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-   -   How do you turn corners? (http://www.unicyclist.com/forums/showthread.php?t=20698)

mike.hinson 2002-09-30 08:25 AM

How do you turn corners?
 
What makes a unicycle change direction smoothly?

A practical question:
can anyone give me some tips to help me turn smoothly, particularly on hills please.

An academic question:
Where does the rotational force come from to make the wheel turn a corner please?

Thanks.

fred 2002-09-30 10:49 AM

Re: How do you turn corners?
 
Quote:

Originally posted by mike.hinson
What makes a unicycle change direction smoothly?

Mike,
since you were putting emphasis on **smooth** turning, you may want to read the nicely phrased introduction to the theory of turning (as it related to spins, but you can ignore those paragraphs) by Ken Fuchs:
http://www.unicycling.org/unicycling...mail/0427.html
If you do not mind a more jerky turning style, a pure action/reaction turn from a standstill is another option. I am convinced that tire friction (and the relationship between friction and speed) plays a role here, but I will leave the details to the more theoretically inclined members of this group.

Have fun,
Fred

mike.hinson 2002-10-01 07:02 AM

Thanks for the link to Ken's excellent article.

Am I to take it from the lack of additional replies that this subject is a bit of a mystery? I thought there would be some advanced maths to be explained, and lots of experiences shared.

When I am cornering on my Uni I always feel like I am forcing it to do something it doesn't want to do & consequently my turns lack the control I would like. This is particularly in the context of Muni.

Please help. Thanks.

john_childs 2002-10-01 07:27 AM

Quote:

Originally posted by mike.hinson
Am I to take it from the lack of additional replies that this subject is a bit of a mystery? I thought there would be some advanced maths to be explained, and lots of experiences shared.
Countersteer.

Do a Google search on "countersteer bicycle"
Google
Lots of stuff on the reason for and physics of countersteering.

Unicycles need to countersteer too. That's how you force the uni to initiate a sharper turn.

Mikefule 2002-10-01 09:01 AM

There are two basic ways to turn a unicyle: the gradual curve, as in following the curve of a road or path, and the sudden sharp turn through 90 or 180 degrees (or more) almost on the spot. (This excludes hopping and turning and all that clever stuff.)

For the gradual turn, the unicycle leans in the general direction you want to turn, just like a bicycle or motorcycle. You need to keep the speed up. Long constant radius turns require concentration - the tighter the curve, the more concentration needed.

For the sharp turn, it is easiest to turn to the right as the right pedal goes down, or to the left as the left pedal goes down.

To see how this works, get off the uni, stand it up, and push down on the pedal with your hand. If you allow it to do so, the uni will lean slightly and turn sharply.

Virtually all of the steering effect comes from the lean and the curvature of the wheel. It is nothing to do with hip snad thighs, gripping the seat or waving your arms, although these things can help in some circumstances. ;0)

Back to counter steering, all you do is you use the pedal steering effect as for a 'sharp turn' to turn the uni a little way to the right, but with out allowing it to lean to the right. As your momentum is carrying you forwards, and the wheel is moved to the right, the effect is to tip the uni onto its left side quite quickly and smoothly, then you pedal round the curve as for a gentle curve.

Of course, once you can do it, you should seldom think about it - just do it. So if you want one simple answer: you steer with the pedals, not the seat.

Ken Fuchs 2002-10-02 04:36 PM

Re: How do you turn corners?
 
>Back to counter steering, all you do is you use the pedal steering
>effect as for a 'sharp turn' to turn the uni a little way to the right,
>but with out allowing it to lean to the right. As your momentum is
>carrying you forwards, and the wheel is moved to the right, the effect
>is to tip the uni onto its left side quite quickly and smoothly, then
>you pedal round the curve as for a gentle curve.


>Of course, once you can do it, you should seldom think about it - just
>do it. So if you want one simple answer: you steer with the pedals, not
>the seat.


Pedals may have some part in steering a unicycle, but to say that
unicycles are steered with the pedals is misleading.

Almost all turning is initiated by a counter-steer. To counter-steer a
unicycle, angular action / reaction is used. To turn left, a
counter-steer to the right must first be done to establish a left lean.
To counter-steer to the right, the upper body must twist to the left (the
action) and in reaction the lower body must twist to the right which is
the right counter-steer. With the left lean established it is now
natural for the unicycle to circle to the left by just pedaling through
it. To get out of the left turn at the desired turn angle, just do a
counter-steer to the left to neutralize the lean and continue straight
forward.

The part the pedals play in counter-steering is they transmit some of
the lower body twisting to the unicycle, but the seat also plays this
role as well. Of course, the pedals have no role in the upper body
twisting other than being a part of the reaction to that action.

Sincerely,

Ken Fuchs <kfuchs@winternet.com>

Mikefule 2002-10-02 06:34 PM

of course, as ultimate wheel riders will tell us, the seat is not essential to the steering. I agree that all turns must start off with some good old Newtonian reaction against a mass - which means (in crude terms) you turn your lower body against the mass of your upper body and/or arms. I don't agree that counter steering is always used - in a turn 'on the spot' for example. However, counter steering is an essential component of steering when riding at any sort of speed.

But back tot he steering with the pedals. It may or may not be literally true, but it is a useful way of 'feeling' what you are doing. Especially with sharp turns, or at low speed, timing the turn to coincide with the pedal going down is a useful skill.

When riding, we don't consciously do physics calculations - we ride by feel. if the 'steering with the pedals' idea feels right and helps a new rider to develop the skill, surely that's all to the good.

Klaas Bil 2002-10-02 11:33 PM

Re: How do you turn corners?
 
On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
<mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

>An academic question:
>Where does the rotational force come from to make the wheel turn a
>corner please?


I read this question as: from what does a rider derive a reaction
force (moment) to turn the unicycle (and wheel) around its vertical
axis. I'm not sure that Mike meant it this way, but anyway this
question was not addressed yet. Countersteering is not an answer.
Whether we do initial countersteering or not, there must be a first
vertical twist but against what does a rider push or pull to bring it
about? This question can be so puzzling that some people are tempted
to say that unicycling is theoretically impossible.

I think Mikefule may be closest to an answer by pointing at the
pedals. If a rider rides relaxed and not in a corner/curved
trajectory, the tyre contact point will actually describe a wiggly
line. Every wiggle corresponds to one pedal stroke. On average, the
contact point is below our centre of gravity. If then the rider would
push one pedal a little harder, the corresponding wiggle will be
larger (or maybe smaller but at least different), hence the tyre will
deviate from the position under the centre of gravity, and here we
have the initial lean that will drive the rider automatically into
riding a curve.

Klaas Bil

If you had this signature, I have forged it.

Klaas Bil 2002-10-02 11:38 PM

Re: How do you turn corners?
 
On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
<mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

>An academic question:
>Where does the rotational force come from to make the wheel turn a
>corner please?


I read this question as: from what does a rider derive a reaction
force (moment) to turn the unicycle (and wheel) around its vertical
axis. I'm not sure that Mike meant it this way, but anyway this
question was not addressed yet. Countersteering is not an answer.
Whether we do initial countersteering or not, there must be a first
vertical twist but against what does a rider push or pull to bring it
about? This question can be so puzzling that some people are tempted
to say that unicycling is theoretically impossible.

I think Mikefule may be closest to an answer by pointing at the
pedals. If a rider rides relaxed and not in a corner/curved
trajectory, the tyre contact point will actually describe a wiggly
line. Every wiggle corresponds to one pedal stroke. On average, the
contact point is below our centre of gravity. If then the rider would
push one pedal a little harder, the corresponding wiggle will be
larger (or maybe smaller but at least different), hence the tyre will
deviate from the position under the centre of gravity, and here we
have the initial lean that will drive the rider automatically into
riding a curve.

Klaas Bil

If you had this signature, I have forged it.

Klaas Bil 2002-10-02 11:43 PM

Re: How do you turn corners?
 
On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
<mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

>An academic question:
>Where does the rotational force come from to make the wheel turn a
>corner please?


I read this question as: from what does a rider derive a reaction
force (moment) to turn the unicycle (and wheel) around its vertical
axis. I'm not sure that Mike meant it this way, but anyway this
question was not addressed yet. Countersteering is not an answer.
Whether we do initial countersteering or not, there must be a first
vertical twist but against what does a rider push or pull to bring it
about? This question can be so puzzling that some people are tempted
to say that unicycling is theoretically impossible.

I think Mikefule may be closest to an answer by pointing at the
pedals. If a rider rides relaxed and not in a corner/curved
trajectory, the tyre contact point will actually describe a wiggly
line. Every wiggle corresponds to one pedal stroke. On average, the
contact point is below our centre of gravity. If then the rider would
push one pedal a little harder, the corresponding wiggle will be
larger (or maybe smaller but at least different), hence the tyre will
deviate from the position under the centre of gravity, and here we
have the initial lean that will drive the rider automatically into
riding a curve.

Klaas Bil

If you had this signature, I have forged it.

Klaas Bil 2002-10-02 11:48 PM

Re: How do you turn corners?
 
On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
<mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

>An academic question:
>Where does the rotational force come from to make the wheel turn a
>corner please?


I read this question as: from what does a rider derive a reaction
force (moment) to turn the unicycle (and wheel) around its vertical
axis. I'm not sure that Mike meant it this way, but anyway this
question was not addressed yet. Countersteering is not an answer.
Whether we do initial countersteering or not, there must be a first
vertical twist but against what does a rider push or pull to bring it
about? This question can be so puzzling that some people are tempted
to say that unicycling is theoretically impossible.

I think Mikefule may be closest to an answer by pointing at the
pedals. If a rider rides relaxed and not in a corner/curved
trajectory, the tyre contact point will actually describe a wiggly
line. Every wiggle corresponds to one pedal stroke. On average, the
contact point is below our centre of gravity. If then the rider would
push one pedal a little harder, the corresponding wiggle will be
larger (or maybe smaller but at least different), hence the tyre will
deviate from the position under the centre of gravity, and here we
have the initial lean that will drive the rider automatically into
riding a curve.

Klaas Bil

If you had this signature, I have forged it.

Klaas Bil 2002-10-02 11:53 PM

Re: How do you turn corners?
 
On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
<mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

>An academic question:
>Where does the rotational force come from to make the wheel turn a
>corner please?


I read this question as: from what does a rider derive a reaction
force (moment) to turn the unicycle (and wheel) around its vertical
axis. I'm not sure that Mike meant it this way, but anyway this
question was not addressed yet. Countersteering is not an answer.
Whether we do initial countersteering or not, there must be a first
vertical twist but against what does a rider push or pull to bring it
about? This question can be so puzzling that some people are tempted
to say that unicycling is theoretically impossible.

I think Mikefule may be closest to an answer by pointing at the
pedals. If a rider rides relaxed and not in a corner/curved
trajectory, the tyre contact point will actually describe a wiggly
line. Every wiggle corresponds to one pedal stroke. On average, the
contact point is below our centre of gravity. If then the rider would
push one pedal a little harder, the corresponding wiggle will be
larger (or maybe smaller but at least different), hence the tyre will
deviate from the position under the centre of gravity, and here we
have the initial lean that will drive the rider automatically into
riding a curve.

Klaas Bil

If you had this signature, I have forged it.

Klaas Bil 2002-10-02 11:57 PM

Re: How do you turn corners?
 
On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
<mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

>An academic question:
>Where does the rotational force come from to make the wheel turn a
>corner please?


I read this question as: from what does a rider derive a reaction
force (moment) to turn the unicycle (and wheel) around its vertical
axis. I'm not sure that Mike meant it this way, but anyway this
question was not addressed yet. Countersteering is not an answer.
Whether we do initial countersteering or not, there must be a first
vertical twist but against what does a rider push or pull to bring it
about? This question can be so puzzling that some people are tempted
to say that unicycling is theoretically impossible.

I think Mikefule may be closest to an answer by pointing at the
pedals. If a rider rides relaxed and not in a corner/curved
trajectory, the tyre contact point will actually describe a wiggly
line. Every wiggle corresponds to one pedal stroke. On average, the
contact point is below our centre of gravity. If then the rider would
push one pedal a little harder, the corresponding wiggle will be
larger (or maybe smaller but at least different), hence the tyre will
deviate from the position under the centre of gravity, and here we
have the initial lean that will drive the rider automatically into
riding a curve.

Klaas Bil

If you had this signature, I have forged it.

GILD 2002-10-03 11:40 AM

six times klaas!
a new record?
whatever caused this is causing more of it at the moment


mike, i'm curious, why the need for 'smoother' turns?

mike.hinson 2002-10-03 02:58 PM

> I read this question as: from what does a rider derive a reaction
> force (moment) to turn the unicycle (and wheel) around its
> vertical axis. I'm not sure that Mike meant it this way, but
> anyway this question was not addressed yet.

All answers are interesting & lead to further understanding, I am also trying to understand where the force comes from to _continue_ turning the unicycle (and wheel & unicyclist) around its vertical axis as the unicycle continues to be ridden around a curve.

/\/\


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