With a car licence here in Greece you are allowed to drive scooters up to 80 cc, all quads and (new at TopGear) trikes - and of course pushbikes
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Although you may see a different behaviour, helmets are obliged (in all shops included). If the police catches you without, you will be charged a high penalty (I remember something like 400,-€ per person!).
In the meantime there are only two huge bike-rentals left: TopGear and Sunriders:
I don't know it for Sunriders (think it's the same), but the pickup-service at TopGear from and to your hotel is completely free. Even if at least you decide not to rent, they will drive you back without costs.
Both have good mechanics (Giorgios at Sunriders and Prokopis at TopGear).
TopGear is completely independant from travelagencies like TUI, Neckermann etc..
Sunriders had (up to now?) contracts with some of them, what means, that the reps get a percentage (15%?) of the hire-sum.
To be honest this mostly is required by the reps "if you don't pay me, I won't recommend your business or even say bad things about it". This is definitely not fair, because both shops have good bikes and differ mostly by the choice of the models.
My recommendation: Take a look at both and make your decision independantly
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By the way: During the high season from end of July until end of August you better make a reservation at least 2 days before, to get the special model you like.
In more than 20 years coming to Roda and watching this business -I'm sorry to say this- most problems with bikes were caused by the tourists themselves not listening to the bike-introductions or advices:
Driving too fast without helmets,
being drunk,
using bad roads or paths and wondering about a flat tyre,
not following the contract,
being late (so the next customer has to wait)
or using the bikes, like no one would do with his own properties.
Maybe it's surprising, but it's true:
Both do their very best to bring you home safely!!!