Who is making Yao Ming's custom bike that I read about in the USA Today article (linked on front page)? I've been told that Hujsak Custom Bikes are very high quality. He is based in Wimberley, and he specifically says on his web site that he builds frames for people up to 7'-6" tall. I can personally vouch for Steelman Cycles. The quality is fantastic, and they are super-strong.
It wouldn't even be close: Largest Bicycle The world's largest bicycle is "Frankencycle", built by Dave Moore of Rosemead, California, USA. It is 3.4 m (11.1 ft) high, with a wheel diameter of 3.05 m (10 ft).