Quicksilver involves climbing
I'll 2nd Quicksilver. Go to the Hacienda entrance and follow the fire road clockwise. (See the map at the trail head) All fire road and great views of the valley and surrounding hills. I'll be a bit careful on the decent as you can get going pretty fast... My favorite fire road workout in the whole south bay area.
I love Quicksilver for the views and wild life. The dirt roads there are shady and cool as well. But I'm not sure it's right for a new beginner, as there is some 3 miles long of constant moderate climbing of 1200' involved if you go all the way to the peak. But there are some smaller options involved (see below)
Here's specs from my GPS (follow with PDF map from the official park page
). [EDIT: Fixed Link]
From Hacienda Entrance to the picnic table at the Cape Horn intersection on Mine Hill:
1.2 miles, 510' of climb.
From Cape Horn to English Town, continuing on Mine Hill on the first left:
0.8 miles, 320' of climb
From English Town to Bull Run via the shady back trail by turning right at the English Camp intersection;
0.9 miles, 240' of climb.
If at Bull Run you turn left and come back to English Camp via Castillerro in the other direction, you do a short loop around all the tourist spots. Overall you'll do around 6 miles and 1200' of climbing. From my house, I do a longer loop down to Guadalupe Dam on the back trails of Randol and it's 16 miles, 2000' of climb from my house.
One other option is after climbing the first mandatory 500' to Cape Horn, take the second from the left road to Randol trail, that's fairly level with a lot of shady up and down mild climbs of 10's of feet and some nice views. I've seen some beginners go a mile or two on Randol until they're tired and come back and take the fast free ride back to Hacienda. It's only got one mine to see, most are up on the other route I mentioned. But that could be incentive for another trip when in better shape.
There's lots of tourist places like old ghost towns and old mine camps to see as incentive, if you want to take your time. But again, I wouldn't do that for a beginner as there's a lot of climbing for the miles. Nevertheless a good beginning/intermediate ride once she's more in shape.
Other ideas in the South Bay:
Yet another option is Wood Trail at the top of Hicks Rd in Sierra Azul. It's fairly level with about 400-500' of climbing over 3 or 4 miles, with super views. In winter there's lots of little waterfalls on the shady road. Hicks turns off of Camden near Meridian, and you drive all the way to the top. There's two parking lots - a small one with bathroom for Woods Trail in Sierra Azul, and a bigger one on the other side of Hicks for the back entrance to Quicksilver that's legal. It might even be an easier way to get to the ghost towns at the top of Bull Run with better views. You may have less than 700' of climbing overall with a loop from that direction. And if you follow Mt. Umunhum Rd to the top, there's a little 0.8mile flat trail to Bald Mt. with great veiws.
Slow Rider Organizations
Finally, look at the mere mortals organization
. They do lots of easier rides to get people in to MTB. They have a lot of fun easy slow rides and a no-drop policy. Contact the leader before you ride, so you can get advice and they know to expect you.