Researcher also has free (speech and beer) schematics for making your own sensor and replicating the experiment.
Have you heard of this concept? Does it ring true for you? Do you live somewhere where cars pass you dangerously?
Wear a helmet or don’t, but either way, society is responsible for making bicycling safer, and encouraging more people to take a bicycle over a car trip. Mandatory helmet laws reduce the number of people cycling, and the safety in numbers factor.
That generally depends on the road width and how easy it is to see oncoming traffic etc. but is definitely a good strategy for certain situations. If a driver gets stuck behind me on a bendy road I will also try to signal them if I see no oncoming traffic around the bend, so they know when to do a safe wide overtake.