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Thundurburd · 12-24-2007, 11:35 PM

It may seem like a black art but we all have to live by the same laws of physics. Torque and horsepower are what they are because of basic definitions and applies to planes, trains, and automobiles (and motorcycles.) Not that it's always easy to come up with a technical explanation why something happens, but if we have a result that doesn't match our prediction it's not because we have violated a law of physics, it's because there is something we missed, always.

In the case of a motorcycle the engine and drive train deliver a torque to the rear wheel. Depending on the radius of the rear wheel the torque applied will result in two forces acting on the wheel. One on the bottom pushing on the road and one at the the center of the wheel pushing the motorcycle forward. If the mass is known we could calculate the acceleration and in turn other performance data. My point is that it is a known science.

It's really that simple, assuming of course we have frictionless bearings, no wind resistance, full traction, and other good stuff they keep in the physics lab. Notice that there is no mention of horsepower. The motion of the motorcycle and the work done is all determined from forces and torques, and drive train ratios. Power is a calculated value and is the rate at which work is being performed. A useful piece of information perhaps, but not exactly what moves the bike.

I gather that different engine configurations (thumpers, v-twins, in-lines) have different torque and horsepower curves. That makes sense to me. My guess is that your descriptions of the sensations riding different types of motorcycles is the result of engine configuration and drive train characteristics such as gear ratios, shift points, and so on, as determined by the designers as best they could to obtain some goal given what they had to work with.

Haven ridden only one bike this year I have no practical knowledge of anything but mine.

However, the same laws of physics apply to all of us. A torque is a rotational force, and horsepower is the rate of work being done.

Regards,

-Tburd

12-24-2007, 11:35 PM	#34 (permalink)
Thundurburd Foil Inspector Joined: Jul 2007 Bike: 2007 Black S50 Location: SE Wisconsin Posts: 953	It may seem like a black art but we all have to live by the same laws of physics. Torque and horsepower are what they are because of basic definitions and applies to planes, trains, and automobiles (and motorcycles.) Not that it's always easy to come up with a technical explanation why something happens, but if we have a result that doesn't match our prediction it's not because we have violated a law of physics, it's because there is something we missed, always. In the case of a motorcycle the engine and drive train deliver a torque to the rear wheel. Depending on the radius of the rear wheel the torque applied will result in two forces acting on the wheel. One on the bottom pushing on the road and one at the the center of the wheel pushing the motorcycle forward. If the mass is known we could calculate the acceleration and in turn other performance data. My point is that it is a known science. It's really that simple, assuming of course we have frictionless bearings, no wind resistance, full traction, and other good stuff they keep in the physics lab. Notice that there is no mention of horsepower. The motion of the motorcycle and the work done is all determined from forces and torques, and drive train ratios. Power is a calculated value and is the rate at which work is being performed. A useful piece of information perhaps, but not exactly what moves the bike. I gather that different engine configurations (thumpers, v-twins, in-lines) have different torque and horsepower curves. That makes sense to me. My guess is that your descriptions of the sensations riding different types of motorcycles is the result of engine configuration and drive train characteristics such as gear ratios, shift points, and so on, as determined by the designers as best they could to obtain some goal given what they had to work with. Haven ridden only one bike this year I have no practical knowledge of anything but mine. However, the same laws of physics apply to all of us. A torque is a rotational force, and horsepower is the rate of work being done. Regards, -Tburd __________________ Like Roseanne Roseannadanna would say: "it just goes to show you, it's always something." Last edited by Thundurburd; 12-25-2007 at 01:16 AM.