I'd be carefull buying a bike without sitting on it...a test ride is recommended

You never know the meaning of pain until you ride a bike that doesn't fit...1" is HUGE on a bike

The most critical measurement on a bike is the top tube length, and all manufacturers have unique specs...also the seat tube length that most quote doesn't reflect the true size.

My wife rides a 17" bike, yet the seat on my 17"(medium) MTB comes up to her shoulder

Just a "heads up"