1) There are no easy routes via the dirt to the summit - well, almost to the summit
2) Sunscreen works (you find this out when you don't wear it)
3) Regardless of how nice you are, some hikers will always dislike you because you're on a bike
3a) See #3 above but insert "equestrians" in place of "hikers"
4) Hikers and cyclists can get along, really (I had several nice conversations with hikers)
5) There are some steep a$$ trails on Mt. Diablo (Burma, Mother's)
6) Most of the wildflowers are gone at this point
7) Water is still running very cold though down in the lower creeks
8) It could be 50 degrees out but the trail up Wall Pt. will always be hot and you'll be baking in the sun
8a) Same with wind - it could be blowing 30mph but you won't feel any wind on Wall Pt.
9) Carry either a rattlesnake kit or cell phone with you (didn't need either, but man the conditions were ripe)
10) Mt. Diablo is a true jewel that most take for granted