This guide will refer to the sides of the hub as Drive Side and Rotor Side - see below for the pictures of each
This service can be performed with the hub still in the wheel or taken out from the wheel.
Remove the chain. Take the wheel off of the bike. Remove the brake rotor.
Remove both of the nuts from the rotor side of the hub.
Loosen the cone that was under the nuts you just removed. You need to loosen this by 3 or 4 threads/full rotations.
Use the Hub Wrench on the drive side of the hub to loosen the core from the main assembly. The inserts on the wrench will fit into these holes on the hub - see the picture below.
To loosen the core of the hub from the main assembly unscrew in a counterclockwise direction with the hub wrench.
Tip: If you are having difficulty use a vice to hold the hub steady in place. Wrap something around the hub before clamping it in the vice to make sure it doesn't get damaged!
With the inner core loosened fully remove the cone of the rotor side of the hub.
Finish unscrewing the core - rotate counterclockwise until the core can be separated from the hub.
Replace the old core with a new core making sure to screw the new core in facing the correct direction.
Torque the new core in a bit with the Hub Wrench when it is fully hand tightened. Don't tighten it too much.
Reinstall the cone on the rotor side ensuring it is oriented correctly - see the picture below. Make sure it is tight but not TOO tight - if this is too tight it will interfere with the shifting of the bike.
Reattach the nuts on the rotor side - it doesn't matter which one you put on the inside or outside.
Reinstall any other attached hardware to the hub/wheel such as brake rotors or chainring. Reinstall the wheel onto the bike and put the chain back on.
If you are still having trouble, please submit a support ticket using the same email you placed your under. Please note in the ticket your Biktrix order number, the trouble you are experiencing and include photos of the issue.