Circular taping around the proximal phalanx is frequently used by rock climbers to treat tenosynovitis and to prevent injuries to the A2 pulley. The aim of this study was to determine the biomechanical effectiveness of such taping. Devices were built to measure physiological bowstringing in vivo, and to determine the force of bowstringing as well as the force applied to the pulley tape. Two kinds of taping on 16 fingers were measured during the typical crimp grip position. Taping over the A2 pulley decreased bowstringing by 2.8% and absorbed 11% of the force of bowstringing. Taping over the distal end of the proximal phalanx decreased bowstringing by 22% and absorbed 12% of the total force. Circular taping is minimally effective in relieving force on the A2 pulley. It is probably ineffective in preventing pulley ruptures.