I was a motorist before I became a cyclist, and discovered something... so I set out to test it.
I was discussing this very subject with a friend (in a car on the way to college, back in the day). Knowing the point I wanted to prove to him, I secretly counted all the motorcycles and bicycles we encountered during a half hour city trip. When we arrived at campus, I asked him, "how many motorbikes and cyclists did you see on the way here?" He looked at me sincerely puzzled and said, "none." I counted nearly thirty, about half of which he had over-taken!
I remember my friend often when I cycle on roads... I always assume that every car out in the street DOESN'T see me...
... and another 2 things I observed:
1) on the odd occasion that motorists do see cyclists, they are often regarded as a nuisance.
2) drivers who are considerate and courteous to cyclists, are usually cyclists as well.
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