A bicycle telescopic apparatus includes a first tube having a receiving space, a second tube telescopically received in the receiving space of the first tube, a position detector configured to detect a relative position between the first tube and the second tube in a longitudinal direction of the bicycle telescopic apparatus, and an output device configured to output a signal based on a detected result of the position detector. The signal can control a bicycle component other than the bicycle telescopic apparatus. A detecting point of the position detector is located in the receiving space of the first tube.