Originally Posted by gruppo

Unscrew the clamp bolt, insert a penny in the slot, and carefully tighten the bolt against the penny. This will increase the diameter and simplify the installation. Also, lightly filing the inside edge of the stem clamp (Which won't show) will also help to minimize scratching. As has been mentioned, there are a couple different bar/clamp sizes (25.8 & 26.0), but using the penny tech tip and smoothing the clamp has allowed me to complete any road/track bar - quill stem combination without scratching.