Well, a 56cm frame would basically be a 22 inch frame. I'm currently using a 23 inch frame for commuting now. I have a 31" inseam which is basically 79 cm. The 23 inch frame is actually a little too big for me, a 22inch would be perfect. So given that, I think it may be a little small on you, but not terribly small. I'm sure it can be quite workable with the right stem, cranks, and seat post.