What a bike wants...

[CaptCrashIdaho]

Found the following video during a back and forth with a newer rider while discussing bike stability.

http://www.youtube.com/watch?v=ePGSxhxXr8s

What you're seeing here is a motorcycle, under power, doing what a motorcycle wants to do--run straight and true. This is why you have to be willing to steer a bike to get it to change direction, the desire to run straight and true increases with speed--that's the math part--so as you go faster, the bike becomes more challenging to turn.

One of the concerns MotoGP fans had about a young, skinny Valentino Rossi and small guys like Dani Pedrosa is that they would lack the upper body strength to turn the bikes on big fast tracks for the 20 to 30 laps required.

This video also points out the problems people have with running wide in turns because "the bike wouldn't turn" which actually means "I was unable or unwilling to steer my motorcycle."

A bike, at speed, doesn't want to fall down--it wants to run straight and true. Steering is accomplished by countersteering. Know this and be willing to act and you've made the first step to be in control of your ride.

[Badlands-4-2]

That is crazy. I am not nearly so brave.

[beginner]

I asked this question earlier. Suppose that bike had a radio controled servo so the brakes could be applied remotely. If the front and rear brakes were applied for a hard stop would the bike stay stable until it reached a low speed or would applying the usual amount of braking force on the front cause the bike to be unstable and fall because there is no one steering?

[Dodsfall]

Unless there is abnormal pavement defects or a tree in the way, the motorcycle would only fall after the speed was reduced enough for the stabilizing gyroscopic forces to be overtaken by gravity.

[CaptCrashIdaho]

Unless there is abnormal pavement defects or a tree in the way, the motorcycle would only fall after the speed was reduced enough for the stabilizing gyroscopic forces to be overtaken by gravity.

Excellent point. One of the things that new riders do is attempt to make things more complex than they need to be. It's valuable for noobs to know that bikes are stable when under power AND under braking. Keeping your head and eyes UP will help tremendously in this area.

There's a reason we call big time braking "burying the nose" or "planting the front".

Bikes are inherently stable at speed and, when you're braking, all those forces help keep the bike upright unless you make some kind of goofy steering input. The two biggest dangers are making big steering inputs or locking the front. Riders like Beginner spend a majority of their time in the dirt where (due to surface) the bike is actually more forgiving of steering inputs AND more likely to lock up--this adds to his misunderstanding of how streetbikes behave.

[Biker Dash]

Another thing that helps the bike remain stable is the rake and trail. That helps pull the wheel center, due to the nature of the geometry and forces acting on the wheel. Thats why cruisers feel more stable and sportbikes feel more nimble in general. It really takes a serious malf brought on by the rider to cause the bike to go down, either by inexperience, recklessness, or outside influence, as Dods pointed out.

[LukeDuke25]

Good video. Shows why two bikes handle completely different!

[daw840]

That's pretty awesome.

[distantThunder]

HAHAHAHA !!! Good one.

Tomorrow morning ... I'm gonna pack a lunch for my motorcycle,
and send it off to work by itself.
I'll stay home and watch TV.
Beats me why I'm even ridin'. :-)

distantThunder

[Tdubb]

Nice video Captcrash. And a great way to show what a bike wants.

[ralphlong]

That is one of the coolest videos I have ever seen!

[marine_mike]

I am so glad I read this thread. I took my bike down the street for the first time today and remembered this. Man, even at low speeds the bike wants to straighten up. Thank go it was a dead end street and thank god there was a large area in front of the building. Eventually I got it. Now I just have to learn to keep off the throttle.

[coda729]

man he about took out the camera man as he cut off through the grass pretty wild video

[JohnnyQuid]

That dude is a wild man! (both of em for that matter) Cool video Crash!

[Peter Darby]

Cool video. One of the survival techniques you eventually learn is in some emergencies like whacking something in the road to let the bike do its thing with no inputs from you. It is upright and moving and wants to stay that way. Anything you do can only upset that and put you on the ground. I will even relax my arms so the front wheel can wobble and buck then return to straight and narrow on its own.

[Kinkikowboi]

So is this why you want to accelerate out of a turn? To straighten up faster? So like if you feel like you're turning too hard and you start leaning, would accelerating keep the motorcycle up?

[FreepZ]

So is this why you want to accelerate out of a turn? To straighten up faster? So like if you feel like you're turning too hard and you start leaning, would accelerating keep the motorcycle up?

You accelerate in a curve to keep in control. If you try to maintain a constant speed, the engine will jerk between slowing you down and speeding you up. Jerkiness in a curve is bad news. If you slow down in the curve, you eliminate the jerkiness, but there are other problems. The slower the bike, the less stable, so the more difficult it is to balance during the curve. The safest thing to do is to accelerate out of the curve. You don't get the jerkiness and you do get more stability.

Unless you're going very slowly, the best way to stop leaning is to relax your arms and let the bike right itself.

[FreepZ]

That video is impressive, but watching a bike ride itself is no surprise to me.

If you want to see how stable your bike is, I would suggest doing this experiment.


Get your bike up to about 60 mph on a straight road.
Loosen your hold on the bars (but don't let go).
When you feel comfortable enough, you can let go one hand (I suggest your left hand) and then both. (Be sure to grip the bike with your legs!)
You will find that the bike does not fall over.
If you're really feeling comfortable, and still going fast (since your engine is going to slow you down pretty quickly once you release the throttle), try to make the bike lean. You'll find that it's pretty impossible to do that.


You can jerk around a lot on your bike and it will just keep on going straight!

[BioInclined]

An object relies on its base, input and result to determine its action. It's not that it will be less stable at lower speeds, rather it is easier to be influenced.
Imagine walking in a straight line, constant speed, never twisting your hips,neck,shoulders, etc at all...now some one gently pushes you on the shoulder at roughly 90 degree angle as you pass them. Your reaction from the input will be to strafe(side step since keeping facing forward) a fair amount.
If you repeat this at a jogging pace or even running, following all the same straight forward rules, with the same amount of input from the push, it will NOT have as much of a result. The action will be the same though, you strafe a bit. You have the same amount of mass moving at a higher rate, your energy forward now more greatly negates the input from the push.
A bike will function the same way(tire technology helps but is not the only factor)
I built a remote control motorcycle when I was younger from scratch, so understanding the basics was needed.
A bike(any) under perfect conditions, level ground, locked perfectly alined wheels, launch perfectly straight etc, will NOT down itself until absolute 0 velocity/speed. If it can maintain a 1 mph rate, it will not go down. It's one of those things that's hard to comprehend since it needs perfect conditions and we don't experience the moment of a constant 1 mph and if we try it tends to be "shaky" from human reaction and our bodies not being one with the mass that's directly connected to the wheels.

Sorry for the length, was up all night doing school stuff so the brains going a million miles a minute.

[Gold5th]

That video is impressive, but watching a bike ride itself is no surprise to me.

If you want to see how stable your bike is, I would suggest doing this experiment.


Get your bike up to about 60 mph on a straight road.
Loosen your hold on the bars (but don't let go).
When you feel comfortable enough, you can let go one hand (I suggest your left hand) and then both. (Be sure to grip the bike with your legs!)
You will find that the bike does not fall over.
If you're really feeling comfortable, and still going fast (since your engine is going to slow you down pretty quickly once you release the throttle), try to make the bike lean. You'll find that it's pretty impossible to do that.


You can jerk around a lot on your bike and it will just keep on going straight!

I used to ride no hands on throttle lock, push on a peg and I could steer.