It doesn't discriminate between different types of road users, it is the distance that a vehicle will travel before coming to a stand when making an emergency stop. At 20mph, that distance is comprised of a 'thinking time' over which the vehicle will cover 6m and a braking distance of another 6m. That is for good visibility and road surface conditions. The braking distance doubles in the wet.I don't understand that, 20 mph isn't very fast so the braking distance definitely isn't 12m. It's what I've been taught, as it makes overtaking cyclists much safer.
Where does it say in the highway code you must leave 12m for cyclists??
Following a cyclist as close as 2m at 20mph might make it safer for you in your crash resistant box but it doesn't do anything for the cyclist's chances. The one-sided mindset of many motorists is something that cyclists have to live with.
Oops, just beaten to it by JamesT.