how much faster?

well, what kind of riding do you do? If its for sheer distance
purposes, you should probably look into a coker.

e39m5

--
e39m5
------------------------------------------------------------------------
e39m5's Profile: http://www.unicyclist.com/profile/9836
View this thread: http://www.unicyclist.com/thread/40623

yeah, it's faster, but they're both slow as hell. Get a bike if you are
actually thinking about practicality.

--
gerblefranklin - Trials Unicyclist

http://gallery.unicyclist.com/Trials-Muni

Nick's main man.

"The genesis of genocide is like a Pagan religion; carefully hidden,
woven into the holidays of a Christian."-Immortal Technique
------------------------------------------------------------------------
gerblefranklin's Profile: http://www.unicyclist.com/profile/4295
View this thread: http://www.unicyclist.com/thread/40623

Musketman wrote:
-"This is a boring question but is a 24" tyre much faster than a 20"
tyre? Cuz im sick of pedaling so fast and going nowhere"-

The simple answer is:
Yes, a 24" is noticeably faster than a 20".

But, whenever I'm pedaling a 24" it feels like the thing is going
nowhere. Consider a 26" or even better, a 29" Unicycle.

--
roadkill - Crash Test Dummy

"Anyone who has never made a mistake has never tried anything new." -
Albert Einstein
------------------------------------------------------------------------
roadkill's Profile: http://www.unicyclist.com/profile/9784
View this thread: http://www.unicyclist.com/thread/40623

Multiply the diameter times pi to find out the circumference. Subtract
the smaller number (small tire) from the big one. Whatever's left over
is how much farther you'll go with each turn of the pedals.

This of course rules out *pedaling faster*...

--
johnfoss - The wilder Wilder

John Foss, the Uni-Cyclone
"jfoss" at "unicycling.com" -- www.unicycling.com

"Read the rules!" -- 'IUF Rulebook'
(http://www.unicycling.org/iuf/rulebook/) -- 'USA Rulebook'
(http://www.unicycling.org/usa/competition/)
------------------------------------------------------------------------
johnfoss's Profile: http://www.unicyclist.com/profile/832
View this thread: http://www.unicyclist.com/thread/40623

say after me "'Constant Footspeed Hypothesis'
(http://tinyurl.com/cmjmd)"

say it 'again' (http://tinyurl.com/88n98) and 'again'
(http://tinyurl.com/bqdqc)

happy reading

--
GILD - Waffle-[censored], Time-bider and JCTK

if you can't say anything good about someone, sit right here by me.--
'alice' (http://www.timeanddate.com/worldclock/custom.html?) 'roosevelt'
(http://tinyurl.com/963jr) 'longworth' (http://tinyurl.com/78ybd)

I feel like a fugitive from the law of averages.-- William H.
Mauldin
...using nietzsche's metaphysics to escape from
christianity...-'metro_tramp on the value of metaphysics'
(http://tinyurl.com/4sjw6)-
it's hard to be sure, and good to be paranoid...john childs on life on
the internet
'NAMASTE!' (http://tinyurl.com/4qcxw)
'Dave' (http://www.lyricsdir.com/d/deep-purple/child-in-time.php)
------------------------------------------------------------------------
GILD's Profile: http://www.unicyclist.com/profile/657
View this thread: http://www.unicyclist.com/thread/40623

If I did my math right (I got up 45 minutes ago, which isn't long for
me) if you pedal at the same rpm, a 24 inch goes 1.2 times as fast as a
20 inch.

--
Unicyclist of Oz - Level 5 Unicyclist

"-Hello. How are you?
-No cucumber."
--My dumb brother talking to a Subway employee
------------------------------------------------------------------------
Unicyclist of Oz's Profile: http://www.unicyclist.com/profile/9862
View this thread: http://www.unicyclist.com/thread/40623

If you want speed but still want to unicycle, why not just learn to
glide down hills which would make it faster and less tiring, or you
could just get a geared unicycle.

--
ur - Unicycling Revolution
------------------------------------------------------------------------
ur's Profile: http://www.unicyclist.com/profile/4199
View this thread: http://www.unicyclist.com/thread/40623

...in that case, get a motorcycle.

gerblefranklin said:

*yeah, it's faster, but they're both slow as hell. Get a bike if you
are actually thinking about practicality. *

--
mscalisi - Not such a newbie anymore
------------------------------------------------------------------------
mscalisi's Profile: http://www.unicyclist.com/profile/4961
View this thread: http://www.unicyclist.com/thread/40623

Ken Cline said:

*'GILD said:

say after me "'Constant Footspeed Hypothesis'

Do you mean to imply that the "constant footspeed hypothesis" is a
good model for describing the speed we obtain on different unicycles?*

no, but it's a hell of a fun read

the posts i linked to make it quite clear that it's more of a bit of fun
and a very broad 'rule of thumb' than serious scientific stuff
i've allways enjoyed the discussions around that topic and i didn't want
a new person to the forum to never know the same joy

--
GILD - Waffle-[censored], Time-bider and JCTK

if you can't say anything good about someone, sit right here by me.--
'alice' (http://www.timeanddate.com/worldclock/custom.html?) 'roosevelt'
(http://tinyurl.com/963jr) 'longworth' (http://tinyurl.com/78ybd)

I feel like a fugitive from the law of averages.-- William H.
Mauldin
...using nietzsche's metaphysics to escape from
christianity...-'metro_tramp on the value of metaphysics'
(http://tinyurl.com/4sjw6)-
it's hard to be sure, and good to be paranoid...john childs on life on
the internet
'NAMASTE!' (http://tinyurl.com/4qcxw)
'Dave' (http://www.lyricsdir.com/d/deep-purple/child-in-time.php)
------------------------------------------------------------------------
GILD's Profile: http://www.unicyclist.com/profile/657
View this thread: http://www.unicyclist.com/thread/40623

Ken Cline said:

*Unfortunately, this theory ignores the energy required of the
rider.
If reduce wheel size and crank size proportionally with that, you'll
quickly find you can't spin fast enough to keep up with the original
wheel. The reason is that your foot has to accelerate faster on the
smaller wheel, and that takes more energy.

As an alternative, I suggest considering a "constant foot
acceleration
hypothesis", where pedalling energy, rather than foot speed, is
maintained as a constant. If you do this, you find that the cranks
on
smaller unicycles need to be proportionally smaller than those on
larger wheels to maintain the same forward speed. This means you
have
proportionally less torque on the smaller wheel, which is
consequently
harder to control. If you keep cranks within a reasonable range
(which depends on rider skill), you'll find that bigger wheels go
faster.
*

It is a rule of thumb, no-one's suggesting it's anything more than that.
However, lots of experienced riders of short cranks / big wheels seem to
think it's a pretty good one. In my experience over thousands of miles
on each, it works okay between a 29" and a 36" wheel until you get to
very silly short cranks (<100mm) on the 29er where you're just so
lacking in control that the bumps take you off.

It's nice to calculate some super clever answer, but that's never going
to be much use as a rule of thumb that you can just work out in your
head. It still going to be inaccurate due to the many variables ignored
by both methods, such as the different weight of the wheel relative to
the foot / the moving parts of the body / the rider, the differing
accelerations of various body parts and how that relates to the
acceleration of the foot, ie. what percentage of the body weight you're
accelerating is just going round in circles etc.

Joe

--
joemarshall - dumb blonde

my pics http://gallery.unicyclist.com/album483
------------------------------------------------------------------------
joemarshall's Profile: http://www.unicyclist.com/profile/1545
View this thread: http://www.unicyclist.com/thread/40623

joemarshall said:

It is a rule of thumb, no-one's suggesting it's anything more than that.
However, lots of experienced riders of short cranks / big wheels seem to
think it's a pretty good one.

As a rule of thumb it is great. Changing crank length proportionally
with wheel size makes sense since it yields equal force on thewheel
when making control corrections.

What doesn't make sense is pretending that pedal velocity is a primary
factor in determining riding speed. It is not. The term "constant
footspeed hypothesis" is misleading. Come up with a different name
and I'll stop complaining.

Ken

Ken Cline said:

*As an alternative, I suggest considering a "constant foot
acceleration
hypothesis", where pedalling energy, rather than foot speed, is
maintained as a constant. If you do this, you find that the cranks
on
smaller unicycles need to be proportionally smaller than those on
larger wheels to maintain the same forward speed. This means you
have
proportionally less torque on the smaller wheel, which is
consequently
harder to control. If you keep cranks within a reasonable range
(which depends on rider skill), you'll find that bigger wheels go
faster. *

Have you run any sample calculations for constant foot acceleration
compared to constant foot speed? I'm too lazy to run the numbers right
now and it has also been a long time since I've done any dynamics so I'm
all rusty with the equations.

I can see how acceleration is a better measurement than speed since your
feet are moving in a fast circle. Anything moving around in a circle is
accelerating even if it is moving at a constant speed.

--
john_childs - Guinness Mojo

john_childs (att) hotmail (dott) com
Gallery: '' (http://www.unicyclist.com/gallery/john_childs)
' Unicycling Bookmark List' (http://backcountry.unicyclist.com/) ::
'World Clock' (http://tinyurl.com/a99y3) >>>'Click Me'
(http://tinyurl.com/963jr)<<<
------------------------------------------------------------------------
john_childs's Profile: http://www.unicyclist.com/profile/449
View this thread: http://www.unicyclist.com/thread/40623

musketman said:

*This is a boring question but is a 24" tyre much faster than a 20"
tyre? Cuz im sick of pedaling so fast and going nowhere! *

Let's make it interesting, then. A 20" tire dropped from a tall building
is much faster than a 24" tire that is on the floor. They are the same
speed when they are duct-taped together. Putting a person on a unicycle
with one of these tires attached in a conventional manner adds
complications which make it not as fun or interesting.

A 20" tire fired from a canon is much faster than a 24" tire thrown from
a mule. A 24" tire being carried by a camel, however, is faster than a
20" tire at the bottom of a still pond.

--
harper - TANKED at GASWORKS

-Greg Harper

B L U E S H I F T

"My world view has come crashing down like a drunk clown on a giraffe,
riding through a cactus patch..." -evil-nick on "Entry of the
Gladiators"
------------------------------------------------------------------------
harper's Profile: http://www.unicyclist.com/profile/426
View this thread: http://www.unicyclist.com/thread/40623

mscalisi said:

*...in that case, get a motorcycle. *

...with a 1000cc engine. Anything smaller than that is just too slow!

--
corbin - Treehouse Muni Rider

http://www.corbinstreehouse.com
------------------------------------------------------------------------
corbin's Profile: http://www.unicyclist.com/profile/7561
View this thread: http://www.unicyclist.com/thread/40623

GILD said:

*say after me "'Constant Footspeed Hypothesis'
(http://tinyurl.com/cmjmd)"

say it 'again' (http://tinyurl.com/88n98) and 'again'
(http://tinyurl.com/bqdqc)

happy reading *

Thanks GILD. These are great posts.

Lots of fun to read.

--
munipsycho - CrashTestDummies are us.

=====================
'Victory belongs now to this small tree.'
(http://munipsycho.com/stories/a_little_tree.jsp)

'The UniSkills Assessment' (http://www.munipsycho.com/uniskills_2.jsp)

I can fly too. But I can only fly down.
-Little Bear

Imagine all the people
Riding on one wheel.
J. Lennon. (paraphrased)
------------------------------------------------------------------------
munipsycho's Profile: http://www.unicyclist.com/profile/9589
View this thread: http://www.unicyclist.com/thread/40623

john_childs said:

Have you run any sample calculations for constant foot acceleration
compared to constant foot speed? I'm too lazy to run the numbers right
now and it has also been a long time since I've done any dynamics so I'm
all rusty with the equations.

Yes, but before I go on, I'm not claiming this is very useful. The
problem being that as cranks get really short, you lose mechanical
advantage for controlling the unicycle and watse energy trying to
maintain stability.

That said, the equations are pretty simple. The magnitude of
acceleration, a, needed to keep your foot spinning on the pedal is

a = l*v^2/r^2

where l is crank length,
v is the unicycle's speed, and
r is the wheel's radius

Keeping forward speed and pedal speed constant yields the equation

l1 / r1^2 = l2 / r2^2

In words, crank length grows with the square of wheel size.

Concretely, taking a coker with 175mm cranks as the largest likely
combination and scaling down yields the following table of
iso-accelerated unicycles:

36" with 175mm cranks
29" with 113mm
26" with 91mm
24" with 78mm
20" with 54mm

To compare a different combination, you can multiply all the crank
lengths by the constant of your choice.

Ken

To be meaningful, I think you'd have to take into account leg mass,
which is different for the different sections of the leg. Shorter
cranks use much more movement of the lower, less massy sections of the
leg than longer cranks.

And mules are even massier! So the mire gets deeper...

--
U-Turn - As long as my feet keep movin'...

Weep in the dojo... laugh on the battlefield.
'LiveWire Unicycles' (http://www.livewireunicycles.com)
'Strongest Coker Wheel in the World'
(http://www.unicyclist.com/gallery/albup39)
'29er Tire Study' (http://u-turn.unicyclist.com/29erTireStudy/)
'New York Unicycle Club' (http://www.newyorkunicycle.com)
-- Dave Stockton
------------------------------------------------------------------------
U-Turn's Profile: http://www.unicyclist.com/profile/691
View this thread: http://www.unicyclist.com/thread/40623