Passing a cyclist is an overtaking manoeuvre, just like passing any other vehicle, it requires the driver to slow down, look, check if it’s safe to pass, indicate, move out when safe to do so, or wait if not, and then pass a a reasonable speed.
The Safe passing distance varies with other factors, such as:
- speed of overtaking vehicle
- speed of cyclist
- size of overtaking vehicle
- weather/light conditions
- road surface
Half a lane is a good minimum, and if the cyclist is in the middle of the lane, that means moving entirely into the next lane, as bikes may need lateral room, to turn and to avoid road conditions, debris, etc,
Some drivers only partially leave the lane when the cyclist is travelling at road speed in the centre of the lane, or don’t move over at all when the cyclist is on the left of the lane, and on most Hong Kong lanes, either of these acts are highly dangerous, and are a constant problem with cycling. Too many drivers apparently treat cyclists as obstacles instead of other vehicles on the road.
Drivers should only overtake if there is clear road ahead as it is not necessary to pass cyclists when approaching slow or stationary traffic ahead since the cyclist will catch up to the traffic only a few seconds after the other vehicle would have reached it anyway.