Originally Posted by
avzay66
I just dissolved a stuck stem with drain-out (some drano clone that sells for $3 in walmart).
It may work on this bike because the fork looks steel. Basically I cut off the stem with the hacksaw, sanded the inside to increase the surface area of the aluminium, and stuck the steerer tube with the remains of the stem into a gallon milk container with water. Then I proceeded to dump the whole can of drain-out into the gallon container and set it outside overnight. After a crazy reaction the stem was completely dissolved in about 6 hours. This method is probably dangerous (sodium hydroxide is very toxic and caustic), but in my hands it worked great. This is probably a last resort method.
As for cannondale - for commuters I prefer bikes with fender/rack mounts on the dropouts, which road bike cannondales rarely have.
Using this process, the OP could see his headtube dissolve with draino or any ammonia based product.