>> Tom Nakashima wrote:
>>> I've watched a gyroscope, why is it that it has great leaning capabilities,
>>> while
>>> riding a bicycle does not and riding on rollers even less of a lean angle?
>>> Is it because the gyroscope is pivoting on one point rather than two?

> A Muzi <[email protected]> wrote:
>> I suspect the normal steering behavior of a bicycle is limited on
>> rollers. Look over the excellent 'Building An Unrideable Bicycle' for
>> background on 'normal'.
>> The motion of the rims/tires, which is trivial to a moving bicycle,
>> probably has some effect on the rollers where our arcs across the
>> pavement are absent. You can tell I'm speculating. Any other roller
>> riders care to comment? The bike definitely handles differently on
>> rollers and I'm grasping at why exactly. The net effect though is that
>> style which would be merely sloppy or inefficient on the road will dump
>> you off the rollers.

[email protected] wrote:
> Here's a theory.
> On pavement, you can do two things: lean into turns and steer the
> contact patch under your center of gravity.
> On rollers, you can't lean. If you do, you either fall down or else
> stop leaning and steer the contact patch back under your center of
> gravity as quick as you can.
> There's just no centripetal force, no actual turn on rollers, to allow
> the normal leaning that pavement provides.

Yes that's right.
But it's magnitudes harder to trackstand on rollers with the wheels not
turning.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[sergio]

On 5 Set, 16:55, "Tom Nakashima" <[email protected]>
> Sorry, actually when riding rollers, it's 3 points contact.
> Two contact points on the rear, and one on the front.

Please, differentiate between a contact point and a pivoting point. No
more than one at a time for a rigid body in rotation about it.
Just a matter of wording?

Sergio
Pisa