Safe riding, speed choice and following distance
Speed and distance
Choose a speed that lets you stop within the distance you can see to be clear. The legal maximums are 50 km/h in built-up areas, 80 km/h outside built-up areas and 120 km/h on motorways, but rain, gravel, darkness or traffic may make a much lower speed correct. Use a minimum two-second following gap in good conditions and at least four seconds in rain or on slippery roads. Braking distance rises with the square of speed, so doubling speed roughly quadruples stopping distance.
Lane position
Ride where you can see and be seen, but avoid lingering in blind spots. On a single carriageway, a position that gives you a view past the vehicle ahead and an escape route to the side is usually better than riding directly behind it.
Worked example
At 80 km/h you are covering about 22 metres per second. A two-second gap is therefore about 44 metres. In rain you double it to about 88 metres. If you instead left 22 metres, you would have only one second and almost no margin if the car ahead braked hard.
Traps that cost marks
Treating the speed limit as a target; counting the gap from the car ahead's rear bumper rather than a fixed roadside point; forgetting that wet brakes and tyres need gentler input; following a large vehicle so closely that you cannot see potholes or debris.