last weekend, we biked from san geronimo to the point reyes lighthouse and back (here's the route on google maps). this must be one of the most beautiful rides in the bay area, the diversity of the scenery is really fascinating (mount hamilton is longer and also very pretty, but you don't get all the coastal scenery). the ride was 110km (68 miles), starting from the intersection of sir francis drake boulevard and nicasio valley road. the ride is reasonably flat, but there are many rolling hills, in particular once you get to point reyes. riding time was 3:40, your time may vary, but you can assume to be as fast as for other rides in the bay area. water is available in nicasio, in point reyes station, in inverness, and at the lighthouse.
starting from sir francis drake boulevard, you first make your way up a small hill and then through some forest to nicasio. from here it's rolling hills and open landscape (everything in california golden shades, i.e. it's sun-burned dry grassland) next to some lakes, among them nicasio reservoir. then a short descent and towards point reyes station, a small town with many highway 1 travelers and bikers showing off their hardware. then it's a couple of flat miles towards tomales bay, a bit alongside the bay, and then up a pretty steep (but short) hill towards the lighthouse.
from the top of the hill, it's a long gradual downhill and the vegetation changes a couple of times, from forest to bushland and then grassy openings, but its always green out here because of all the fog. from here on it's a constant up and down, but thankfully the road has been recently repaved (only to the turnoff to drake's beach, though). you pass several historic farms, which make you think how it must have been out there before motorized vehicles came along. for some reason, the roads at these historic farms are also in historic condition, but in most cases it's only a short stretch of bad road.
the last hill is by far the steepest (including a dinosaur-proof cattleguard), but not too long. this part of the road is really rough, the last farm and the final climb are not very pleasant, but the scenery makes up for it. after the final climb you ride along the ridge with the ocean to your left and right. you cannot really ride all the way to the lighthouse, because that's a really long staircase, but you'll be able to ride past the parking lot to the
visitor center, which is just a small shack. the lighthouse is on the eastern tip of the hammer-shaped peninsula, there also is a road to the western tip, but i did not try it. very likely more beautiful views over there, give it a try...