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Selasa, 22 April 2008

Bike trials


Bike trials is a form of mountain biking derived from motorcycle trials. The rider negotiates man-made and natural obstacles without their feet touching the ground. It originated in Spain and is said to have been invented by Ot Pi’s father (a world champion motorcycle trials rider). As it is hard for small children to control motorcycle trials bikes, he had wanted his son to learn and to practice motorcycle trials on an ordinary push bike instead of a motorbike.

At the most basic level, trials riding can be summed up as bicycle handling skills. It evolved from motorcycle trial riding (riding up, over obstacles, man-made or natural) into an off-season bicycle pastime. It now has a strong — though small — following, and can be seen worldwide. Skills taken from trials riding can be used practically on any bicycle for balance, for example controlled braking and track standing, or balancing on the bike without putting a foot down. Trial bike characteristics include, but are not limited to: powerful brakes, wide handlebars, light parts, low gearing, a thick rear tire that provides grip, a heavy emphasis on frame geometry, and no seat.

It is completely different from individual time trial races, which are an element of road bicycle racing.

Rules

The general principle in a bike trials competition is to ride a number of pre-marked sections (usually 2 laps of 10 sections or 3 laps of 7 sections), the winner being the rider with the least points at the end of the competition.

Currently there are two official types of competition rules, enforced by the UCI and BikeTrial International Union.

The maximum number of points that can be obtained in each section is 5, the lowest (and best) score is 0 points or ‘clean’. The most common way to gain a point is by putting a foot down within a section; for this reason points are sometimes known as ‘dabs’. Certain rules enforce the number of points gained within a section, for example, putting both feet down will result in 5 points. Exceeding the time limit for the course will either result in 5 points (BIU rules) or an additional point for every 15 seconds over the limit (UCI rules).

UCI

Within UCI rules, if any part of the bike except the tires touch any object in the course, a dab will be given. The UCI rules were changed to this format after too many competitions ended in a draw and riders were forced to ride an extra section. UCI rules also allows riders to compete in both mod and stock categories.

When a rider is in a section, neither tire is allowed to cross the side boundary tape even if the wheel is in the air. The rider’s hands must remain on the handlebars. Riders in the 26″ class must also have six working gears.

The UCI Mountain Bike & Trials World Championships are held annually and crown a 20-inch and 26-inch wheel trials world champion.

BIU

The rules are unlike UCI scoring and parts of the bike (for example, bash guard or bash ring, cranks and pedals) can rest on an object without resulting in a ‘dab’. The level of riding for the elite 20″ class is regarded as the highest in bicycle racing since the section beginner is set at the highest technical level[attribution needed].

Bike Design

Trials bikes are often designed without regard for attaching a seat. Competition riding does not require seating down and the omission allows for a lighter bike which interferes less with the body movements of the rider. Brakes must be more powerful than standard bicycle brakes in order to prevent the wheel from moving when hopping on uneven surfaces. Tires and rims are wide allowing low pressures and increased contact and grip. Gear ratios are lower then on most bicycles in order to provide the power and quick acceleration needed to move the bike at the typically low speeds of trials riding.

According to current competition standards there are two classes of trials bike recognized. As the distinguishing characteristic of the classes is the bike's approximate wheel diameter, the classes are known as 20″ and 26″. These specific sizes were adopted from previously available bikes.

20″ — ‘Mod Bikes’

The first purpose made and commercially available trials bikes were manufactured by Montesa a mototrials company and were based on the modifyed bmx bikes that riders had been using. These 20″ wheeled trials bikes have become known colloquially as Mod bikes.

26″ — ‘Stock Bikes’

Early mountain bikes were well suited to the trials riding being done and so a separate class was introduced for them. 26″ used to refer to mountain bike kept in original condition. 26″ classed bikes were required to have at least six working gear ratios and a seat. Now, however, this designation is often used to describe any trials bike with 26″ wheels.

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