Been gone for a while, So the bike below is mine and has a standard lower headset cup and a lowered lyrik solo air (140mm) so it is a bit taller then a stock distortion. With that said its bb height is 13 inches exactly but It pedals so well and stays high in its travel so I don't have to worry about clipping pedals.
the medium distortion fits my two friends perfect and they are 5'6 and 5'8. I would say if you are 5'10 or higher then go with the Large. I am just under 6 feet tall and use a 50mm stem on a large and i love the fit. a bit compact but the setback seatpost helps keep it stretched out on the ups and the smaller cockpit feels great on the DH
The thing is setback post is problematic on the limbs. I know it's not a typical climber bike and I'm a hair under 5'11'' but I use my trailbike also for fitness training (or at least I used to) so feeling cramped scares me a bit.