ColaJacket

But, unfortunately, in some locations, it is necessary.

There's a reason why a lot of the crazy traffic videos come from Russia. That's because people have learned that the police and others may try to do thing to either harass or extort you. But if you have a dashboard cam, that harassment and extortion goes down dramatically.

Think of it as pretty much the same for bicyclists. Some drivers will harass cyclists (e.g. throw things, roll coal, threaten you), but if you have a helmet cam, then they are less likely to do so, and more likely to pay for it if they do.

And as others have mentioned, if you're in an accident, it is not your word against theirs.

GH