It's funny you say that. I was on a NuVinci hubbed bike a few months ago and kept getting passed by others on Citibikes, which I though strange because I was riding hard and am in good cycling shape. It dawned on me then that it could be the hub for some reason. The next bike I took was a three speed and it felt much faster. I've always found some to be faster than others but this was pretty clearly the hub.

That said, my Citibiking days are over since I retired. If I want to bike I'm always starting from home now.