Motorcycling Physics & The Forces that Keep You Safe – webBikeWorld

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The picture I’ve placed above is an interesting one. For those not in the know, it’s an image from the “MotoGP Lean Angle Experience. ” Long story short, it allows regular punters like you and I to experience what it’s like to lean at a purported 64°, just like our collective racing heroes a. k. a. Rossi, Márquez plus Miller. And while it may just seem like a pleasant way in order to waste 15 minutes at your local MotoGP event in between the races, it’s actually a genius idea that does something very important in terms of motorcycle rider training .

See, as we all know far too well, the real challenge with learning about motorcycle physics is that if you get it wrong, you can end up seriously hurting yourself in a motorcycle crash . Compare that will to some thing like cooking or music, where mistakes are just annoying occurrences that you make, figure out and move on from.

But help to make a proper mistake in the world of motorcycling and the consequences can be hospital, permanent disability, or even an one -way trip to the big MotoGP racetrack in the sky. The result associated with this game’s high-stakes is that most riders treat the art of riding a bike kind of like a game of Russian roulette—and rightly so. No one should try and get their knee down during their very first ride on a bike. That would be insane.

a graphic showing the relative lean angles achievable by different types of motorcycles
The current moto lean angle leaderboards are ruled by the 64 degrees commonly seen inside MotoGP bikes. Image Via: Moto GP

But what this big “bike on a hinge” attraction in the Moto GP does is allow people to push the particular limits associated with motorcycle physics safely; it shows them what happens when a bike leans and provides a greater level of understanding regarding the forces at play. It also breaks down the process into something easy plus memorable—and the majority of importantly, this lets participants understand what happens when the bike leans without all of them actually having to attempt a similar move from high speed.

In essence, they are learning the theory of movement and physical interactions before putting it into practice. That, my custom leather race suit wearing friends, is exactly what they call physics .

So let’s put our moto mortar board hats on and look with what actually is happening when you ride your beloved motorbike down the road and through a set of corners. I’m going to break this whole she-bang straight down into three main parts: acceleration, braking, and cornering.

Naturally, cornering is the big daddy when it comes to bodily forces, so let’s leave that one in order to last for when you’re properly warmed up.

a rider on a motorcycle performs a wheelie while also sitting on the bike's tank
Whatever you do, don’t do this. Image via the: BBC

1. Acceleration Physics

What we are doing here is bringing a common, garden-variety motorcycle through a standstill up to a comfortable cruising speed. Needless in order to say, at a standstill and with the engine turned off, a motorcycle only has one main force acting on it, plus that’s gravity.

Gravity & Torque

Go ahead and turn the particular engine on. It now has two forces working on it: the law of gravity and a large rotating mass spinning inside of this. Put simply the pistons, crankshaft and other assorted gubbins that form the revolving mass inside an engine create “torque” (a force that may cause an object to rotate regarding an axis). Rev the particular engine and Sir Issac Newton’s third law kicks in here—and it states that “For every action (or force) in nature there will be an equal and opposite reaction. ”

In this particular case, as the engine spins up, it also exerts an equal and reverse force on the bike itself. In the case associated with my BMW and its boxer engine, whenever I rev the motor at the standstill, the particular entire bike rocks to the right. This is, in fact, the counter-clockwise rotation of the engine’s crankshaft pushing against the rest of the bicycle and trying to spin the entire bike within a clockwise direction.

Thanks to gravity, the particular crank’s rotational axis, as well as the fact that will the bike is resting on the ground, this force translates to the top of the bike moving towards the right.

a motocross motorcycle performs a wheelie
Given enough rear wheel torque and contact patch friction, this will eventually happen. Picture with the Motorcycle Legal Foundation

Yet the best “opposite forces” here are usually the ones that propel you and your bike forward, namely those that this particular very same rotating engine is usually imparting upon the back wheel. It does this simply by pushing the particular bike forward and in another example of Newton’s third law, it also sees the bike by itself push against the road, or if you want to be really dramatic about it, it’s really the bicycle trying in order to spin the particular entire planet in the equal plus opposite direction to the bike’s direction associated with forward travel.

Take this idea to its logical conclusion, and a bike that had enough mass and rpm could stop and/or change the planet’s spin—but that’s a Friday beers conversation we’re not going to have here.

A drag bike without its fairings displays it's considerable length
A drag bike’s wheelbase is definitely long, with the rider and engine as far away from the rear wheel while possible to make it harder with regard to the bike’s torque to induce a wheelie. Image via Plex Tuning

So basically, the force of the engine turning can be transmitted in order to the back wheel, which pushes against the road plus moves the particular bike ahead. And as most motorcycles have a fairly short wheelbase as compared to their own centre of gravity and its distance above the road’s surface, a motorbike that has enough torque applied to the rear wheel will ultimately raise its front steering wheel off the ground.

This is why drag bicycles tend to sit low plus have very long rear swingarms: the longer the wheel base of the particular bike, the harder it is for the torque pumping out of the rear wheel to lift the particular bike’s front off the ground. And in drag bikes, it’s all about how much force a person can impart to the particular ground without looping the bike and having the thing land on top associated with you; hence their epic length.

Why Motorcycles Stabilize As You Ride

The other force that comes into play on this point is the particular force from the bike’s 2 wheels spinning. Now, unlike the turning force of the engine, this force isn’t just present under acceleration. Instead, it is present at all times and is certainly entirely reliant around the speed that both the wheels are re-writing at. The motorcycle won’t want in order to wheelie in case you are cruising at a constant speed, but the angular momentum generated by the mass from the spinning wheels and tyres is constant. And thanks to the rules of conservation associated with angular energy, the bike’s spinning tires will often keep the motorcycle upright and travelling in a straight line.

Don’t believe me? Then think about how many times you have seen a MotoGP rider have an off only to see their particular bike correct itself plus continue upon in a directly line until it hits a barrier. That, the friends, is the wheels conserving angular impetus. And how many of you have seen a stationary bike stand up by itself without the stand? Exactly none, right? Again, that is because the bike’s wheels are usually not spinning—and therefore there are exactly no forces at work apart from gravity.

The final primary force here is furthermore regarding good ol’ Newton. He also stated that objects in rest will remain at rest. So when you apply the throttle and the bike moves off, your body will want to stay stationary. At gentle accelerations this is barely perceptible, but if you actually give it some beans, the particular bike will certainly launch forwards and you will get the feeling of your body wanting to slide backward off the bike.

The most natural reaction here is to tighten your grip within the bars, but guess what? That’s right, your primary handhold for the bike is also the accelerator; and that’s that part that makes the bicycle go faster. Ever heard of whiskey throttle? Boom.

The particular other (albeit more minor) force from play the following is wind resistance, which furthermore pushes towards you and the bike. But we won’t go into that right here because unless you plan on a session with the local race track, the causes aren’t enough to have any meaningful effect at regular speeds. Certainly not 1 that’ll endanger you.

ACCELERATION SAFETY LESSON: During acceleration, rpm forces may counteract the force associated with gravity keeping your bike’s front wheel on the particular road, reducing the effectiveness of the steering and possibly raising the front wheel off the floor. The pressure of a motorcycle’s content spinning wheels keeps the bicycle upright plus wanting to head straight. Your body will want to “stay behind” when your own motorcycle accelerates, affecting your posture, grip upon the pubs and exactly how much accelerator you are applying.

2. Braking Physics

Marc Márquez performs a stoppie on his Honda Repsol MotoGP racing motorcycle
Marc Márquez teaches us a few physics. Picture Via: Reddit

I’ll avoid repeating myself here, so rest assured that a bike will always have the particular force of gravity pressing it downwards and if it is moving, the wheels will have angular momentum. But what happens whenever you use the brakes on a bike? Funnily enough, it’s pretty much the exact opposite associated with what occurs once you accelerate hard. If you believe about this, the bike under hard speed will wheelie, but what does a bike below hard brake do? That is right, it’ll do the reverse wheelie, or a “stoppie”. Fun when you are expecting it and can control it, but super dangerous and even deadly if you aren’t.

Friction & Inertia

When you utilize the brake systems with sufficient force, the particular friction that occurs between the front tyre as well as the road’s surface does the opposite in order to the bike that motor torque will; as the particular bike’s centre of gravity is above the road’s surface, this will tend to try and rotate the entire bicycle around the particular point where the tyre is in contact with the road since the bike’s mass is over that point. Again, in the event that the bike was as long and low as a car, this particular wouldn’t happen.

The very same forces lift the rear steering wheel off the ground, really reducing the effectiveness inside the overall stopping equation. In cars, the weight distribution will be different, so you’ll never see the car do an emergency braking system manoeuvre plus flip on its roof. Instead you’ll just see it dive so the particular nose goes down and the rear comes up. Likewise, a car under strong acceleration forces will raise its nose and squat at the back.

Like on vehicles, ABS—or anti-lock braking systems—on bikes stops your wheels from locking up entirely under heavy braking. For cars, this particular is important as you can’t steer a car along with locked tires. But as an additional bonus on bicycles, it’ll also stop a person from being launched over the bars of a bike that will otherwise would have done the spontaneous cartwheel. Make zero mistakes, a full emergency stop on a motorcycle is usually a very dangerous and avoid-at-all costs event, yet it’s great to know that ABS has your back (and your hands, face, legs and arms) if it does happen.

The other “same but opposite” force right here is the particular one exactly where the body that is in motion may wish to stay in movement. So instead of being forced from the back of the bike as with speeding, here you will be forced forwards towards the handlebars since the bicycle slows plus you do not. Luckily there’s no opposite to whisky throttle (no, vodka braking is not a thing) and your average riding position means that it’s a lot easier to deal with braking causes simply by pushing contrary to the bars than this is regarding “pulling” velocity forces.

BRAKING SECURITY LESSONS: Hard braking on the bike without having ABS may raise the rear wheel and perhaps throw you over the handle bars. Of almost all the emergency situations that can occur on a bike, hard braking may be the one you want to avoid the particular most. In case there’s real speed involved, it will almost always put you within serious danger. And despite what seasoned bikers will tell you, it’s incredibly hard in order to modulate your own braking push on the non-ABS motorcycle in an crisis. 95% of riders—even the good ones—will simply apply all the brake at once given a big enough scare.

3. Cornering Physics

Marc Márquez takes a corner on a MotoGP circuit at an extreme lean angle
Sweet, sweet equilibrium. Image via Motogp

OK. This is where the rubber REALLY strikes the street. The physics involved in handling a bike are super complex, thus we’ll only cover away the most important ones right here. Sharpen your imaginary pencils and pay attention. It could save your life.

Picture the snapshot associated with a motorcycle taken mid-corner. These aren’t your typical urban corners, either. While the physics are usually largely the same, for the sake of argument, let us imagine a big sweeping rural corner. The ones that last more than a few seconds and see you and the bike leaned over the good amount. Here there are 3 main makes at play.

Equilibrium (Balance) & Centrifugal Force

At this imaginary frozen moment, the particular bike is definitely leaned over at (say) 45 degrees. Now obviously if you did that while stationary and with your feet in the pegs, the bike would just come crashing down. Yet why doesn’t it? It’s because there is a good equilibrium—or balance—of forces pulling the bicycle downwards (gravity) and seeking to push it upright. This straight one is a “centrifugal” force. Centrifugal quite literally means “centre fleeing”; plus now you can see why. This force pushes you away from the center of the turn.

a diagram show the forces at play when a motorcycle leans through a corner
Image Through: Reddit

In short, the particular lean the rider imparts over the bike by their inputs into the ’bars and transferring their bodyweight towards the inside of the particular corner counteracts the power that wants your bicycle to be launched off the road and in to the undergrowth like a kid on a merry-go-round that’s been spun up too fast.

The particular life-saving drive here is of course the friction between the bike’s wheels as well as the road. It is the exact same friction that also helps your own wheels rise off-road whenever pinning the particular throttle plus smashing the brakes above, so just if you think friction maybe kinda sucks, here it is saving your existence. No rubbing, no cornering.

And all that’s only considering the makes at have fun with in a single axis associated with a bicycle leaning. Right now imagine looking at all the particular other pushes at perform. The wind resistance pressing you and the bike backwards. The angular momentum of the spinning wheels attempting to sit down the bicycle upright plus keep it going within a straight line. And to all that, you can add the particular angular energy and torque forces on play because the engine in the bike changes both revs and undergoes changes of angular impetus as its spinning bulk is moved around. Plus what about the whole countersteering thing? My god. The particular helmeted mind boggles.

Now you can probably start to picture the reason why it’s actually not a good concept to brake hard mid-corner. Or speed up hard. Adding a rapid change in speed and friction to this already complex formula and just about all hell can break loose.

A motorcycle racer suffers a "highside" crash on a racing track
A highside crash is often caused by the sudden modify within the chaffing coefficient among the bike’s rubber and the road. Image via Shifting-Gears

In the end, the truth that motorbikes can part at most now seems kind of remarkable, doesn’t this? It’s furthermore mindblowing in order to know just how far you can take this entire equation when you look at a MotoGP bike handling. Them getting their knees, elbows plus even helmets (gulp) to touch the ground is nothing more compared to an attempt by the riders to reach a cornering equilibrium, but in this case that will balance enables them to corner quicker without being thrown off.

Similarly, in case you wanted to build the world’s fastest MotoGP bike, all of you’d need to do would become to allow it to lean more than further than the sixty four degrees all of us referenced in the start of this piece.

a rider takes a corner on a MotoGP circuit at an extreme lean angle
Elbow down! Picture via Tuned Trends

As the velocity through the corner increases, therefore do the Centrifugal forces wanting to toss you off. Balance that with a greater lean angle—hence allowing more gravity to come into play to balance the centre fleeing—and a person, my friends, now have a race winning bike. If you could just figure out how to keep enough rubber on the road, where in order to put the rider’s feet and how to design the bike that looks like an upside down pyramid.

Put it all together properly and this is what physics (and a buttload of skill) can do.

CORNERING SAFETY LESSONS: Cornering the motorcycle is about balancing your lean angle (i. e. the force gravity is pulling over the leaning bike) with the centrifugal forces trying to lift the bike up plus push you to the outside of the particular corner. A large percentage of cornering accidents occur with the phenomena associated with target fixation; a condition where a rider loses faith in the particular bike’s ability to corner and returns it to an upright position, therefore running wide. Always look through a corner  and never into it, and not make any sudden applications of brake, throttle or steering once you have committed in order to a corner. Remember that the weakest link in the particular chain will be you; almost all motorcycles can corner much harder than you can.

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