On my way to work this morning (driving) I had the oddest experience. Very busy road, man on bike starts to wobble and look really uncoordinated. He looks really unwell. He then collapses and falls from bike across road/pavement. I stop car as does person on other side get out of car and me and a cyclist/woman on the other side rush up to him. He then proceeds to get up, say "only joking" and cycles off. This looked like someone having a seizure or something very serious. He fell heavily on the road. It totally shook me up. Would appreciate your thoughts.