I have no idea what the shortest is. With my ape armed draw length, I can't shoot a short bow, at all. I had a nice little bow I shot really well with, 58", but the limbs couldn't take the strain of a 32" draw length. It broke, and I was devastated.

I can tell you that short recurves have some real disadvantages. Less speed. More finger pinch. More problems with stack. All combine for poor accuracy beyond 20 yards. They're handy when hunting in thick brush, but the manueverability comes at a price.

I think a fair rule of thumb on bow length is no shorter than twice your draw length. That'll get you past most of the problems.