Posts Tagged ‘bike’
Tuesday, July 5th, 2011
Mountain bike trials
Briton Joe Oakley receives a one-point penalty for “dabbing” the ground with his foot. The official indicates this with a raised finger.
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 fewest 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 or a hand 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).
Riders inspecting a section, as permitted under UCI regulations.
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. Before beginning a section, a rider is allowed to walk through it, and examine all the elements, but must not enter it with their bike.
The UCI Mountain Bike & Trials World Championships are held annually and crown a 20-inch and 26-inch wheel trials world champion.
Bicycle trial rider
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[who?].
The rules are the same as the “BIU” but only people belonging to a club or school can compete in these, these are for lower level students to learn how to compete.
Close-up of the cranks of a trials bike. Note the very small chainring.
Trials bikes are often designed without regard for attaching a seat. Competition riding does not require the rider to sit 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 than 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’
A rider on a 20″ trials bike.
The first purpose made and commercially available trials bikes were manufactured by Montesa a mototrials company and were based on the modified bmx bikes that riders had been using. As a result of being based on BMX bikes, the rear dropout spacing is 116mm. 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. Stock bikes have a dropout spacing of 135mm. There is a subcategory of Stock trials bikes, sometimes called ‘Modstock Bikes’: these bikes have 26 inch wheels but have horizontal dropouts like on mod bikes as opposed to vertical dropouts on stock bikes. The spacing of the dropout is often smaller, to fit the rear hub of a 20″ bike. Horizontal dropouts become more and more common.
24 ‘Street trials hybrid Bikes’
These bikes have 24″ wheels and usually have horizontal dropouts, although they are spaced to fit a 135mm hub as on a 26″ bike. They are not legally allowed to compete in competitions but suit riders with a more “street” style. (e.g.spins, manuals, bunnyhops)
Bicycle trial rider about to jump (in Spain)
Trial riding requires very good brake control, and as a result, bicycle trials riders sometimes have unusual brakes. On the front wheel, good brake modulation is usually the goal, whereas in the rear, maximum braking power is more important.In the rear, riders will often run special hydraulic rim brakes with frame stiffeners called brake boosters, and they sometimes grind their rims to create a rough surface and even put roofing tar on their rims to make them sticky. Disc brakes are also common. UCI regulations only stipulate that the bike must have a working front and rear brake.
A highly artificial course consisting of trucks and earthmoving equipment, at the 2009 world championships.
UCI regulations stipulate that a course consist of at least 14 sections per course, including repeated sections. At most two sections can be composed entirely of artificial elements. Both sides of the course are marked with plastic tape, and there must be a clear stretch of 3 metres prior to the finish line, in order to prevent riders jumping over the line from an obstacle. Maximum obstacle jump heights are specified, from 0.80 to 1.80 metres depending on category. The sections, each approximately 60m in length, are laid out on a circuit to allow riders to ride from one section to the next, but whether the sections have to be completed in order depends on the individual competition.
^ “In Spain around 1980, Pedro Pi, a Montesa executive and rider, started trialsin. Pedro also designed the 20×20 Montesa trials bicycle, which evolved into the Monty.”
^ a b http://www.uci.ch/Modules/BUILTIN/getObject.asp?MenuId=&ObjTypeCode=FILE&type=FILE&id=34595&LangId=1
The spacing of the drop outs is 116mm, the same as on a mod trials bike.
Wikimedia Commons has media related to: Trial bikes
Biketrial Federation UK – the forward-looking British Trials Organisation
Trials from the Union Cycliste Internationale
UK BikeTrial – an inclusive governing body
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Mountain bike racing
Cross-country Downhill Freeride Dual slalom Four-cross Marathon 24 hour Enduro Epic Trials
Olympic Games World Championships World Cup
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