Originally Posted by
bigvegan
It's a pretty silly move when you can buy a new threaded fork online for less than $100, and keep your threadless fork as a backup.
Or stay threadless, keeping your fork & headset.
Mind you, I'm generally opposed to the BF tradition of answering every "How do I...?" with "Why would you want to...?" as I myself like to do all sorts of things to bikes without any need (or even ability) to justify them to others. But, just out of curiosity... Why would you want to?