Sport to the exclusion of everythng else

I was also in the beginning very afraid of riding a bike

Me too. I had not understood the function of pedals and thought that my feet would have to rotate in parallel with the wheel. Marvelously unnatural things, wheels. School taught me never to trust sport or those who promote it.

I refused to even try to ride a bike until I’d worked out how it was possible to balance it, and how to take corners – neither of which is widely understood by people who are nonetheless perfectly capable of skillfully riding a bike.

I also understand how a cat can twist around in the air, and how it’s possible to “pump” a swing. I’ve never actually tried to emulate the cat, though (although ice skaters and gymnasts sometimes do very similar things).

Funny, we have lingering leftovers of the bike riding spammer. ;-)

Marvelously unnatural things, wheels.

As far as I’m aware, science hasn’t actually explained how a bicycle works. Oh, sure, the mechanism of a bike is pretty simple, but when you’re rotating pedals to spin wheels, what is it that keeps you upright? It’s pretty easy to keel over and fall if you’re not moving, but once you’re moving it’s actually a fair bit harder. Taken to illogical extremes with motorbike racing when they take turns tilted at an angle that by all accounts should plant them into a tree at high speed, yet they stay on the road.
Weird things, bikes.

until I’d worked out how it was possible to balance it

You’re one up on me then. I don’t know how to balance it. I just know that if I push the pedals, I go forwards and don’t fall off (usually!). I know it works. I don’t know how it works.

although ice skaters

There’s another conundrum every bit as freaky as the bicycle. It was once thought that friction and body weight melted ice so the skate glided along, refreezing afterwards. It’s now believed that how a skate actually works is that the top layer of the ice (in contact with the air) has a weaker bond between its atoms, so it exists in a state between ice and water, and the skate actually glides along this. It would imply that there are air conditions that would make the ice too cold to be suitable for skating upon? I dunno – ask somebody who lives far to the North. ;-)

I refused to even try to ride a bike until I’d worked out how it was possible to balance it, and how to take corners

The key to both is counter-steering. It’s more noticeable on the heavier motorcycle, but in both cases to turn left the initial turning of the bars is to the right. This moves the wheels to the right of the rider’s C of G, hence inducing a lean to the left. The steering is then turned slightly left, leading to a left turn, with the rider’s CofG inside the turn, where it needs to be for balance.

It would imply that there are air conditions that would make the ice too cold to be suitable for skating upon?

I’ve been on skates that refused to grip on the ice, and when I complained they were blunt was told it was down to the ice temperature. I didn’t believe it then, and now?

The key to both is counter-steering.

Is this why tricycles are not so stable changing direction?

Is this why tricycles are not so stable changing direction?

In effect, yes. You can’t lean a tricycle into a corner, so the rider has to lean aggressively in order to move the C of G inside. It’s worse for a sidecar outfit when turning towards the sidecar. Watch the sidecar racers to see how extreme that has to be.

There used to be tracks where the general public could hire motor tricycles. That stopped for safety reasons, and they are now replaced with quad bikes. The difference here is if you feel the tricycle is going into a corner too fast, and hit the brakes, it’s almost guaranteed to flip, as the force exerted by the C of G ends up outside the line between the front wheel and the outer rear wheel.

As far as I’m aware, science hasn’t actually explained how a bicycle works.

Just ‘cos you’re not aware of it, doesn’t mean to say it’s not happened. Alan Adams’s post just after yours explains it correctly.

I worked it out for myself, in my head lying in bed, when I was about ten. The following day I borrowed a bicycle and rode it successfully, and became a keen cyclist very quickly thereafter, since when I’ve ridden all over the UK, and widely in western Europe and India, much of it on a tandem.

I do not think there any creatures whose bodies incorporate wheels for locomotion. But I do remember seeing some drawings musing on what such beasts (Rotopods) might look like. Was the artist Artzybasheff, Escher, … ? Has anyone seen these? I presume that man + bicycle is more efficient than pedestrian man. But how does that compare with equestrian man? Do bicycles count as part of evolution? Put not your trust in the feet of men (from the Psalms, I think). Brains are better, on the whole.

I do not think there any creatures whose bodies incorporate wheels for locomotion.

The Trolleymen, in the cartoon series Flook, by Trog. I dimly remember them from my childhood.

Bacterial flagellae rotate, does that count?

man + bicycle is more efficient than pedestrian man. But how does that compare with equestrian man?

Sadly I don’t recall the source, but I do recall reading an analysis of this: man + bicycle is considerably more efficient than equestrian man, indeed considerably more efficient than a horse without the deadweight of a man on its back.

But man + bicycle is dependent on the infrastructure of a decent road surface. Man + mountainbike on rough country is far less efficient than a horse, even with a man on its back. Can’t even compete with a running man.

Bacterial flagellae rotate, does that count?

I think it does – I think the original statement needs to specify “multicellular organisms.”

Just ‘cos you’re not aware of it, doesn’t mean to say it’s not happened.

That’s the how more than the why.

https://bikehike.org/do-scientist-know-how-bikes-work/

The wiki article delves deep into the maths of how balancing and such works – https://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics

That’s the how more than the why.

Yes. There are complications, but the basic how like that was enough that I got straight on a bike, and quite consciously rode it according to the theory I’d worked out in my head, as distinct from the Countersteering skill is usually acquired by motor learning and executed via procedural memory rather than by conscious thought mentioned in the wikipedia article.

Having studied dynamics as part of my mechanical engineering degree, nothing in the wikipedia article is news to me, and I rather think it does explain, in considerable detail, how a bicycle works – and the original statement was about how not why anyway…

The gyroscopic effects are significant on motorcycles, especially when racing, but they’re really not significant for ordinary bikes, with much lighter wheels and lower speeds. Contrary to some folks’ beliefs, gyroscopic effects are perfectly well understood, not merely in precise mathematics, but also in terms of why they work like that. The cat twisting in the air problem is a bit more complicated, because unlike a wheel, (different parts of) a cat can rotate about different axes simultaneously…

For entertainment, here’s a passage from my novel, The Reminiscences of Penny Lane – like many recounts in that novel, this one is based on my own history. Some of the recounts are pretty close to my actual experiences, others somewhat less so. I leave you to guess how closely this one follows reality:

http://clive.semmens.org.uk/Fiction/Penny/Rocketry.html#bike

It would be almost impossible to incorporate the wheel into a living creature, mostly due to coupling the blood supply into a rotating appendage, added to the wear and tear of the axle joints. I suppose that slugs, snails and even centi/millipedes come closest with their ripple-effect motion.

As a child I had one of those little tops, resembling a button mushroom, that you flick with finger and thumb. To begin with they sit spinning on their fat end and then they stand up on their stalk.

not merely in precise mathematics

There was usually a question on Euler’s equations for rotating bodies in the maths tripos each year.

To begin with they sit spinning on their fat end and then they stand up on their stalk.

Classic precession of the single axis of rotation due to an externally applied (and continuously varying…) torque…