I came upon the scene in my car within a minute of the accident. 2 witnesses were at the scene - a male witness comforting the rider and a female witness on her phone to 911. The rider was motionless and unresponsive. I could hear the bike was still running, about 50' from the rider, so I ran over and turned the bike off.
The rider missed the turn (off ramp south of the the tunnel that goes to 1st Ave) and from the damage to the bike, looks like the bike hit the barrier very hard rear-first - rear wheel missing a couple of chunks and rear tire mangled, and the front of the bike looks OK except for some scrapes.
The rider was about 75' from the point of impact with the concrete barrier, and the bike another 50 ' down the road. I left when the fire department arrived - ambulance was nearly there.
Rider looked to be seriously injured, barely communicating and not moving - I hope he is OK. He was wearing a leather jacket and armoured pants. Fortunately, both witnesses stopped to help - this is not a case where people saw a rider hurt and kept on going.
I didn't see what happened, but I can repeat what the 2 witnesses said (and will say to police). The male witness said he was sliding off the bike & getting his knee near the ground "racer style" and the female witness said "you could not believe how fast he was going when he passed her" leading to the corner. I cannot pass judgement because I have done the same thing too often at that same corner,
I have picked up a lot of fallen riders at the track - it sure is different to see it on a public road.
Be careful out there, and I hope the rider is OK.