Abstract: A pedal stroke adjuster includes a pair of crank frames each of which is mounted on one of the crank arms of a bicycle or exercise machine. A mounting bracket, mounting blocks and spacers are used to align each crank frame in a vertical position when connected to a crank arm. The sides of the crank frame provide guide rails for a pedal mounting block and in one embodiment of the invention one of the guide rails is notched to receive a spring-loaded detent latch that is located in the pedal mounting block. A finger operated release mechanism is provided so that the latch may be removed from the notch and the position of the pedal mounting block changed. In an alternate embodiment, each guide rail is notched. The notches are offset so that the detent latches can be readily contained in the confined space of the block. In another embodiment of the invention, a threaded rod is used to move the pedal mounting block up and down within the crank frame and along the guide rails.