Originally Posted by
genejockey
It's not just height. There's also inseam. Not trouser inseam, but rather floor to crotch when in bare feet. Then there's flexibility. Wrench Science has a fit calculator, but there are others, that can help you figure out what size is likely to fit.
You can make a smaller bike fit with longer seatpost and stem. Too big is more challenging.
Exactly. Back in the day the pros went with the smallest frame that worked because it was lighter.