Here is a video that Wired released a few days ago that discusses the details of the tow hook and the little bar: https://youtu.be/cZhrqKrljig

it's probably not just a bar, but a roller that spins.

Looks to me like a lever hooked to the brake lines, so if she hits the bar the wheels brake. That's how I would hook it up anyway :)

Dunno what they did to the brakes vs standard bicycle brakes, but I'd be very worried about activating them automatically at ~170mph. With those speeds and the winds, it wouldn't take much to set you tumbling across the ground. I would expect they only brake very carefully and gently until they get the speeds back down some.

At those speeds, even maximum braking is gentle - the blocks near instantly heat up and lose material. There's a reason why car and motorcycle use heavily cooled and much stiffer as well as more abrasive materials for brakes.

You have to be really careful to engage both front and back brakes at the same time though.