Easily the biker's fault. Although if he's like a ton of bikers he will blame cars 100% of the time because a biker is always right in their mind. I think the law tends to favor the car in front even if they do stop suddenly, because the guy behind could have been paying attention and following less closely.

I had some idiots cross in front of me a few days ago, they decide to sprint across a high speed intersection a few seconds after it turned green in the middle of the night when you can barely see them. Good thing there wasn't a biker behind me, because I had to stop much faster than that red car.

Blame policymakers for stupid people, hahaha. I bet I know how that guy votes.