50cm = 19.68"
I'm 5'9" tall, pretty average from what I understand. If I had a penis that big it would reach roughly halfway down my shin, leaving 7-8" ground clearance. A real "low rider," so to speak.
Bignlong, you have a mighty impressive penis no doubtedly, but unless you're over 8 feet tall I'm gonna say you're closer to the 9 - 10.5" range, based on pictures on your blog where it clearly shows your member barely reaching halfway down your thigh (hard to say for sure due to camera angle tricks, hence the 1.5" variance I'm estimating), not halfway down your shin. Overall, you're probably bigger than 99% of guys, so why fib?