As an anecdote I've seen this happen a few times (in New York of all places!) and it's incredibly annoying. My observation is that the riders who tend to do thi

As an anecdote I've seen this happen a few times (in New York of all places!) and it's incredibly annoying. My observation is that the riders who tend to do this are often inexperienced, which makes the entire situation worse: they wobble on the sidewalk and disrupt pedestrian flow dramatically because everyone gives them way wider berth.