Wolf Tooth 107 BCD Chainring - 40t Compatible SRAM 107 BCD Drop-Stop B 4-Bolt BLKWolf Tooth 107 BCD Chainring 40t Compatible with SRAM 107 BCD Drop Stop B 4 Bolt Black. The Wolf Tooth 107 BCD Chainring for SRAM cranks is compatible with most new SRAM 1x road cranks that use the 107 BCD spider including the SRAM AXS Power Meter Spider. This chainring uses the patented Wolf Tooth Drop Stop B Wide Narrow tooth profile that is optimized for drop bar bikes and designed best wear life mud clearance and chain retention. Drop Stop