Earphones / Headphones: Where to try, what to buy?

Because the speed difference between car and cyclist, is far greater than car and car.

Smart guy^

you have to be far more alert cycling, so many careless wankers on the road.

This too^

Theoretically we'd all be aware of all other road users around us. The reality is cyclists go unnoticed. We need to be extra vigilant to compensate.