# Balancing logic (or something like that)...

If I can ride slowly and confidently along a 2m x 5cm plank (raised 20cm) 5 times in a row, then why can’t I ride along a similar 10m long plank?

I’m sure there’s a perfectly logical explanation but I’m puzzled given the fact that I was riding it slowly. I guess I’ve never had the chance to try a 10m long plank under the same conditions but I strongly doubt I could do it. I was also riding it backwards which is something I’d never tried before. It’s great fun!

Andrew

P.S. I’m doing some northshore style riding at a school fete tomorrow.

Re: Balancing logic (or something like that)…

Could that be why?

If you did try the 10 and fail, was it before or after you went 5?

Danie

Re: Balancing logic (or something like that)…

Maybe it is this? If you ride the 2 m long plank you may have accumulated some side-to-side imbalance by the end of the 2 m, but that’s not a problem because you then ride off it. However if the plank continues it is a problem.

Klaas Bil

Probably because you’ve only been going about 2 pedal revolutions so you don’t really have the distance or the time to get any real balance problems. For example, I can most likely wheelwalk the aforementioned 2m long skinny because it’s over before I get a chance to do any mistakes but on a 10m long version, I can barely get halfway because by the time I’m at 4 meters, all the minor balance problems I had at the 1m mark are severely magnafied. My advice is to first try it without having to hop onto it because that’s harder, and just ride along it. Try and remember to balance only with your arms, because balancing with your hips will wobble the wheel. It’s kinda like wheelwalking in my opinion. Hope my ramblings help. Keep riding.

My question is why can I ride a 6" wide curb, which is raised about 6" off the ground, but I can’t ride a foot-wide raised section which is 2 feet off the ground? Oh, I know. Fear.

Yeh, I guess you’re right. I haven’t come across any 10m x 5cm things but I’d love to give it a try.

It’s interesting isn’t it. I’d have no troubles freemounting something 20cm wide on the ground but today on one about 1.5m up I could only do it about 1/3 of the time. It’s really frustrating. I guess part of it is because I wasn’t trusting myself to put my weight on the seat as much.

Andrew

You balance a unicycle like this: the unicycle starts to fall, and you move the wheel in that direction until the contact patch is slightly ‘ahead’ of the fall.

On a narrow plank, that presents no problems in the forward/backward directions, because it’s a simple matter of accleration and deceleration.

But the side to side balance on a narrow strip is difficult. If your centre of mass (“centre of gravity”) moves 3 inches to the right, an the plank only lets you move your wheel 2 inches to the right, then you’re in trouble.

On a short plank, you will have enough control to keep the unicycle more or less on the vertical. On a longer plank, minor errors will cause a certain amount of wobble. Your attempts to correct the wobble may be imperfect, and the small errors will accumulate until you run out of “wobble room”.

Practice and confidence will reduce the problem, but it will always be there, whether you make 1 metre, 5 metres or 10 metres.

There is the other method of balancing to consider: arm and upper body waving. As a physics problem, this is complex. If you simply shift some of your weight to the right, there will be an equal and opposite reaction. This means that the unicycle might become more vertical, but the centre of mass of the combined unicycle and rider will not have moved laterally. So you you’re no better off. (A leaning unicycle or a leaning rider - either way, you’re out of balance.)

However, more can be achieved by circular movements of the arms. If you move your arms like aeroplane (airplane) propellors, then as the arm moves outwards over the top of it’s travel, it will have more effect than when it moves back inwards at the lower part of its travel. I think the term is ‘angular momentum’, but I’m sure someone will correct me.

Anyway, practise, and set steadily increasing goals and you will improve.

Good luck.

Also consider: is the actual skinny you are riding physically as stable?

Different length example:
Given a 2x6 board (approx 1.5"x5.5" or 4cm x 14cm).
If the board is 6 foot (2m) long supported only at the ends,

• then it will be relatively stable for it’s whole length.
If the board is 30 foot (10m) long supported only at the ends,
• then it will have a pretty good amount of flex, particularly in the middle.
If the board is 30 foot (10m) long supported every 6 feet (2m),
• then is likely (at least) as stable as the 6 foot (2m) board.

Different height example:
If a very solid pipe is bolted to the concrete ground

• then is will not noticibly shift at all.
If the same solid pipe is bolted on 3 foot (1m) supports
• then it may shift noticably unless both:
• the supports are quite solid, and
• the bolts are solid and have no play

Note: In either of the above cases, better skill will definitely help, because with better balancing skills, your adjustments should be smaller, so the skinny will move around less. And, with the skinny moving around less, balancing is easier, which means you should be more on balance, and your adjustments will be smaller yet, so the skinny will move around an even lesser amount. And, with the skinny moving around an even lesser amount, balancing is even easier yet, so …

.duaner.

Re: Balancing logic (or something like that)…

Mikefule <Mikefule.tqp9g@timelimit.unicyclist.com> wrote:

>But the side to side balance on a narrow strip is difficult. If your
>centre of mass (“centre of gravity”) moves 3 inches to the right, an the
>plank only lets you move your wheel 2 inches to the right, then you’re
>in trouble.

Crucial assumption:

The arms must be held straight out ready to be used like a balance pole.

The key to staying on a narrow strip after one’s centre of gravity moves
to one side of the wheel is to move the effective centre of gravity back
over the (sideways) centre of the wheel, without moving the wheel
sideways relative to the strip. This is done by quickly lowering the
arm towards which one is losing balance and simultaneously raising the
other arm. (This could be called the balance pole effect without the
balance pole.) Effectively, the falling arm’s resistance to gravity
becomes zero or even negative and the rising arm’s resistance to gravity
doubles in magnitude or more. This arm movement shifts the effective
centre of gravity back over the wheel and ideally a little beyond to
lose balance slightly in the opposite direction which allows the arms to
be moved again to a straight out position such that the centre of
gravity is directly over the wheel (in at the least a sideways sense).

These are the simplest arm movements that allow one to regain sideways
balance. I strongly recommend they be used when shifting the wheel
sideways is not sufficient to regain balance. I have no comment on the
effectiveness of more complex arm movements on sideways balance.

Sincerely,

Ken Fuchs <kfuchs@winternet.com>

Re: Balancing logic (or something like that)…

You can. But some part of your brain or body may still need to be convinced. Sometimes you can’t convince yourself completely until you’ve done it a few times. Just keep at it.

For the longest time (which continues even now) I could not ride elevated skinnies (or WIDIES in my case) because of what my brain told me. I first tried walls that dropped off 12" to 24" on one side, were flat topped about 12" wide (this is REALLY wide), and had grass on the other side at the top of the wall. They were essentially retaining walls. My brain ALWAYS told me, “fall to the side where there is grass and no drop NOW!” Even when I reversed direction I would always fall immediately to the safe side even though it was the other direction.

I am slowly overcoming this obstacle of “common sense” by repetition as others have pointed out. I have ridden elevated skinnies as high up as 5 feet and as narrow as 6 inches but I always fall to the safest side and frequently when I don’t really have to bail. You will overcome.

Well said Harper. Me too! --chirokid–