I seem to remember studies showing
that if you cycle politely, stick to cycle lanes on roads and keep as close to the curb as possible, you're more likely to be killed by a driver because they take less care. Cycling practically in the middle of the road is much safer as nobody tries to overtake you when there isn't really enough room.

Also that if you wear a helmet, drivers assume you're more experienced (despite the reverse generally being true) and so take less care and give you less room.
(Skittlemcfluff ......................, Fri 2 May 2008, 7:03, Reply)