We have been hiring Motorbikes on many Greek islands over the years but one thing is a must-------
NEVER just jump on one and ride away, there are many checks which YOU should carry out such as, brakes, suspension, tyres,lights,steering. etc etc
Always wear your helmet ( despite many locals not doing so ) and have comprehensive insurance.
Example, on one occasion doing the checks while the bike was on it's centre stand i noticed the bearings in the rear wheel had gone.
Fortunately, we have never had any mishaps and discovered many OFF the beaten track places to visit and beaches ALL to yourself.
Tip, when riding keep checking your rear view mirror, watch out for potholes, appropriate speed and observation for the conditions and regard every other driver as an idiot, you'll be ok !!