This bassline by Matt Freeman of Rancid is actually a lot simpler than it sounds. The hard part is the speed. The intro is fast to begin with, but then the tempo speeds up throughout the song. The trick is to start by practicing it very slowly and then working up to the speed of the record.
The intro figure is based on a mixolydian scale in E, which major scale with a flat 7th. It's not as complicated as it sound, E is the V chord of A, which is the key of the song. If you play an A major starting on the E, you get the mixolodian scale. The best part is the begining of the second measure, where a countapuntal texture is created. The C#s form one melody and the G# to A a second one.
The verse is more of a ska bass riff, and the toughest part is getting the decending figure at the end of the 4 bar figure.
The intro figure is based on a mixolydian scale in E, which major scale with a flat 7th. It's not as complicated as it sound, E is the V chord of A, which is the key of the song. If you play an A major starting on the E, you get the mixolodian scale. The best part is the begining of the second measure, where a countapuntal texture is created. The C#s form one melody and the G# to A a second one.
The verse is more of a ska bass riff, and the toughest part is getting the decending figure at the end of the 4 bar figure.