I was in Sidari 2 years ago and there was a bicycle hire shop on the main road through the resort (just past the petrol station opposite Billys Bar) that also rented out fans. I can't remember the exact price but I remember it being cheap. I don't know the apartments you mentioned so I don't know if this shop would be close or not. If you're at the Canal D'Amour end of the resort it will be no good but I'm sure they'll be other places aswell.

Steve