A replacement Bayonet fork and stem kit is like $900. I that they keep the cost of the complete TK1 kit down by using a standard fork.
EDIT:
I was confused by this, too.
The older TK1 came with a Bayonet system:
I don't know when (wasn't paying attention), but one day they switched the colors and started shipping the TK1 with a standard stem. Maybe when the offered it as a complete bike?
Now the TK FRD frame kit is the only one with a Bayonet system (even though I suspect you can buy a Bayonet stem/fork system and put it on the current TK1).
The TK FRD is not to be confused with the $2,6000 USD T
A FRD used by some in the Olympics: