That being said, when the idea for this new segment came about I knew exactly which class I wanted to "teach" first and that was Bushings 101. Bushings are a key piece of hardware that often gets overlooked by many disciples of skateboarding and not seen as the fine tune tweaking tool that it is. To begin the shreducating, I believe it is important to fully understand the function and purpose of a bushing. The bottom bushing acts as the seat for the hanger to rest upon the base plate,connecting the two all the while forming a beautiful, mutualistic relationship in which they join together as a single component, sealed together by the kingpin and associated washers clamping down upon the top bushing (if washers are desired by the rider, more to come on this in a minute). These seats allow the hanger the rotate around the pivot point giving the rider the ability to turn and guide the board in any direction of their choosing. In essence this urethane doughnut is your skateboards rutter, coming in various shapes and durometers, aimed to steer your ship precisely how you want it Cap'n!
Lets start with the first of those two variables: Shapes. The shape of the bushing is very important and should reflect the discipline of riding trying to be accomplished. The two basic shapes of bushings are barrels and cones, each having their respective variations and spin offs. The shape of the bushing its self determines the range of motion the hanger is allowed to travel, thusly, cone bushings would allow a greater range of motion, i.e. more turny, than a barrel bushing due to the reduced surface area as a result of the tapered design. The hanger is offered less resistance and therefore more responsiveness is the felt by the rider during carves and tight turns. The down side to this lack of resistance offered by a cone bushing is the danger of speed wobble is increased exponentially as momentum increases. The vibrations and natural balance of the truck is very dynamic and easily affected by road conditions which is why the barrel bushing is better for dampening those vibrations out and maintaining crucial hanger stability. For a basic rule of thumb I tend to follow the suggestion that cone's are for a more surfy ride while the barrels are meant to remain stable even as the speed increases to critical rates.
The second variable to discuss is durometer. Durometer is the measure of hardness of the urethane in question. The technical process of determining the "duro" is accomplished by how far a needle is able to penetrate the urethane. This rating is a number which falls on the A scale (which is why one set of numbers on your wheels always has an "A" after it) which operates under the rules that the higher the number, the harder the duro. How duro pertains to the performance of the ride is as such: the harder the bushing, the less carvey the ride will be, the lower the number the more carvey it will be. A higher number bushing is composed of harder urethane that does not have the physical give that a softer urethane would. Therefore when the hanger encounters a bushing of a high duro during a turn it will not allow as much rotation to occur as it would when it encounters a similar bushing of a softer duro. The range of duro's offered generally runs from 78A all the way up into the upper 90A's depending on which company's product you are dealing with. Harder bushings tend to lean on the more stable side at speeds where softer urethane is more susceptible to exaggerating vibrations and imperfections of your riding surface.
JAH Bless and support your local skate shops