Originally Posted by
Steel Charlie
Motorcycles don't use a quill stem.
Threadless bicycle headset adjustment is secured by the top cap bolt AND the stem clamping on the steerer.
Bicycles and motorcycles front end assemblies of any kind have practically nothing in common. And motorcycles switched to tapered bearings a few decades ago.
Motorcycles have a welded nut on top of the triple clamp to hold down the top triple clamp. I guess they used that threadless friction fit top bolt method to the limit but welding that tension fit nut in place.