yes, old san pedro road is rideable on a road bike. it's paved going up from pacifica, then a bit of singletrack 'til it meets the service road, then a gravel service road. there's a fork where you can talk the old paved road down (bumpy), or the service road (straight shot, steep--i've not taken it).
you can actually stay off of highway 1 everywhere north of the ritz carlton. might be a bit tricky to figure out, but at least know that the bike path starts at the light just after sam's chowder house and is a good choice w/o much complication.
A good route to old san pedro:
* In Daly City, get to Skyline Dr (just west of 35). It'll climb then drop down fast the the coast. Turn left. Follow the roads west of 1 'til you're forced onto (a bike path next to) 1 just past sharp park. take the first right, follow the bike path 'til you get to rockaway beach, stay ocean-side of the highway to find the bike path. stay on the path to the taco bell, stay ocean side (yes) a bit further just past the fresh and easy. Turn left onto the service road, across highway 1, onto the bike path on the far side. At the T intersection, turn right. Keep going straight on the 'driveway' and through the fence and you'll end up on Higgins, keep going straight. Once you get to the top it's obvious but it is also signed.
92 has got to be nasty, esp. from the bottom of the giant switchback on the ocean side to the ocean--no shoulder, flat, high traffic.
Oh another alternate if the weather is foggy on the coast: stay inland. (skyline/bike path/canada/portola/alpine/skyline/9 is a nice route though much longer and hillier than the coastal one.)