There are a few roads from the South Bay to San Francisco. US101 (Bayshore Freeway) runs flat and straight, and is the one that most trucks take. I-280 (Junipero Serra Freeway) is the more scenic freeway. Neither is for bikes. CA82 (El Camino Real) was used centuries ago by the Spanish missionaries, and is now a stroad. CA35 (Skyline Blvd) is the backroads route along the hills of the peninsula. Guess which ride was on my bucket list? The bulk of the climbing work is in reaching Skyline Blvd — I did it by taking CA9. Fortunately, that part is shady, and I did it early in the morning. The long descent to Crystal Springs Reservoir is truly exhilarating. That segment joins CA92, though, which gets more traffic. There is no shoulder, so you're taking the full lane along with the cars — and roughly at the same speed as them. Going north past CA92, it becomes less of a pure workout and more a test of skills. There's the weather, which goes from full sun to chilly ocean mist. There are many more cars — in fact CA35 joins I-280 briefly and also becomes a freeway for a short section. Then, when you get to the Great Highway in San Francisco, there are a few treacherous sandy patches, which you must hit with your wheels straight and with enough momentum to coast through. If I hadn't planned on going to San Francisco and taking the Caltrain back, I'd pick a route that avoids everything north of CA92. (This ride is part of a multi-day trip: https://ridewithgps.com/journal/8752)