Very interesting and educational - particularly as I ride a Felt (though a 2011 model, maybe not the same design, and also I assume she was riding a TT bike?)
Can you clarify the three statements that I've bolded? If her weight on the saddle is reduced and she's moving her weight forward, how is she loading the rear triangle?
Originally Posted by
JohnJ80
I stepped through this slowly trying to get frame by frame. What you see is that she has her weight down in a tuck and the saddle is relatively lightly loaded. As she gets the impulse input, you can watch the seat atop the seat tube start to oscillate and the amplitude increases with each wobble. So this was a resonance issue and not an underdamped situation. That is a serious frame design problem and the fault of the frame. As she makes that carved turn, she has her right knee pointed toward the center of the radius she's circumscribing in her turn. If she could have brought that knee back to the top tube, that *might* have helped her regain control but I suspect it was the rear triangle of the bike that was in resonance. At any rate, as she was carving the turn she was loading up the rear triangle and that's the energy that is provided the oscillation.
Bottom line here, I don't think there is anything she could have done to get this back under control. You can see her stand up a bit from the seat as she hits the thing/dip in the road probably pitching her slightly forward. That unloads the seat more and removes any damping she might have been able to provide. Any change in her side to side body position (knee in, etc...) would have caused her radius to decreased and there would have been insufficient time and space to get it under control. She would have just crashed in a different place. Her efforts to try and correct the steering probably just added delay to the steering which would translate into a phase shift in the frequency domain and probably made it more unstable.
So, I'd hang this one solidly on the frame manufacturer (Felt?) not on Chloe. This also dramatically and sadly puts the lie to the comments made earlier that modern frame designers and their designs have eliminated the problem. They haven't and she's proved that with this crash. Furthermore, it's fair to stipulate that she's among the best bike handlers alive with one of the best maintained state of the art bikes around and it damn near killed her. If I'm not mistaken, she rides on FELT frames. They have a little engineering soul searching to do. This turn was not something that was out of reach for speed or terrain by recreational amateur enthusiasts and I'm sure it's a stock frame of their best build.