Not buying the zerk fitting idea, at all... that would take a lot of grease and application is extremely indirect. Filling the headtube with grease? Really?
Originally Posted by
rootboy
Actually, though some do look like grease zerks, I believe they were meant for oil. At first I thought they squeezed the head tubes full of grease, but read differently several years ago, somewhere. It may have old ties to racing as you mostly see these on vintage 40's to 60's racing bikes, I think. Old grease may not have had the properties we're used to today, so they had to "doctor " it occasionally to keep it working.
That's my theory anyway. Probably misguided BS.
Grease hasn't changed that much in the last 50 years. Even if you go to an extreme, before lithium grease was common, what they used wouldn't be all that different from what is being used for general lubrication today. Grease has gotten better for high temps, extremely high loads, longevity, and wider spectrum of use... but the fundamental properties for a non-disc wheel bearing type of grease hasn't changed much.