What makes a bike turn
- Thread starter jellyrug
- Start date
The paradox of cornering is that you have to perform many tasks before and during the cornering. You have to adjust your entry speed, you have to shift your body weight, continue to apply and some point open up the throttle during the cornering. While it seems very technical and challenging, the paradox of it is that all you have to do is to look where you want to go and let the bike go there.
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Peace!So, you countersteer, lean the bike down, the wheels still look straight, why does it turn? LOL it turns because the tires diameter on the sides is less than the center, therefore decreasing the diameter of the rotating mass of the tire and producing a turn. The gyroscopic forces of the spinning wheels keep the bike from falling over. You as the rider have to counter steer the handle bars to keep the tires side diameter from pulling the bike down on its side. Thats why you counter steer. Your body mass shifting from side to side has more to do than the handle bar input in the turn. Thats why the wheel looks (stays) straight.
Why can you corner faster when you drag a knee, instead of just keeping your position? Dragging a knee allows you to control your turn angle better that's why you turn faster. A friend of mine is a ama racer and he has debated on whether to use a knee or not. Its a stability issue and the issue of the clearance of your foot on the foot peg.
Why can you corner faster on four wheels, than on two? Simply because 4 flat automobile wheels produce 8+ times the gripping force of 2 round motorcycle wheels. The contact patch of a motorcycle wheel is very small thats why the rear wheel is fatter than the front on super bikes.
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OUTLAW1300
Registered
My head is starting to hurt with your brain busters man. I guess its all about gravity and physics?
TruWrecks
Banned
You don't counter-steer during the turn. You counter-steer to start the turn. Once the bike is leaned into the turn it will keep turning as long as the speed stays the same. If the speed increases the bike will begin to stand back up. The centripetal force pushes the bikes mass away from the direction of travel. If the bike slows down it will continue to fall closer to the ground until it maintains a speed, or hits the ground. The front wheel will turn into the turn a bit after the bike leans into the corner. The pictures below show this very well. Kudos the the member of the second photo. My apologies that I forgot your screen name.
Body position has more to do with applying a riders weight to help set the suspension up for the corner, and transferring the center of gravity lower on the bike by putting pressure on the pegs. The effective CG will drop about a foot on the bike making it more stable through the corner. If you are doing this correctly you will feel it in your thighs very quickly. After a 20 minute track session my thighs were burning. At the end of the day, and six track sessions, my legs felt like jelly. The next morning I felt like I had just run for 10 or 15 miles.
Having the knee on the ground, in my opinion, has more to do with looking cool than actual riding. If you are leaning the bike so much you can't avoid dragging a knee you better be on a race track. You can hang off a bike and never touch a knee down in the corners, even if you have your bike leaned enough to grind hard parts. MotoGP riders lean their bikes so much that their body parts are in the way. Knees dragging in that case are purely from the rider using it as a gauge for how much more lean angle they have left before they run out of traction. Racers also use rear sets that are high enough to keep their feet from dragging on the ground even when the engine casing is just millimeters from scraping.
Jellyrug is correct about the car tires. At 8x the contact patch most cars have about a 2:1 advantage over a motorcycle for traction. Also, car tires have harder sidewalls and reinforced shoulders. That helps apply more pressure to the road as the car leans away from the direction of the turn. Anti-sway bars reduce the body roll and that also puts more pressure on the shoulder of the outside tires. Keeping the tire tread surfaces parallel helps to reduce loosing grip surfaces during the corner.
This is from my own experience and opinions. I might not have all the details correct, but that it the information I have gleaned from several years of riding, attending a performance riding school, and listening to experienced racers in the pit areas between track sessions.
Body position has more to do with applying a riders weight to help set the suspension up for the corner, and transferring the center of gravity lower on the bike by putting pressure on the pegs. The effective CG will drop about a foot on the bike making it more stable through the corner. If you are doing this correctly you will feel it in your thighs very quickly. After a 20 minute track session my thighs were burning. At the end of the day, and six track sessions, my legs felt like jelly. The next morning I felt like I had just run for 10 or 15 miles.
Having the knee on the ground, in my opinion, has more to do with looking cool than actual riding. If you are leaning the bike so much you can't avoid dragging a knee you better be on a race track. You can hang off a bike and never touch a knee down in the corners, even if you have your bike leaned enough to grind hard parts. MotoGP riders lean their bikes so much that their body parts are in the way. Knees dragging in that case are purely from the rider using it as a gauge for how much more lean angle they have left before they run out of traction. Racers also use rear sets that are high enough to keep their feet from dragging on the ground even when the engine casing is just millimeters from scraping.
Jellyrug is correct about the car tires. At 8x the contact patch most cars have about a 2:1 advantage over a motorcycle for traction. Also, car tires have harder sidewalls and reinforced shoulders. That helps apply more pressure to the road as the car leans away from the direction of the turn. Anti-sway bars reduce the body roll and that also puts more pressure on the shoulder of the outside tires. Keeping the tire tread surfaces parallel helps to reduce loosing grip surfaces during the corner.
This is from my own experience and opinions. I might not have all the details correct, but that it the information I have gleaned from several years of riding, attending a performance riding school, and listening to experienced racers in the pit areas between track sessions.
I know how it works, but it is hard to explain.
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dragonbusa
Registered
my bike turns for cold beer and pizza
wow...
crackerhead25
Registered
My brain is starting to itch???
trojan2k
Registered
I will be paying extra special attention to this thread!!! LORD knows I need more skill development time and less 'fly by the seat of my pants' time. 
Good reading... 
Good reading... 
It's magic.
Sometimes :blush:
jetsetter
Registered
That's about as short and sweet as it can be put and still get the general point across. The only point I didn't see addressed was why the bike turns when leaned. That is because of the shape of the tires... When leaned over, the contact patch on the ground is "shorter" toward the inside of the turn, and as the tire rolls, the smaller circumference toward the inside doesn't go as far as the larger circumference toward the outside of the turn. Since the inside doesn't go as far as the outside, the bike turns.
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