Speed: time, distance, and energy
Higher speed increases the distance traveled during your reaction time, the braking distance, and the motorcycle's kinetic energy.
Meters per second
At 50 km/h, a motorcycle travels about 14 m each second. At 90 km/h, it travels about 25 m, and at 130 km/h, about 36 m.
Distance traveled before you act
You might spend a second checking a mirror, assessing an obstacle, or choosing a line. The motorcycle keeps moving throughout that time. At a higher speed, it covers more meters before you act.
The speed difference matters in traffic too
The speedometer does not show how quickly you are closing on a particular car. When overtaking or filtering between lanes, assess both your own speed and the closing rate.
A closing-speed example
If you are traveling at 90 km/h and the car ahead is traveling at 70 km/h, the difference is 20 km/h, or about 5.6 m/s. If both speeds stay constant, the gap between you shrinks by roughly 11 meters in two seconds.
Sources · 1
- Физические основы классической механики
Перемещение, скорость и время; PDF: с. 7-8.
Used for: Calculate distance from speed and time.
Open source
Reaction distance
The motorcycle keeps moving while the rider notices a threat and begins to act. The higher the speed, the more meters it travels during that time.
Braking distance
Braking distance is the distance from the start of braking to a complete stop. Together with reaction distance, it makes up the total stopping distance.
Braking distance grows faster than speed
With the same grip and braking technique, braking distance grows faster than speed itself. A small increase in speed requires a disproportionately greater distance to stop.
A short gap forces more abrupt action
With a short following distance, you have to brake harder and change your line more abruptly. There is less space and time for smooth braking or a gradual change of line.
Sources · 2
- Физические основы классической механики
Перемещение, скорость и время; PDF: с. 7-8.
Used for: Distance traveled during the selected time before braking begins.
Open source - Физические основы классической механики
Работа сил и изменение кинетической энергии, формулы (1.42)-(1.44); PDF: с. 13.
Used for: Relationship between braking distance, work done by a force, and the reduction in energy.
Open source
Kinetic energy
Kinetic energy grows with the square of speed: doubling speed quadruples the energy. That energy must be dissipated during braking, and in a collision it affects the severity of the consequences.
Where the energy goes under braking
During braking, some kinetic energy becomes heat in the brakes. The higher the starting speed, the more energy the brakes must dissipate during a single deceleration.
Mass affects energy too
At the same speed, kinetic energy increases in proportion to the combined mass of the motorcycle, rider, passenger, and luggage. If that mass increases by a quarter, the energy of motion increases by a quarter too.
Reassess your distance after accelerating
After accelerating, you will need more distance to brake. Even if traffic has opened up, look further ahead. Leave enough distance to the next corner, car, or road entrance to slow down again.
Sources · 2
- Физические основы классической механики
Кинетическая энергия, формула (1.44); PDF: с. 13.
Used for: Energy is proportional to mass and the square of speed.
Open source - Физические основы классической механики
Работа сил и изменение кинетической энергии, формулы (1.42)-(1.44); PDF: с. 13.
Used for: Work done by braking forces reduces kinetic energy.
Open source