The advantages of the BMW telelever fork are experienced during compression. In comparison to a conventional telescopic fork: 1. Wheelbase remains relatively constant- telescopic forks decrease wheelbase. 2. Trail increases at nearly the same rate that it decreases with telescopic forks. 3. Castor angle increases at nearly the same rate that it decreases with telescopic forks.
All three of these characteristics improve handling under deceleration and braking. In order to achieve the needed geometry, the end of the fork tube needs to articulate in the top triple clamp. This is done with a rubber bushing in the top triple tree that permits some angular movement. The problem is that the piece in the end of the tube that goes in the rubber bushing is not pressed tight enough into the fork tube. My guess is that only forks that get hard use and bottoming from riding on unpaved roads, dirt and rocks are actually at risk, but the way these recalls go they have to fix every one regardless.
Here is a youtube video posted by someone who experienced the failure: [youtube]_mXkdr4ZBAs[/youtube]
This is a video of the fix:
https://www.youtube.com/watch?v=TaGaR9Fn4WE#t=125.095853 Norm Kern
