The headset uses a 1" upper bearing and 1 3/8" lower bearing (S202500004).

Shiv TT features a new one piece base bar and stem which helps improve front end stiffness and handling, S200800008.  The replacement basebar includes the stem mounting hardware, which is also available separately. 

A cover for the stem area helps route brake hoses and Di2 wires while improving aerodynamics, S200800008.

Many options are available for extension tower stack spacers, including two sets of angled spacers. They are available in a kit, S209900031.  Tower hardware is also available for replacement in a kit, S209900028.

Refer to pg. 12 of the user manual to determine the proper combination of stack spacer and bolt.

New extension sockets mount to the tower stack spacers, S209900029.  The extension sockets have a 22.25mm inner diameter, making them compatible with many aftermarket extensions.

New arm cups mount to the extension sockets, S209900026. Arm cups are mountable in several positions fore/aft and left/right.  

Replacement pads for the arm rest cups are also available, S209900027.