I've not ridden in 20 years, but I'm currently building a new bike, and I'm getting really varied advice about what the correct crank arm length is for me. I'm 6'1" if that means anything. I have a 20" S&M Intrikat frame and I've been told to go as high as 180mm, then that that was way too long for flatland, and that I should do a 160mm. Confused.com. Any words of wisdom out there?