Originally Posted by warrantchief

Do *not* get the 50cm. IRO measures frames from the center of the BB to the TOP of the seat tube. When you notice his seat tube stick out 2-3cm over the TT, you can see why he recommends getting the next size bigger. I'm 6'2" and I ride a 62cm angus. I normally ride a 59.

Check out this page: http://www.irocycle.com/id21.html

Now ignore the numbers he refers to his frames and pay attention to the ST c-c and TT c-c.

Measure the ST and TT of your current bike and compare. It's possible the "53" is too small and you need a "56" I'd be more worried about the TT length when considering what kind of riding I was going to be doing.

Good luck...