This is the place where the UCI World Cup has been held for the last three years. It won't be held there again in the near future. Politics of some sort. For the most part this trail is a mixture of single and doubletracks. It is best done heading up the hill from the parking lot on the jeep road to the 'crossover.' From here you can continue up the hill to Lake Marie. If you have a couple of sandwiches, fig bars, and drinks this is THE place to enjoy it. You might even run into a few people trying their hands at fishing in the lake. I can't say if that is good, bad or indifferent, but from the look of the lake, I don't know if the fish are served on the tables in the Napa Valley. If this sidetrip is of no interest, you can continue around the lake on a nice singletrack that will take you to the top of the ridge. This offers a nice view of the northern San Francisco bay area. If more climbing is NOT what you want, from the 'crossover, you can head back down the hill via a fun singletrack. This weaves in and out of the manzanita. Some sections can be extremely technical, and getting off and walking is encouraged if you are so inclined. This part of the park is a blast! It requires skill, a bit of finesse, a sense of adventure (manzanita groves do that to you) and a helping of guts. As you climb a little hill through the remains of an old mining shack, be prepared for a fun, switchbacked descent towards the park entrance. Be careful since the last time I rode the trail, a rather extreme section of boulders just after the crest of this hill. It was quite a surprise and caused me to get off and walk. When you come to the bootom of this hill you will proceed across a stream twice and next to a frisbee golf course. The trail rolls over a liitle hill and you are back at the park entrance. Skyline Park is a trial that is great for all kinds of rides. I would recommend it for a nice leisurely ride in the spring. It is BEAUTIFUL. Take a picnic lunch and just ride, stop, ride, stop, etc. until you are tired. It is well worth the trip. If you are feeling more in the training mood, I would suggest doing the loop above as many times as possible. You will get a workout!!