I feel a bit daft asking this, I'm sure it's a really obvious answer! I've never bumped my pram up or down steps, is there a knack to it, or is it literally just roll off the edge of the step onto the next one? I've got an oyster, and an obaby stroller, I'm guessing it would only work with the stroller! Also, how many steps is it ok to do this on, eg we live in a second floor flat, stairs aren't steep but I assume this wouldn't be recommended on so many stairs?