Originally Posted by
Prowler
As a good friend used to say "I only had one day of schoolin and that day was singin, so you'll have explain this to me real slow."
Way out here in the woods, I've only seen HS's where the top press-fit in the tube is a cone/race and the bottom is a cup. Bottom cone/race fits onto the fork crown and top cup threads onto the steerer. NO way to reverse them. But are you folks saying there are headsets where both upper and lower cups are press fit into the head tube? So the top cone is threaded onto the steerer. WHY, fear g'sake? Seems life a fine way to get water into the top bearing assembly then, inevitably, the lower.
In rebuilding many bikes, seems that more headsets have both cups press-fit into headtube, but I’ve seen the reverse for the upper pair - cone in headtube and cup threaded on the steerer. Now that I think about it, that’s the arrangement in the lovely Stronglight A9 and other roller bearing HS’s. The water risk mentioned with the upper pressed in cup has never been a problem because the upper cone often has an “over cup” creating a labyrinth seal or similar.