Originally Posted by trackhub
A lot of it seems to come from well-meaning, but sadly misinformed parents and other authority figures from childhood. Toss in some other random family members (like that strange uncle or oddball aunt that every suburban family seems to have) along with scout leaders, and the list gets rather long. I call this "the cycle of entrenched misinformation". This cycle is damn near impossible to break.
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All comes from the basic rule to walk/hike against the flow of traffic... these folks are just projecting their walking rules to cycling, as they see cycling as a form of "pedestrianism."
One might think that arrows on BL would solve this... but apparently some folks even ignore arrows. One might think that constantly approaching road signs on the wrong side of the road might be a hint... But apparently road signs are not meant for cyclists. Oh well.