You've got mirrors on a motorbike though, right? On a bike, unless you're an SPD sandal-wearing tourer with bar-end mirrors etc, you're relying on shoulder-checks to see what's going on.
Edit: Also, on a motorbike you're less likely to have faster traffic speeding past you with a gap of a few centimetres.
Of course, but in cars and on motorbikes you've also got mirrors, so your situational awareness is better than on a bike, where the only way to check behind you is a shoulder check.
You've got mirrors on a motorbike though, right? On a bike, unless you're an SPD sandal-wearing tourer with bar-end mirrors etc, you're relying on shoulder-checks to see what's going on.
Edit: Also, on a motorbike you're less likely to have faster traffic speeding past you with a gap of a few centimetres.