Dirt climbs are fun, and while I've not ridden up this one (I've hiked it, and I've ridden down part of it), I decided to make a profile for it since it was recommended to me by a friend.
Montara Mountain is often overlooked when cyclists think of large climbs in the Bay area. The reason is that unlike many other large hills, there's no paved roads to the top. However, this was not always the case, and the "Planet of the Apes" route follows what was the inland road ("San Pedro Mountain Road") between Pacifica to the north and Half Moon Bay to the south. This road was replaced by the Devil's Slide portion of Highway 1, and nature quickly asserted control. The "road" is now in many places little more than single-track, it's paved past evident only in broken patches of crumbling asphalt.
This route begins at Grant Ranch, the southern extreme of Planet of the Apes. It then climbs steeply to a "Y", a left the route to Pacifica along San Pedro Mountain Road, the right the route of interest here, to the mountain summit. From there it's fairly straightforward until a dirt path to the left rises sharply to the summit viewpoint.
A Strava segment is here:
The profile shows just how challenging this route is:
My rating formula, which gives a big weight to extended sections a significant multiple of 8% grade (altitude gained at steady 20%, for example, counts 12 times as much as altitude gained at steady 8%), rates it 242 on the "Old La Honda = 100" scale.