BIKES.TXT{8"}8"]TEXTttxtB &bhξDesigning the Ultimate Bike No single bike design is the ultimate for all tracks. The following section will explain the effects of various bike properties on bike performance. With this information and a little experimentation, you should be able to design bikes for all types of tracks. Of course, you then have to learn to ride them. Power and Weight This one is simple. To make the fastest bike possible, you always want maximum power and minimum weight. To minimize the weight, minimize the bike weight, the front wheel weight, and the rear wheel weight. Brake power determines how much braking occurs when you bring your throttle down to decelerate. You will probably want to set this at it's maximum value so that you can slow down as quickly as possible. Bike Geometry This requires a little more thought. The parameters that affect overall bike geometry are front and rear wheel radius, front and rear distance, front and rear height, and rake angle. In general, you want the center of gravity (the location of the weight of the bike) to be as low as possible. A top heavy bike tends to flip over more easily (especially when you try to accelerate quickly). So front and rear height should be kept as low as they go. The only reason to increase these values might be for appearance sake (e.g. creating a tall "Monster Bike"). A large wheel radius tends to roll over small bumps easier, but a large radius make the entire bike taller and hence raises the center of gravity, which works against you. The front and rear distance determine how far the front and rear suspension and wheels are located from the center of the bike. Increasing these values tends to make the bike more stable for two reasons. First, increasing the wheel base makes the geometry inherently more stable because it moves the points that contact the ground farther from the center of gravity. Second, increasing the wheel base increases the moment of inertia of the bike which makes the bike more difficult to rotate. Keep in mind that a stable bike may not always be what you want. Increasing the moment of inertia decreases the "gyration" effect which is explained in "Riding Tips". A simple and important fact to remember is that increasing the rear distance allows you to accelerate faster without flipping over backwards. The rake angle is the angle between the frame and the front suspension. A "chopper" usually has a very high rake angle, which makes the bike look cool, but doesn't help the handling very much. A lower rake angle allows the front suspension to absorb the bumps in a vertical direction better (which is the direction that most of the bumps affect the suspension), but you also want to absorb the bumps in a horizontal direction as you run into them, so some rake angle is usually desired. You'll have to play with this. Suspension This probably the most important aspect to designing the ultimate bike (and also the most difficult) is the suspension. The suspension consists of the front and rear travel, the front and rear spring rates, the front and rear compression damping, and the front and rear rebound damping. The wheel weights also affect the suspension, but as mentioned above, it is gererally best to have these weights set to their minimum values. When designing suspension for a particular bike, there are some general concepts to keep in mind. The first goal is to keep the rear wheel in contact with the ground as much as possible since acceleration is caused by the power transfer between the wheel and the ground. Second is that you want to use all of the suspension that you have. In general, you want the suspension to "bottom out" (you hear a "clank" when it bottoms out) once or twice in a race. This way, you know you are using all of the available stroke. If it bottoms too much, your suspension is too soft and if it doesn't bottom at all, it might be too stiff. The suspension travel is the distance that the wheel can travel up and down. For a motocross bike, you generally want this to be as large as possible so the suspension can do the best job at absorbing bumps and the impact from high jumps. Increasing the travel raises the center of gravity, however, so you will want to bring the travel down when designing a drag bike, a hill climb bike, or a trials bike. The spring rate is the stiffness of the spring that the suspension rides on. A higher spring rate will be able to absorb the impact from large bumps and high jumps better, but a lower spring rate will allow the suspension to absorb small bumps better. Keep in mind that if you lower the suspension travel, you will probably have to increase the spring rate since the spring has less distance in which to do it's job. If you have a suspension with springs and no damping, the bike will just bounce like a pogo stick. For fun, you can try this by setting all damping to zero. In a real bike, damping is done by the oil in the shock absorber. As the suspension compresses and rebounds, the shock resists, or damps, the motion. If you push down on the hood of your car and then let up, the car should come back up and stop. If your shocks are bad, it might bounce up and down a few times. If you had no shocks, it would bounce up and down and up and down for a long time. The difference between compression damping and rebound damping are when they work. Compression damping works when the suspension is being compressed and rebound damping works when the spring is pushing the suspension back out. If your rebound damping is set too high, the suspension will compress when you hit a bump, but the damping will keep the suspension from recovering (the wheel coming back down) before you hit the next bump. In an ideal situation, you would want the wheel to be all the way down for each bump. Compression damping resists the compressing motion of the suspension. It acts to stiffen the suspension, like the spring rate does, but since it's not a spring, it doesn't help to provide the force to push the suspension back out. The trick to designing the ultimate suspension is in finding the proper balance between spring rate, compression damping, and rebound damping. Trial and error is often the best teacher. Keep in mind the goal of keeping the rear wheel in contact with the ground as much of the time as possible. Gear Ratios Gear ratios determine the relative speeds between the engine and the rear wheel when you are in a particular gear. The most important setting to adjust is probably the ratio for the highest gear. The higher you set it, the faster your bike can ultimately go on a flat surface, but the higher you go, the less torque you can generate to accelerate your bike. This is why lower gears have lower ratios. You use those lower gears to get the torque you need to get the bike moving, then switch to the next gear when you start to run out of engine speed in that gear. The gear ratios should be spaced so that you can increase speed from one gear to the next. Auto/Manual Transmission If you turn off auto transmission, you will have to shift the bike yourself using the X and Z keys. The first time you press the X key, the motor will start. The next time you press it, you will shift into first gear. The race will start one second after your motor starts, but you won't be able to shift into first until the race starts.n N~. }d H І$UU> BIKES.TXTTEXTttxtBTEXTttxtB GH// /. NU& XRP "f XRP 2l !RhP Lhjs" K\(n Tdbi T h$"2, ~$.d$* T hb   V f    )  3   @ MonacoPFFnX4t*nstyl"EFNT.ETAB:EPOSF