Originally Posted by
terrymorse
I have never accepted this "compression plug must be long enough to cover entire stem clamp" argument.
The compression plus was not intended to provide mechanical support for a carbon steering tube. It was intended to avoid scratching or gouging the inside of the steering tube.
Then again carbon fiber works best when it can act against something that can handle compression. A tube works, but it's not optimal as the only thing CF has to pull against is the thickness of the tube. Put an incompressible piece of metal inside the tube and tighten it against the carbon and you've got a pretty darn strong piece of tube. The expander can essentially be tightened to pretty ridiculous torques and the steerer won't break as the carbon is working with its strengths. Not so with a stem and outside compression.