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Comment by jl2718 | Hacker News Reader

This is insanely dangerous. One whiff of the slipstream and you are dead.

As for physical difficulty, the bike setup she uses takes about 1.5 watts per mph of rolling/gearing resistance, although the back end of the slipstream gives some forward pressure. The drag vehicle is likely the limiting factor.

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Is it that dangerous? I thought motorcyclists wearing protective gear were safe if they fell slid to a stop. The danger would be from crashing into other things, but most of this place looks flat?

If she fell out of the slip stream, she wouldn't have fallen over. She would have been thrown off the bike by hitting the 175+mph wind. It would be like walking out of your house into a Category 5 hurricane. She could have been tossed and likely died.

plenty of motorcycles doing 300 mph at Bonneville (there's even a Triumph mc named after the place). Her posture isn't ideal I agree compared to drag and speed trials bikes https://youtu.be/3Cq-DfTTPFw

These motorcycle drivers are continuously exposed to wind pressure though, in her case she would be suddenly exposed to it which probably would be not unlike hitting a wall.

In addition, her bicycle is not aerodynamic and likely weighs between 20-30 lbs, whereas a race a race motorcycle is very aerodynamic and might weigh between 400-500 lbs.

I'm sure the rolling weight of the wheels would dramatically impact stability as well.

Yeah, that's what I was thinking. A few times she wobbled and I thought how terrifying it must be.

I wonder if the slipstream would tend to keep her inside it - I mean, would she in some way be repelled back into the slipstream if she strayed towards the edges? Or is that wishful thinking?

I think it is unlikely. Firstly, in drifting into the slipstream, she would experience a powerful torque, twisting her away from the center-line (and maybe creating gyroscopic precession of the wheels around the bike's longitudinal axis). Secondly, the slipstream will be very turbulent. Thirdly, the speed is well above a human body's terminal velocity of around 120mph, so the slipstream is powerful enough to pick her up and throw her to the ground, especially given that drag goes by the square of velocity.

Yes, I think you're right about the turbulence. It's not like it would have a smooth edge.

Many people jump out of planes in 200+ km/hr of wind without getting snapped into pieces. Perhaps it's comparable to that.

If the aerodynamics of the bike-rider system are stable at 200 mph, it could be okay, but only as long as they didn't fall over.

Is that wind directly in the opposite direction? If so I'd expect them to be blown immediately back into the plane.

Apples and oranges.

Actually I've done this. You have to push your body out past the boundary layer before you jump outward. A lot of people do get blown back in, but I've also seen the diagonal running dive work at fairly high speeds.

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