Sacramento Pacific International Trials Society is dedicated to the observation of the motorsport of Observed Trials.
Observed trials is the cheapest and safest form of motorcycle competition. It’s also easy to get into-and a sport the entire family can enjoy. At the same time, trials can be the most scientific and challenging of all two-wheeled motor sports. Trials can be used as a skill refiner for dirt riding, as a way around parental objection to the hazards of other forms of cycle competition, or as an end in itself. As a sport that emphasizes throttle control, traction sensitivity, balance, boldness and split-second reactions and execution, trials will improve performance in any two-wheeler activity.
For those not interested in competition, a trials motorcycle can function as the ultimate trail bike. It’s built to compete in the toughest terrain imaginable, so trail riding can seem like child’s play.
Observed Trials is a test, a trial of rider and machine over rough terrain that’s scored by officials observing the action.
Trials competition began evolving in England around the turn of the century, shortly after the invention of the motorcycle. The famous Scottish Six Days Trial dates back to 1909.
Initially, a trials competitor’s main concern was keeping his machine going around a dirt road loop. Then, to make these reliability competitions more interesting, event organizers began adding hills to climb. Instead of just racing to the top, the riders attempted to climb the slopes without putting their feet down. They began to score their ability to get through these marked-off sections of hillside.
Today’s riders are still scored for their ability to travel over difficult terrain without touching their feet to the ground. The idea is to avoid accumulating points. Just like golf, low score wins.
Contestants ride a marked loop, like enduro competitors, but stop along the route to ride scored sections that are marked with start and finish gates and boundary markers. Usually, a section takes ten to twenty seconds to complete. Like enduro competition, there’s a time limit, but a trials is not a race.
Trials activity in the U.S. has plenty of room for growth, using the sport’s popularity in nations like England, Spain, France, and Italy as a basis of comparison. The sport is showing signs of increased popularity with stadium events. As more and more people have the opportunity to view observed trials, the sport should experience increases in both competitors and those who appreciate the training and skills demonstrated by the nation’s best riders.
Today’s trials motorcycles have short wheelbases (approximately 52 inches) and steep head angles (approximately 27 degrees) to facilitate turning. The gas tank is both small and slim. Capacity is rarely much more than a gallon. The seat is spartan since the bike is ridden standing on the pegs for maximum control. The handlebars are positioned so the rider may stand comfortably and shift his weight rapidly forward or rearward.
The footpegs are both higher and closer to the rear axle, compared to other off-road motorcycles. This makes stand-up riding more comfortable. The real benefits, however, are a very light front end that will lift easily and improved rear tire traction. The soft two-ply radial tires with special trials pattern for maximum grip also assist traction. Low air pressure (seven pounds or less in the front, five pounds or less in the rear) let the two-ply tires get as much ground grip as possible. Trials suspension is extremely soft to soak up the bumps and twitches. The stand-up rider assists his mechanical suspension by using his legs, flexing at the knees, to help cushion the bumps.
Ground clearance, as might be expected, is on the tall side, generally at least twelve inches.
The heart of any trials motorcycle is its tractor-like engine. There are no displacement categories in trials. Most bikes run from 200cc to 350cc. Some smaller displacement bikes are built for younger or smaller riders.
The engine is designed to pull strongly from the very bottom of its power range. Trials-type power is achieved with a low compression ratio, mild porting and timing, exhaust pipes tuned for low rpm response, and relatively small carburetors with jetting designed to eliminate hesitation.
Heavy flywheels are added to the crankshaft to further smooth the power. Because of the flywheel effect, riders are able to close the throttle and coast over extremely slippery terrain, then smoothly turn on power to regain momentum. All of the engine specifications have one purpose-to improve traction.
That’s the key to success in trials riding: holding traction-avoiding a slip that will require using a foot to get the bike under control again.
Trials motorcycles have three extremely low gears, and two or three taller gears for trail riding. First or low gear offers a putt-putt-putt-walk-along-beside speed.
Second and third gear are not that much faster.
A bonus from all of this emphasis on bottom end power and torque is a significant reduction of exhaust noise. Trials motorcycles are the quietest off-road bikes built.