After the 1 km warm up run a 30 km long bike ride is ahead of the triathletes. This bike ride is considered hilly and will test the athletes climbing and handling skills as you go both up and down. For those who are not fluent in gibberish, (read the imperial system) the highest point on the course is at 100 meters, on the second climb if you look at the map on the right. The same spot will also be reached on the way back to the Marina.
For me the best thing about this races is that it goes close to the iconic landmark bridge "The Golden Gate." It's something that many of us have seen in the 90s in the intro of Full House and that usually everybody knows about. even though the bike course looks cool I would have liked it to be situated even closer to the San Francisco city center, but I guess that would be very hard to do.
The course goes westward, past the Golden Gate bridge, and towards the Golden Gate Park. Once the participants get there, they will turn around and bike approximately the same route back towards the marina. This means that the road will be shared with cyclists going both ways. Caution is therefore important, and crossing the yellow line can be seen as valid reason for disqualification.
This is also a non-draft race, where illegal drafting can lead to disqualification. This shouldn't be as relevant in the uphills, but in the downhills and on the flats there are huge advantages to be made by getting close to the person ahead. There are officials all around the course to check if people break the rules. On the different YouTube films I have seen so far there are many places where the road is too narrow and there is no other way than to bike in traffic.
The bike course closes two hours after the swim closure time (three hours after the start), which should be plenty of time to bike the 30 km. If somebody is too slow they will be picked up by the sweep car driving at the back.