Believe it or not, Fenix's own bike mount the Fenix Bike Flashlight Mount AF02 will work with almost any Fenix light.
However, there is a modification you must do.
First you will be using it upside down. The hinging side of the mount will attach to the handlebars, not the other way around which is what Fenix says.
Second, you need to go to Lowes and get two bolts that are longer and thread through the stock mount.
Third, you will have to get a small bolt and lockwasher to replace where Fenix's mount hinges. Stock, the top and bottom are very loose. With a lock washer and small bolt, I made them extremely tight and hard to turn. But I situated the mount to the angle I wanted before I tightened the bolt.
I could fit my TK40, TK45, and TK35 extremely snugly on my bike afterwards without movement or shudder going over bumps.
EDIT: BTW I found the TK35 to be the perfect bike light. It has the best balance between throw, flood, and form factor. And when biking through the wind, the flashlight does not get as hot on turbo as when it's just sitting in one place on turbo.