FWIW, the Stanford Cycling page has brief descriptions of lots of route and climbs in the bay area, esp the peninsula. This is what they have to say about Pierce:
Originally Posted by Bostic
Pierce Rd. (0.7 miles, 280 ft, 7.9%)
This climb starts at the intersection with Mt. Eden Rd and ends by the Mountain Winery gates, a good spot for nature break and refueling. The bottom of the climb is well paved but steep at around 10%. After a minute of climbing, one is welcomed by a respite of flatter section of 5-6% grade. Following the pair of sharp hairpins the road steepens to ~8% but the end is nigh!
I can't vouch for its accuracy though ...