BMX freestyle
Each run begins when a rider is prompted to start and they move from their starting position, at which point the 60-second countdown clock is initiated. The rider can choose where they start in the park.
The clock continues regardless of a crash or bike failure. In the case of the latter, the rider must get another bike or fix theirs to carry on.
Judges stop assessing a run when the clock hits zero.
If a rider is still in motion when the time runs out, any remaining trick fully completed – i.e., both wheels are in contact with a flat surface of the park – within three seconds after the time stops is counted.
If a rider's run exits the boundaries of the park, anything they do there is not considered by the judges. Safety railings at the edges of the park are considered part of the park boundaries.
BMX racing
All riders start in designated gate positions with their front wheels placed against the gate, grounded and stationary, awaiting the starter's call and sound indicating the go-ahead to begin.
Races are rife with contact due to the nature of the sport, and therefore crashes can and do occur. Despite the obvious impact on times, those who do happen to crash can still earn points if they're able to finish.
In its rulebook, cycling's world governing body (UCI) calls interference "a complex offense." Commissaires decide if it's worthy of infraction.
The UCI does state the forbiddance of forcing another rider off the track, and any contact "with the intention of impeding that rider's progress so as to overtake [them] or cause [them] to be overtaken by another rider," as well as "team riding" or helping competitors gain higher positions.
Flags are utilized by officials to indicate specific communications: green means the race is not obstructed and racing can proceed; yellow means the track is obstructed and riders should be held at the gate; and red means riders should stop immediately and await further instructions.
Mountain biking
A course's lap length must be between 4-6 kilometers, taking about 80-100 seconds to complete, and every kilometer must be marked by signage that indicates the distance remaining. A mass start.
Riders must permit any faster rider to overtake without obstructing, and if they exit the course for any reason they must enter between the same two course markers from which they exited.
Road
The courses are defined by the paved road available to road traffic. Markings are used when possible to signify boundaries.
Feeding zones, positioned along the course, provide a way for riders to get food and drink. It's closely monitored to ensure each rider is being supplied by only a fellow team member. Vehicles are also used in some cases to stand by for nourishment or technical support.
In the time trial, each rider from a stationary position is released by a holder, at which time the clock begins on their run.
If one rider is caught by another, they may neither lead nor follow in the slipstream of the rider who caught up to them. The approaching rider must then keep a 2-meter lateral gap between the two of them.
Track
Movements likely to hinder the race result along with collusion between riders can result in disqualification. All riders also must have at least one hand on the handlebar at all times.
A rider or team gains a lap when they have caught up with the rear of the largest racing bunch on the track, and likewise, loses a lap when they are caught by the largest bunch on the track.
False starts can be ruled and are indicated by a double-pistol shot. For standing-start events, two starts are permitted before a DQ.
A fall or mishap on the track can sometimes result in a neutralization in which, similar to a NASCAR caution lap, the field slows and stays in position for some time before carrying on.
In the sprint, a maximum of two standstills are permitted for each race, no longer than 30 seconds each, at which point a starter directs the leading rider to continue. If they fail to do so, the starter can stop the race and declare the other rider the winner.
In the team pursuit, a team is caught when the opposing team arrives at or within a distance of 1 meter of it. If this occurs in a qualifying round, the catching team wins, signified by a pistol shot, and must stop so the team that's overtaken can finish and record a time for ranking purposes. If a final, the race is over.
The race ends when the third rider crosses the finish line for the final time at full distance, or if an aforementioned catch occurs.
If a mishap occurs in the first half-lap, the race is stopped and restarted. Past that, a team must go on with three riders.
In the omnium points race, a flying start is utilized after one neutralized lap. If more than half the riders happen to fall, the race is stopped and a new start is taken from the location of the fall.
In the keirin, a motorized bike riding within the sprinter line paces the field by gradually increasing its speed from 30 kph to 50 kph, leaving after the home straight pursuit line with three laps to go.
If one or more riders pass the leading edge of the derny's front wheel before the pursuit line when it leaves the track, the race is stopped and rerun without the riders, who are disqualified.
If a mishap occurs in the first half-lap, the race is stopped and restarted. Past that, no mishap is taken into consideration.
In the team sprint, each rider leads a lap. Men's teams have three riders, and women's teams have two riders. Those that aren't the finishing rider drop out after their lap, moving toward the outside of the track after making sure their front wheel's leading edge crosses the pursuit line ahead of the next rider's leading edge.
A draw is decided by the best time made in the last lap.
In the Madison, the teams of two are required to carry the same rider number but in different colors to help distinguish.
A first group of riders comprising one rider from each team start the race with a neutralized lap followed by a flying start; meanwhile, the second group of teammates must remain motionless.
Teammates can relay one another at-will by a touch of the hand or the shorts. Teams lapped one or several times risk removal.
If a mishap occurs, there's no neutralization and the teammate rides alone. If more than half the riders happen to fall, the race is stopped and a new start is taken from the location of the fall.
In the omnium elimination race, the last rider in each intermediate sprint is eliminated until one rider remains – the winner. A flying start follows one neutralized lap, and a sprint is run every second lap.
The last rider is determined by the position of their rear wheel on the finish line. Any lapped riders take the place of the last rider. In rare cases when a decision can't be made on which riders should be eliminated prior to the riders crossing the pursuit line on the back straight after the sprint, then no riders will be eliminated until the next sprint, indicated by a green flag at the starting line.
In the omnium tempo race, only the leader of each sprint – conducted every lap following the first four laps of the race – is awarded one point for each sprint won, including the last. Lapping the field gets 20 points, and being lapped loses a rider 20 points.