In his autobiographical Life on the Mississippi,Mark Twain writes of setting out as an apprentice to a Mississippi river pilot and expecting to learn the river, and finding out that instead, he had to do something harder: learn to read the river.
Working out the correct lane position for riding a bicycle likewise requires reading the street. The linked video (above) from the League of American Bicyclists, and even more the associated discussion, contain many claims about "the" correct lane position, one commenter going so far as to argue that a study from the UK establishes the correct lane position for bikes, worldwide. To his credit, the researcher concerned say he makes no such claim.
I would argue that no one rule works for lane positioning, even in a given city. In Toronto, the situation changes all the time. A ride on Queen Street at 1400 (2pm) on a week day, with parking in place, takes place in a very different cycling environment from a ride at 1700, with the parked vehicle removed (we hope) and large numbers of commuters filling the street. At any given moment, the cues that predict motorist behaviour, from the sound of engines to the configuration of their vehicles, allows a cyclist to decide when it makes sense to pass, and when it does not, how far into the lane to ride to keep the drivers passing at a safe distance, when to ride in the kerb lane and when not to.
It takes much less time and effort to learn to read the street than Mark Twain needed to learn to read the Mississippi, but it does take some effort and attention. Precisely because novice cyclists need time to learn the skills of reading traffic, bicycle lanes make sense: they allow new cyclists to observe traffic from a cyclist's eye view and a protected position on the road. But neither bike lanes nor any single technique offers a solution to bicycle safety: that comes primarily from education and enforcement directed at motorists, the operators of the really dangerous vehicles. The best safety measures cyclists can take for ourselves depend on observation and learning.
