this topic seems to be drawing the same idiotic comments you get on every 'fastest' debate. let's be logical:
Someone with a top speed rating of 100 would have to be Usain Bolt, because he represents as fast as man can go. Based on that, no rugby player should have that kind of speed. Other Olympic standard sprinters would have to be 98/99.
Leigh Halfpenny is Quicker Than Usain Bolt! http://www.magnersleague.com/news/6463.php