acceleration unicycle

I don't know of any unicycles with 'derailleurs'. The problem is that
on a unicycle you need to be able to put pressure backwards to correct
your balance and even without a freewheel mechanism you have to keep the
chain tight so it doesn't slip on the chainrings. Well that's my
understanding anyway.

Do a little search (click on 'search' at the top right of the page) for
'uni.5' or 'geared hub' or 'schlumph' for info about alternatives.

Andrew

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The answer to the question is "no", but it is the wrong question!

So far there is no system for changing gear ona unicycle while you are
riding it, and there are various technical reasons why it is unlikely
that such a device will ever be made. There are one or two people
making unicycles with 2 gears, but you have to stop and get off to
change.

However, why ride a unicycle, but go to all that trouble to make it more
like a bicycle? Why not ride a unicycle but add a front wheel and
handlebars? :0)

The whole point of a unicycle is its simplicity, and the need to cope
with the compromises. You choose a wheel size, a tyre, a set of cranks,
and then make the most of the set up that you have chosen. You can
choose wheels from about 16 inches to 36 inches, and cranks from about 4
inches to about 7 inches. There is a huge variety.

Then you just ride. That's the whole point. I've ridden 20 miles on a
20 inch, 24 on a 24, 30+ on a 28, and 50+ on a 36 inch wheel. Some
people who write in this forum ride 50 - 100 miles in a day, over
mountains and cross country. Look for threads with the words ëpic"and
"Coker" in them. You will be amazed and inspired.

People have ridden across America on 24 inch basic unicycles.

It sounds like you haven't tried long distance unicycling yet, but you
already want to find a way of improving it. That's the wrong approach.
Buy a 24 inch unicycle and get the miles in. It is a very special
method of transport - faster than walking, slower than bicycling, more
challenging than either. You get to see the scenery, the wildlife, and
meet people. You get fit, you enjoy it, and you get a great feeling of
achievement.

Read a few threads, look at a few galleries, and see what can be done
without a derailleur! ;0)

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Quoted message said:

So far there is no system for changing gear ona unicycle while you are
riding it

Have you read about the adaptation of the Schlumph hub? That design
allows you to change gears on the fly by kicking a little nub (much like
the old KH cranks) with your ankle. I believe they're also considering
adding some sort of lever under the seat or something along those lines
to their design. There's a little bit of info on their site. I just
realised I've been spelling it wrong...

http://www.schlumpf.ch/

Andrew

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Quoted message said:

The whole point of a unicycle is its simplicity

[begin rant]

You unicyclists makke me sick! Simplicity? I don't think so. Lah di
dah, look at me sitting down while I ride. On a saddle. With a
handle. And a frame with bearings, no less. Maybe even a trip
computer.

If you want to argue that simplicity is the way to go, ride an
ultimate wheel and show the rest of us the one true way (with
apologies to BC wheel purists). Otherwise, why not let people have
fun riding what they like and thinking up new challenges, whether
technical or physical.

Ken

If you want to argue that simplicity is the way to go, then walk naked
and barefoot.😄

I have an ultimate wheel, on which I am not particularly good.

I agree with your basic point that it's up to each rider to choose
his/her own level of simplicity or complexity. However, I do maintain
that if you try to make a unicycle too much like a bicycle (shiftable
gears, for example) you are in danger of missing the point. It would be
like having a motorcycle with a roof, windscreen wipers and two extra
wheels for stability.

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[quote="Mikefule"][B]So far there is no system for changing gear ona unicycle while you
are riding it, and there are various technical reasons why it is
unlikely that such a device will ever be made.
[/quote]

not being "technical" cannot argue at that.
Ideally and topologically I bet this *is* possible: now if you tell
me that there is no steel that will support the stress or the friction I
can't argue.

Quoted message said:

However, why ride a unicycle, but go to all that trouble to make it
more like a bicycle?

Mikefule said:

I agree with your basic point that it's up to each rider to choose
his/her own level of simplicity or complexity. However, I do maintain
that if you try to make a unicycle too much like a bicycle (shiftable
gears, for example) you are in danger of missing the point.

I get it, but you are missing my point. You've chosen a particular
level of complexity that you seem to feel represents "proper"
unicycling. Any more or less and for *you* the experience is
diminished. You put that forward as your idea of "the point" of
riding. That's fine with me. More power to you.

It's when you start telling the rest of us how to enjoy the sport that
I object. It is patently not the case that the "whole point of
unicycling is its simplicity". For many, the point is the difficulty
yet tantalizing attainability of riding. For some, it is competition.
For a few it is realizing mechanical innovations (like shiftable
hubs). There are unicycle racers, dancers, clowns, and on and on.
I see lots of "points", not one.

From a broader perspective, I've seen differing goals and technologies
as a common feature of all the outdoor sports I have participated in
through the years. Many sport climbers "miss the point" and never
seek out the adventure of traditionalist detractors, but then the old
traditionalists missed out on the transcendance of succeeding on a
route requiring absolutely every iota of gymnastic ability,
visualization, and focus that at-your-limit sport climbing requires.
The squirt boater with intimate knowledge of every eddy and underwater
current might look down at a rafter yelling "wheeeee" and at the same
time miss out on a simple part of joy of getting out to ride down the
river. And let's not even discuss skiing vs. snowboarding!

My point is that there's more than one way to skin a cat. If you want
to look down at attempts to build shiftable unicycles as missing the
point I'm not about to stop you, though I will tell you that you may
be the one missing a point. When you tell others there is only one
proper way to enjoy what is, after all, a contrived sport, well, then
I'll start arguing that there's more to the picture than what you
happen to be focused on.

Cheers,

Ken

The main problem with gears is play, or lash. That is, if you want to
change gear, then there has to be some slack in the system to allow that
to happen. If there is some slack in the system, then that causes
problems with smoothness of pedalling (especially idling, or when
changing speed) because the cranks will move a tiny bit before the slack
is taken up. The geared systems that have been experimented with
generally use "sun and planet" gears, as found in a conventional hub
gear (e.g. Sturmey Archer), but selection of gears involves getting off,
changing gear, then making sure everything is tight so there's no lash
in the system.

I suppose this could be overcome, but rememebr that the market would be
very small indeed (a few hundred units worldwide?) so there would be
massive R&D costs, and no savings on economies of scale. I think geared
unicycles are doomed to be the province of the enthusiast and inventor,
rather than a commercial propostition on any major scale.

But back to the original point: a Coker with 170mm cranks gives the same
mechanical advantage as a bicycle with a 36 inch gear. That's like
having a mountain bike with a 1:1.38 gear ratio. Say 40 teeth at the
front and 28 at the back, or 36 front, 26 back. That's a pretty low
gear.

Basically, all unicycles are in a low gear compared to any conventional
bicycle. The problem with hill climbing is usually technique, stamina
or over-ambition.

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Given the recent auction of the 26/39er, I think several hundred units
worldwide is a wildly optimistic figure.

On the subject of shifting on the fly, I think the reality is that few
people could master shifting without a dismount even if the unicycles
existed. For most, a mid-motion shift would meet with a swift udp or
faceplant. I think the concept is overrated.

Mikefule said:

*
I suppose this could be overcome, but rememebr that the market would
be very small indeed (a few hundred units worldwide?) so there would
be massive R&D costs, and no savings on economies of scale. I think
geared unicycles are doomed to be the province of the enthusiast and
inventor, rather than a commercial propostition on any major scale.
*

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wobbling bear said:

*because I need a geared-down Coker to go up steep slopes:
why? because my doctor does not want me to continue to tear my muscles
apart and tear my tendons... *

Sounds like you are pushing too hard. With improvements in technique it
will probably be possible for you to learn to ride steeper climbs
without damage. But of course you will have to be very careful working
at it. There's a big difference between a pedaling technique where you
push down super hard, and one where you make strong, smooth circles with
your feet.

For health reasons, I'd suggest a smaller wheel for the rides with steep
climbs. Like a 28" or 29", which would be much lighter than the Coker,
and hence easier on the muscles and tendons.

A shiftable hub would be much more expensive than most of us are willing
to invest, and it might be easier to just walk up the hill... 🙂

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Mikefule said:

*a Coker with 170mm cranks gives the same mechanical advantage as a
bicycle with a 36 inch gear. *

Does gear inch on a bike actually take into account crank length? I
thought it was just based on the rollout of the bike in that gear being
equal to a certain circumference of larger wheel.

If that's the case, a Coker with *any* size cranks is a 36 in gear, but
that doesn't mean much if you want to talk about crank length.

The gearing problem for unicycles has been solved. But there is not
enough market demand for the hubs to be worth manufacturing. A shiftable
geared hub would have a similar problem, only it would be less worth
manufacturing.

This doesn't mean the inventors out there shouldn't build prototypes and
develop the concept. I want to try one!

Meanwhile, there are always cruder ways to get gearing. The simplest is
with a chain drive. If you don't want your unicycle to be tall, you can
use and inner and outer hub setup to gear the wheel on its own axle.
This is going to add some weight and some friction in the drivetrain,
but I've ridden a working one (in 1982). But it wasn't shiftable.

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johnfoss said:

*Does gear inch on a bike actually take into account crank length? I
thought it was just based on the rollout of the bike in that gear
being equal to a certain circumference of larger wheel.
*

Yes and no. I specifically referred to mechanical advantage, and in
doing so I made a rather sweeping assumption that most bicycles have 170
mm cranks (or as near as makes no odds).

Describing bicycle gears in inches arose from the need to compare modern
"safety" bicycles with penny farthing "ordinary" bicycles. In the days
of the penny farthing, the macho factor was wheel diameter, and the
general perception was that big wheel = fast. (I cannot recall ever
reading of great attention being paid to crank length.)

The idea is that if you gear up on a 2:1 ratio (e.g. 48t front, 24t
rear) and have a 26 inch wheel, that is in some sense "equivalent" to a
52 inch wheel (48/24 X 26 = 52).

However, it is not enough to say that a Coker is a 36 inch wheel and is
therefore "equivalent" to a bicycle with a 36 inch wheel because
unicyclists are much more adventurous with their crank lengths. A Coker
with shorter cranks may be faster on the flat, but it requires more
pressure on the pedals to get it up hills - which is what prompted the
discussion. (Not teaching John to suck eggs, but explaining for those
who are less familiar with the principles.)

So the point I was trying to make was that a Coker with the same sized
cranks as a bicycle should be no harder to pedal up hill than a bicycle
with a 36 inch gear (ceteris paribus).

In practice, ceteris aren't paribus, of course. Bicycles are nasty
heavy things with inefficient chain drive. And every skoolboy kno that
short wheel bases are good for hill climbing.😉

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Uh, so how do I get the stuff to come out of this here egg?

😄

Anyway, yes a Coker is roughly equivalent to a bike with a 36 inch gear.
The "roughly" part is where you account for different cycle weights,
drive system friction, and crank length. Hmmm. That's a huge amount of
wiggle room for us nerds here in the newsgroup. Oh well, you're not
going to get an exact comparison between a uni and a bike anyway.

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johnfoss said:

*you're not going to get an exact comparison between a uni and a bike
anyway. *

Here's one: a unicycle has half as many wheels as a bicycle.

How exact were you hoping for?😄

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I did say nerds, right?

Maybe I should have said super-geeks. Not sure what works best for the
UK... :p

For geeky example, the bike also has more frame, a drivetrain,
handlebars, etc. Take away the extra wheel and you have all that extra
hardware.

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