There's more SAG support on Cinderella than any other ride I've done. A few years ago I got a flat during the ride, and as soon as I'd gotten the wheel off a SAG pulled up to do the rest. So, there's plenty of SAG for mechanicals, and to take you back if you can't finish. But... it's not a race, the hills are not difficult, and there are several well-stocked rest stops, including a lunch stop, all making 65 miles very doable.