Originally Posted by joejack951

Yes, sort of. While a full headset is provided, there is no reason aside from aesthetics to replace the lower portion of the headset. I’ve heard from a few customer running expensive headsets that they just left the original lower portion intact. There’s also nothing keeping you from swapping back to that Dura Ace headset later down the road (as would be the case if you modified the fork for a threadless headset).

For the upper, it is a little known fact that my initial innicycle concept did not include a full headset. I initially set out to design an integrated upper race and threadless adapter that would replace only the lock nut and upper race of the original headset. I have CAD somewhere for this design, at least for the Stronglight A9 headset on my Trek 660. It was only when I then started looking into how many variations I’d need to cover all the common headsets on the market that I realized it would be a mistake to proceed that way.

I could go into all the reasons but suffice to say making matching upper races and cups is a lot easier than reverse engineering and producing matching parts for a lot of headsets.

So while that doesn’t help you reconcile your Dura Ace dilemma, hopefully it sheds some light on why the innicycle exists as it does.