What is a good way to learn how to ride a bike on rollers? After seeing a few questions about rollers pop-up, such as this one, it has spiked my interest in these things again.

So how do you learn how to ride on rollers? How long does it take you to get the hang of it? Is it like learning to use clipless pedals where you are almost guaranteed to fall off a couple of times before you get it nailed?
how do you learn how to ride on rollers?



Believe you can do it.
Do it!
Do it in a doorway.
Practice



  How long does it take you to get the hang of it?


Took me about 30 min. on a set of plastic parabolic rollers before I felt comfortable enough to take the rollers out of the doorway and just be next to a wall.


  are almost guaranteed to fall off a couple of times before you get it nailed?


No... and maybe. Depends on your comfort level of being on a bicycle, hand eye coordination, and what kind of rollers you are riding on. I have yet to ride off of or fall off of my parabolic rollers. I had spent a lot of time on a bike before ever getting on the rollers the first time and my balance is fairly good. 

If I had learned on a pair of cylindrical rollers, I think I would have ridden off or crashed at least a few times before really getting the hang of it. Not looking down and getting the wheels spinning makes a big difference. The hardest part is getting going. I found it fairly easy to start out by holding on to the doorway and having my bike in a middle gear so I didn't have to shift when starting out. I would then have one hand on the top of my handlebars and start pedaling. Focusing on getting my wheels spinning, I would slowly let go of the doorway but keep my hand there so I could grab the doorway when I wanted. Once I was starting to get comfortable, I slowly let go of the doorway and put both hands on the handlebars. Success!!


http://www.flickr.com/photos/bikeride/250957762/