I think I could handle walking, but no way on god's green earth would I be on that trail on any bike! I've back-packed one of the "lesser used" trails in the Grand Canyon and had similar drops - the thick red wall band you see in most canyon photos happens to be 500 ft. The gal I was leading was pooped and wanted to stop on the trail to sleep, I got her to hike back about 1/4 mile to a safer (wider) space when it finally sunk into her thick head that if she rolled over she'd be dead.