Originally Posted by
tatfiend
I am 5' 11" and went with the 20" frame Big Dummy based primarily on top tube length compared to my other bikes with flat bars. I probably could have also fit an 18" pretty well but I was influenced by the fact that the worst fitting bike I ever had was a too small frame bike sold to me by an LBS when I first started riding again. IMO a case of their selling the size they had in stock rather than fitting it to me but I was too ignorant at the time to know what I needed.
I feel that happened to me with my current bike turned Xtracycle. Which is part of why I'm looking at the Big Dummy as I'm tired of putting money into it to get it to feel right. It's a bit reversed though in that it's always felt too big.
It's interesting that you're going for the 20". I've read a lot of comments about how the top tube is extra long and people end up with a smaller size than they thought.