Sarah Hammer has been a Felt athlete for some years now. The TK1 has only been changed minimally since the 2008 Olympics when I worked on them. The Bayonet 2 system is still used despite a change to the DA model allowing for lower handlebars. The only update noticeable is the seatpost/seat mast configuration that seems like a great step in the direction of increased adjustability while maintaining packability (in a conventional bike case).
Track athletes typically use the same bike for both pursuit and mass start events and Hammer is no exception. She (or her mechanic) simply change the entire knuckle (stem and bar assembly) on her TK1. Casey Gibson shot her bike while ready for the pursuit portion of the women’s omnium where Hammer finished second overall.