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Comment by syncsynchalt | Hacker News Reader

Motorcycles turn at speed by a similar principle, though the cones arrangement is a bit flipped around.

I usually demonstrate it with two solo cups put mouth-to-mouth, to make a pair of facing cones that represents the motorcycle tire. The starting condition is that you're above parking lot speeds, and the bike is stable and is dynamically inclined to stay perfectly upright. To go left, you turn the bars right to upset the stable bike onto the left cone, and it goes left. To go right you turn the bars left and it upsets the bike onto the right cone, and goes right.

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This can also be easily experienced with a bicycle. Just push the handlebar forward on one side and watch/feel it tip over to that side instead of the other side where the wheel is pointing to.

Just be careful when doing this and don't fall.

In fact even for a bicycle at the lowest speeds counter-steer is required. Now that people have read this there will be a whole new group of people who on their next bike ride will think "According to theory i must be subconsciously turning the handlebars left in order to perform a right hand turn?"

And then will you notice yourself doing it. It's quite remarkable. All those years you thought you turned the handlebars into the turn. You've actually been turning them the other way subconsciously in order to lean into the turn.

One of the ways I keep myself occupied on long empty highway rides is to turn my cruise control on and keep myself in the lane by "punching" my handlebar. Punch the left side to turn left and the right side to turn right.

I’m completely lost now.

You’re talking about a motorcycle?

I didn’t know any of them had cruise control. I think the parent post is talking about a push bike.

But on the off chance there is a push bike with cruise control…

Yes, I'm talking about motorcycles. Most touring bikes have cruise control these days. Ducati's newest Multistrada even has radar cruise control and auto-braking.

Dang that sounds awesome. And it's only $25k. Problem is i would kill myself on a bike

The risk is definitely quite great and requires personal responsibility. Avoiding drug and alcohol use and using modern safety gear (not DOT junk) greatly reduces the probability of serious injury, but cannot eliminate it. It is a fantastic pastime, though.

There's always dirt riding, track riding, and mountain biking to scratch the itch without traffic!

I loved motorcycling, but gave it up because I could not accept the risk (about 7 to 10 times more likely to die per mile driven vs a car). The most common (about 45%) cause of a motorcycle fatality is a car making a left turn into a motorcycle. I took a lot of training classes, had good gear and always practiced my situational awareness, but after my advanced riding instructor with over 35 years of experience and the best gear money can buy was killed instantly by a driver in a minivan texting while making a left turn, I gave it up.

The feeling of riding a motorcycle is truly amazing and I absolutely miss it, but the risk factor is simply too high for me to be worth it.

DOT is the 'minimum' requirement. There are certainly better helmets. That said, the DOT requirements came into being in response to the number of junk helmets in the 1960s/1970s. It provided a minimum bar that a rider could rely on. After some states actually mandated DOT helmets, there was a huge market for fake DOT stickers from riders that were still wearing crap helmets for 'style' points. Mostly cheap half-buckets.

I started riding in the dirt at age 15, racing 3/8 mile dirt track at 16, and motocross at 17. Got my first street bike at 19. Rode about 100K miles until I moved from a rural part of the country to a heavily urban area, and gave it up because it was no fun in heavy traffic.

Avoiding alcohol and drugs, definitely. Wearing good safety gear, also definitely. I trashed one helmet in my life, walked away with zero injury. Equipment includes proper shoes, pants, jacket. I had one high speed slide, head never touched the ground, but I lost a couple patches of skin, and that was with leather. Modern materials are better. Denim is worthless. Also, carefully choose who you ride with. I had a number of peers that I would not ride with, they were accidents waiting to happen, and I didn't want to get caught up in their dumb ass mistakes.

What happens when turning a bike while riding with no hands? Does the lean induce the handlebars to counter-steer briefly, or is the counter-steer not necessarily because the lean is already happening?

Not sure the counter-steer makes you actually turn fully the opposite direction, it might be a force you apply in opposite but overall the handlebars still turn into the turn?

When you turn the handlebars to the right, it caused the bike to lean to the left. When you stop applying force to the handlebars, the front wheel “falls into line” with the left hand lean and they turn to the left.

However, it’s so subtle that in practice you don’t feel them turn back to the direction of the turn and it fully feels like you’re steering right to turn left.

The countersteer just causes the bike to lean. If you’re riding with no hands, the countersteer doesn’t happen.

*Edit*: Maybe I’m wrong about this. There’s another comment below that says that the counter steer does happen through leaning alone.

I think you are right (but we could both be wrong).

The way I experience countersteer is that it pulls the bottom of the bike towards the outside of the curve, in order to lean or maintain a lean. If you lean with balance it’s not needed.

I just tested it on my bike on my way home and we are both definitely right :) There's no countersteer when you lean with no hands on the handlebars.

With no hands, the equilibrium lean angle is controlled by the rider shifting weight (centre of gravity) from side to side. The caster angle on the front wheel is the negative feedback mechanism that keeps the bike balanced.

Last time I saw this discussion I checked what I was doing and found that I don't usually countersteer when turning so it does not actually seem to be required. It was a while ago so I don't remember the details but I do remember making a very low speed turn with my hands positioned to not be able to countersteer and it worked fine. I'm guessing the alternative is to lean before turning.

At very low speeds (tight turns, i.e. high curvature of the bike's path), the highly-curved path requires steering into the turn. However for most turns (higher-speed) the curvature is less significant so the handlebars don't really turn at all - you do however need to apply a force to the handlebars to establish and maintain a lean into the curve - this force being in the opposite direction to the turn (i.e. when turning right, you push forward on the right handlebar).

>However for most turns (higher-speed) the curvature is less significant so the handlebars don't really turn at all

Is it possible to turn a bicycle at higher speeds without leaning? Ie turn like a car by just turning the front wheel. I've tried it a few times and it's been very difficult.

Horizontally, a bicycle is an inverted pendulum: to accelerate it in one direction it must lean in that direction. It's still possible to keep the frame of the bike upright in a turn but as the rider you would have to shift your weight into the turn to compensate.

If you consider the whole system (bike and rider) as a point mass on a stick, it's still leaned over (centre of mass of not above the tyres) in that case.

I'm still not convinced countersteering is ever necessary since it is obviously possible to lean a bicycle without turning the handle bars at all. Why wouldn't lean first then turn the way you are turning work? Or even lean while turning the direction you want to go. I am slow in general and for me most turns are sharp and low speed.

Any kind of serious turning involves lateral acceleration. The bike must lean (well, the centre of gravity must be offset laterally from the wheels contact patches) to compensate. It's an inverted pendulum, with a feedback mechanism (caster angle of the forks) and the combined effects of gravity and centrifugal force (from the rider's perspective). There are also minor secondary things like gyroscopic effect of the spinning wheels.

The equilibrium position (lean angle) of this feedback system can be shifted by the rider either by applying force to the handlebars, or shifting the centre of mass away from the middle (leaning your body to the side).

It's possible to steer by only shifting weight, but a bike with locked handlebars would not stay upright (no feedback mechanism). Applying force to the handlebars is the way to get maximum control authority over the system.

Edit: more detail... the tilt angle is defined by the lateral offset between the centre of mass and the wheel contact patch. The rider shifting his weight achieves this by moving the centre of mass, while using the handlebars moves the wheels to the side while leaving the centre of mass (mostly) unmoved. Of course, the wheels' contact patch can be moved further and faster laterally (by steering) than the rider's weight can be shifted (which is limited by the rider's flexibility).

Sounds like you are agreeing with me then? I'm not saying no handlebars at all, just that if you want to turn right it doesn't seem to actually be necessary to slightly move the handlebars left first, which is the claim that is often made when this discussion happens.

I agree it's possible in principle to ride a bike without the handlebars (have done this myself on many occasions, including motorbikes), but more dynamic maneuvers do require use of the bars (e.g. swerving to avoid an obstacle).

Sudden maneuvers are an essential survival skill on two wheels, and it's important to understand how to steer rapidly. A rider who just steers intuitively is vulnerable to a phenomenon known as "target fixation": becoming mentally focused on an obstacle and steering into it. Having a rational understanding of how to steer allows the rider to exert conscious control over the bike's direction in these situations.

That is actually not what I experience at all. After I first read about the counter-steering thing on bicycles, I tried to observe exactly how I corner. I never was able to observe counter-steering, and forcefully counter-steering felt very wrong. I just somehow succeed in reaching the correct leaning angle for whatever turn I want to make.

Whatever happens must be too subtle to notice, and/or completely subconscious.

This can be demonstrated easily to someone who doesn't believe they are doing it. Just ask them to ride their motorcycle with only the right hand on the throttle and their left hand off the bar.

Just to add this explicitly, to expand on some specifics, motorcycles have the added complexity of angular momentum and its effects. As you mention, turning the wheel effects your lean angle through angular momentum conservation. The cone then is the dominant factor causing the bike to turn.

The speed matters because as the speed is faster, a smaller angle change in the handlebars corresponds to a bigger sideways tilt motion of the bike.

Counter-steering.

It comes intuitively if you've ever ridden a bike at more than a sedate speed.

Uh, no. Motorcycle racers learned about countersteering in the 70s. Before they had no idea.

You realise that motorcycles existed for literally decades before it had a name, how where they turning corners at speed, hell how was I doing it in the 90s on scramblers when I was a kid, no one taught me, it’s intuitive.

Totally correct. At speed, you simply cannot turn without counter steering. If you tried to turn by turning your bars in the direction you wanted to go, you simply won't go there.

At some point, someone noticed racing bikes counter steer really severely so you can easily see the wheel is actually pointing the opposite way. But the reality is that even at "won't fall over" speed on a bicycle, you're already doing the exact same thing. When you lean, you counter steer. Otherwise you'll high-side like a missile.

One of the Wright brothers has a quote about this (before they were airplane makers they were bicycle makers, the bicycle being the latest mechanical marvel of their time). The summary of the quote is that the action is intuitive but nobody realizes (or even admits) that they're doing it:

> I have asked dozens of bicycle riders how they turn to the left. I have never found a single person who stated all the facts correctly when first asked. They almost invariably said that to turn to the left, they turned the handlebar to the left and as a result made a turn to the left. [...] I have never found a non-scientific rider who had particularly noticed it and spoke of it from his own conscious observation and initiative.

The existence of counter-steering is still controversial to some riders, to the point where machines like the "No B.S. Bike" were created to demonstrate it as a necessary effect: https://soundrider.com/archive/safety-skills/nobsbike.aspx

Another way to demonstrate it on a bicycle, you can do something pretty much every child has already done numerous times: ride without your hands on the handle bars (hands free).

To turn, you lean in the direction you want to go. But what way does the handle bar turn when you do that? It counter steers! You will fall if it doesn't (which is essentially what the No B.S. Bike demonstrates).

The irony is that the majority of people will think you're making it up when describing counter steering, yet they are already doing it without even thinking about it all the time.

The first time I read about counter steering, I thought "man, this'll take forever to practice" until I realized it's really the only way one ever does it.

The main advantage to knowing is that you can stop wasting energy with footpeg weighting or unnecessary leaning and use bar pressure. (weighting and body position have their uses but for most riders in most situations countersteering is the most efficient technique.)

That's when they call it push steering. But it's really the same thing. When you push, you are causing your bike to counter steer. You are literally pushing the bar forward, even if you think you are pushing downward, which is by definition a counter steer.

I think a lot of people assume those are different things. But they aren't. You simply can't turn at speed without counter steering, regardless of how you visualize the mechanics.

You are spot on for people who think pushing with their foot on the inner foot peg has an effect. I'm sure it does, but it's a lot of wasted effort given that the end result you are looking for is the bar turning the opposite direction, and you'll be doing that whether you are conscious of it or not. It takes far less effort to simply not think about it, and do what comes natural since your arms and hands will inevitably do the right thing without any "different" theories interfering.

It's also why 3 wheel bikes are notorious for throwing the rider high-side if they corner too quickly. It stops you from leaning, so there is no ability to counter steer. You end up behaving more like a London double-decker bus in the turn.

Also, understanding how to steer greatly enhances the ability to apply abrupt steering inputs - e.g. swerving around obstacles.

I blame that more on the people who "explain" it. Bad explanations of relativity or quantum mechanics have nothing on countersteering - everyone who talks about it does it as "woo, this super mysterious thing".

In particular people say you can't turn left without first turning right and vice versa, which is obviously nonsense - if that were true as stated then it would be impossible to ever turn at all.

If it came so intuitively, there should be less videos like this: https://www.youtube.com/watch?v=VVE79XT8-Mg

This is a helmet cam video from a motorbike rider riding straight into a truck at high speed. It should probably have a NSFW tag or warning.

It is a bit of a brutal watch. FWIW it says the rider survived, and it does clearly demonstrate how countersteering can be non obvious in some situations. (In the video the rider is already in a corner and needs to tighten his line (sharpen the corner). Instead of counter-steering, he tries to simply turn the bars into the corner more, which has the opposite effect, and causes him to hit the truck.)

A little context is nice. The guy survives. Still a good video.

This is a good, relevant video and should not be so heavily downvoted. Yes, it is NSFW, but we're all adults here and this is an informative video aimed at adults, to teach the subject and demonstrate where it _applies_.

The only time I ever notice it is if I'm riding up really close to a curb or something and it feels like it's somehow pulling me in, like there's no way to steer away from it.

Intuitively it feels weird, but logically it makes sense - if I'm too close to something, I can't turn briefly towards it in order to get away from it.

Same thing in mountain biking and getting up on the edge of the trail. It can look like you just rode straight up it for no good reason, but in reality you intuitively felt that you had no room to counter steer without running the front wheel off the track.

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