Anyone here ever use a quill stem on a CF tubed frame before and care to share if it worked out?
The answer, in my mind, depends on what bicycle the post is being installed in. If the tube set is thin gauge tubing, then the answer is a resounding NO.
A wedge offers an incredibly powerful mechanical advantage. I would not want to give-er-a-try, just to see if the tubing bulges. And that bulge, if it did form, might not do so just during installation. The potential for damage (to the tubing) is presented when in use, also. So...
I would not do it and, if those seat posts were of much value, the design would still be in use today. Perhaps my reasoning is flawed, but I don't see many high end bikes (then or now), be they steel, aluminum or carbon fiber, fitted with an expander inside their tubes.