Starting from San Jose (you would want to start here), not so good of a ride to Observatory. Watch out the bikecycles, motorcycles will watch out for you . It's 1/3 or 1/4 of the way to the whole route. Probably will take you up to 30min to get there.
Once you past the observatory.... what a ride! For the most part it's a smooth ride. Make sure you take livermore at the split or you'll end up at patterson highway 5.
Just want to remind anyone going all out on this mountain, not to cross the yellow divider or you might hit a biker. Don't want to take someone's life being stupid. Basically to drive over your limit. If your going to drift, drift at night because I guarantee you will hit motorcycle in the day time.