Originally Posted by the beef
The threaded headset required constant adjustment. After a crash in the middle of a ride it was knocked loose, and not knowing enough or having the proper tools to tighten it correctly I was forced to ride it loose to get back home. The threading got damaged, and pretty soon the headset was coming loose pretty much on a weekly basis, even after taking it down to the shop to get it tightened multiple times. My headset and quill stem also creaked - a lot. Every hard stroke up a hill would give me a very confidence-inspiring squeak or groan from the whole setup, even with all the bolts tightened down.
IThreaded
-Comes loose, requires constant adjustment
-Requires a flat 32 mm wrench to properly maintain/tighten
-Creaky (for me at least)
-Lack of stiffness
-Always a little bit of play between fork and steerer, even when tightened down
-Admittedly, looks very beautiful when done right
-Adjustable
Threadless
-Non-adjustable
-Lack of 'classic look'
-Much stiffer, tighter
-Adjustment requires minimal tools
Been riding for 50 (oops 51) years and have yet to have the "...comes loose..." problem on a good quality Threaded headset. Using Campy, Stronglight, or Tange (campy copy) only. Creaking stem is easily fixed with the application of a small strip of aluminum shim made from a RED BULL can. Won't even see it...Sorry old school thinking.
I have a number of bikes threadless as well as my older steel threaded ones. Still ride about 5K miles per year distributed between all my bikes, so none of my bikes are what one would deem as "wall art."
Good luck