We were about 5 miles south of Mt Judea on 123. There are some wicked curves on that road, but the one he went down on wasn't really that bad. He was bringing up the rear, so nobody saw him go down. He couldn't remember what happened, but it looked like he just got too close to the rocks and slid off. His bike is lowered and stretched, so that may have had an effect, but we had ridden much tighter curves than that one, that he did just fine on.
I tried to call him today, but he was resting. I'm going to try again later.