I was a spin instructor at Gold's Gym for several years.
This is the bike we used. It fit people under 5 ft to over 6 ft who weighed 100 lbs to 350.
With proper care, they will last a lifetime.
http://profitnessmd.com/proddetail.php?prod=SBST-505
http://www.spinning.com/spinning-sho...r-bike-pro.asp