It&rsquo;s a frigid Friday night and forty bicyclists have convened on Polish Triangle, aka Bum Island, the three-sided plaza at Division/Ashland/Milwaukee, populated by homeless guys and a hotdog vendor, and carpeted with pigeon droppings. It&rsquo;s a bigger crowd than usual for the Wicker Park Critical Mass, one of several &ldquo;mini masses&rdquo; on the first Friday [...]