Hopping Adjustments

I’d like to thank Kris Holm for his support and input regarding my “Hop Along
MUni” article. The points about making small adjustments instead of larger pogo
stick bounces is absolutely correct. When I first started to hop, my balance was
rough and I needed largers adjustments. Now just a few little hops is all that
is needed. As
my/your balance and control improves you will conserve movement to only that
required to achieve your purpose. When hopping up the sides of rocks in small
chunks is like using low gear. Once at the top, dropping with your back foot
slightly below horizontal works well to divert some of the energy of impact
to forward motion. When going off things it’s quite natural and comfortable
to use this crank position I’ve found. Kris’s input appears below for easy
reading. Glad to see Kris pitch in and I hope others will do the same. Happy
Trails. “The Muniac”

Hi,

That was a very informative article by Scott the “Muniac”! Just 2 things I
thought I’d add/reinforce:

Good hopping technique during trials on a unicycle is somewhat different than
hopping on a pogo-stick. Most of the time, the hops can be thought of as
adjustments within a still-stand, as opposed to bouncing. This mindset makes
each hop much more precise than springing up and down all over the place.

For drops, you can either drop with the seat out in front (gripping the side of
the seat) or between your legs. Seat-out-in-front drops are good if there is no
room to roll the wheel upon landing, such as when hopping down onto a boulder.
Most of the time, however, it’s more effective to drop holding the front of the
handle with the seat between your legs. In the latter case, the most important
thing is to get the wheel rolling upon landing!!! This will reduce the load on
the axle to a huge degree. I usually land with my back foot somewhat lower than
the front foot, and roll through the power position (horizontal), upon landing.
The video Evolve has a good illustration of what I mean by rolling through the
landing of a big drop (although the Muniac was right- there is only 1 minute of
Trials Uni in this video. However, the bike trials stuff is really inspirational
and gives good examples of what should be possible on a unicycle).

Cheers,

Kris.

RE: Hopping Adjustments

> I am still not certain of this theory of rolling to help break your fall. If
> you are to roll (as in speed up when you hit the ground) then you must apply
> more force to the forward pedal than to the rearward pedal. It seems that this
> would be bad as well, because although the rear pedal isn’t stressed as much,
> the forward pedal is stressed even more than if there were zero rollout.

But you’re not applying more force. Same jump, same amount of force. The
question is how to dissapate the energy. If you land “static”, both pedals take
an equal amount of stress, applying twisting forces to the axle (and cranks).
And it all happens in the same direction.

If you add some roll to your landing, the idea is for the wheel to rotate
while you are absorbing the impact. So the landing force is partially rotated
against your crankset as you absorb it, presumably spreading out the stresses to
the cycle’s parts.

Mind you, this rolling while landing is a fairly advanced skill. The main
prerequisite is being able to land the jump in the first place, before worrying
about adding the roll.

Hope this helps… I never took a physics class in my life, but I can “feel”
it.

John Foss, the Uni-Cyclone (reply to jfoss@unicycling.com)
http://www.unicycling.com

“Downhill sucks.” - George Peck, on the downhill course at NUC '99

RE: Hopping Adjustments

> I am still not certain of this theory of rolling to help break your fall. If
> you are to roll (as in speed up when you hit the ground) then you must apply
> more force to the forward pedal than to the rearward pedal. It seems that this
> would be bad as well, because although the rear pedal isn’t stressed as much,
> the forward pedal is stressed even more than if there were zero rollout. So
> you only break one side of your axle.
>
> UNLESS… Unless by “rolling out” you are somehow increasing your
> stopping distance by more than you are increasing the load on your forward
> pedal. Could this be what is happening? Help me out here-
>
>
Here’s my take on this. The 3 foot drop gives potential energy to your mass;
when you roll off that drop, the energy turns into a force vector that’s
heading almost straight downward, courtesy of gravity. By rolling through the
landing, that force is distributed and dissipated (as John said); it doesn’t
simply go straight down, but also goes forward. But this begs yet another
question–if someone (not me!!) hopped off, say, a picnic table sideways, would
a rolling landing make a difference in the same way it would if the rider just
rode forward off the table’s edge? That is, the motion taking the rider away
from the table isn’t toward the front, but to the side of the unicycle; the way
the uni & rider would respond to the force vectors would be quite different,
wouldn’t they?

If I’d paid better attention in those statics and dynamics courses as an
undergrad, I’d probably be able to talk about this more clearly (but I also
wouldn’t have found myself on the English faculty, so fair enough …) Peter

Re: Hopping Adjustments

When you drop off something, it’s true that you do punch the rear wheel before
you continue rolling. However, the force involved is much less than stopping
dead. In addition, this technique works when you land on steep ground, where you
most likely could not have stopped anyway. In cases where you are dropping off
an embankment that ends on less-steep ground, try landing so that you impact the
last 6" of the embankment (or so). This starts the wheel rolling, takes most of
the shock out of the drop, and (if you do it right), should leave you rolling
slowly through the landing area.

-Kris.

— Chris Reeder <reed8990@uidaho.edu> wrote:
> I try to keep my weight off the seat when going off ledges, because when I hit
> the seat it’s because my legs (shock absorbers) weren’t enough to break the
> impact. The seat, of course, stops me REALLY FAST, so much that it hurts. So I
> try to stay off the seat.
>
> Another way of looking at the forces on the pedals is in terms of energy.
> Energy is a force times a distance. So, I weigh 165 lb (unicycle included) and
> I drop off, say, a three foot ledge. The kinetic energy right before reaching
> the ground is 165 lbs * 3 ft= 495 lb*ft. That means it will also take 495
> lb*ft to break my fall when I hit the bottom. Now let’s say I have about 8
> inches of flex between bending my knees and tire flex before I bottom out onto
> my seat and get hurt, so I have to stop at the bottom in 8 inches (.67 ft).
> (495 lb*ft)/0.67 ft = 738 lb of force applied to the pedals to get me stopped.
> Not bad. But if you lock your knees, as George already indicated is BAD, you
> decrease your stopping distance to about three inches (tire flex plus a little
> flex in your ankles) and you get (495 lb*ft)/0.25 ft = a whopping 1980 lb.
> Indeed, a good way to break axles.
>
>
> I am still not certain of this theory of rolling to help break your fall. If
> you are to roll (as in speed up when you hit the ground) then you must apply
> more force to the forward pedal than to the rearward pedal. It seems that this
> would be bad as well, because although the rear pedal isn’t stressed as much,
> the forward pedal is stressed even more than if there were zero rollout. So
> you only break one side of your axle.
>
> UNLESS… Unless by “rolling out” you are somehow increasing your
> stopping distance by more than you are increasing the load on your forward
> pedal. Could this be what is happening? Help me out here-
>
> Chris
>
>
>
> george peck wrote:
>
> >>
> >
> > You could land without rollout and put zero force
> (your mass plus
> > whatever acceleration) on the pedals. But, ooooh,
> that would hurt
> > because the spine would take it all.
> >
> > Or, you could stand up, or have the seat in front,
> and let the pedals
> > take it all. To reduce the impulse ( force per
> unit time) you want to
> > spread the landing out over as long a time period
> as possible…this
> > means taking the shock with the knees and
> distributing the force over
> > the time interval it takes to compress. But, this
> is very hard to do,
> > the tendency being to lock up, and let the pedals
> take the full
> > instantaneous hit…very bad…this creates huge
> bending moments at
> > the axle ends.
> >
> > Or, you could roll out, which basically converts
> some of the bending
> > moment on the axle to torque on the axle. The more
> you roll, the more
> > you tend to lessen the bending moment and dump
> that energy into
> > torque.
> >
> > george
>
>


Do You Yahoo!? Talk to your friends online with Yahoo! Messenger.
http://im.yahoo.com

Re: Hopping Adjustments

<!doctype html public “-//w3c//dtd html 4.0 transitional//en”> <html> <font
color=“#3333FF”>Peter,</font> <br><font color=“#3333FF”>I think what you’re
trying to say is that my momentum vector is going downward, courtesy of
gravity. Now it takes force to change my momentum from vertically
downward to vertically stopped. But, to stop all of my downward motion,
plus add some forward motion, that will take even more force. That
still leaves us with a broken axle and not much explanation. But I’m going
to go out and try it today. I hope it’s true, even if we don’t
understand why.</font><font color=“#3333FF”></font>
<p><font color=“#3333FF”>Another thought-- if the forward rollout were
downhill, rolling forward would effectively increase your vertical stopping
distance, and would require less force to cushion you. But I assume we
were talking about landing on the flat.</font><font color=“#3333FF”></font>
<q><font color=“#3333FF”>Chris</font> <br><font color=“#3333FF”></font>
<br><font color=“#3333FF”></font> <font color=“#3333FF”></font>
<r>“Kittle, Peter” wrote: <blockquote TYPE=CITE> <br>Here’s my take on
this. The 3 foot drop gives potential energy to your mass; <br>when you roll
off that drop, the energy turns into a force vector that’s <br>heading almost
straight downward, courtesy of gravity. By rolling through <br>the landing,
that force is distributed and dissipated (as John said); it <br>doesn’t
simply go straight down, but also goes forward. But this begs yet <br>another
question–if someone (not me!!) hopped off, say, a picnic table <br>sideways,
would a rolling landing make a difference in the same way it would <br>if the
rider just rode forward off the table’s edge? That is, the motion <br>taking
the rider away from the table isn’t toward the front, but to the side <br>of
the unicycle; the way the uni & rider would respond to the force vectors
<br>would be quite different, wouldn’t they?
<s>If I’d paid better attention in those statics and dynamics courses as an
<br>undergrad, I’d probably be able to talk about this more clearly (but I
also <br>wouldn’t have found myself on the English faculty, so fair enough
…) <br>Peter</blockquote> </html

Re: Hopping Adjustments

Well I know youre sopposed to roll if you fall out of a car. But riding off a 3
foot drop has no forward momentum, only downward. So by pedaling forward I dont
think it would dissapate the force since you actually have to pedal to go
forward. I think if you fall your gonna hit at set amount of force, this can be
dissapted by shock absorbers or other things, but unless you have rocket
boosters your gonna land at the same force wether you pedal or not. I think.

“Kittle, Peter” <pkittle@csuchico.edu> wrote in message
news:A154FC0C2AC8D111BE4F00805F6FDFF6F2A087@MESQUITE
> > I am still not certain of this theory of rolling to help break your fall. If
> > you are to roll (as in speed up when you hit the ground) then you must apply
> > more force to the forward pedal than to the rearward pedal. It seems that
> > this would be bad as well, because although the rear pedal isn’t stressed as
> > much, the forward pedal is stressed even more than if there were zero
> > rollout. So you only break one side of your axle.
> >
> > UNLESS… Unless by “rolling out” you are somehow increasing your
> > stopping distance by more than you are increasing the load on your forward
> > pedal. Could this be what is happening? Help me out here-
> >
> >
> Here’s my take on this. The 3 foot drop gives potential energy to your
mass;
> when you roll off that drop, the energy turns into a force vector that’s
> heading almost straight downward, courtesy of gravity. By rolling through the
> landing, that force is distributed and dissipated (as John said); it doesn’t
> simply go straight down, but also goes forward. But this begs yet another
> question–if someone (not me!!) hopped off, say, a picnic table sideways,
> would a rolling landing make a difference in the same way it
would
> if the rider just rode forward off the table’s edge? That is, the motion
> taking the rider away from the table isn’t toward the front, but to the
side
> of the unicycle; the way the uni & rider would respond to the force
vectors
> would be quite different, wouldn’t they?
>
> If I’d paid better attention in those statics and dynamics courses as an
> undergrad, I’d probably be able to talk about this more clearly (but I
also
> wouldn’t have found myself on the English faculty, so fair enough …) Peter

Re: Hopping Adjustments

Okay, I went out and tried it. An easy 15" ledge on the Main Street fountain in
Moscow, Idaho. Here’s what happens:

In order to ride off the ledge, you are already rolling. (3-4 mph, probably) So
when you hit the ground, you naturally keep rolling. Like Kris said, landing
with the rear pedal low works well. Then by the time you’re done absorbing the
impact, your front pedal is low, but not out of reach.

Next, I tried to stop on a dime when I landed it. I wasn’t very successful at
stopping on a dime, but essentially you end up putting most or all of your
weight onto the rear pedal in order to come screeching to a halt. That’s why
it’s hard on axles.

So the jumping sideways off the picnic table thing-- adding rollout would only
make that worse.

Chris

Jacob Koski wrote:

> Well I know youre sopposed to roll if you fall out of a car. But riding off
> a 3 foot drop has no forward momentum, only downward. So by pedaling forward
> I dont think it would dissapate the force since you actually have to pedal
> to go forward. I think if you fall your gonna hit at set amount of force,
> this can be dissapted by shock absorbers or other things, but unless you
> have rocket boosters your gonna land at the same force wether you pedal or
> not. I think.

Re: Hopping Adjustments

Okay, I went out and tried it. An easy 15" ledge on the Main Street fountain in
Moscow, Idaho. Here’s what happens:

In order to ride off the ledge, you are already rolling. (3-4 mph, probably) So
when you hit the ground, you naturally keep rolling. Like Kris said, landing
with the rear pedal low works well. Then by the time you’re done absorbing the
impact, your front pedal is low, but not out of reach.

Next, I tried to stop on a dime when I landed it. I wasn’t very successful at
stopping on a dime, but essentially you end up putting most or all of your
weight onto the rear pedal in order to come screeching to a halt. That’s why
it’s hard on axles.

So the jumping sideways off the picnic table thing-- adding rollout would only
make that worse.

Chris

Jacob Koski wrote:

> Well I know youre sopposed to roll if you fall out of a car. But riding off
> a 3 foot drop has no forward momentum, only downward. So by pedaling forward
> I dont think it would dissapate the force since you actually have to pedal
> to go forward. I think if you fall your gonna hit at set amount of force,
> this can be dissapted by shock absorbers or other things, but unless you
> have rocket boosters your gonna land at the same force wether you pedal or
> not. I think.

Re: Hopping Adjustments

Okay, I went out and tried it. An easy 15" ledge on the Main Street fountain in
Moscow, Idaho. Here’s what happens:

In order to ride off the ledge, you are already rolling. (3-4 mph, probably) So
when you hit the ground, you naturally keep rolling. Like Kris said, landing
with the rear pedal low works well. Then by the time you’re done absorbing the
impact, your front pedal is low, but not out of reach.

Next, I tried to stop on a dime when I landed it. I wasn’t very successful at
stopping on a dime, but essentially you end up putting most or all of your
weight onto the rear pedal in order to come screeching to a halt. That’s why
it’s hard on axles.

So the jumping sideways off the picnic table thing-- adding rollout would only
make that worse.

Chris

Jacob Koski wrote:

> Well I know youre sopposed to roll if you fall out of a car. But riding off
> a 3 foot drop has no forward momentum, only downward. So by pedaling forward
> I dont think it would dissapate the force since you actually have to pedal
> to go forward. I think if you fall your gonna hit at set amount of force,
> this can be dissapted by shock absorbers or other things, but unless you
> have rocket boosters your gonna land at the same force wether you pedal or
> not. I think.

Re: Hopping Adjustments

Chris Reeder <reed8990@uidaho.edu> wrote:

>Okay, I went out and tried it. An easy 15" ledge on the Main Street fountain in
>Moscow, Idaho. Here’s what happens:

>In order to ride off the ledge, you are already rolling. (3-4 mph, probably) So
>when you hit the ground, you naturally keep rolling. Like Kris said, landing
>with the rear pedal low works well. Then by the time you’re done absorbing the
>impact, your front pedal is low, but not out of reach.

>Next, I tried to stop on a dime when I landed it. I wasn’t very successful at
>stopping on a dime, but essentially you end up putting most or all of your
>weight onto the rear pedal in order to come screeching to a halt. That’s why
>it’s hard on axles.

The above sounds perfectly reasonable.

>So the jumping sideways off the picnic table thing-- adding rollout would only
>make that worse.

However, this last conclusion is false. I would expect that rollout
perpenticular to unicycle motion would also reduce stress throughout the impact,
since more spokes are stressed and give and the stress on the axle is
distributed over the arc of the angle tranversed during impact.

Without rollout, the energy of impact is distributed over a minimum number of
spokes and minimum volume of the axle. The stress is concentrated over the same,
smallest part of the wheel possible throughout the entire impact.

With rollout, the energy of impact is distributed over more spokes and through a
greater volume of the axle. The stress is distributed throughout the entire
impact arc.

Sincerely,

Ken Fuchs <kfuchs@winternet.com>

Microsoft has finally found someone it can’t bully into submission: US
Department of Justice - http://www.usdoj.gov/atr/cases/ms_index.htm Yahoo links

Re: Hopping Adjustments

Ken Fuchs wrote:

> >So the jumping sideways off the picnic table thing-- adding rollout would
> >only make that worse.
>
> However, this last conclusion is false. I would expect that rollout
> perpenticular to unicycle motion would also reduce stress throughout the
> impact, since more spokes are stressed and give and the stress on the axle is
> distributed over the arc of the angle tranversed during impact.
>
> Without rollout, the energy of impact is distributed over a minimum number of
> spokes and minimum volume of the axle. The stress is concentrated over the
> same, smallest part of the wheel possible throughout the entire impact.
>
> With rollout, the energy of impact is distributed over more spokes and through
> a greater volume of the axle. The stress is distributed throughout the entire
> impact arc.
>
> Sincerely,
>
> Ken Fuchs

Actually, whether you stress five spokes for 0.1 seconds or stress 20 spokes
each for 0.025 seconds, the stress level you’ve subjected each spoke to is the
same, and in fracture mechanics it still counts as one stress “cycle” toward the
life of the part. So you haven’t gained anything by rolling. You’ve just
decreased the amount of time that any one spoke is stressed. And like I said,
the amount of time doesn’t matter, yet the number of times does.

Chris Reeder

Re: Hopping Adjustments

<!doctype html public “-//w3c//dtd html 4.0 transitional//en”> <html>

<blockquote TYPE=CITE> </blockquote> <Kris Holm wrote: <br>
<Seat-out-in-front drops are good if there is no<br> <room to roll the
wheel upon landing, such as when<br> <hopping down onto a boulder. Most of
the time,<br> <however, it’s more effective to drop holding the front<br>
<of the handle with the seat between your legs. In<br> <the
latter case, the most important thing is to get<br> <the wheel rolling upon
landing!!! This will reduce the<br> <load on the axle to a huge degree.
I usually land<br> <with my back foot somewhat lower than the front foot,<br>
<and roll through the power position (horizontal), upon<br> <landing.<font
color=“#3333FF”></font>
<p><font color=“#3333FF”>Could someone explain to me why rolling on impact will
lessen the stress on the axle? Does it also lessen the stress on the
body?</font><font color=“#3333FF”></font>
<q><font color=“#3333FF”>Chris Reeder</font> <br> </html

Re: Hopping Adjustments

--------------AD595B7CF782DD7C7F78491B Content-Type: text/plain;
charset=us-ascii; x-mac-type=“54455854”; x-mac-creator=“4D4F5353”
Content-Transfer-Encoding: 7bit

Chris Reeder wrote:

>
>
>>
>
> <Kris Holm wrote: <Seat-out-in-front drops are good if there is no <room to
> roll the wheel upon landing, such as when <hopping down onto a boulder. Most
> of the time, <however, it’s more effective to drop holding the front <of the
> handle with the seat between your legs. In <the latter case, the most
> important thing is to get <the wheel rolling upon landing!!! This will reduce
> the <load on the axle to a huge degree. I usually land <with my back foot
> somewhat lower than the front foot, <and roll through the power position
> (horizontal), upon <landing.
>
> Could someone explain to me why rolling on impact will lessen the stress on
> the axle? Does it also lessen the stress on the body?
>
> Chris Reeder
>

You could land without rollout and put zero force (your mass plus whatever
acceleration) on the pedals. But, ooooh, that would hurt because the spine would
take it all.

Or, you could stand up, or have the seat in front, and let the pedals take it
all. To reduce the impulse ( force per unit time) you want to spread the landing
out over as long a time period as possible…this means taking the shock with
the knees and distributing the force over the time interval it takes to
compress. But, this is very hard to do, the tendency being to lock up, and let
the pedals take the full instantaneous hit…very bad…this creates huge
bending moments at the axle ends.

Or, you could roll out, which basically converts some of the bending moment on
the axle to torque on the axle. The more you roll, the more you tend to lessen
the bending moment and dump that energy into torque.

george

--------------AD595B7CF782DD7C7F78491B Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: 7bit

<!doctype html public “-//w3c//dtd html 4.0 transitional//en”> <html>
<p>Chris Reeder wrote: <blockquote TYPE=CITE> <blockquote
TYPE=CITE> </blockquote> <Kris Holm wrote: <br>
<Seat-out-in-front drops are good if there is no <br><room to roll the
wheel upon landing, such as when <br><hopping down onto a boulder. Most of
the time, <br><however, it’s more effective to drop holding the front
<br><of the handle with the seat between your legs. In
<br><the latter case, the most important thing is to get <br><the wheel
rolling upon landing!!! This will reduce the <br><load on the axle to a
huge degree. I usually land <br><with my back foot somewhat lower
than the front foot, <br><and roll through the power position
(horizontal), upon <br><landing.
<q><font color=“#3333FF”>Could someone explain to me why rolling on impact will
lessen the stress on the axle? Does it also lessen the stress on the
body?</font>
<r><font color=“#3333FF”>Chris Reeder</font> <br> </blockquote> You could
land without rollout and put zero force (your mass plus whatever
acceleration) on the pedals. But, ooooh, that would hurt because the spine
would take it all.
<s>Or, you could stand up, or have the seat in front, and let the pedals take it
all. To reduce the impulse ( force per unit time) you want to spread the
landing out over as long a time period as possible…this means taking
the shock with the knees and distributing the force over the time interval it
takes to compress. But, this is very hard to do, the tendency being to lock
up, and let the pedals take the full instantaneous hit…very
bad…this creates huge bending moments at the axle ends.
<t>Or, you could roll out, which basically converts some of the bending moment
on the axle to torque on the axle. The more you roll, the more you tend to
lessen the bending moment and dump that energy into torque.
<u>george</html>

--------------AD595B7CF782DD7C7F78491B–

Re: Hopping Adjustments

I try to keep my weight off the seat when going off ledges, because when I hit
the seat it’s because my legs (shock absorbers) weren’t enough to break the
impact. The seat, of course, stops me REALLY FAST, so much that it hurts. So I
try to stay off the seat.

Another way of looking at the forces on the pedals is in terms of energy.
Energy is a force times a distance. So, I weigh 165 lb (unicycle included) and
I drop off, say, a three foot ledge. The kinetic energy right before reaching
the ground is 165 lbs * 3 ft= 495 lbft. That means it will also take 495 lbft
to break my fall when I hit the bottom. Now let’s say I have about 8 inches of
flex between bending my knees and tire flex before I bottom out onto my seat
and get hurt, so I have to stop at the bottom in 8 inches (0.67 ft). (495
lbft)/0.67 ft = 738 lb of force applied to the pedals to get me stopped. Not
bad. But if you lock your knees, as George already indicated is BAD, you
decrease your stopping distance to about three inches (tire flex plus a little
flex in your ankles) and you get (495 lb
ft)/0.25 ft = a whopping 1980 lb.
Indeed, a good way to break axles.

I am still not certain of this theory of rolling to help break your fall. If you
are to roll (as in speed up when you hit the ground) then you must apply more
force to the forward pedal than to the rearward pedal. It seems that this would
be bad as well, because although the rear pedal isn’t stressed as much, the
forward pedal is stressed even more than if there were zero rollout. So you only
break one side of your axle.

UNLESS… Unless by “rolling out” you are somehow increasing your stopping
distance by more than you are increasing the load on your forward pedal. Could
this be what is happening? Help me out here-

Chris

george peck wrote:

>>
>
> You could land without rollout and put zero force (your mass plus whatever
> acceleration) on the pedals. But, ooooh, that would hurt because the spine
> would take it all.
>
> Or, you could stand up, or have the seat in front, and let the pedals take it
> all. To reduce the impulse ( force per unit time) you want to spread the
> landing out over as long a time period as possible…this means taking the
> shock with the knees and distributing the force over the time interval it
> takes to compress. But, this is very hard to do, the tendency being to lock
> up, and let the pedals take the full instantaneous hit…very bad…this
> creates huge bending moments at the axle ends.
>
> Or, you could roll out, which basically converts some of the bending moment on
> the axle to torque on the axle. The more you roll, the more you tend to lessen
> the bending moment and dump that energy into torque.
>
> george

Re: Hopping Adjustments

Chris Reeder wrote:
>
> Could someone explain to me why rolling on impact will lessen the stress on
> the axle?

By rolling on impact you are putting less force on the pedals and more on the
seat. When the force is on the pedals, there is a lot more stress on the axle
since the force is applied on a crank arm and applies leverage to the axle. This
causes both a moment and torque on the axle. If force (weight) is put on the
seat, this translates to a direct force on the axle where the bearings are and
then results in a smaller moment and no torque applied to the axle resulting in
less stress on the axle.

To stay on the unicycle you have to have some force on the pedals, however, the
less you apply to the pedals and the more to the seat, then there will be less
stress on the axle.

> Does it also lessen the stress on the body?

A little bit since you are rolling in the direction that the unicycle and your
body are already going. The stress on the body will also be in a different
place… where ever the force is applied.

    ___________ =================================================== ___ /_/
    / / / / Kevin Gilbertson - mail@gilby.com <a href="http://gilby.com/">http://gilby.com</a> / _ '/ / /
    _'\_ / IT-Labs: gilb0179@itlabs.umn.edu \_ /_/_/,___/ / Free
    Unicyclist.com e-Mail at <a href="http://unicyclist.com/">http://unicyclist.com</a> /\/ /__________/ World
    UNICON X: <a href="http://www.unicycling.org/iuf/unicon10">http://www.unicycling.org/iuf/unicon10</a> \__/
    ========================================================

Re: Hopping Adjustments

So you’re saying that in order to reduce the stress on the axle, you should just
sit on the seat when you drop off the ledge and let the frame take the blunt of
it. OUCH!!!

Please write again if this is not what you had in mind.

Chris

Kevin Gilbertson wrote:

> Chris Reeder wrote:
> >
> > Could someone explain to me why rolling on impact will lessen the stress on
> > the axle?
>
> By rolling on impact you are putting less force on the pedals and more on the
> seat. When the force is on the pedals, there is a lot more stress on the axle
> since the force is applied on a crank arm and applies leverage to the axle.
> This causes both a moment and torque on the axle. If force (weight) is put on
> the seat, this translates to a direct force on the axle where the bearings are
> and then results in a smaller moment and no torque applied to the axle
> resulting in less stress on the axle.
>
> To stay on the unicycle you have to have some force on the pedals, however,
> the less you apply to the pedals and the more to the seat, then there will be
> less stress on the axle.
>
> > Does it also lessen the stress on the body?
>
> A little bit since you are rolling in the direction that the unicycle and your
> body are already going. The stress on the body will also be in a different
> place… where ever the force is applied.
> –
> ___________ =================================================== ___
> /_/ / / / / Kevin Gilbertson - mail@gilby.com http://gilby.com / _ '/
> / / '_ / IT-Labs: gilb0179@itlabs.umn.edu _ ///,__/ / Free
> Unicyclist.com e-Mail at http://unicyclist.com // /__________/ World
> UNICON X: http://www.unicycling.org/iuf/unicon10 __/
> ========================================================

Re: Hopping Adjustments

Chris Reeder wrote:
>
> So you’re saying that in order to reduce the stress on the axle, you should
> just sit on the seat when you drop off the ledge and let the frame take the
> blunt of it. OUCH!!!
>
> Please write again if this is not what you had in mind.

That’s somewhat right, but if you do put no force on the pedals the unicycle
will roll out from underneath you. That’s what the unicycle wants to do to
balance the forces applied to it. What you need is the point where you have
enough pressure on the pedals to have control over the unicycle and then the
rest on the seat. When you have less force on the pedals then the wheel will
move and that will make it where less force is applied from your body to the
unicycle and result in less stress overall.

George Peck’s explanation is the same concept as mine, but his explanation is a
little better.

    ___________ =================================================== ___ /_/
    / / / / Kevin Gilbertson - mail@gilby.com <a href="http://gilby.com/">http://gilby.com</a> / _ '/ / /
    _'\_ / ICQ: 12611076 AIM/AOL: UnicyclingGilby \_ /_/_/,___/ / Free
    Unicyclist.com e-Mail at <a href="http://unicyclist.com/">http://unicyclist.com</a> /\/ /__________/ World
    UNICON X: <a href="http://www.unicycling.org/iuf/unicon10">http://www.unicycling.org/iuf/unicon10</a> \__/
    ========================================================