Newcommer. Questions on fast unicycles

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Hi everybody. I'm a disegner of fast bikes (for speed records) and this
is one of my recent ideas (modyfied centaur (it had two wheels
before)). It has drive from hands and legs. Very beta drawing, just
idea.

I wold love to hear from unicycle experts :
1. would it be ridable?
2. are there hubs with integrated planetary gear for unicycles?
3. would it be possible to turn?

I like this bike bacause it's simple and has good aerodynamics = high
speed.


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mozg
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Nice idea!

How does the hand pedalling work?

T.


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Hi everybody. I'm a disegner of fast bikes (for speed records) and
this is one of my recent ideas (modyfied centaur (it had two
wheels before)). It has drive from hands and legs. Very beta
drawing, just idea.

Sounds cool - very cool.

I wold love to hear from unicycle experts :

I'm nowhere near an expert, but I'm going to stick my oar in anyway :-)

1. would it be ridable?

One thing I've learnt on these forums is that almost anything is
ridable :-) No matter how crazy an invention, there's always going to
be someone who can handle it.

I bet many people would be able to ride it sitting upright and not
using the hand cranks. Transferring to hand cranking too would be
interesting - you'd have to be going slow enough that you could grab
hold of the cranks.

Riding this would require decent balance - you wouldn't be able to
flail your arms around ;-) I don't know how much hand cranking would
disrupt one's balance...

What wheelsize were you thinking of? 36" wheels seem to be popular for
speed / distance riding, although geared 29ers have some merits too.

Oh, and a little safety point: it'd be really nice if you could fall
off the front of this without getting your feet tangled in any
machinery ;-) Although given you're unlikely to be able to run out of
a speed record attempt maybe that's not so important!

2. are there hubs with integrated planetary gear for unicycles?

Yes, see http://schlumpfdrive.com and search the forum history for
Harper's Blueshift and uni.5.

The Schlumpf hub is shiftable on the fly, Harper's hubs offer a choice
of two ratios you can change with a toolkit (by adjusting the torque
arm if I remember correctly - which I may not do).

Also, look for PurplePhaze which achieves much higher ratios using a
jackshaft system. Again adjustable using a toolkit, but a bit more
work. It also featured a "tuck" handlebar arrangement, vaguely like
your proposal (without the hand drive). OuttaPhaze is a proposed
production variant of this design.

3. would it be possible to turn?

If it could be ridden, then it could be turned.

I like this bike bacause it's simple and has good aerodynamics =
high speed.


--
mark williamson

Dave: Just a question. What use is a unicyle with no seat? And no
pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!
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Cool drawing.

1. would it be ridable?
Yes, nearly anything's ridable.

2. are there hubs with integrated planetary gear for unicycles?
Yes, but might not work with a chain drive.

3. would it be possible to turn?
I assume you mean steer, yes also.

3 1/2. Do good aerodynamics make a fast unicycle?
No. They (generally) don't go fast enough for distorting your body
position to be better than an ergo position that lets you balance,
breathe and pedal faster.

You don't want to pedal with hands and feet at the same time. When
pedaling with fee, we use one hand to stay steady on the cycle, and the
other to help in balancing. You can get by with no balancing hands,
which we generally do in road racing, but on the track things happen
fast, and a free hand can be very useful.

The fastest unicycles currently are 36" wheels, and geared-up 29"
wheels. Someday maybe geared-up 36" wheels. Read up on those to learn
more about what a fast unicycle currently is, then work from there.


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johnfoss

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johnfoss wrote:

3 1/2. Do good aerodynamics make a fast unicycle?
No. They (generally) don't go fast enough for distorting your body
position to be better than an ergo position that lets you balance,
breathe and pedal faster.




For existing unicycles, this is certainly the case, but if we really
start to push the limits of technology, it may not be the case forever.
If someone wanted to start doing Bonneville Salt Flats-style speed
records on a unicycle, he could develop something like this with a gear
of something like 80 or 90 gear-inches, which would go fast enough to
get benefit from an aerodynamic position. Once you get above 20 mph,
aero drag starts to take over as your major limiting speed factor.

A challenge would be that you'd have to find someone who was not only a
strong rider, but also willing to pilot an unstable one-wheeled
contraption at speeds above 20 mph. Not to mention, an unstable
one-wheeled contraption with a row of sharp teeth aimed at your neck.

I wouldn't expect the hand-crank to be worth the extra complexity, but
you could construct something with a seat and bars which put you in a
more aerodynamic position than is normal on a unicycle.


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tholub
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tholub wrote:

A challenge would be that you'd have to find someone who was not only a
strong rider, but also willing to pilot an unstable one-wheeled
contraption at speeds above 20 mph. Not to mention, an unstable
one-wheeled contraption with a row of sharp teeth aimed at your neck.




Not a challenge at all. just browse our galleries and take your pick of
the freestyle/street teenagers



I really hope you make this thing. . . I agree that a 1 to one ratio
would be pretty important for balance issues. would we be able to keep
that 1-1 while shifting?

I also think the best advice i can offer you is: go get a unicycle!!!
learn how to ride it (we'll all help as much as we can) and then uuse
what you learn to help you build this marvel!!! you can get a nice
starter unicycle (Torker LX) for under a hundred bucks.


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I think aerodynamics does start making a difference at something like
15mph or so. Given there are quite a few people who can hit 20mph
without problems, they'd probably get benefits from better
aerodynamics.

The position looks very cramped, maybe moving the handle higher would
be nicer. alternatively if you're bothering making a chain drive from
the handle to the wheels, why not have the pedals on a chain drive too,
that way you could lie the person right down, making for a very aero
position. It'd be jolly hard to ride an upside down recumbent unicycle
but I'd guess there are people who could. If you had guards so you
didn't hit your hands on crashing and kept the rider as low down as
possible it could be much more rideable, as you might be able to launch
from the lying down position.

Like Mike says, plantetary gears are a bit limited in how high they go,
although on the 36" wheel with the 1.55x gearing, it is equivalent to
quite a decent sized bike gearing.

Joe


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joemarshall wrote:

The position looks very cramped, maybe moving the handle higher would
be nicer. alternatively if you're bothering making a chain drive from
the handle to the wheels, why not have the pedals on a chain drive too,
that way you could lie the person right down, making for a very aero
position. It'd be jolly hard to ride an upside down recumbent unicycle
but I'd guess there are people who could. If you had guards so you
didn't hit your hands on crashing and kept the rider as low down as
possible it could be much more rideable, as you might be able to launch
from the lying down position.
Joe



I was looking at the riding position.. I think it might be harder to
shift your weight forward and backwards with your body so horizontal. I
agree that the rider would be better off sitting more vertical


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Sgaterboy
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probably, some gyrostabilizer could be used.

To create gear such schema could be used: chain goes flom legs drive to
hands drive and than from hands drive to wheel. Standart bicycle
components could be used.

I would say that hands drive can give some advantage if it is well dome
and you have enough muscules. I was riding centaur for half a year and
I can tell I like it. And I want to build something that uses my hands
power.


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mozg
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I we look at bicycles (and tricycles) where fore and aft stability is
not a significant issue:

The Tour de France involves high speed riding uphill and down hill for
long distances. If there were any advantage for hand/foot combined
power in this type of riding, someone somewhere would have made the
point, even if the rules had not allowed them to enter the race.

Ditto for track racing and time trials and so on.

Bicycles weren't always the shape we see and accept now. They have
evolved this way for a number of valid reasons.

The exception is straight line maximum speed, where HPV enthusiasts
often go for a recumbent position, with the rider bracing his back
against the back of the seat, and pushing extra hard against the pedals
and turning a very high gear.

I have ridden purely hand-cranked vehicles. It's hard work.

I doubt that in any but the most carefully selected circumstances, the
additional weight and complexity of the hands/feet drive and the
additional co-ordination problems that come with it, would be anything
but a disadvantage.

Add to that the further problem of balancing on one wheel...

This is no more than an interesting idea, which is right up there with
kangaroo unicycles, geared-up giraffes, and the like, as fun to try,
but inherently less effective and efficient than a conventional (or
geared) uni.


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rather early in his life.)
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