Thanks for the advise Scott. I'm not trying to go fast, just trying to properly execute the turns. I am one of those that kind of has racing blood. Doing it correctly is more important than doing it quickly. I do tend to slow more on entrance then throttle out of the apex. It will be fun to get back up that way next week. I will have 4 or 5 days to play.
Janet
Janet, if you have not already done so, I HIGHLY recommend reading
Twist of the Wrist I and II by Kieth Code. They are written with racing in mind. However, the techniques he discusses are 100% valid on the street. Kieth Code is ALL about cornering. Reading those books, particularly the second one, radically improved my riding skills. You can usually get both as a set off of Amazon pretty cheap.
Another great book is
Proficient Motorcycling by David Hough. He covers a lot of the same stuff, but with a street riding/survival orientation.
You know, I always get lost when folks talk about suspension. Maybe it's just that I'm not exactly sure how a bikes "supposed" to feel, or maybe I get bogged down in the terminology. I'm not sure, but when the whole suspension topic comes up, I feel as lost as a Yankee in a collard patch.
To many people, suspension is kind of a black art topic. The basic job of suspension is to keep your tires in contact with the road. There are three components of suspension: the spring, the damping, and the mass. The literal form of the spring and damping may not always be the same. A solid beam of steel has all three built into it. It has mass. The structure of the steel deforms and stores energy like a spring (which makes sense because springs are generally steel). As the metal deforms, it dissipates energy. However, by separating the three elements into their component parts, it is much easier to develop a mass spring damping system that can be fine tuned.
Picture a weight hanging on a spring. If you pull the weight down and then let it go, it bounces up and down, eventually coming to rest after many up/down cycles. A shock or fork has oil in it. When the shock is compressed or extends (rebounds), the oil is forced through small holes (orifices). The resistance of the oil to being pushed through the holes is called damping. Damping is affected by the size of the holes and the viscosity (weight) of the oil used. Damping takes the energy from the compression/rebound stroke and converts it to heat to be dissipated. The damping is ideally designed so that the spring can compress and rebound, but it does not keep doing it over and over. So if you have your weight hanging by a spring and you have a damper on it, when you pull the weight down and let it go, it should spring up and down only a few times before it comes to rest. Under damped, means the weight will just keep going up and down. Over damped means it will go up once (slowly) and stop.
The size of each component affects all others. If you have a really large mass, then you generally need a larger spring and more damping capacity. If you have a small mass, then you generally need a smaller spring and less damping capacity. Now think of your motorcycle cruising down the road. The mass of your bike rests atop the suspension. When you hit a bump, that is similar to getting the mass in the example above moving. The compression damping on your bike should be such that the forks compress to absorb the bump but keep the wheel from flying up off the road, the spring should store enough of the energy from the bump to re-extend the wheel back down to maintain contact with the pavement as the tires come over the backside of the bump, and the rebound damping should be such that forks don't extend to fast (causing the pogoing effect). If all of this is adjusted properly, the bike feels like it is gliding over the bumps. The main mass of the bike (you, the motor, and the body) ride smooth while the wheels are going up and down with the pavement.
Spring stiffness is a measure of how much force is required to compress the spring a given distance. It is usually expressed in terms of lbs/in or Kg/mm (although the proper form in metric units should be Newtons/mm since Kg is a mass and not a force unit). So if you have a 300 lb/in spring, this means it takes 300 lbs of force to compress the spring one inch. A straight rate spring will have the same stiffness throughout the entire range of compression. Thus each additional inch of compression for the 300 lb/in spring requires an additional 300 lbs of compressive force. A progressive rate spring is one that has different stiffness ratings depending on how far it is compressed. It may only take a few lbs to compress it the first inch or so, but to keep compressing it requires ever greater loads. If you look at a straight rate spring, the distance between the coils is the same everywhere. On a progressive spring, the distance is smaller on one end and gradually gets larger as you move to the other end of the spring.
On your bike, you will often hear people speak of the preload on a spring. Your bike is sitting on springs and the weight of the bike, you, and all your gear and luggage compresses the springs. Generally, you want your suspension set such that in riding trim with you and all your stuff the suspension is compressed about 1/3 of its range of travel (at least as your starting point for further fine tuning). Thus, if the suspension travel on your forks is 5" from fully extended to fully compressed, you would want the forks to compress about 1.66 inches. The way you adjust this is by setting the preload on your spring. Preload is simply the term used to describe the act of precompressing the spring on one end so that it forces the fork/shock to extend out further. If you have too little preload, the suspension will compress more than the desired 1/3 and thus it won't have enough travel left to absorb the big bumps before it bottoms out. Too much preload will mean that the suspension is overextended and when it tries to rebound, it may reach the full length of extension too soon and thus be unable to stay in contact with the pavement. On forks, there is usually a shaft that sticks up out of the center of the fork caps with a slot for a flat head screwdriver. Screw in to add preload, screw out to reduce it. On the rear shock, there may be a stepped collar that you turn with a spanner wrench, or on the nicer units, there is a remote preload adjuster knob which accomplishes the same thing as the collar but with finer adjustments.
If the preload is properly set on front and back, the bike should be sitting pretty close to level and the weight bias should be slightly forward. Many bikes are around 51-55% of the total weight on the front and 49-45% on the back. On a bike with long travel suspension, too much or too little preload on either end can have a dramatic affect on the handling of the bike. If the front end sits too low (not enough preload on the front, too much on the back, or both), the front end might feel kind of twitchy and unstable. If you have the opposite condition where the front end sits too high, the steering may seem heavy and slow. Preload affects the rake/trail of the forks which in turn affects the handling.
You will also hear folks talk about adjusting the compression and/or rebound damping a few clicks. What they are referring to is the knobs used to adjust the compression and rebound. They have a notched feeling to them and they move in definite steps or clicks when you turn them. It may be hard to believe, but once you start to develop a feel for the suspension and how it is behaving, an adjustment of a click or two, or a slight change in preload, can really have a noticeable impact on the handling of the bike. The clicks on the damping are changing the size of the flow path for the damping oil. For a given oil weight, making the orifices smaller increases damping. This is generally the result of adding or going "in" a few clicks. To decrease damping, you come "out" a few clicks. On nicer bikes, you have fully adjustable suspension where the preload, compression and rebound damping, can all be adjusted both front and rear. Many bikes only allow for preload on the front, and preload/compression on the rear. Some, like the KLR, have no adjustment up front. The only thing that can be changed is preload and that has to be done by removing the fork caps and inserting spacers of different lengths on top of the spring. The rear can be adjusted for preload in five steps and the compression can be adjusted in five steps.
Really fancy suspension will have both a high speed and low speed damping circuit. Think of large smooth bumps when you think of the low speed damping. Think of harsh sudden bumps when you think of high speed damping. Having the hi/lo speed adjustability allows the suspension to be tuned for both types of impacts. Also, on rear shocks, you will often see remote oil reservoirs. This allows the oil to better dissipate the heat built up from the shock damping under heavy use. If the oil cannot dissipate the heat, its viscosity properties change which can have a serious impact on the damping characteristics of the suspension.
On race bikes, they take suspension to the next level. Forks and shocks work primarily in the up/down direction. They cannot handle side loads. Thus the more the bike leans, the less the suspension is able to absorb and deal with pavement irregularities. This is why you might hear people talking about the lateral stiffness of the bike frame, the swing arm, and the forks. They try to keep things very stiff in the plane of the suspension stroke, but then they play with the stiffness of the forks, frame, and swingarm in the plane perpendicular to the suspension stroke (think side to side). This is what I was talking about earlier where a simple metal beam has all three elements: mass, spring and damper, built into it. By playing with the lateral stiffness of those parts, they are effectively using those parts as extensions of the suspension system for handling loads when the bike is heeled over to the ridiculous 50+ degrees of lean angle they achieve now. Further, the tires also act like a spring damper system. The metal, rubber and air pressure all act like a spring and damper system. The weight of everything that moves with the forks or swingarm is called the sprung weight. The lower this weight, the faster the suspension can react to changes in the surface. This is one of the reasons why racers put such a premium on ultra light wheels and braking components. The other big reason is to reduce the gyroscopic forces on the front wheel so that it takes less effort to steer the bike.
The theory of suspension is pretty straight forward. It is the successful application of it that is the black art. One has to understand what is happening with all the various elements of the suspension system before one can decide what to adjust to fix any problems. However, getting this level of understanding is very difficult and is usually the result of MUCH pre race testing. If you watch any racing, sometimes you will see top racers struggling to go fast on certain tracks. This is seldom a lack of horsepower and more often either a tire issue or a suspension issue. If they get those two things sorted, then the rider is usually more relaxed and not fighting the bike and is thus able to ride much faster with less effort. The same is true for you and me on the street if we are riding somewhat aggressively.
Good suspension is like a lot of other things. When you have never had it, you just don't know any better. Once you have had it, it is very difficult to go back to bad suspension because now you know better