It’s a warm afternoon in the heart of Cambridge’s Kendall Square. The cabbies lined up at the curb josh one another. Young technologists on the sidewalk throw around jargon like “start-up” and “SEO,” short for search engine optimization. The whole square, in the midst of a major renaissance, seems to thrum. So it’s only natural that this is where I find one of the busier neighborhoods for Hubway, the nearly two-year-old bike-share program that operates in Boston, Cambridge, Somerville, and Brookline. I knew it was popular — as of late May the service had some 8,000 members who had collectively logged more than 830,000 trips — but I hadn’t realized how effortless it was to grab or leave a bike at one of the 108 stations. Like hummingbirds around a flower, bikers pulled up to and away from the station in a flash, taking or latching a bike in a matter of seconds. Hubway stations have brought their own catalog of sounds to area streets, from the more high tech (a distinctive beep and whirr when you return a bike) to the timeless (the click-click-click from the bike’s freewheel when you ride one away). With horns blaring from clogged streets nearby, it seems like sweet music.