I'm riding 165s on my recumbent. After I had my knee 'scoped, I just couldn't turn the 170s I had on it at the time. (Your mental picture should be a glorious spring day, and me out in the backyard unable to make the cranks go all the way 'round. That incident ended in frustrated tears). I'm 5'8" when I stand straight, and my 6'2" father used to ride the same saddle without changing stirrup length, BTW.

As several have said, shorter cranks are out there. They are a Godsend if you have knee problems.