I resent this dumbing-down of bike sizes. The traditional system, which specifies seat tube length (C-C or C-T), top tube length (C-C), and perhaps either bottom bracket height or standover height, served several generations of cyclists very well and should be retained, although today's sloping top tubes admittedly make it a bit harder to work out comparable size specifications. Yes, I agree that the ultimate test is largely subjective, but it would be very useful to be able to compare sizes from catalogues or the Internet while narrowing down one's choices for a few test rides. I also agree that, particularly for a mountain bike or hybrid, top tube length is more important than seat tube length.