Post by hecklercn on Mar 8, 2007 12:55:46 GMT 7
BIKE DYNAMICS AND HANDLING SKILLS
A very insightful article submitted by Tony Youngberg.
When dealing with bikes handling characteristics there are two main features: Vertical load and Horizontal load. The Vertical load will create friction and traction between the surface and the tire as seen when you push down on something. With Horizontal load (lateral inertia), you reduce the traction or vertical load and translate it into horizontal load. This happens when you lean the bike past a given angle where vertical translates to lateral. In this instance, the end of the bike with the most weight will be the one to "wash out" or lose vertical load to horizontal load ö a slide! It’s a simple law of movement.
Techniques that help cornering are leaning the bike more than the body, using the hips as tools to lean the bike while the torso remains more or less upright. Accompanied by pressing down on the inside grip while leaning in a turn, forces the rear end outward by pressing the seat into the inner thigh of the inside leg reducing the tires vertical load and increases its lateral load forcing the rear end to slide. While at the same time applying vertical load to the front tire. You can also pull up on both grips in the corner if the lean angle is hard enough to exceed the rear tires lateral load capabilities forcing the bike into over steer ö one must take caution in this technique as you must be at or beyond a specific lean angle with adequate speed to maintain that lean angle!
You can get a feel for this technique by simply standing over your bike with it stationary. Put your left foot on the left pedal in the down position, hover your butt over your saddle - now press down and forward on the right hand grip pressing the saddle into your inner right thigh. The result is the back tire sliding to your left. Now try this while leaning the bike over at a 45 degree angle. It slides out much easier! This is the basic technique minus the foot being on the ground.
Bike setup is crucial to the riding technique. If you try the same technique with your weight all the way forward on the bike, you will find that it has a different effect ö it will most likely push the front end out because you are increasing lateral load to the front of the bike and decreasing vertical load to the front tire. Look at it like you’re now making the front wheel the back wheel.
A bike with a long stem and flat handle bars puts you in a forward position and doesn’t allow for much "body English" in the turn, and throws your weight forward and straightens your arms effectively reducing your ability to lean the bike more than the body, and reduces your leverage over the bike in the corner and puts you in a more "delt raise" position.
A bike setup with a short stem, riser bar, and low saddle puts you in a centered position with less weight over the front of the bike, allowing for a more control type posture. This setup aids in the technique by allowing you more leverage over the rear of the bike and puts you in more of a "bench press" position versus a "delt raise" position.
The advantages to a “long stem” setup come when you are climbing. It positions you forward to a more "control type position" when the bike is climbing a steep ascent ö not much unlike that of the control position of the short stem combo when flat or down hill. This can be helpful though unnecessary•
You can just as easily climb with the "short stem" combo by simply altering the bends in your arms and position of your elbows and the angle at which you are pulling on the bars.
Another problem seen commonly with novice riders is their tendency to straighten their arms when entering the apex of a corner or when hitting rough terrain.
In a corner, if you straighten your arms out forward you are in essence helping to push the front of the bike out and decrease vertical load on the front and make the front much less compliant to the terrain changes as well as forcing harsh fore and aft weight transferring (also a component of both vertical and lateral load). Once again, a short stem combo can help overcome this error by positioning the rider in a more "control type position" giving you more confidence and less of a Îout in front of the bike feeling ö in return, allowing you to be more comfortable with keeping your arms bent and your head low.
Leaning is another crucial component of cornering. To steer the bike correctly with this technique ö you must LEAN the bike more. If you try to steer without leaning, the bike dives in the opposite direction, and on a loose surface, will cause the front to slide before "Augering" in and sending you flailing. Whereas leaning sets the bike up for proper vertical and lateral load. The further back your weight is, the more you may want to lean.
These are among some of the basics, there are many other effects and techniques including bike geometry, suspension (a whole topic on its own but the same rules apply), tires (air pressure, size compounds), etc•.
You go where you look, is very important as well. A big mistake I have made from time to time is not looking through the corner, but instead looking to the outside of the apex where I don’t want to go. I have found that this can really affect how the bike handles. I have had situations where looking to the outside of the corner makes the bike under steer, yet the same exact corner taken while looking THROUGH it will make the bike over steer nicely, and line you up for the straightaway. Its important to look where you want to go and not where you don’t want to go.
Also, taking the right line is crucial. Taking the right line for your setup is important because this will allow you to drift the rear end through the corner and will help prevent under-steer. Each setup has a different line that has to be taken to avoid under steering, finding that line takes practice with the setup and changes when you change the setup.
Angulation: part II - Leaning body with bike. Leaning the bike more than the body can be very useful especially on really loose surfaces and or S turn sweepers, but there is a variation of this - Leaning the body with the bike. With this technique, drop your hips into the lean with the bike, and try to maintain a relatively straight line right down your back, through the bike and down through your wheels keeping just your head upright (perpendicular to the ground). Iâve found this technique works well to drive the rear end out into a nice power slide.
This is the technique that Palmer utilizes. You basically are dropping your body into the lean with the bike, as if you were a piece of the bike ö or an extension of the seat tube.
You can also combine techniques - drop the hips with the saddle, but keep your upper body and head upright ö much like that of an F1 road racer. This applies a lot of horizontal load to the rear while applying vertical load to the front!
Bar position: Is important, having the bar in a position that allows you to press down on the inside grip with adequate leverage requires you to have a short stem and a high rise bar to put the bar in a position that allows you the optimum leverage in a corner without having to lean heavy on the front end trying to put yourself in a position for better leverage. With a bar in a position closer to the body, applying the right pressure on the inside grip in a corner is much easier and the bike handles much better. With a longer stem setup, you have to shift a lot of weight forward to get in a leverage position, and this can cause the front end to wash and or auger in.
After all this comes the actual application and mental concentration. When you have a feel for the techniques you may do well to not think of them. Keys to a good run are:
* Concentrating on where you are going
* Not thinking about the trail, your bike, or technique for say
* Looking through the corner
* Don’t think about what you don’t want to happen. i.e. Don’t think about the front sliding, but rather visualize the back sliding.
* Visualization as mentioned above
* Sitting down in most corners
* Leaning the bike ö not turning it! Lean, don’t steer!
* Applying adequate pressure to the inside handlebar grip
* Focusing on what your trying to accomplish with any given technique / not thinking of the technique itself.
* Keeping your head low in corners and technical descents
* State of Mind!
My best run ever through a windy section at local DH run was utilizing the following:
* Sitting down in corners
* Not thinking
* Visualizing what I wanted to do and the way to do it
* Leaning, NOT turning the bike
* Looking through the corner
* Visualizing the rear wheel drifting
* Concentrating on success
* Not thinking about the front sliding or anything negative - but rather feeling positive and just leaning it as hard as it will go and not thinking bout the texture of the ground or traction.
Realistically, it's probably 85 percent mental, and 15 percent technique to achieve successful cornering skills!!! After getting a feel for the technique it all becomes a state of mind as to whether or not you perform well.
Ride the way you want it to feel. Feel the way you want it to ride!
"•The consciousness of self is the greatest hindrance to the proper execution of all physical action." - Bruce Lee
"Give up thinking as though not giving it up. Observe techniques as though not observing." - Bruce Lee
"To corner with this technique you have to just ÎWill itâ to happen." - Brad from Noble canyon
"•Feel! It is like a finger pointing to the stars ö Donât concentrate on the finger or you will miss all that heavenly glory" - Bruce Lee
--Written by Troy Youngberg
A very insightful article submitted by Tony Youngberg.
When dealing with bikes handling characteristics there are two main features: Vertical load and Horizontal load. The Vertical load will create friction and traction between the surface and the tire as seen when you push down on something. With Horizontal load (lateral inertia), you reduce the traction or vertical load and translate it into horizontal load. This happens when you lean the bike past a given angle where vertical translates to lateral. In this instance, the end of the bike with the most weight will be the one to "wash out" or lose vertical load to horizontal load ö a slide! It’s a simple law of movement.
Techniques that help cornering are leaning the bike more than the body, using the hips as tools to lean the bike while the torso remains more or less upright. Accompanied by pressing down on the inside grip while leaning in a turn, forces the rear end outward by pressing the seat into the inner thigh of the inside leg reducing the tires vertical load and increases its lateral load forcing the rear end to slide. While at the same time applying vertical load to the front tire. You can also pull up on both grips in the corner if the lean angle is hard enough to exceed the rear tires lateral load capabilities forcing the bike into over steer ö one must take caution in this technique as you must be at or beyond a specific lean angle with adequate speed to maintain that lean angle!
You can get a feel for this technique by simply standing over your bike with it stationary. Put your left foot on the left pedal in the down position, hover your butt over your saddle - now press down and forward on the right hand grip pressing the saddle into your inner right thigh. The result is the back tire sliding to your left. Now try this while leaning the bike over at a 45 degree angle. It slides out much easier! This is the basic technique minus the foot being on the ground.
Bike setup is crucial to the riding technique. If you try the same technique with your weight all the way forward on the bike, you will find that it has a different effect ö it will most likely push the front end out because you are increasing lateral load to the front of the bike and decreasing vertical load to the front tire. Look at it like you’re now making the front wheel the back wheel.
A bike with a long stem and flat handle bars puts you in a forward position and doesn’t allow for much "body English" in the turn, and throws your weight forward and straightens your arms effectively reducing your ability to lean the bike more than the body, and reduces your leverage over the bike in the corner and puts you in a more "delt raise" position.
A bike setup with a short stem, riser bar, and low saddle puts you in a centered position with less weight over the front of the bike, allowing for a more control type posture. This setup aids in the technique by allowing you more leverage over the rear of the bike and puts you in more of a "bench press" position versus a "delt raise" position.
The advantages to a “long stem” setup come when you are climbing. It positions you forward to a more "control type position" when the bike is climbing a steep ascent ö not much unlike that of the control position of the short stem combo when flat or down hill. This can be helpful though unnecessary•
You can just as easily climb with the "short stem" combo by simply altering the bends in your arms and position of your elbows and the angle at which you are pulling on the bars.
Another problem seen commonly with novice riders is their tendency to straighten their arms when entering the apex of a corner or when hitting rough terrain.
In a corner, if you straighten your arms out forward you are in essence helping to push the front of the bike out and decrease vertical load on the front and make the front much less compliant to the terrain changes as well as forcing harsh fore and aft weight transferring (also a component of both vertical and lateral load). Once again, a short stem combo can help overcome this error by positioning the rider in a more "control type position" giving you more confidence and less of a Îout in front of the bike feeling ö in return, allowing you to be more comfortable with keeping your arms bent and your head low.
Leaning is another crucial component of cornering. To steer the bike correctly with this technique ö you must LEAN the bike more. If you try to steer without leaning, the bike dives in the opposite direction, and on a loose surface, will cause the front to slide before "Augering" in and sending you flailing. Whereas leaning sets the bike up for proper vertical and lateral load. The further back your weight is, the more you may want to lean.
These are among some of the basics, there are many other effects and techniques including bike geometry, suspension (a whole topic on its own but the same rules apply), tires (air pressure, size compounds), etc•.
You go where you look, is very important as well. A big mistake I have made from time to time is not looking through the corner, but instead looking to the outside of the apex where I don’t want to go. I have found that this can really affect how the bike handles. I have had situations where looking to the outside of the corner makes the bike under steer, yet the same exact corner taken while looking THROUGH it will make the bike over steer nicely, and line you up for the straightaway. Its important to look where you want to go and not where you don’t want to go.
Also, taking the right line is crucial. Taking the right line for your setup is important because this will allow you to drift the rear end through the corner and will help prevent under-steer. Each setup has a different line that has to be taken to avoid under steering, finding that line takes practice with the setup and changes when you change the setup.
Angulation: part II - Leaning body with bike. Leaning the bike more than the body can be very useful especially on really loose surfaces and or S turn sweepers, but there is a variation of this - Leaning the body with the bike. With this technique, drop your hips into the lean with the bike, and try to maintain a relatively straight line right down your back, through the bike and down through your wheels keeping just your head upright (perpendicular to the ground). Iâve found this technique works well to drive the rear end out into a nice power slide.
This is the technique that Palmer utilizes. You basically are dropping your body into the lean with the bike, as if you were a piece of the bike ö or an extension of the seat tube.
You can also combine techniques - drop the hips with the saddle, but keep your upper body and head upright ö much like that of an F1 road racer. This applies a lot of horizontal load to the rear while applying vertical load to the front!
Bar position: Is important, having the bar in a position that allows you to press down on the inside grip with adequate leverage requires you to have a short stem and a high rise bar to put the bar in a position that allows you the optimum leverage in a corner without having to lean heavy on the front end trying to put yourself in a position for better leverage. With a bar in a position closer to the body, applying the right pressure on the inside grip in a corner is much easier and the bike handles much better. With a longer stem setup, you have to shift a lot of weight forward to get in a leverage position, and this can cause the front end to wash and or auger in.
After all this comes the actual application and mental concentration. When you have a feel for the techniques you may do well to not think of them. Keys to a good run are:
* Concentrating on where you are going
* Not thinking about the trail, your bike, or technique for say
* Looking through the corner
* Don’t think about what you don’t want to happen. i.e. Don’t think about the front sliding, but rather visualize the back sliding.
* Visualization as mentioned above
* Sitting down in most corners
* Leaning the bike ö not turning it! Lean, don’t steer!
* Applying adequate pressure to the inside handlebar grip
* Focusing on what your trying to accomplish with any given technique / not thinking of the technique itself.
* Keeping your head low in corners and technical descents
* State of Mind!
My best run ever through a windy section at local DH run was utilizing the following:
* Sitting down in corners
* Not thinking
* Visualizing what I wanted to do and the way to do it
* Leaning, NOT turning the bike
* Looking through the corner
* Visualizing the rear wheel drifting
* Concentrating on success
* Not thinking about the front sliding or anything negative - but rather feeling positive and just leaning it as hard as it will go and not thinking bout the texture of the ground or traction.
Realistically, it's probably 85 percent mental, and 15 percent technique to achieve successful cornering skills!!! After getting a feel for the technique it all becomes a state of mind as to whether or not you perform well.
Ride the way you want it to feel. Feel the way you want it to ride!
"•The consciousness of self is the greatest hindrance to the proper execution of all physical action." - Bruce Lee
"Give up thinking as though not giving it up. Observe techniques as though not observing." - Bruce Lee
"To corner with this technique you have to just ÎWill itâ to happen." - Brad from Noble canyon
"•Feel! It is like a finger pointing to the stars ö Donât concentrate on the finger or you will miss all that heavenly glory" - Bruce Lee
--Written by Troy Youngberg