be sure to talk to some of the locals, go to one of the bike shops in town and get maps! the desert can be very unforgiving if you wander off trail for even a little while. there are jeep trials running everywhere! so sometimes even the most famous and well marked trails are hard to stay on. let someone, ie ranger, folks where you are staying or whomever ya can, know where you are going and when to expect ya back. there are LOTS of horror stories(and way too many deaths) of mtn bikers and hikers lost there. not saying that would or could happen to you. just take the precautions necessary to be safe. do NOT climb down any slickrock. from up top ya may not see it, but its not uncommon for folks unfamiliar with the terrain to climb down thinking they can get to the road they see below and get stuck where they can no longer go down nor get back up. last time i was there it was may. an optimal time really, but still desert. lots of water, electrolites(you will sweat like the dickens and not even know it). emergen-c is easy to carry and full of all the electrolites yr body needs to take the fluids into your cells. carry at least one bottle to use for that. if you've used it you know how sticky it is, and ya dont want in it in yr camelbak-major growth of tiny fuzzy critters fast! recommend ya have a camelbak like system with 2 100 oz bladders. seems like a lot of weight to carry(over 6 lbs each when full) but there is absolutely no place to get water once ya hit the trails. i usually carry peanut butter. not the "organic" kind i use at home. its just peanuts n salt. i want the cheap highly sugared stuff out like that. sugar for fast energy, and all the otherwise crappy oil and of course the peanuts n salt. salt makes ya thirsty(thats why theres so much in gatorade-but gatorade doesnt have magnesium nor potasium, both critical for osmosis). i have a friend who sets his watch alarm to go off every 15 minutes to remind him to drink. they recommmend at least one gal per person per day but im not sure thats enuf for someone raging on the trails on their mtn bike. most importantly is to pack yr cells full of water for the two or three weeks before you go. dont drink lots of coffee nor alcohol while there nor the two weeks before.
and by the way HAVE FUN!!!!