I’m a regular bike commuter (all but ~5 days in 2012!) and I take CaBi around DC in the middle of the day. I ride in on my bike, then ride CaBi around to meetings and lunches, allowing me the flexibility of one-way trips (e.g. taxi to a meeting, CaBi back to the office) and the added security of not having my bike locked up in places I’m not that familiar with (my husband’s bike was stolen from the Mall 3 years ago ). When I know I’m taking CaBi, I’ll bring my commuting helmet with me into my office and wear it on CaBi. When I don’t know ahead of time / forget and don’t have time to run back for it before heading out, I ride helmetless. I’m not riding that fast on CaBi anyway, and I’m an even more conservative rider when I’m sans-helmet.
Though I do feel a bit naked when I feel my hair blowing in the breeze…