100% of my solo rides are using a single, wired, earbud, in the curbside ear, so I can easily hear a passing cyclist and hold my line, or so I can give a passing car as much space to pass as I can reasonably give, thereby mitigating risk. I have wireless buds too, but don't use them on the bike, because I like knowing if the bud falls out, it's tethered (with the wire under my jersey) and the bud can be easily put back in without me needing to take my eyes off the road.