I couldn't really follow focus a fast moving cycle in low light as I'm using a series I 300mm f2.8 and the manual focussing on that thing is dreadful. But even if it had had full time manual focussing, I doubt if I could have followed the bike in that light (I was also using flash so couldn't just hose either).
Ah... point taken . The rapid action of your shooting situation is far more demanding than my typical wedding reception. I know that I certainly could NOT pull that off.... I feel your pain.