You look at the damn thing and think “Who is the insane bastard who decided this was safe and necessary for biking?” But lots of people use them and the argument is that it’s more of a natural movement (albeit on a flat surface) in comparison to using a trainer. With a trainer, you mount your rear tire on the roller but it does elevate you slightly so if you don’t have a riser, the feeling of you going slightly downwards is a little disconcerting.
With a roller, you are level and rolling without moving forward. However, you will have to be paying real close attention when you get on one. Do not get on one if: you’ve got ADD, you daydream a lot or you are just a complete and utter moron. You can seriously hurt yourself if you are not paying attention so heed solid advice and err on the side of caution.
Okay, first thing you’ve got to do is adjust the roller so that the front roller is a tad further than your front hub axle on your bike. If you don’t, you are going to drive right off your rollers, probably into your kitchen and most likely, crash into a door. Make sure you are in a relatively easy gear on the cassette so that you aren’t grinding to get some initial speed up.
Next, find a place that has support so that you can lean against something when you first get on. Use a hallway or a doorway. Some use chairs but do this only if you’ve been training on rollers for a while and are used to it or have heavy chairs.
Now the tricky part: get the pedal you’re mounting on (it should be your drivetrain side) at 6 o’clock. Clip in with that foot. One hand grips the handlebars, the other grips your source of support (wall, door jamb, chair). Throw your free leg over and start pedaling to get yourself clicked in. Hold on if you need to but getting the speed up helps keep you straight and not wobbly. Keep your grip nice and loose and pedal through with your hips.
It takes a bit of concentration so none of that texting while riding!
I've included another video of a trick you can do once you get good on rollers.