>If you lean left, front wheel will "do" countersteering itself (same as noted).

I am not sure. If you lean left, then the handle bar ll slightly turn left automatically.

In actual countersteering, it greatly helps only because it helps to quickly initiate a tilt in the required direction. For example, if you want to go to left, then turn the handle bar to the right, which causes the front wheel to slight start to offset in the right, which in turn causes the whole bike to tilt to left, and once it start to tilt to the left, then the normal process of turning is applied...

It's always countersteering. Doesn't even matter if your hands are on the bars (really).

When you lean to (your) left, the center of mass of you+bike goes left of the plane of the wheels, this causes the front wheel to rotate away (i.e. right) from the motion slightly which causes you to bank left and the front wheel comes around to meet it until you are in equilibrium again.

Countersteering doesn't "help", it's just unavoidable. Being aware of it helps you have better control. At very low velocities the effect is so minor you probably can't notice (and steering angles are large).

> When you lean to (your) left, the center of mass of you+bike goes left of the plane of the wheels, this causes the front wheel to rotate away

This does not seem correct. Why does it cause the front wheel to rotate away (right) ?

If you lean a stationary cycle to the left, the front wheel will turn left.

  Why does it cause the front wheel to rotate away (right) ?

Answer is : "it's complicated" , which is why this subject causes confusion. There are many arguments about the exact dynamics (combinations of gyroscopic effects, torques, center-of-mass motion), but empirically it is pretty clear that two wheeled vehicles like bikes/motorcycles do not turn without counter-steer.

Not at all complicated. A bike is made so that the front wheel will turn in the same direction as the bike is leaned. This has a simple stabilising effect. Bike leans right, front wheel turns right, increased centrifugal force from the sharper turn will unlean the bike to the left.

> Bike leans right, front wheel turns right

Agree. But this is not what the other person is saying.

Except, it doesn’t at first. Which is why this is counter intuitive.

If you lean your body to the left the bike reacts by leaning to the right. Your body can only move by pushing the bike in the opposite direction.

I shouldn't have mentioned 'leaning left'.

If I'm in contact with the top of my bike and not steering the bars, I can either push the top of the bike left or right. I push the top of the bike to the left. The bike and I have separate moments of intertia around longitudinal axis. Without any other forces involved (just my bum and the top of the bike pushing each other), the bottom of the bike i.e. the contact patch would move to the right. However, there's friction between the tyres and the ground meaning that doesn't happen. Instead, the ground pushes the bottom of the wheels to the left. This means the only external force on the union of rider and bike is from the ground pointing leftwards. This pushes the COG to the left.

While the motion of the top of the bike may cause some countersteering in the front wheel if left free, you can resist this by pushing the right side of the handlebars i.e. steering left. So we now have a bike tilting to the left, with the front wheel pointing forwards, and the COG to the left of the contact patches. The front wheel can be gently pushed to point left.

No countersteering involved.

That is bullshit. If I just lean to the left, the bike does not "react" by leaning to the right. If I lean to the left without touching the handle bars, the cycle ll start turning to the left.

With counter steering, it can be made much quicker and in a much responsive fashion.

The point is that the wheel, which is free, will turn to the right first. The bike will lean to the left as this takes the two wheels out of line. The wheel will follow to the left.

There is nothing magical about countersteering, it’s just the way cornering works with bikes.

Don’t believe me? Set up an angle indicator and video it.

A bike is standing straight, completely still, with the front wheels completely straight. According to you, if I lean this stationary bike, to left, you are saying the front wheel will turn to right, right?

Counter steering is a property only while it is rolling forward. You’ll have to be moving reasonably fast to notice it easily.

In context this was clear but I should have been more explicit.

The part you are missing is the gyroscopic procession from the wheels. When you try turning the wheel to the left, you create a force that is 90 degrees to force.

If you just turn the handlebars (which would cause the bike to lean in the direction of the turn), you will end up creating a force at the top of the wheel in the opposite direction of your tilt. (e.g. the force will be at 12 o'clock)

If you just lean in the direction you'd like to turn, the wheel will turn in the opposite direction of the lean. (e.g. there will be an opposite force at 9 o'clock)

In order to turn you must always briefly steer in the opposite direction you'd like to turn, so that you may lean in the direction you'd like to turn, which will allow you to turn the wheel in the direction of the turn without upsetting the bike.

I learned this fact about 2 years ago and I've been hyper-aware of the fact ever since. Try as I might, it's literally impossible to steer a bike without counter-steering.

The fact that you absolutely must counter-steer to turn is one of the reason why inexperienced bike riders tend to fall over when they need to steer in an emergency, because they just twist the handlebars, which catapults them off the other side.

Knowing this also helped me finally learn to ride a bike with no handlebars, since you have to lean opposite the direction you'd like the wheel to go.

It's timing dependent. Turning right and momentum 'pushes' your body to the left, but with the correct timing you end up countering that force while keeping the bike absolutely vertical.

PS: Picture how a car turns, the wheels are vertical and you can you can turn without counter steering just fine but the weight externally offset. The difference with a bike / motorcycle is just how difficult it is to balance.

It is not timing it is balance of mass and conservation of energy. Car has totally different mass distribution. So energy conservation is also different.

> countersteering is always required

Only on a motorbike.

The steering geometry is exactly the same.

The only time you steer left to go left is if you're going so slowly that the only reason the bike doesn't fall over is because of your near-superhuman balance. That is to say, when you're practically at a standstill. Anywhere approaching walking pace or above, if you try to turn left by steering left, you'll fall off the right hand side before you make any appreciable turn.

> if you try to turn left by steering left

Well, if you're leaning left when steering left, I don't see how you'll fall to the right

That's the issue; how do you lean left to start with? If the human-bicycle system has its center of gravity over the wheel line, shifting your weight relative to the bike doesn't move the center of gravity - you lean one way, the bike leans the other, and you end up in the same overall position. The only way to initiate a lean to the left is to countersteer to the right.

That's weird since I don't think I'm countersteering when turning.

Or perhaps I'm doing it unconsciously?

> Or perhaps I'm doing it unconsciously?

You are. I proved this to myself once by applying pressure to the handlebars using only the palm of my hands on the backside of each handle. Even at very slow speeds, I could not for the life of me turn left by applying pressure only to the right bar (to turn the front wheel to the left). No amount of leaning helped. To lean the bike, I needed to create some external force to push it over. Leaning my own body to the left just made the bike lean to the right.

I'll have to check, because I don't believe it. I wonder who's right: me or a bunch of randos on an internet thread.

I've seen the same claim from a lot of people who seemed to have thought about it a lot: that you always countersteer on a two-wheeled vehicle, but you only do so consciously if you're riding a very fast vehicle or you want to turn extremely quickly. (A deliberate countersteer is taught in some bicycle safety classes as an "emergency quick turn".)

This is counterintuitive to me as a regular cyclist, but I realize that most of my cycling skills are completely unconscious, so I don't have a lot of confidence in my ability to describe exactly what I'm doing on my bike.

I've only ever riden a bike and very rarely at high speed (for a bike), so that explain why I never had to countersteer consciously.

That's what I used to think until I started taking motorbike lessons.

At first I was having a hard time turning, because this whole counter-steering thing didn't come naturally to me and I would try to turn the handlebars to the left if I wanted to go left, but the bike would go the other way witch was pretty scary.

I then internalised this and the next time I rode a bike I tried this out, and indeed, this is how it works. If I turned the handlebars left at any considerable speed, the bike would lean to the right and start turning right, with the handlebars going right. It would go a slight bit left at the very beginning, but then it would go all the way right.

When I think about it, at slow speeds (say below 25 km/h - 15 mph) I only turn the handlebars and lean the bike. However, I can lean the bike at those speeds, so no counter-steering is required. I first lean the bike and then turn the bars. However, it's very difficult to have it lean any useful amount at speed. And this is where counter-steering is useful.

Here's a video where this is all explained, complete with fixed handlebars (that don't steer the wheel) to show how just leaning doesn't do much : https://www.youtube.com/watch?v=8_5Z3jyO2pA&feature=youtu.be...

Granted, this is way more noticeable on a motorbike that on a bicycle. Maybe the weight of the wheels and of the whole bike has something to do with it. If I lean a 10 kg bike but stay upright on it, the centre of gravity doesn't move much. However, on a 300 kg motorcycle, it moves quite a bit more.

> If you lean left, front wheel will "do" countersteering itself

The same applies to a bicycle.

> Only on a motorbike.

Only above a certain speed, at low speeds countersteering will not work

Similarly above a certain speed on a bicycle countersteering is the only way you can turn

Some people seem to describe this difference as unconscious countersteering versus deliberate countersteering, that is, that the difference isn't really whether you're countersteering or not, but whether the countersteer is large enough that you have to do it "on purpose".