An adjustable pedal system for changing the position of pedals along the crank arms of an exercise bike. The system provides a locking member, such as a rack, located along the crank arm and a locking member, such as one or more gear teeth formed on a slide sleeve to which the pedal is affixed. Thus the slide sleeve and pedal can be slid along the crank arm to the desired position whereupon the locking members intermesh to positively lock the pedal in the desired location. The intermeshing is maintained by a clamping device, such as a thumb screw that is tightened to lock the pedals in the desired location and loosened to disengage the locking members to allow the movement of the pedals to another location. The system can be operated without the need for tools and can be retrofitted to existing exercise bikes.