I was there in late June, the weather was perfect (mid 80's). I was there right before the heat wave moved from Texas to the east coast. Managed to ride the Dragon twice (different days), both times I was at the start around 8:15 AM. Never saw another bike for the entire trip down the Dragon. Went back around 6:00PM one day to hit the gift shop, there was a stream of bikes going both ways at that time. I just did the gift shop and rode 129 the opposite direction from the Dragon. I tried to get my passenger to ride it one day when there was light rain, but she said F... that...LOL.
So I suggest anybody wanting to ride without getting hit head on, get there just after sunrise. You can go as fast as you want without harming anybody else. Or you can poke along if that is your desire.