[carlhu]

The video ends with a brief second where the cyclist explains what prevented even higher speed. I make out: "too much vibration...", "knees rubbing...", "unable to continue increasing power output". Would love to hear more about this.

[QuotedForTruth]

Note the video was from last year when they failed to set the record. This year they've done it. They probably will release a video of this year's efforts eventually.

[bjourne]

I believe it is because the vehicle is very aerodynamically unstable. When you ride a normal upright bike, it will fall over unless you actively spend a little effort balancing it. Here is a video of a crash: https://www.youtube.com/watch?v=i5Dapy1xUq0 Note how it wobbles to the right when he pushes the right pedal, then to the left when the left pedal is pushed.

[trevorcreech]

Here's the current video of them actually beating the record: https://www.youtube.com/watch?v=33clAZoaLWs