While I agree with you that we shouldn't prematurely absolve anyone of responsibility, the speed limit on that road is 40mph. It's possible that Covey reached this speed or above heading downhill, but very unlikely that she was traveling more than, say, 45mph.
If a driver had turned in front of a car going 45, causing a collision, no one would talk about the speeding car "flying around the corner." It would be a failure to yield to oncoming traffic, period.
AFAIK the yellow signs are "advice" rather than law. I make a point of at least doubling the "advice", visibility and governing speed limit permitting.
Why would you make a point of doubling the advised limit? I can't imagine your stopping ability is actually twice as good as average.
In other words, for no reason other than hubris/machismo, you're choosing to significantly increase your likelihood of wrecking your car (and/or others' vehicles) and possibly killing or maiming yourself (and/or others).
It just takes a bit of black ice, loose gravel, spilled oil, confusing shadows, distractions in the car (like spilled coffee) or outside of the car (like a bird or rock hitting your windshield, or a deer leaping into the side of your car -- to use examples that have happened to me personally), another distracted driver who has veered into your lane, and boom, you're done. They're done. Maybe the 12-year-old riding a bike on the side is done.
Sorry, this is an overreaction to a throwaway comment, but bad drivers who think they're good drivers are friggin' everywhere, and the resultant loss of life and limb is staggering.
The speed limit is exactly that, a limit. From the CA driver's handbook: "California has a "Basic Speed Law." This law means that you may never drive faster than is safe for current conditions. For example, if you are driving 45 mph in a 55 mph speed zone during a dense fog, you could be cited for driving "too fast for conditions."
Limits are based on ideal conditions. This includes the vehicles stopping ability. If a bike is incapable of braking as quickly as a car then the rider should not be travelling at the posted limit.
If a driver had turned in front of a car going 45, causing a collision, no one would talk about the speeding car "flying around the corner." It would be a failure to yield to oncoming traffic, period.