A snap block structure for a pair of mountaineering bicycle shoes each having a bottom formed with two protruding spiked blocks and two threaded locking holes located between the two spiked blocks. The snap block structure includes a snapping member mounted on the bottom of each of the mountaineering bicycle shoes and having a top face integrally formed with a protruding block mounted between the two spiked blocks of each of the mountaineering bicycle shoes. Thus, the mountaineering bicycle shoes are available for a mountaineering bicycle pedal and also available for the road-use bicycle pedal by provision of the snap block structure, thereby enhancing the versatility of the mountaineering bicycle shoes.