I don't think that's an assumption (it's certainly not one for me). Bikes are great, most folks could use bikes. Some folks cannot, and we should ensure our spaces are available to all of us.

And I deal with a similar issue in my own life -- not due to a disability, but due to another form of discrimination. Believe me, I'm well aware that spaces aren't designed for everyone. If I gave the impression that bikes were the only or universal option, then of course I apologize!