If you?re working on your bike, even if just doing mild maintenance, you need to be aware of torque. It isn?t only the thrill you get when you open the throttle and your bike surges forward?it?s also the rotating force you apply when you?re tightening a bolt, whether it?s an oil drain plug or an axle nut.
What is torque" Loosely speaking, torque is simply the application of a force, some distance from an axis, to create a twisting action. As the diagram below shows, if I double the length of the wrench, I can get the same torque at the bolt by halving the force.

It?s measured in units that relate to the lever arm length and the force applied at a particular distance. On the imperial scale, torque is measured in pounds-force-feet (lbf ft)?but often listed as ?ft.-lb.??and on the metric scale, it?s measured in newton meters. This is an important concept, for not just bolts and nuts and other fasteners on your motorcycle, but also concepts like acceleration. To start with, we just need to understand the relationship between this lever arm length and the force that you apply at the end of it.

Why is torque important" Well, we need to go back a few steps. Bolts are used to clamp parts together. The size and type of bolts on a bike depend on the expected stress they?ll see in service: Engineers have determined through calculation, testing or simulation what sort of forces might act on the joint.
For example, the bolts that hold your cylinder head onto the cyli...