I'm asking this because a small bike racer made a statement that I don't quite agree with. Is it possible, once leaned into a turn and hanging off, to tighten the line by steering INTO the turn? Or does it always require counter-steering or slowing down to tighten the turn at higher speeds?
How tho? If steering into the turn reduces lean angle, how does it help tighten the turn? Does it maybe make a difference if the bike is small and light or if the speed is lower?
Any time I hear a discussion with "counter-steering" I cringe because it's generally made by people who don't get the physics behind motorcycle steering.
If I want to tighten a line, and I'm very close to the limits of traction, generally I'll ease off some of the maintenance throttle that was holding me on my trajectory. Can't come off the throttle too fast of you loose the front. Yeah, basically slowing down.
If at the limits of traction and you want to tighten the line while maintaining a speed, steering into the turn will wash out the front.
And any change in direction for a given speed requires counter-steering. And if you are tightening a line you better have some lean angle to spare.
What Zaph said is basically what I think, but I haven't ridden track, so I don't know from personal experience.
Related question: For a given speed and given lean angle, does hanging off simply allow more velocity, or does it actually help the bike turn sharper without leaning more?
Hanging off gives more ground clearance for the bike allowing you to take a corner a little faster before hard parts start grinding. A quicker velocity requires more overall shifting of the center of mass into the inside of the turn. This usually entails the bike leaning or you hanging off and leaning. Think of the rider and bike as a complete system. The center of mass shift to the inside of the turn while turning is a relative constant for velocity and turn radius. If the rider just stays centers on the saddle, the bike will have to lean more to get the center of mass shift it needs. If the rider hangs off more and shifts more of their weight to the inside of the turn, the bike itself has to lean less as the system as a whole(rider and bike) has met the CoM needs for that turn and speed. This is of course if you're clearance limited versus traction limited.
How tho? If steering into the turn reduces lean angle, how does it help tighten the turn? Does it maybe make a difference if the bike is small and light or if the speed is lower?
Directly steering the bike mid-corner into the turn would be exactly doing a counter-steering input to the outside of the turn. At faster than congested parking lot speeds this will end up with you picking the bike up and widening the turn.
All that makes sense to me. Now, the actually physics of how the bike turns, that's another story. This is just about what the rider does consciously or subconsciously to make a turn happen.
Counter-steer to lean. Lean to turn. Lean more to turn sharper. Hang off to turn at a higher velocity for a given lean angle. Yes? Or hang off for more traction and better suspension response.
Ah! See. That last thought it what leads to thinking hanging off allows for a sharper turn without adding lean angle. More traction just allows you to go faster, not turn sharper at a given lean angle, right?
Hanging off moves the center of gravity allowing you to take the same curve with less lean. Or, when on the track, take a curve even faster when at max lean.
It's a combination of physics, centrifugal force, and the geometry of the tire. If you steer into a turn while leaned, the bike will stand up or the front wheel will wash out.
Counter-steering works due to a fun physics phenomenon (say that 5 times fast...) called 'Gyroscopic Precession'. Any time you have a rotating mass (exactly like a motorcycle tire), you have a gyroscope. Precession means when a force is applied to a rotating mass, the force acts 90 degrees later in the plane of rotation. Basically, you "turn" the bars to the right by pushing on the left bar. This causes a right-hand force to be applied to the "nose" of the tire and a left hand force to be applied to the "tail" of the tire. Following the direction of rotation, this equates to the right hand force acting at the bottom of the tire and the left hand force acting at the top, leaning the bike to the left. If you are at any appreciable speed (above a walking pace, really) you WILL see precession. I would recommend NOT trying to turn "in" to the turn to tighten the line unless you want to run wide and/or wreck.
Note, the amount of force required to actually TURN the tire (due to another gyroscopic property called 'Rigidity in Space' which is why spinning objects are more stable, think Frisbees, footballs, or toy tops) any appreciable amount to tighten the turn would have you rolled over to the other side and off the bike on the ground. The steering angle of the tire does not actually change that much when riding at speed.
"If the camber thrust generated is insufficient to match the cornering force needed, then we just turn the bars a bit more into the corner, or in other words introduce a positive slip angle. Under those circumstances where excess cornering force is available it becomes necessary to apply negative slip angles, i.e. to steer out of the turn."
"A car derives its cornering force by means of a slip angle, which is to say that the driver turns the wheels in more than the line of the bend. As if he wanted to take a tighter curve. A bike on the other-hand achieves the same end through an effect known as camber thrust, which is a consequence of leaning into a corner. The tyre then acts like part of a cone and tries to turn a tighter circle than the actual bend. Centrifugal force straightens this circle closer to the desired path, and relatively small slip angles are then used to correct any errors."
What you're reading is actually slightly different than turning in or out. What he's describing is the force from the camber of the tire's profile. In a turn this is the bikes propensity to want to continue to "drop" into the turn (not enough camber thrust,) or "stand up" (too much camber thrust) in order to maintain a certain line. Ideally, most super sports are designed with their geometry to be neutral in handling(turning.) Usually once you have your line set in the turn and the throttle constant, you don't have to apply further pressure to maintain the turn. But if your camber thrust is too low, you're going to have to maintain constant pressure to the outside of the turn to maintain the turn. Bikes that tend to want to fall into the turn without pressure tend to feel very heavy to pick back up out of the turn. Some bikes though have a tendency to want to stand up all the time and require a lot more counter-steering input to maintain the turn. The problem is, for the setup that is under-producing camber thrust, putting any force to the outside bar beyond maintenance will just end up picking the bike back up out of the turn. In this case, easing a little pressure on the outside bar will tighten the turn a bit more until you back back up to maintenance pressure on the bars.
My interpretation of the linked article is the same as described above ^^
Taking different bikes around different corners at different speeds will require different force application on the bars to maintain the lean. Could be in, could be out depending on these 3 (and many other) factors.
Seriously just don't think too hard about the whole direct steering while at speeds. If you need to tighten a line on a public road use more counter steering if you have the traction or use a bit of rear brake to tighten it while slowing down. The rear brake does not run you wide because it doesn't compress the forks like chopping throttle and front brakes do. I don't like recommending coming off throttle to anyone because it's all too easy to chop the throttle in a panic situation. Just keep the throttle neutral. Just ride slow and smooth and you will eventually become faster and smooth naturally.
I found this video it explains it pretty good about steering a motorcycle.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Kawasaki Ninja 300 Forums
297.3K posts
32.3K members
Since 2010
A forum community dedicated to Kawasaki Ninja 300 motorcycle owners and enthusiasts. Come join the discussion about performance, modifications, classifieds, troubleshooting, and more!