Me thinks Brakes and maneuver instead of Horn would be a better option here

[1olbull]

I think you're high on perception/response time. Whenever one is on a motorcycle he/she is (or should be) in a state of heightened awareness, especially for transitory hazards. In such a state, average adult (non-impaired) response time from perception to application of brakes could be as short as .75 seconds, or less than 1/2 of what you're quoting. (I, myself, have been professionally tested at .61). I am aware of human factors experts ringing in, as you do, at 1.5 seconds or longer, but they are, ordinarily, considering situations where a heightened state of awareness is not present, or distractions (passenger conversations, radios, cell phones and the like) are present. Plus, if we assume that the brakes on his sport bike are high powered (and possibly, ABS), then we might also shave a few feet off of the stopping distance. (I understand that neither of us is controlling for coefficient of friction of the roadway surface, since, in this problem, that is an unknown. Likewise, we cannot control for the condition of the rider as impaired or unimpaired, nor can we control for the rider's level of skill - especially braking skill.)

Indeed, I could be totally off in my estimate of his initial distance, it might have been as little as 60 feet or as much as 150 feet. Without knowing more about the camera focal length and lens angle of view - these are variable also.

All things considered, your estimate, given what we know here, is just as likely as my own and neither could be conclusively eliminated. That's what makes this kind of thing so much fun.

@ksquared
Sorry for the tardy response - been very busy.
I am NOT "ringing in" anything. Many factors affect perception response time. My opinion is based on the actual response times of un-alerted drivers/riders in circumstances similar to the collision at hand.

Considerable human factors testing in a number of scientific studies have shown response time for motorcyclists in emergency situations to be pretty much the same as those of cage drivers. What is gained by the rider's closer proximity to the brake controls is given back with the more complex application of the two levers for two separate brakes (if even used). Furthermore, all but the professional and highly skilled riders (like 5%) only develop friction values of .55g to .65g as opposed to the .75g average of cages. Also do not discount brake lag time, usually in the .250 millisecond range.
Best Regards,
1olbull