This is the famous ride in San Diego area. I started the ride from the town of Pala in the valley, with the adjacent Indian reservation and a large casino, at elevation of 404 feet. The ride went past orange groves and steadily climbed up. After about 10 miles or so, I turned left to the South Grade Road, which was a steep 7-mile, 7-degree climb with multiple switchbacks. The climb indeed never stopped till the very top was reached at the elevation of 5240 feet. Several bike riders passed me; there were also quite a few of motocyclists, going up and down. The weather was perfect, not too hot, with birds and flowers everywhere; the oak trees provided the shade. I was going the lowest gear at about 6 miles per hour.
At the top I filled up my bottle with a fresh water and went another five miles to Palomar observatory, which was at 5620' elevation, first, going downhill, then, painfully, uphill. I went down the same way I came in, which was about 40 mile roundtrip.