I try to give sufficient space for the cyclist to fall off without being in collision with me. This means that a faster and more stable cyclist will get less space than one who appears uncertain and or wobbly.

I will give a horse rider far more space than I would a cyclist. From experience horses are very unpredictable and can move sideways very quickly, far quicker than a car even at very high speed could get past them.

I hardly ever overtake a motorcyclist, they are usually too fast, unless we're both in a traffic queue or they are a pootly scooter, in which case treat as if a cyclist.

(I realise that I'm probably lecturing on the sucking of eggs!)