aluminium – (Al) a metal used for lightweight bicycle parts. The density of aluminium varies from 2560 to 2800kg/m3, making it much lighter than steel. The tensile strength of aluminium is also much lower than that of steel, which explains why aluminium parts are often oversized compared to their equivalent steel counterparts (albeit still being lighter).
allen keys –hexagonally shaped wrench keys that fits inside hexagonally hollowed out Allen bolts of corresponding size. The most common Allen bolts found on modern bikes include 4mm for adjusting the brake levers, the slave cylinders and the headset bolt, 5mm for the stem clamps and wheel axle bolts and 8mm for the crank axle bolts.
axle – the centre line in the bottom bracket or the hubs, around which the cranks or the wheels rotate, respectively.
back hop – jumping backwards with the bike
bailing out – jumping off the bike to land on your feet and avoid the full effect of a crash
balance – the position where you can stand without falling to either side of the bike, with your centre of gravity positioned somewhere over the balance line.
balance line - the line that joins the two contact points between the tyres and the ground or the obstacles.
bash plate – the rugged plate fixed underneath the bottom bracket shell of 20-inch trials bikes, that prevents knocks and damage to the chain and front sprocket.
bash ring – the outer ring that mounts on the outside of the front chain ring or sprocket on 26-inch and 24-inch trials bikes to protect the chain from knocks.
benjamins – at UCI competitions, 11 and 12 years old riders who follow the sections marked in blue for both 20-inch and 26-inch categories
BIU – BikeTrial International Union – one of the original ruling organizations of bike trials with its own agenda of international competitions.
bleeding kit – syringe and tubing with hollow fitting screws designed to purge and replace the oil in an hydraulic brake system.
bottom-bracket – the rotating mechanical part fitting at the base of a frame and holding the crank arms.
brake booster – a horse-shoe shaped mechanical part that bolts onto the brake’s mounts to rigidify the frame. This prevents the rear-stay tubes from flexing upon brake pressure and increases the braking performance. Some frames are built with special reinforcements to act as an integrated brake booster.
buckled wheel – a wheel whose shape is no longer a perfect circle but a wobbly eight.
bunny hop – a jump at cruising speed, relying entirely on body language, with a compression phase followed by an extension phase at the end of which the rider tucks and pulls up the bike in the air.
category – refers to the bikes of a same wheel size, for example the 20-inch mod bikes category or the 26-inch stock bikes category.
cadets: at UCI competitions, riders who are 15 and 16 years old, following the sections marked in black.
caged pedals – pedals consisting of a serrated metal cage bolted onto a four-branched pedal body.
calluses – areas of skin that grow thick in response to repeated pressure and friction. In bike trials, calluses are common in the palms of the hands where the skin rubs against the bar grips.
centre of gravity – the virtual point where all the weight of a rider and his/her bike can be considered to be concentrated. The rider looses perfect balance when his/her centre of gravity is no longer positioned vertically over the balance line.
chain-splitter – a special tool with a movable pin that can push its way through a chain’s junction pivot pin to separate two chain links.
chain stay – the lower tubing on a frame that joins the bottom bracket shell to the rear axle. Its length is measured from the bottom bracket (BB) shell centre to the rear wheel axle.
chain-tensioner – a sprung device with one or two jockey wheels, that maintains the chain under tension and avoid accidental chain skipping.
chain tugs – special bolts that pull the rear wheel axle away from the bottom bracket in order to tension the chain.
clean – to clean a section is to ride it successfully with no penalty points
correction hops – small adjustment hops that help maintain a rider’s balance on an obstacle, usually after landing on it.
crank extractor – a special tool with dual coaxial threads, the external one fitting in the crank arm’s internal thread, while the inner one receives a thick capped bolt pushing against the bottom bracket axle.
cross over – the hydraulic hose that links the two slave cylinders on a hydraulic rim brake.
crouching – the action of bending your knees and lowering yourself so that you are close to the bike, leaning forward slightly. This is often the best way to lower your centre of gravity before a drop or before an impulse.
disc-brake – brake system where very hard compound pads (often a special ceramic or fibre compound) clip and hold onto a rotor that is mounted on the hub’s flanges (hence stopping the wheel). Braking performance is not affected even if the wheel is buckled.
dab – to touch the ground or an obstacle with a foot, even lightly, to correct your balance. You can accumulate up to five dabs in a given section.
drive train – the transmission assembly, including the pedals, cranks, bottom bracket and freewheel, linked to the rear wheel sprocket via the chain.
drop gap – jumping across a gap, from a high obstacle to a lower obstacle
drop off – jumping down from a high obstacle to the ground or too a lower obstacle
drop outs – the slots that receive the wheel axles either at the tips of the fork, or at the rear end of the chainstays. The rear drop outs can be horizontal (the wheel axle is adjusted horizontally), or vertical (the wheel axle butts against the top of the vertical slot in the frame.
elite – at UCI competitions, riders who are 19 years old and up, follow the sections marked in yellow in either the 20” or 26” category.
endo – balancing position on the front wheel, with the rear wheel lifted.
finish – the gate marking the exit of a section. The exit is validated by the front wheel axle crossing the tape line.
five – the maximum number of penalty points that can be given in any section. If two riders make five the same section, the advantage will go the rider who went further.
flat tyre – refers to having a punctured tyre with not enough pressure to ride properly.
focused – the state of mind in which a rider will concentrate on his/her riding performance, without being disturbed by non-critical events or its surroundings.
foot – good foot/front foot – the foot that you naturally keep in front when performing a trackstand or that you are most comfortable positioning on the front pedal when standing with the pedals level with the ground. Pedal kicks are best performed with that front foot.
foot – lazy foot/back foot – the foot that you would normally keep at the back when performing a trackstand. The back foot is mostly used to back-pedal, ratcheting the freewheel backwards, or to counter-balance the front foot pressure, but never to kick the pedal.
freeride – style of moutain biking involving heavy-duty suspensions and big jumps over natural or man-made terrain.
freewheel – the mechanism within the sprocket that disengages from the crank driveshaft when the chain runs counter-clockwise (pedalling backwards) or when the rear wheel turns faster than the pedalling motion (crank axle).
freewheel remover – a special tool designed to remove the freewheel from a crank arm or from a rear wheel hub.
gap – any distance between two raised obstacles.
gap up – jumping across a gap, from a low obstacle to a higher obstacle
gates – the entry and exit points of a section, marked as Start and Finish respectively.
gear ratio – the relationship between the numbers of teeth on the front and rear sprockets. It is obtained by dividing the number of teeth on the front sprocket by the number of teeth on the rear sprocket.
grind – using an angle grinder, the rough texture obtained on the rim flange to increase friction and braking performance. Both the rim and the brake pads tend to wear down more quickly.
grinder – a power tool that uses metal cutting or grinding discs. Can be used for grinding rim flanges in order to texture them, enhancing pad friction and braking performance.
grip – the adherence or hold one rider has over the bike (via the handlebars grips and the pedals) and over the obstacle he/she rides thanks to the tyres.
hook - position in which the bike is hanging from the front wheel or from a pedal, to the top edge of an obstacle.
HS33 – the most popular hydraulic rim brakes among trials riders, manufactured by Magura.
hydraulic-brake – brake that relies on a hydraulic system (with pistons and hoses) for the transmission of force between the lever and the brake pads. Hydraulic systems de-multiply the force needed at the lever input while outputting maximum pressure at the pads level. Hydraulic brakes deliver far superior braking performance than cable brakes.
hydraulic hose – the reinforced tubing that contains the oil or other pressure liquid ensuring hydraulic force transmission between the brake lever’s piston (master cylinder) and the brake pads’pistons (slave cylinders).
indoor – any section comprising obstacles built with man-made materials (such as concrete pipes, pallets, truck tyres, car wrecks, skips etc..) which could be assembled indoor. These sections are called indoor even when they are assembled outside.
ISIS splined – refers to a standard of ridges on an oversized bottom bracket spindle. The ridges secure the crank arms on the axle. Because they are hollow, ISIS splined bottom brackets tend to be lighter and stiffer than their square taper equivalent.
juniors – riders who are 16-18 years old at UCI competitions, ride the sections marked in red.
line – an imaginary track that a rider will try to follow in a section, as the best possible riding path he/she can visualize.
line of balance – imaginary line that joins the two points of wheel contact with the ground.
lip (of a jump) – the curbed take-off section of a jump
lurch – to make a sudden movement with a lot of body language to set the bike in motion backwards or forwards or from side to side.
magnesium – (Mg) a metal much lighter than aluminium, yet stronger, often used to make aluminium-magnesium alloys (magnalium or magnelium) that are overall lighter and stronger than most common aluminium alloys. The density of Magnesium is 1738kg/m3.
manual – after initiating a wheelie, cruising on the rear wheel without pedalling. This only works with enough initial momentum, or down a slope. A nose manual is the same move performed on the front wheel.
master cylinder – in a hydraulic brake system, the cylinder that receives the brake lever input (in the lever body) and pushes the transmission liquid through the hoses to displace the slave cylinders.
mental block – the opposite of positive mental imagery, mental blocks come from visualizing the moves going wrong, not convincing yourself that the obstacles are within your reach.
mental imagery - the specific images and mentally re-created obstacles that allow a rider to rehearse his/her riding techniques while at rest.
mental preparation – consists of using mental imagery to review your riding techniques mentally with positive outcomes, and to boost your level of confidence before riding.
minimes: at UCI competitions, riders who are 13-14 years old, follow the sections marked in green on either 20-inch or 26-inch bikes
mod bike – any trials bike with 20-inch diameter wheels. Initially, mod bikes were just modified BMXs (bicycle moto cross).
momentum – the force that keeps you moving after you have initiated a movement, say when you pedalled the full run-up distance. It is the inertial force which gives you the traction forward when you jump on an obstacle.
nose-pick - in trials riding or BMX, to land on the front wheel first, usually with a blunt stop to balance the bike on the front wheel.
natural zone – a trials course marked over natural terrain and obstacles, such as rocky outcrops, river beds, slanted grounds, wood logs, tree roots etc.
neutral zone – ahead of the start line, a 3-metre zone designated for one single participant to take his turn in a section.
observer – in each section, the person observing the rules and counting the penalties points visibly with one hand while a pilot rides through the section. The observer also triggers a stopwatch to keep a tab on time and informs the rider of the remaining time (limited to 2 minutes and 30 seconds).
obstacles – the natural or man-made elements over which one can ride in a zone.
old-school – a bike set up and a style of riding that corresponds to older models of trials bikes no longer in fashion. This includes many bikes prior to circa 2000, most of which had a full seat and less optimised geometries.
OTB (over the bars). Refers to a crash where the pilot falls over the handlebars.
patch – piece of rubber material used for puncture repairs, self-vulcanizing on the inner tube when put into contact with a special glue.
pedal hop – a small hop forward performed using the action of a pedal kick for thrust.
pedal up/ pedalled bunny hop – a jump which combines the cruising speed of pedal acceleration with strong body language, decomposed in a compression phase followed by an extension phase accelerating on the front pedal before tucking to pull the bike in the air.
pedal kick – the action of kicking the front pedal while releasing the rear brake to leap forward.
penalty points – the number of points logged by an observer while a competitor rides through a specific section. The maximum number of penalty points in any given section is five.
pivoting – the action of turning the full bike sideways, in rotation over the front or the rear wheel.
platform pedals – pedals consisting of a single platform on which pins are directly bolted or integrated.
poussins – at UCI competitions, riders who are 9 and 10 years old, following the sections marked in white in the 20-inch category only.
punch-card – the card on which the observer logs the penalty points by punching small holes with a clipping device, choosing a mark from 0 to 5 in the section he observed.
puncture – the hole leaking air from a tyre or an inner tube.
pre-competition practice – warm up session outside the marked sections where riders can check and tune their bikes.
reach – the distance measured from the centre of the bottom bracket shell to the top centre of the head tube.
riding down – simply rolling down from an obstacle in a progressive and continuous movement, with the front wheel first.
rig – an other way to name a frame or a bike
rim-brake – brake system where the braking force is applied by friction pads to the rim of a wheel. The rim flange can be textured with an angle grinder to increase the friction but brake pads will wear down more quickly.
rim tape – the thick ribbon tape covering the rim spoke holes on the inside, to prevent the inner tube from rubbing against the holes’ sharp contours.
rolling pedal kick – a variant of the pedal kick where the kick is not performed suddenly from a standstill but comes as an acceleration to finish off a progressive pedalling approach.
roll-over – the technique that consists in riding over an obstacle in a continuous pedalling motion
rotor – the metal disc designed with a friction surface for disc brakes to rub their pads
run-up distance – the pedalling distance necessary to build up enough speed and momentum required for certain techniques. For example, bunny hops, rolling pedal kicks, front wheel hooks all require a few pedal strokes’ worth of run-up distance.
section – riding corridor delimited over several obstacles by coloured tape ribbon and arrows. The entry and exit are indicated with the words Start and Finish respectively.
shin-pads/guards – shin protections, sometimes combined with knee protections, worn to prevent scratches and injuries caused by the pedal grips when a rider accidentally slips off his/her bike.
side hop – a basic technique to hop sideways with the bike, combining body language with a controlled pedal kick.
slave cylinders – the parts in a hydraulic brake system that enclose the pistons on which the brake pads are directly mounted. On a hydraulic rim brake, there is one slave cylinder on each side of the rim, each slave cylinder receives the same pressure. Their displacement is small but they deliver a high force.
smooth rim – a rim whose flanges have not been ground. Braking performance in the wet is usually fairly poor.
snail cams – curved metal cams that fit on the rear wheel axle and that can be adjusted manually to push the rear wheel axle away from the bottom bracket. They replace chain tensioners on mods but also on some stock bikes.
snake bite – a double puncture that occurs when the rim flanges punch their way through the inner tube. This happens upon landing too heavily on an obstacle. Bigger tyres, more air pressure, and smoother receptions will all contribute to avoid these instant flats.
spacers – rings of determined thickness that fit between two mechanical parts mounted on the same axle to space them apart. Spacers can be used to isolate and position a sprocket on a rear hub, to distance a crank arm away from the bottom bracket shell, or to change the vertical position of a stem on the fork’s steerer tube.
spoke key – special slotted key used to adjust the tension of individual wheel spokes by turning the appropriate spoke nipples. It can be used to build wheels but also to true buckled wheels after an impact.
spoke nipple – the hollow nut that mounts on each spoke to secure it to the rim.
sprockets – any of the front chain ring, freewheel circumference or the rear cassette rings with their tooth-like parts sticking out to keep the chain moving. Often referred to front or rear sprockets.
square taper – the four-sided taper on a low-range bottom bracket axle.
star-fangled nut – a special nut with barbed steel flanges, that is forced downward into the steering column (upper part of the fork) to secure the headset’s adjustment bolt.
static hop – a technique whereby a rider performs a hop purely based on body language, starting from a stand still without any pedal kick.
steel – alloy of iron (Fe) and carbon (C), usually containing between 0.2 and 1.5 percent carbon, often alloyed with other metals to enhance its mechanical properties. The density of steel varies from 7480 to 8000kg/m3 depending on the particular alloy (specific gravity of 7.4 to 8, that’s much heavier than water of specific gravity 1 with a density of 1000kg/m3)
steering tube (or steerer) – the tube that prolongs the fork into the frame’s head tube. It can be cut to fit the exact height of stem and spacers’combination.
stem – a part that clamps on the steering tube of the forks and that holds the handlebars. Changing the stem can change how the bike feels.
stock bike – a trials bike with 26-inch diameter wheels, called stock because the first trials bikes with this size of wheels were general-purpose mountain bikes available from stock.
tailwhip – trick in which the frame of the bike is rotated a complete turn around the bars (spinning around the headset axle).
tape – plastic ribbon used together with arrows and pointers to mark the trials courses. Once a rider has entered a section, crossing the tape with the front or rear wheel axis (or just hovering over it) is penalised by 5 points.
tar – black solidified hydrocarbon substance that can be used to increase the pads friction on a rim’s braking surfaces. The tar gets sticky when hot, it works best when rubbed on dry smooth rims. It can be found in some roofing materials or aside roadworks.
thread – refers to the helical ridge pattern on a cylindrical bolt or within a hollow nut. The ridge enables the conversion of a rotational force into a linear movement.
through-hole axle – a special drop out configuration with no adjustment slot but a single hole through the frame. The bolts reach the wheel axle through the frame, the rear wheel position is completely fixed.
titanium – (Ti) a strong corrosion-resistant metal with a tensile strength equal to that of common, low-grade steel alloys, while being about 45% lighter. The density of titanium is 4500kg/m3.
torque – the force couple that causes the wheel to rotate. A larger front sprocket yields more torque on the rear wheel, so do longer crank arms.
trackstand, locked, free – staying on the bike without putting a foot down. This is the default mode for any trials rider resting within a section. A trackstand is locked when the rider rests or leans the front tyre against an obstacle to secure his/her balance.
true - refers to a wheel that is not buckled, whose rim flanges stay evenly spaced from both sides of the frame.
urban trials – riding trials in urban settings usually involves a lot of square edges and walls, hence there are many opportunities for front wheel taps, side hops, and gaps, also dubbed TGS.
visualization – the mental exercise that allows a rider to set himself/herself into a specific context and imagine the optimum sequence of moves that will allow him/her to ride successfully out of a section.
wall ride – riding on slanted or vertical walls after an initial jump impulse towards the wall.
wheelbase – the distance measured between the two wheel axles of a bike.
wheelie /nose – riding continuously on one wheel, usually the rear wheel. The nose wheelie refers to riding on the front wheel, for example down a slope.
wheel tap – a technique consisting in hitting the edge of an obstacle with the front tyre to obtain a compression and bouncing effect that thrusts the bike upwards.
wheel transfer/swap – the action of transferring/swapping one wheel in place of the other on top of an obstacle. This is the basis for many moves landing on the front wheel and finishing on the rear.
women: at UCI competitions, female riders who are 15 years and over, ride the sections marked in pink.
yoke – on some modern frames, the reinforced curved part that links the chainstays to the bottom bracket shell. Often machined from a beefy part, the curved yoke gives more clearance to thick trials tyres compared to chain stays directly welded to the bottom bracket shell.
zero – refers to the absence of penalty points when riding a section clean. If two riders finish a section with no penalty points, the advantage goes to the rider who was faster.
zone /supervised – a zone is an area under the supervision of an observer, where one or several sections are marked with tape and arrows.