i'm 6'1"ish and my inseam is 32"... 33 would be getting too close to the goods for comfort. the fuji i just got is a 56. i could probably ride a 57/58 okay (my old schwinn is a 60ish, but kinda large), but i really like the way the 56 fits me. lots of clearance, and i can still get the seat up where i need it... it's comfortable. way more comfortable than the schwinn i was riding; i think the huge difference there is the reach. though i'd say any smaller and it might be too small... if iro's really run significantly "small" then maybe up it to a 58? it just depends on preference. but i think the standard for frames is, when in doubt, go smaller? i don't know, i'm a noob. and i always make tl;dr posts. i'm shutting up now