For some time now we planned stems for Cannondale Lefty and Headshock forks. Until recently those forks were built using a steerer tube stem size of 1.5625″.
Cannondale is now building bikes with standard (two fork legs) 1.5″ forks, and we make 1.5″ stems and plan more sizes as well.
Cannondale also ships some new Lefty equipped bikes with their one piece steerer tube/stem assembly, named OPI. We do not make a stem that will fit an OPI equipped bike.
Cannondale also makes a Lefty Supermax with a tapered steerer tube. This steerer tube fits the 1.5625″ bearing, but tapers to 1.5″ to allow the use of standard 1.5″ stems.
Since the previous standard for the stem clamping area of teh steerer tube is no longer being used we will not make a stem for the older 1.5625 Cannondale Lefty/Headshock steerer tube.
We will continue to make and expand the 1.5″ stem line.