We have an apartment in Calais Beach Fethiye, and visit every year
I have my own bikes out there so don’t need to hire, most of the bike shop only hire/sell very low end bikes
It is very hot in the day but I still ride, just make sure you take loads of bottles of water. There are loads of tracks you can just get out and ride, though no maps are available so you have to use your own sense of direction.
Other activities worth doing
Calais Surf club
Boat trip for snorkelling, beer and BBQ
Oludeniz paragliding
Jeep Safari (ask for one without carpet shop stop off )