I've ridden this trail twice now - I absolutely love it, but it is the most physically demanding trail I've ever done. Like Slickrock, it's easy to underestimate. You look at the trailmap and think "It's less than 15 miles, and we shuttled up the hill to the trailhead (VERY WORTHWHILE), so it shouldn't be too bad..." The first 3 miles from the trailhead up to the overlook into Castle Valley is rough. The combination of heat, altitude, and technical ledges make it a workout. It's not all that steep, but the broken, ledgy surface prevents you from getting any momentum going, or enjoying a steady pace. The first time I rode this was in late August, and I was sweating like never before and wondering if this trail was worth it - but once I got to the overlook point I changed my mind. Totally amazing views. The ride down is quite challenging (and long), but a lot of fun. I've done bigger dropoffs on this trail than I ever have before - and totally loved them. But especially your first time - always be prepared to walk! Especially once you reach the singletrack and Jackass Canyon. I've been told the whole thing is rideable without even putting a foot down- probably true, but all I have to say is that I'd like to see it. The singletrack has some of everything - steep spots, tight passes between boulders, ledges, gravel, exposure, and a couple big step-ups that, unless you're a trials rider, you'll be carrying your bike up. Overall, a beautiful, challenging, and fun trail. You'll want a full suspension bike for this one - probably a downhill bike if you want to do all the biggest drops. Don't forget a good tool kit - your bike and body will be rattled beyond belief - and lots of water and food.