Seems like all these headsets with routing require 52mm ID head tubes.
I'm assuming Columbus or Reynolds will produce them eventually. If not, it's time to get some 4130 on the lathe, and see if Peter at Ceeway sells the braze-in lower Columbus integrated bearing races separately from the top ones.
44mm headtubes look chunky as it is on round tubed bikes. What would a ~55mm OD HT look like
@Brommers started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
Seems like all these headsets with routing require 52mm ID head tubes.