The “Setup Key,” in the correct position for your bike, paired with the correct “Setup Cog,” allows chain gap pre-adjustment without the use of a B-Adjust screw in the repair stand (without sag) so that the chain gap will be correct when the bike moves into the sag position while riding. No more phoning a friend for chain gap setup! Please refer to the Eagle Transmission setup information in the AXS App or AXS Web to determine the proper Setup Key position for your specific bike. Additional information from the Eagle AXS Transmission manual is shown below.