I'm 6'1, usually ride road bikes at 60cm+ with a fist/fist and a half of seat tube showing. I'm looking to buy a used MTB and sizing agreement has me confused, mostly because whatever sizing chart I referred to suggested a 21" MTB, which translates to a 58-59cm frame.

My question is this: Do MTBs generally fit a little smaller than road bikes?

I am posting this in the Mechanics forum also.

Thanks in advance for any wisdom, an let me know if I failed to include any other useful information.