Kryptonite's Transit FlexFrame U-Bracket makes it easy to carry your U-lock on your bike so it's always handy. This simple mount fits on frame tubes from 25 to 80mm in diameter and it accepts most 13 and 16mm-diameter round-shackle U-locks. Plus, the clamp rotates so you can perfectly align the lock with your bike to keep it tucked out of the way.
I found that the installation instructions are ridiculously difficult to understand, the wording is poor and the pictures totally insufficient. When one spends this much money in the lock + frame, one generally expects either an easier way to mount it or at least good instructions.
Bottom LineNo, I would not recommend this to a friend