This sunny afternoon I rode the whole length of Santiago Canyon Road in the eastbound direction. My observations:
1. I must respectfully disagree with
2seven0 (see, e.g., post #1373); the pavement (at least in the bike lane) is not pristine. Many lengthy patches of sand and loose gravel on the surface (from gravel truck spills?), and one spot (over a culvert) where the top two layers of the pavement is missing from almost the entire width of the bike lane, exposing the sharp-looking medium size black rocks beneath. Thankfully I did not get a flat after riding over that spot.
2. The route has much more climbing than I had expected. I really wished for a 12-28 cassette (instead of my usual 12-25 cassette). I need to get much fitter before I ride Santiago Canyon Road again.
3. I saw a white ghost bike (near Loma Ridge Road) which made me sad and slightly worried for the remainder of the ride.
4. Also unexpected were the long, white-knuckled descents at each end: (a) from about Loma Ridge Road down to Irvine Lake, and (b) from about Gertner Estate Road down to Cook's Corner. Since I was worried about gravelly patches I had to scrub some speed.
On my way home I rode Glenn Ranch Road from El Toro Road to Portola Parkway (past Oakley HQ) to fit one last climb into my route. Turned out to be a really bumpy ride (especially the descent from Saddleback Ranch Road to Portola Parkway) because of the top layer of the road is missing due to road work.