# Brakes? How?

I know Mike has recently bought a coker and although I haven’t ridden one yet I have read that the coker wheel has a fair bit of momentum of its own, which coupled with the wheel size/crank length (nicely mathematically explained by gaus) will make more of a difference to a lighter rider.

With a unicycle wheel acting as a flywheel the larger and heavier the wheel the more energy it can store and therefore more energy to accelerate/decelerate it, even through only half a rotation. The mass of a coker is (discarding added extras) constant but the mass of the rider is variable. And don’t forget about the elastic energy of the spokes (oh no I’m not going there).

What is the mass of a coker wheel? Does anyone have the time to work out the numbers on this? I don’t, I’m waiting for my 24” Nimbus II with 3” Gazz to arrive, that should have some momentum

Gary

Aha! You all probably saw I replied to this and thought I touched off world war 4. (3 had something to do with the axis of evil and its schenanigans related to spoke tensions). I just wanted to comment on how funny it is to see everyone “threading” lightly and mentioning that this was their LAST contribution to the conversation. I also tried to find out what Morris dancing was. I still don’t know, but judging from the outfits: very cool (sorry Mike).
-gauss

Re: Brakes? How?

I don’t think this applies to brakes, but maybe to the direction this thread
went.

I mainly ride urban; street and sidewalks.

My 26" w/Metro Duro slick was fitted with 102mm cranks the other day. This
was the only change, so there wasn’t any change in momentum (for a given
rpm). These 102’s make the rotations of the wheel much smoother with less
acceleration and decceleration at each half revolution. I have large
powerful legs which are probably a detriment to riding smoothly over sticks
and concrete joints and maintaining a smooth cadence. I overpower with
longer cranks and these short ones smooth out the revolutions because of
their ratio to the tire radius.

Am I rambling or what?

Anyway, I’ll get many more miles on these 102’s and probably get smoother
real quickly.

Doug

RE: Brakes? How?

> movement of the feet as possible. With clips/straps/cleats (etc.) the
> rider actually exerts an upwards force on one pedal at the
> same time as the downward force on the other pedal. Additionally, the
> rider is able to push the pedal forwards at the top and backwards at
> the bottom.
>
> On a uni, sprinting, all of this is possible except the
> upwards force - unless you are willing to wear
> straps/clips/cleats etc.

On a bike, you always pedal within a relatively comfortable range of
cadence. Even when going fast, you are pedaling at a speed where you:
a. Still need to push hard on the pedals
b. Have enough time to exert force on the pedals all the way around the
circle

When sprinting on a (racing-sized) unicycle, your speed is limited not by
your power output, as it is on a bike, but by your ability to pedal
super-fast (over 200 rpm) while still staying on the thing. All of your
strength is used to make your feet stay in the circular motion they are
making, which mostly translates into the up and down motion in which you’re
moving them. The muscles that get sore if you start racing when not used to
it are mainly the upper quads, from lifting the thighs. You actually don’t
have to apply that much power into the pedals because wind resistance is
barely a factor. All energy is used to simply keep your feet on the pedals.

> In which case you can only read this if you have a laptop
> at your hospital bed. ;0)

Dang right! If you attach your feet to the pedals, it’s not a question of
whether you can go any faster, it’s a question of what’s going to happen to
you when you eventually mess up.

> Ignoring problems arising from the tyre slipping as the
> slope gets steeper, it is easy to see that the steeper
> the slope, the more weight you need on the uphill pedal
> to achieve equilibrium.

I’ll remind everyone again that I’m not a physics expert. But I’m pretty
sure this is where the argument breaks down. Weight is not what you need on
the pedal. You need force on the pedal. If you have the force without the
weight, you don’t compromise your traction and tire yourself out as much.
Weight is not equal to force. If it was, pulling up on the seat wouldn’t so
anything.

> So, more weight = more control in this specific situation.

Translate “weight” to “leg power.”

> Going up hill, more weight gives more torque, but at the
> expense of the fact that you have to lift that weight all
> the way up the hill.

Like riding a downhill bike “the hard way.” But again, you want power. You
don’t drive a unicycle by standing on the pedals. Your pedals are like
pistons, and your legs are the connecting rods. They bend and unbend, and
unless you are going super-slow, your legs are in constant motion. You put
the power in to apply the necessary force. A heavier rider has more downward
foot-force available, but it’s still the strength of his muscles that
applies it through a pedal stroke. And it’s his cardiovascular fitness level
that determines how long he can keep it up.

> Thus, a heavy rider may be able to get the uni to go up a steeper
> slope, but will have to work harder than a lighter rider to get
> up a given hill.

No, being heavier does not increase your traction. Pure weight will limit
the angle of slope you can ride. The lighter rider will always be able to
“stick” to the steeper slope. All other things being equal, the lighter
rider will have an easier time, not only riding up, but also riding down the
hill.

6’, 4" Brett Bymaster, at around 150 pounds, can ride up the steepest stuff
I’ve ever seen anybody climb. This was with relatively unlimited traction,
in Moab, Utah. See the steep pictures near the top of this page:

In bike racing, it works a little differently. Light guys tend to be the
better mountain climbers, though some big guys also do well. But the little,
lightweight guys are nearly always at a disadvantage on the downhills.
This has nothing to do with unicycling, though. They are going so fast that
the light guys have too much frontal area in relation to their mass, and
can’t coast as fast as the bigger guys. Pedaling or not, they have an
aerodynamic disadvantage, which forces them to use more energy to equal the
heavier riders.

Riding a regular unicycle down a hill, you have to use effort to resist the
force of gravity. The more you (or the cycle) weigh, the more you have to
work.

> On the flat, the rider’s weight will make little difference except
> perhaps in the limited case of accelerating/decelerating on a
> big wheel with small cranks.

No, accelerating/decelerating any wheel. But it’s much less difference
than you would feel on a hill.

Along with that, the rotational weight of your cycle is very important. If
you talk to bicyclists, they say how any weight you can reduce from the
wheels is equal to removing twice as much weight from elsewhere on the bike.
This is because every time you change your speed, you have to work against
that weight to do so. This means, for efficiency you want the lightest wheel
possible. Unfortunately for unicycles, especially on trails, you also want a
wheel that can take the punishment, so unicycle wheels tend to be heavy.

Stay on top,
John Foss, the Uni-Cyclone
jfoss@unicycling.com

Howard Stern: “How many wheels does a unicycle have?”
The beautiful but vacant, recently-crowned Miss Howard Stern:
“…Four?”

Re: RE: Brakes? How?

This part is correct.

This part is incorrect. F=ma, weight is force.

Re: Brakes? How?

Hi John,

>The muscles that get sore if you start racing when not used to
>it are mainly the upper quads, from lifting the thighs.

If you are riding properly, the pedals are lifting your thighs, R and
then L, cyclicly. The quads are used to push the pedal down via
extending the leg at the knee joint.

>I’ll remind everyone again that I’m not a physics expert. But I’m pretty
>sure this is where the argument breaks down. Weight is not what you need on
>the pedal. You need force on the pedal. If you have the force without the
>weight, you don’t compromise your traction and tire yourself out as much.
>Weight is not equal to force. If it was, pulling up on the seat wouldn’t so
>anything.

In this case, weight is the force of gravity on essentially the rider.
the force of the rider’s weight. This allows a force to be applied to
the pedal that exceeds the rider’s weight.

>Translate “weight” to “leg power.”

The force applied to the pedal can not exceed the rider’s weight plus
the force on the seat applied in an upward direction. If this limit is
exceeded, the rider will be launched off the pedals and accelerated
upward briefly off the unicycle with likely loss of control.

>Like riding a downhill bike “the hard way.” But again, you want power. You
>don’t drive a unicycle by standing on the pedals. Your pedals are like
>pistons, and your legs are the connecting rods. They bend and unbend, and
>unless you are going super-slow, your legs are in constant motion. You put
>the power in to apply the necessary force. A heavier rider has more downward
>foot-force available, but it’s still the strength of his muscles that
>applies it through a pedal stroke. And it’s his cardiovascular fitness level
>that determines how long he can keep it up.

I’m sure we all agree that any muni rider must be in good shape.

>No, being heavier does not increase your traction. Pure weight will limit
>the angle of slope you can ride. The lighter rider will always be able to
>“stick” to the steeper slope. All other things being equal, the lighter
>rider will have an easier time, not only riding up, but also riding down the
>hill.

A heavier rider will cause the tire to be pressed harder into the
ground, providing a greater tire contact area (more traction).
A heavier rider will have to apply force to the pedal that is in ratio
to his greater weight, i.e. and 50% heaver rider would need to apply 50%
more force to the pedal. However, the heavier rider has the advantage
due to the constant weight of the unicycle used (for example 15 pounds
or 7 kg). Thus the 50% heavier rider doesn’t have to apply 50% more
force, but 40-45% more force due to the constant weight of the unicycle.
Otherwise, the heavier rider’s unicycle would have to be 50% heavier as
well.

>6’, 4" Brett Bymaster, at around 150 pounds, can ride up the steepest stuff
>I’ve ever seen anybody climb. This was with relatively unlimited traction,
>in Moab, Utah. See the steep pictures near the top of this page:
>http://tinyurl.com/2u9

What’s the point of giving an example with unlimited traction uphill,
when the whole point of this thread is the advantages going downhill?

>In bike racing, it works a little differently. Light guys tend to be the
>better mountain climbers, though some big guys also do well. But the little,
>lightweight guys are nearly always at a disadvantage on the downhills.
>This has nothing to do with unicycling, though. They are going so fast that
>the light guys have too much frontal area in relation to their mass, and
>can’t coast as fast as the bigger guys. Pedaling or not, they have an
>aerodynamic disadvantage, which forces them to use more energy to equal the
>heavier riders.

Heavier unicycle riders do have a small advantage going down. It’s just
not as clear as in the above bike racing example.

>Riding a regular unicycle down a hill, you have to use effort to resist the
>force of gravity. The more you (or the cycle) weigh, the more you have to
>work.

However, a heavier unicyclist can go down hill slighter faster than a
lighter rider due to the unicycle weight being equal. Meaning the
heavier rider applies a smaller percentage of his power output in
resisting the the actual weight of the unicycle alone.

The heavier a rider is, the greater the power output can be. Thus,
heavier riders can easily beat lighter riders up hill. Light engines
don’t always lose, but most often do against heavier engines.

>No, accelerating/decelerating any wheel. But it’s much less difference
>than you would feel on a hill.
>
>Along with that, the rotational weight of your cycle is very important. If
>you talk to bicyclists, they say how any weight you can reduce from the
>wheels is equal to removing twice as much weight from elsewhere on the bike.
>This is because every time you change your speed, you have to work against
>that weight to do so. This means, for efficiency you want the lightest wheel
>possible. Unfortunately for unicycles, especially on trails, you also want a
>wheel that can take the punishment, so unicycle wheels tend to be heavy.

In the final analysis, it is lean weight that wins. Clearly, any fat a
(muscle) weight can potentially generate power in excess of the

In terms of power generating weight, ultimately muscle is the weight
that really counts. Bones, connective tissues and nerves, etc. are
necessary, but if these are kept constant, it is lean muscle is what
wins, assuming it isn’t too powerful for the skeletal system. If they
could, any competitive rider would add lean (muscle) weight to his frame
for a competitive edge.

However, again, the main point of this thread was the force applied to
the pedal can’t exceed the weight of the rider, unless the rider pulls
up on the seat. This was in the context of going down steep hills.
Everything else mentioned was a distraction or change in the topic.

Sincerely,

Ken Fuchs <kfuchs@winternet.com>

That’s easy, it a bunch of half drunk (they must have some reason for willingly looking so daft) men prancing around waving handkerchiefs at each other, occasionally smacking each other with big sticks whilst some nutter wanders round walloping them all with an inflated pig’s bladder (it could be a sheep’s bladder though). Is that a fair enough description Mike?

I’ve only seen them in the flesh once, and I vaguely remember a hanky waving move where they stepped forward then back with their knees in the air. It looked remarkably similar to somebody idling a unicycle. Mike, if your dances already incorporate some uni-type moves, why not develop a unicycling Morris dance group?

I can’t really criticise though, has anyone been to a Scottish ceilidh? To the uninitiated it can look like an all out battle. And then there’s the “Highland Fling”, the only dance where you jump about and cut your toe-nails at the same time:)

Have fun!

Graeme

RE: Brakes? How?

> If you are riding properly, the pedals are lifting your thighs, R and
> then L, cyclicly. The quads are used to push the pedal down via
> extending the leg at the knee joint.

This is true for riding at normal speeds. At racing speeds, your feet are
moving so fast that the motion is relatively the same without the pedals.
You are lifting and lowering your feet as fast as you possibly can while

Anyone, even an experienced bike racer, if he switched to unicycle racing
and suddenly had to get used to doubling or tripling his pedaling speed,
will feel it in their upper quads until their body adjusts. In racing you
have to lift your legs up as you pedal. If you don’t, you’ll never be fast.

> I’m sure we all agree that any muni rider must be in good shape.

Indeed. Or be left behind. My conditioning has declined over the last few
years, so I know the effects of being out of shape and trying to keep up on
the trail. Basically a lot of walking on the uphills…

> A heavier rider will cause the tire to be pressed harder into the
> ground, providing a greater tire contact area (more traction).

Definitely true on flat ground. But at some point in steepness of the trail,
I think the extra weight starts to work against you. Unicycle wheels on
steep trails usually lose traction as a result of spurts in the pedal stroke
as well. In other words, if you have a brake, you can apply smoother power
into the wheel and lower your risk of losing traction.

If we’re talking about theoretical conditions in a lab, yes it will be
different from riding an actual trail. Or even on grippy pavement, I think
extra rider weight will not work against you, traction-wise, until you’re
right around the limits of rideability due to steepness.

> What’s the point of giving an example with unlimited traction uphill,
> when the whole point of this thread is the advantages going downhill?

Usually you have to ride up the hill first

The weight/power thing applies when going uphill as well.

> However, a heavier unicyclist can go down hill slighter faster than a
> lighter rider due to the unicycle weight being equal. Meaning the
> heavier rider applies a smaller percentage of his power output in
> resisting the the actual weight of the unicycle alone.

This is true only if you assume equal power output in proportion to rider
weight. For theoretical purposes, I suppose that’s fair. But strapping on a
weight belt, as suggested earlier, will increase rider weight with no
increase of power.

> The heavier a rider is, the greater the power output can be. Thus,
> heavier riders can easily beat lighter riders up hill. Light engines
> don’t always lose, but most often do against heavier engines.

This is not true in bicycle racing. Based on my (relatively limited)
reading, lighter riders, on average, always do better on the climbs.
Unfortunately for unicycling, we don’t have enough experience if this is
true for us or not. The winners of the uphill contests we’ve held at MUni
Weekends and USA conventions have generally been won by relatively light
riders, but then again almost all of the riders were relatively light.

> In terms of power generating weight, ultimately muscle is the weight
> that really counts. Bones, connective tissues and nerves, etc. are
> necessary, but if these are kept constant, it is lean muscle is what
> wins, assuming it isn’t too powerful for the skeletal system. If they
> could, any competitive rider would add lean (muscle) weight
> to his frame for a competitive edge.

True. And not a weight belt.

> However, again, the main point of this thread was the force applied to
> the pedal can’t exceed the weight of the rider, unless the rider pulls
> up on the seat. This was in the context of going down steep hills.
> Everything else mentioned was a distraction or change in the topic.

Sorry about expanding the topic. I have no argument against the amount of
force that can be applied to the pedal. The original post was suggesting
downhill. Both of our arguments say it is not.

Stay on top,
John Foss, the Uni-Cyclone
jfoss@unicycling.com

IF IT DAMAGES PUBLIC AND PRIVATE PROPERTY,

SKATEBOARDING

AND UNICYCLING

IS A CRIME

(Mind where you grind)

RE: Brakes? How?

> This part is incorrect. F=ma, weight is force.

Okay, whatever those letters stand for.

But doesn’t this mean the weight can only be heading toward the center of
the Earth, or in whatever direction some other force has set it in motion?

In other words, anything wrong with the rest of my arguments? Getting my
armchair physics critiqued by someone who knows better is a little scary…

Thanks,
JF

Re: RE: Brakes? How?

F: force, m: mass, a: acceleration
Weight is defined as the force exerted by a mass on the surface of a gravitational body due to its acceleration toward the center of that body.

There is nothing wrong with the rest of your arguments which are thorough, thoughtful and elegant as they always are, and address the question asked as they always do. Like most people I just wince when seeing others play fast and loose with terminology in my field. The “weight is not equal to force” statement cried out for correction. I apologize for the unnecessary and marginally successful attempt at humor at your expense regarding the other quote.

You will have an opportunity to school me in the practical application of F=ma during the 10k.

Re: Brakes? How?

>> If you are riding properly, the pedals are lifting your thighs, R and
>> then L, cyclicly. The quads are used to push the pedal down via
>> extending the leg at the knee joint.

John Foss <john_foss@asinet.com> wrote:

>This is true for riding at normal speeds. At racing speeds, your feet are
>moving so fast that the motion is relatively the same without the pedals.
>You are lifting and lowering your feet as fast as you possibly can while

A controlled cadence is important while racing without pedals?
I though the feet revolve around the axis of the wheel rather that going
(strictly) up and down (lifting and lowering).

>Anyone, even an experienced bike racer, if he switched to unicycle racing
>and suddenly had to get used to doubling or tripling his pedaling speed,
>will feel it in their upper quads until their body adjusts. In racing you
>have to lift your legs up as you pedal. If you don’t, you’ll never be fast.

My riding is much more controlled when I don’t lift my feet off the
pedals. Maybe I just don’t understand the magic of unicycle racing.
Your feet must be one with the pedals (or be one with the force

>> A heavier rider will cause the tire to be pressed harder into the
>> ground, providing a greater tire contact area (more traction).

>Definitely true on flat ground. But at some point in steepness of the trail,
>I think the extra weight starts to work against you. Unicycle wheels on
>steep trails usually lose traction as a result of spurts in the pedal stroke
>as well. In other words, if you have a brake, you can apply smoother power
>into the wheel and lower your risk of losing traction.

Steepness of the trial will not affect the increase in tire contact area
(more traction) that a heavier rider will cause.

Variation in pedal stroke doesn’t change the amount of traction.
However, the rider forces transmitted to the tire tangent to the
ground must not exceed the maximum force of rolling friction of the
tire provided by the traction.

A heavier, more muscular rider can apply smoother braking action via the
pedals that a lighter, less muscular rider.

>> What’s the point of giving an example with unlimited traction uphill,
>> when the whole point of this thread is the advantages going downhill?

>Usually you have to ride up the hill first

>The weight/power thing applies when going uphill as well.

The point being made is a heavier rider has more advantages going down
hill than up hill, so let’s ignore up hill for now.

>> However, a heavier unicyclist can go down hill slighter faster than a
>> lighter rider due to the unicycle weight being equal. Meaning the
>> heavier rider applies a smaller percentage of his power output in
>> resisting the the actual weight of the unicycle alone.

>This is true only if you assume equal power output in proportion to rider
>weight. For theoretical purposes, I suppose that’s fair. But strapping on a
>weight belt, as suggested earlier, will increase rider weight with no
>increase of power.

Actually, I’m assuming greater power generation per kilogram for the
heavier rider since a higher percentage of his body weight can be lean
muscle. Everyone has required dead (non-power generating) weight such
as bones, etc.

>> The heavier a rider is, the greater the power output can be. Thus,
>> heavier riders can easily beat lighter riders up hill. Light engines
>> don’t always lose, but most often do against heavier engines.

>This is not true in bicycle racing. Based on my (relatively limited)
>reading, lighter riders, on average, always do better on the climbs.
>Unfortunately for unicycling, we don’t have enough experience if this is
>true for us or not. The winners of the uphill contests we’ve held at MUni
>Weekends and USA conventions have generally been won by relatively light
>riders, but then again almost all of the riders were relatively light.

What is a heavier or lighter rider is relative. There is probably a
wide range of rider weights that win up hill races. Riders below a
minimum weight will probably always lose and riders above a maximum
weight will probaly always lose as well. At these extremes, both the
light and heavy riders run into different physiological barriers to
increased power output per kilogram. The dead weight of a too light
rider over taxes his minimal muscle volume and the fat of a too heavy
rider over taxes his ample muscle volume (in both caes, low percent
of power generating weight).

One could say that all the lighter bicycle racers win up hill, because
the heavier bicycle racers don’t even bother to enter. One could also
say that all the heavier bicycle racers win up hill, because the lighter
bicycle racers don’t even bother to enter. Again, what is a heavier or
lighter rider is relative.

Only objective, controlled testing can prove anything about our sport.

>> In terms of power generating weight, ultimately muscle is the weight
>> that really counts. Bones, connective tissues and nerves, etc. are
>> necessary, but if these are kept constant, it is lean muscle that
>> wins, assuming it isn’t too powerful for the skeletal system. If they
>> could, any competitive rider would add lean (muscle) weight
>> to his frame for a competitive edge.

>True. And not a weight belt.

The point of the weight belt is a trivial physical fact. The force
applied to the pedal can not exceed the rider’s weight (without pulling
up on the seat). The weight belt would allow a force equal to its
weight to be added to the pedal without the rider being accellerated
into the air and off the pedals.

My point is no one would choose to add a weight belt when they could add
lean muscle instead. The best choice is a “no brainer”.

>> However, again, the main point of this thread was the force applied to
>> the pedal can’t exceed the weight of the rider, unless the rider pulls
>> up on the seat. This was in the context of going down steep hills.
>> Everything else mentioned was a distraction or change in the topic.

>Sorry about expanding the topic. I have no argument against the amount of
>force that can be applied to the pedal. The original post was suggesting
>downhill. Both of our arguments say it is not.

Yes, the original post suggested that dead weight added to the rider
might be an advantage riding down hill. What John and I have argued
doesn’t prove or disprove this theory. Only controlled experiments can
do that.

Sincerely,

Ken Fuchs <kfuchs@winternet.com>

Re: Brakes? How?

In a message dated 6/8/02 2:23:57 AM, kfuchs@winternet.com writes:

<< Steepness of the trial will not affect the increase in tire contact area
(more traction) that a heavier rider will cause. >>

yes it will

RE: Brakes? How?

> >Anyone, even an experienced bike racer, if he switched to
> unicycle racing
> >and suddenly had to get used to doubling or tripling his
> pedaling speed,
> >will feel it in their upper quads until their body adjusts.
> In racing you
> >have to lift your legs up as you pedal. If you don’t, you’ll
> never be fast.
>
> My riding is much more controlled when I don’t lift my feet off the
> pedals. Maybe I just don’t understand the magic of unicycle racing.
> Your feet must be one with the pedals (or be one with the force

For those of you that don’t know him, Ken knows quite a bit about unicycle
racing. And we both agree that your feet must be one with the pedals
(regardless of which side of the Force works for you).

If anyone else is having trouble with my description of pedaling at unicycle
racing speed, I’ll go into further detail. In short, your feet (had better)
stay on the pedals. This means of course that they are moving in circles.
Add gravity to the equation. Your lower legs are essentially going front to
rear, while your thighs are essentially going up and down. That’s why you
sore if you’re not used to it. The big parts of your legs go up and down,
basically as hard as they can.

> Steepness of the trial will not affect the increase in tire
> contact area (more traction) that a heavier rider will cause.

person, balancing (stillstanding) on the same type of unicycle with same
tire and air pressure, would not lose traction at the same moment as the
ground got steeper. This is all theory though, and doesn’t have much to do
with actual riding, paved or unpaved. Just that when the trail gets real
steep, traction is a major factor, until it suddenly disappears.

> Variation in pedal stroke doesn’t change the amount of traction.

Sure it does. But maybe this was what you were saying in the rest of your
paragraph. Accelerating will tend to lift you away from a downhill slope,
while decelerating will press you more into it. These are minor forces. The
major force is sudden changes in the rotational force of the wheel, which
can cause what little traction there is to give way, on a steep hill.

> One could say that all the lighter bicycle racers win up hill, because
> the heavier bicycle racers don’t even bother to enter. One could also
> say that all the heavier bicycle racers win up hill, because the lighter
> bicycle racers don’t even bother to enter. Again, what is a
> heavier or lighter rider is relative.

I was comparing professional road racers. Though lighter guys tend to be the
uphill champions, a minority of genetically gifted bigger guys (such as a
Lance Armstrong) do well also.

> Only objective, controlled testing can prove anything about our sport.

True. We don’t get much of that, but we can use racing results as a crude
form of this. But any racing we do involving hills is basically impossible
to compare, because it’s always a different hill. For track racing, we have
plenty of data.

Stay on top,
JF

Re: Brakes? How?

>> My riding is much more controlled when I don’t lift my feet off the
>> pedals. Maybe I just don’t understand the magic of unicycle racing.
>> Your feet must be one with the pedals (or be one with the force

>For those of you that don’t know him, Ken knows quite a bit about unicycle
>racing. And we both agree that your feet must be one with the pedals
>(regardless of which side of the Force works for you).

Lower case f in force, as in physical force. Remember that forces
usually come in equal and opposite pairs. A rider supplies only one
side of these pairs.

>If anyone else is having trouble with my description of pedaling at unicycle
>racing speed, I’ll go into further detail. In short, your feet (had better)
>stay on the pedals. This means of course that they are moving in circles.
>Add gravity to the equation. Your lower legs are essentially going front to
>rear, while your thighs are essentially going up and down. That’s why you
>sore if you’re not used to it. The big parts of your legs go up and down,
>basically as hard as they can.

When racing, the legs move in the same paths as when riding at a
leisurely pace, just much faster. Unicycling speed will not cause
relativistic effects.

I don’t understand how racing became a topic in a thread about
downhill riding.

>> Steepness of the trial will not affect the increase in tire
>> contact area (more traction) that a heavier rider will cause.

>person, balancing (stillstanding) on the same type of unicycle with same
>tire and air pressure, would not lose traction at the same moment as the
>ground got steeper. This is all theory though, and doesn’t have much to do
>with actual riding, paved or unpaved. Just that when the trail gets real
>steep, traction is a major factor, until it suddenly disappears.

A heavier rider will cause a greater area (traction) of the tire to be
in contact with ground. How can anyone doubt this? This is still true
for a hill of any steepness that is rideable.

>> Variation in pedal stroke doesn’t change the amount of traction.

>Sure it does. But maybe this was what you were saying in the rest of your
>paragraph. Accelerating will tend to lift you away from a downhill slope,
>while decelerating will press you more into it. These are minor forces. The
>major force is sudden changes in the rotational force of the wheel, which
>can cause what little traction there is to give way, on a steep hill.

Traction is the area of the tire in contact with the ground. How does
pedal stroke variation change that?

Pedal stroke variation affects the lateral forces on the tire at the
point of contact with the ground. These lateral forces oppose the
tractional forces and if these lateral forces exceed the tractional
forces, we “lose traction” (the tire slides on the ground). Note that
for a given surface the tractional force potential is a constant, a
limit that the rider and unicycle may or may not exceed. Traction is a
property of the riding surface and tire and is not usually affected by
other parts of the unicycle or the rider.

>> Only objective, controlled testing can prove anything about our sport.

>True. We don’t get much of that, but we can use racing results as a crude
>form of this. But any racing we do involving hills is basically impossible
>to compare, because it’s always a different hill. For track racing, we have
>plenty of data.

We have no useful data from racing records about downhill riding,
because we don’t weight riders and unicycles and we don’t have any
downhill pedaling races.

Has anyone noticed that to a racer, everything is a race? John, if you
has become pretty useless in my opinion, anyway.

Sincerely,

Ken Fuchs <kfuchs@winternet.com>

RE: Brakes? How?

> Lower case f in force, as in physical force. Remember that forces
> usually come in equal and opposite pairs. A rider supplies only one
> side of these pairs.

But never underestimate the power of the dark side.

> When racing, the legs move in the same paths as when riding at a
> leisurely pace, just much faster. Unicycling speed will not cause
> relativistic effects.

They move in the same paths, but not with the same muscle usage. Are you
saying that pedaling fast and pedaling slow will use the same muscles in the
same way? It does not. There is gravity and, more importantly, inertia. Each
time you lift your leg up at such a high speed, you also have to use
additional energy to stop it going up and start it going back down again.
This is not the same form of power usage as pedaling at a normal pace. The
physiological effects are very different in addition to the obvious
difference in power output and effort.

> A heavier rider will cause a greater area (traction) of the
> tire to be in contact with ground. How can anyone doubt
> this? This is still true for a hill of any steepness that
> is rideable.

I don’t doubt this. The question is what happens when you reach the point of
loss of traction. Who loses it first? Somehow I do not think all things
remain equal at this point, but I don’t know which way they would go.

In any case, a theoretical set of results of this would not mean much for
actual riding. In actual riding, keeping your grip on a steep slope (on
dirt) has everything to do with how smoothly you pedal, less to do with your
tire’s contact patch, even less to do with your tire’s tread pattern, and
least of all with the rider’s weight. Perhaps not in that order.

> Traction is the area of the tire in contact with the ground. How does
> pedal stroke variation change that?

Minnesota must be flatter than I remember it.

It does in two different ways. Anyone who rides a motorcycle is intimately
familiar with this. It’s the same thing in a car, but you don’t have to be
as aware of it. The term used in motorcycles is suspension loading. In a car
or motorcycle, if you jam on your brakes suddenly, your wheels will most
likely slide. But if you apply the brakes more gradually, the suspension
takes up more and more load, increasing your traction. You can stop much
quicker this way, by keeping your tires in grip. Suspension or no, your
traction goes way up when you are decelerating. This is very true for
vehicles with wheels in front of each other, and less true for unicycles.
Remember in a car or motorcycle, as the traction increases up front, it
decreases in the rear.

Accelerating, same thing. Do it too hard, and the wheel spins. Do it a
little more gently, and off you go. The same thing happens when you pedal a
unicycle, especially on a steep surface. As it gets steeper, it gets further
and further from being possible to maintain a smooth pedal stroke. It’s more
like taking steps. But when the wheel starts to move (uphill), or tries to
slow (downhill), you have to watch out that the tire doesn’t break loose.

Additionally, on a much more minor note, As you accelerate downhill, you get
reduced. It’s not that minor, and you can definitely feel it when riding
steep trails. When you slow down you get heavier. Your traction increases,
but if you don’t do it gently enough you run the risk of skidding out.

> Pedal stroke variation affects the lateral forces on the tire at the
> point of contact with the ground. These lateral forces oppose the
> tractional forces and if these lateral forces exceed the tractional
> forces, we “lose traction” (the tire slides on the ground). Note that
> for a given surface the tractional force potential is a constant, a
> limit that the rider and unicycle may or may not exceed.

Well said. That’s the hard part, when the going gets steep.

> Traction is a property of the riding surface and tire and is not
> usually affected by other parts of the unicycle or the rider.

No, the rider has a huge effect, and is the thing that usually causes the
breakdown in traction on steep surfaces. If unicycles had smooth electric
motors, we could do much steeper trails before losing our grip.

And no, I’m not worried about a Segway coming along and proving this…

> We have no useful data from racing records about downhill riding,
> because we don’t weight riders and unicycles and we don’t have any
> downhill pedaling races.

Yes to the first and no to the second. We raced downhill in Toronto last
summer, and in the big MUni race at the Snoqualmie Pass in 1999.

> Has anyone noticed that to a racer, everything is a race?

What did you say back there?

> John, if you want to discuss racing further, please start a
> opinion, anyway.

I think we’ve been more constructive than the players in the “wheel puzzle”
debate. But yeah, we’re quite a ways from the original topic. I’ll start a

Stay on top,
Stay on top,
John Foss, the Uni-Cyclone
2002 NAUCC and UNICON Referee
jfoss@unicycling.com

Go to NAUCC and UNICON 2002! www.nwcue.org

Re: Brakes? How?

>> When racing, the legs move in the same paths as when riding at a
>> leisurely pace, just much faster. Unicycling speed will not cause
>> relativistic effects.

John Foss <john_foss@asinet.com> wrote:

>They move in the same paths, but not with the same muscle usage. Are you
>saying that pedaling fast and pedaling slow will use the same muscles in the
>same way? It does not. There is gravity and, more importantly, inertia. Each
>time you lift your leg up at such a high speed, you also have to use
>additional energy to stop it going up and start it going back down again.
>This is not the same form of power usage as pedaling at a normal pace. The
>physiological effects are very different in addition to the obvious
>difference in power output and effort.

In other words one’s legs get tired when racing. The same muscle groups
that are used in touring and also used in racing, but used at peak
performance levels. We agree that the “power usage” in racing is near
maximum otherwise it wouldn’t be racing.

>> A heavier rider will cause a greater area (traction) of the
>> tire to be in contact with ground. How can anyone doubt
>> this? This is still true for a hill of any steepness that
>> is rideable.

>I don’t doubt this. The question is what happens when you reach the point of
>loss of traction. Who loses it first? Somehow I do not think all things
>remain equal at this point, but I don’t know which way they would go.

>In any case, a theoretical set of results of this would not mean much for
>actual riding. In actual riding, keeping your grip on a steep slope (on
>dirt) has everything to do with how smoothly you pedal, less to do with your
>tire’s contact patch, even less to do with your tire’s tread pattern, and
>least of all with the rider’s weight. Perhaps not in that order.

The coefficent of friction between your tire and riding surface is
critical. A bigger value is better!

>> Traction is the area of the tire in contact with the ground. How does
>> pedal stroke variation change that?

>It does in two different ways. Anyone who rides a motorcycle is intimately
>familiar with this. It’s the same thing in a car, but you don’t have to be
>as aware of it. The term used in motorcycles is suspension loading. In a car
>or motorcycle, if you jam on your brakes suddenly, your wheels will most
>likely slide. But if you apply the brakes more gradually, the suspension
>takes up more and more load, increasing your traction. You can stop much
>quicker this way, by keeping your tires in grip. Suspension or no, your
>traction goes way up when you are decelerating. This is very true for
>vehicles with wheels in front of each other, and less true for unicycles.
>Remember in a car or motorcycle, as the traction increases up front, it
>decreases in the rear.

>Accelerating, same thing. Do it too hard, and the wheel spins. Do it a
>little more gently, and off you go. The same thing happens when you pedal a
>unicycle, especially on a steep surface. As it gets steeper, it gets further
>and further from being possible to maintain a smooth pedal stroke. It’s more
>like taking steps. But when the wheel starts to move (uphill), or tries to
>slow (downhill), you have to watch out that the tire doesn’t break loose.

>Additionally, on a much more minor note, As you accelerate downhill, you get
>reduced. It’s not that minor, and you can definitely feel it when riding
>steep trails. When you slow down you get heavier. Your traction increases,
>but if you don’t do it gently enough you run the risk of skidding out.

Pedal stroke variation is the minor adjustments to maintain forward /
backward balance. Pedal stroke variation is not starting or stopping.

If one stops fast enough to cause the wheel to slide, the physics of the
tire / riding surface interface change suddenly and dramatically.
The coefficent of friction starts out at the higher rolling friction
level and jumps instantly down to the sliding friction level. This is
what John calls “losing traction”. Traction doesn’t vanish, it simply
jumps from a high level to to a low level suddenly. This usually causes
the rider to lose control, but the rider can maintain control with the
wheel sliding with enough practice.

>> Pedal stroke variation affects the lateral forces on the tire at the
>> point of contact with the ground. These lateral forces oppose the
>> tractional forces and if these lateral forces exceed the tractional
>> forces, we “lose traction” (the tire slides on the ground). Note that
>> for a given surface the tractional force potential is a constant, a
>> limit that the rider and unicycle may or may not exceed.

>Well said. That’s the hard part, when the going gets steep.

Thank you.

>> Traction is a property of the riding surface and tire and is not
>> usually affected by other parts of the unicycle or the rider.

>No, the rider has a huge effect, and is the thing that usually causes the
>breakdown in traction on steep surfaces. If unicycles had smooth electric
>motors, we could do much steeper trails before losing our grip.

You are confusing the tractional forces which are generated by the
resistance of ground with the forces that oppose traction which are
generated by the rider. These forces must be below

>And no, I’m not worried about a Segway coming along and proving this…

I’d be. It’s braking system is controlled with perhaps a reaction time
of 1 millisecond or better. A human unicyclist may have a reaction time
of about one half a second plus limited power output for nearly one half
of every full cycle.

>> We have no useful data from racing records about downhill riding,
>> because we don’t weight riders and unicycles and we don’t have any
>> downhill pedaling races.

>Yes to the first and no to the second. We raced downhill in Toronto last
>summer, and in the big MUni race at the Snoqualmie Pass in 1999.

We have to have both race results and rider weights for useful data.
Having the first and not having the second, still means we have NO
useful data.

>> Has anyone noticed that to a racer, everything is a race?

>What did you say back there?

How far behind me were you when I reached the finish line of the Great
Wall of China Unicycle Marathon (down and then up the mountain)?
The night before, I drank far too much snake schapps and had a rude
hangover the day of the race. Many of the racers probably did and maybe
didn’t get enough sleep either. Maybe, we should measure the affects of
hangovers and sleep deficent on racing performance.

>> John, if you want to discuss racing further, please start a
>> opinion, anyway.

>I think we’ve been more constructive than the players in the “wheel puzzle”
>debate. But yeah, we’re quite a ways from the original topic. I’ll start a

Actually, I’d like to be more rigorious and accurate about the physics,
but I really don’t have the time to do so. Maybe someone else can do so
or point out problems with John’s arguements or my arguements?

Sincerely,

Ken Fuchs <kfuchs@winternet.com>

RE: Brakes? How?

> In other words one’s legs get tired when racing. The same
> muscle groups that are used in touring and also used in racing,

Muscle groups, yes. Specific areas of those muscles, no. You are not just
working the same muscles harder. the effort is applied differently, not just
the same thing faster. If you simply speeded up the pedaling motion of
normal riding, your feet would flop all over the place. You have to add
additional effort to keep them attached to the pedals. If not anything
else, surely the increase of centripetal (centrifugal?) force means
something to you.

> Pedal stroke variation is the minor adjustments to maintain forward /
> backward balance. Pedal stroke variation is not starting or stopping.

As the riding surface gets steeper and steeper, these two things get closer
to being one in the same. On a short downhill, it’s possible to “roll out”
and let the unicycle pick up lots of speed, as long as this happens near the
bottom. Riding uphill is a better example. You’re going slow. You are
pedaling in “steps,” where you lunge forward and pedal a half revolution,
then pause to let your body get out in front of the wheel again. When it’s
real steep, you have to do it this way because we are not electric motors.
Each time you do a lunge, it has to be smooth enough to keep the wheel from
losing its grip on the ground (picturing dirt again). So you are combining
the adjustments to maintain balance with a pedal stroke variation that
approaches starting and stopping. In uphill situations especially, if this
happens it’s usually a near-instant dismount, so you must avoid it.

So you’re not trying to start/stop, but if the trail is really, really
steep, it gets similar to doing that.

Sure the whole trail isn’t this steep, but the less-steep stuff just isn’t
that challenging, is it?

> You are confusing the tractional forces which are generated by the
> resistance of ground with the forces that oppose traction which are
> generated by the rider. These forces must be below

Not confusing. When you’re out riding, it’s all the same. Tire grips, tire
stops gripping. In most cases it stops gripping due to non-smooth movements
made by the rider. Though it is possible to “power slide,” meaning to skid
downhill for instance, you cannot consider yourself back “in control” until
your wheel is no longer sliding. Or at least until you are deriving some
degree of control from it, such as when riding down giant sand dunes on Long
Island’s north shore.

> I’d be. It’s braking system is controlled with perhaps a
> reaction time
> of 1 millisecond or better. A human unicyclist may have a
> reaction time
> of about one half a second plus limited power output for
> nearly one half of every full cycle.

It’s the pedal stroke that makes our lives difficult. The limited power
stroke, and the fact that we can’t coast, are two of the factors that make
MUni interesting. So what if the Segway beats us. It is, in effect,
cheating. At least it won’t gloat at us when it gets to the top of the
hill…

> We have to have both race results and rider weights for useful data.
> Having the first and not having the second, still means we have NO
> useful data.

Essentially correct, though it one could get rough numbers from looking at
pictures or video. You would have to know not only tire size and model, but
also tire pressure (a little hard to get from the pictures), but at least
you can estimate which riders are heavier than others…

> How far behind me were you when I reached the finish line of the Great
> Wall of China Unicycle Marathon (down and then up the mountain)?

Far. Yes, Ken has beat me in a race or two, of which that one is probably
the most notable, and definitely the most memorable. Kato was first, Ken
second, me third.

This should remind us that the most important factor in a race of this
nature is almost always the engine, not the machine. Ken was in much better
physical shape for long rides on small wheels than I was.

> The night before, I drank far too much snake schnapps and had a rude
> hangover the day of the race. Many of the racers probably
> did and maybe didn’t get enough sleep either. Maybe, we should
> measure the affects of hangovers and sleep deficent on racing
> performance.

Don’t ask about the snake schnapps. Something I didn’t see served anywhere
at UNICON X. Suffice it to say it was made from a snake that was alive when
we entered the restaurant.

I have also competed (and done well) after a severe lack of sleep. I don’t
have the experience with hangover however. My most notable example of this
was the marathon race at UNICON IV. It started early in the morning after an
extremely late-starting IUF meeting that ran until 3:00am or so. I did not
get to sleep until after 4:00. But somehow I came in third in the race,
having even passed 100 miler Floyd Beattie. Again, my training (that year)
must have been superior.

Stay on top,
JF

Re: Brakes? How?

In a message dated 6/11/02 1:59:45 PM Eastern Daylight Time,
john_foss@asinet.com writes:

> No, the rider has a huge effect, and is the thing that usually causes the
> breakdown in traction on steep surfaces. If unicycles had smooth electric
> motors, we could do much steeper trails before losing our grip.
>

Thats it!! we need unicycles with eletric motors!!!
Harper, ready to build the uni.7??
__
Trevor andersen

Re: Brakes? How?

Sorry, I forgot to finish one of my comments before sending my last post
on the subject. Here it is again, this time completed.

>> Traction is a property of the riding surface and tire and is not
>> usually affected by other parts of the unicycle or the rider.

John Foss <john_foss@asinet.com> wrote:

>No, the rider has a huge effect, and is the thing that usually causes the
>breakdown in traction on steep surfaces. If unicycles had smooth electric
>motors, we could do much steeper trails before losing our grip.

You are confusing the tractional forces which are generated by the
resistance of ground with the forces that oppose traction which are
generated by the rider. These forces must be below the maximum traction
of the riding surface and tire, otherwise the wheel will slide on the
riding surface.

I also should have defined a few terms:

Rolling friction: The friction between a rolling wheel and the surface
upon which it is rolling.

Sliding friction: The friction between a sliding object and the surface
upon which it is sliding. The sliding between the object and surface
taers microscopic particles from both the object and surface which act
as a rough lubricate. This fact makes the coefficient of sliding
friction always smaller than the coefficient of rolling friction.

Coefficient of friction: The ratio of the maximum sliding force tangent
to the riding surface and the force, usually gravity, pushing the object
against the surface. For example, a 100 pound rider/unicycle that can
resist a maximum of 50 pounds tangent to the riding surface has a
coefficient of rolling friction of 50/100 or 1/2.

Sincerely,

Ken Fuchs <kfuchs@winternet.com>

Re: Brakes? How?

>> In other words one’s legs get tired when racing. The same
>> muscle groups that are used in touring and also used in racing,

John Foss <john_foss@asinet.com> wrote:

>Muscle groups, yes. Specific areas of those muscles, no. You are not just
>working the same muscles harder. the effort is applied differently, not just
>the same thing faster. If you simply speeded up the pedaling motion of
>normal riding, your feet would flop all over the place. You have to add
>additional effort to keep them attached to the pedals. If not anything
>else, surely the increase of centripetal (centrifugal?) force means
>something to you.

Yes, of course one would have to practice racing to have a reasonable
chance of winning. I assume John is speaking from personal experience
rather than objective physiological data. The muscle groups are being
used faster and as a consequence more concentration and training is
required to control them, but is the movement really different, other
than being faster?

>> Pedal stroke variation is the minor adjustments to maintain forward /
>> backward balance. Pedal stroke variation is not starting or stopping.

>As the riding surface gets steeper and steeper, these two things get closer
>to being one in the same. On a short downhill, it’s possible to “roll out”
>and let the unicycle pick up lots of speed, as long as this happens near the
>bottom. Riding uphill is a better example. You’re going slow. You are
>pedaling in “steps,” where you lunge forward and pedal a half revolution,
>then pause to let your body get out in front of the wheel again. When it’s
>real steep, you have to do it this way because we are not electric motors.
>Each time you do a lunge, it has to be smooth enough to keep the wheel from
>losing its grip on the ground (picturing dirt again). So you are combining
>the adjustments to maintain balance with a pedal stroke variation that
>approaches starting and stopping. In uphill situations especially, if this
>happens it’s usually a near-instant dismount, so you must avoid it.

>So you’re not trying to start/stop, but if the trail is really, really
>steep, it gets similar to doing that.

OK, I understand the point you are making, but I wouldn’t be calling it
pedal stroke variation as the word variation usually implies small
changes when used in the context of amplitude. Not the changes required
to start or stop.

>Sure the whole trail isn’t this steep, but the less-steep stuff just isn’t
>that challenging, is it?

Sorry, I wasn’t considering hills that are too steep to ride up or down,
only those that would be challenging (not those that are nearly
impossible) to ride up or down.

>> You are confusing the tractional forces which are generated by the
>> resistance of ground with the forces that oppose traction which are
>> generated by the rider. These forces must be below

>Not confusing. When you’re out riding, it’s all the same. Tire grips, tire
>stops gripping. In most cases it stops gripping due to non-smooth movements
>made by the rider. Though it is possible to “power slide,” meaning to skid
>downhill for instance, you cannot consider yourself back “in control” until
>your wheel is no longer sliding. Or at least until you are deriving some
>degree of control from it, such as when riding down giant sand dunes on Long
>Island’s north shore.

Sorry, I didn’t complete my thoughts on this subtopic. I’ve done so in
amother post.

Control can be maintained with a sliding wheel. It is probably even
easier than coasting. I’d say that anyone who can glide, can maintain
control sliding the wheel over the riding surface. However, I’d not
aware of any experts at this skill. Who has done this? Probably very
few, because there are more fun and productive things to do on one wheel.

I can understand that you do not think that a more rigorous
understanding of physics can help you ride muni better, but it certainly
can.

>> I’d be. It’s braking system is controlled with perhaps a
>> reaction time
>> of 1 millisecond or better. A human unicyclist may have a
>> reaction time
>> of about one half a second plus limited power output for
>> nearly one half of every full cycle.

>It’s the pedal stroke that makes our lives difficult. The limited power
>stroke, and the fact that we can’t coast, are two of the factors that make
>MUni interesting. So what if the Segway beats us. It is, in effect,
>cheating. At least it won’t gloat at us when it gets to the top of the
>hill…

The point is that a machine could be built that balances on one wheel
and it could easily improve in balance and ride where no human unicycle
rider would dare go.

I don’t understand what is meant by “we can’t coast”, when a significant
number of unicyclists can coast.

>> We have to have both race results and rider weights for useful data.
>> Having the first and not having the second, still means we have NO
>> useful data.

>Essentially correct, though it one could get rough numbers from looking at
>pictures or video. You would have to know not only tire size and model, but
>also tire pressure (a little hard to get from the pictures), but at least
>you can estimate which riders are heavier than others…

Clearly not objective measurement.

>> How far behind me were you when I reached the finish line of the Great
>> Wall of China Unicycle Marathon (down and then up the mountain)?

>Far. Yes, Ken has beat me in a race or two, of which that one is probably
>the most notable, and definitely the most memorable. Kato was first, Ken
>second, me third.

>This should remind us that the most important factor in a race of this
>nature is almost always the engine, not the machine. Ken was in much better
>physical shape for long rides on small wheels than I was.

Thanks for the compliment!

>> The night before, I drank far too much snake schnapps and had a rude
>> hangover the day of the race. Many of the racers probably
>> did and maybe didn’t get enough sleep either. Maybe, we should
>> measure the affects of hangovers and sleep deficent on racing
>> performance.

>Don’t ask about the snake schnapps. Something I didn’t see served anywhere
>at UNICON X. Suffice it to say it was made from a snake that was alive when
>we entered the restaurant.

The snake schnapps was also very high in alcohol content. I’d like to
think that it was the alcohol content that had the most effect on me the
following day.

>I have also competed (and done well) after a severe lack of sleep. I don’t
>have the experience with hangover however. My most notable example of this
>was the marathon race at UNICON IV. It started early in the morning after an
>extremely late-starting IUF meeting that ran until 3:00am or so. I did not
>get to sleep until after 4:00. But somehow I came in third in the race,
>having even passed 100 miler Floyd Beattie. Again, my training (that year)
>must have been superior.

Thank you John for a very interesting discussion. You don’t need to
comment on this thread further on my account.

Sincerely,

Ken Fuchs <kfuchs@winternet.com>