who makes a bimini top that stands up to 50-60mph speeds ?

It's called sunscreen. Just playin. Good question though. Try google also.

My last boat came with one I ran up to 80 (Formula factory top). A couple buddies have bought them from Overtons and regularly cruise in the 50-60 range without issue. (for the last 3-4 years)

My last boat had one from these folks with the solid braces, and it took 50 mph pretty well. Never broke, tore, etc. Lasted 6 years and was in good shape when sold. Made by Carver in the US. Causes a lot of drag, though. Lost 3 mph on top with it up. I just put one on the current boat, but nothing above 50 yet, so no idea how it will do.

http://www.websweeper.com/biminitops/

I had a standard bimini which snapped at 40 mph and ruined the bimini as well as caused damage to my boat. i would recommend these guys. HISPEEDBIMINI.COM They made the bimini i have now and love it.

I had Eric at Seabird Canvass in Tarpon design and build one that he "guaranteed" would be good to 70mph. Frequently run 60-65 with it up and have run 70-72 once or twice and have not had any issues with it during 11 months of continuous use. Pic and more info is on a thread in the Velocity section...