Most cyclists will average around at least 20mph, but the point is drivers doing stupid things leave you dead, whilst not being able to squeeze past a cyclist might delay you by an extra 5 minutes.
YOU may be a conscientious driver, but there are enough idiots on the roads that a cyclist has to be defensive. A mistake on a bike can mean a few bruises, a mistake in a car will kill people. 2 tons travelling at 60mph is a *lot* of energy.
The average weight of a car is 4079 pounds, or 1850.2kg. 60mph is 26.8metres/s.
So, if ke = ½ mv...
1850.2 * 26.8 = 1,328KJ ...and let's say 100KG for your average cyclist & bike. (20mph = 8.9metres/s)
100KG * 8.9 = 8KJ
That's a huge fuckton of difference that a large majority of drivers tend to take for granted.