Sirzy - because sometimes the cycle lanes are shared with pedestrians, or full of gutters, or cars go in them, or they have potholes. Same reason I run on the road sometimes rather than the path - it's smoother!
I try to be considerate to cars, and keep out of their way as much as possible, but unfortunately the council doesn't always consider cyclists in the same way. One road I ride on, it has crumbled at the edges, so I do have to ride out and get in cars way a bit - or I would have an accident!
I think drivers really need to have more patience!! It only takes a couple of minutes out to slow down for some cyclists or a horse.
It might not always be races neither, in our area there are a few organised bike rides too, not races, but organised routes of varying length for all abilities.
I live in Ascot, and for at least 5 days each year the roads grind to a halt and our high st is changed to one way, and dh can't park at the station, and we have to walk or cycle anywhere we want to go. maybe horse racing should be banned too! 