Don't go in the rain. Attempted it with some friends, mostly fixed gear cyclocross bikes (cross bikes are a great choice, BTW, durable but fast) during the recent deluge in late June. Seven inches of rain later, 75 miles, we made the call of shame. I imagine it's a bit easier if you aren't caught up in something resembling hurricane level rains. We will re-attempt it in the fall or next spring. The trail wasn't hard riding at all - bumpy like going down a rough road shoulder - and if not for the torrential rains would not have been a problem. I was running 44:17 and might run 44:18 or :19 if I had to do it again, and take it easier. Good luck with it, bet you'll do fine.