Trials is a competitive motorsport for motorcycles. The objective is to complete a course by maneuvering your bike over or through various challenging obstacles without falling or touching either foot down off the footpeg to avoid falling. The courses are usually in rugged natural settings, but indoor competitions run on artificial obstacles are also popular.
The trials machine is specially designed for this purpose. It has a low center of gravity, large wheels with tires inflated to low pressure for optimum traction, a high-torque engine, very low gearing ratios, a small gas tank, a heavy-duty skid plate under the engine, and a minimal seat (the rider never uses it except when scooting around before or after the running the course). Most importantly, all parts of the trials bike are made of exceptionally strong materials to minimize damage caused by, say, falling from rather high places onto rather hard surfaces, such as rocks for example. Riders, unfortunately, are made of less sturdy materials and are more costly to repair.
Trials demands a broader range of skills and more brainwork than most other motorsports, or any kind of sport at all, for that matter. A fine sense of balance is requisite, as engaging an obstacle may require very slow and careful forward motion or stopping altogether to adjust the bike's attitude for the next move. Strength and endurance are also needed, as are quick reflexes, fast judgement and the ability to analyze an obstacle, plan an attack, and execute the attack with precision, all within a matter of a few yards. It's also helpful to be able to quickly devise and implement plan B when plan A fails, leaving man and machine suddenly airborn in some exceedingly awkward pose. (Note to photographers: to get interesting pictures of riders & bikes, go to a trials run rather a motocross race.) Courage, otherwise known as utter and reckless disregard for one's own life and limb, can also be an advantage where said skills are lacking.
On a walk through nature, most people will see points of beauty, but the trials rider will see a succession of obstacles and automatically begin planning a way to get over, under, around or through them.
Normal person: "Look at that lovely out-cropping of rock over there by the stream."
Trials rider: "Yeah. I could get up there. Le'see, first I'd cross the stream there at the rapids. I'd have to wheelie up onto that boulder to get out of the water. Can't shift my weight forward too soon, 'cuz the wet rear tire's gonna slip. Up on the boulder, I'd stop, work the front wheel around about 90 degrees, drop down a gear and bounce the front wheel off that stone wall and ... ."