Interesting. I wonder if it’s the same fork with a different headset. I was looking at the diagrams and the outer diameter of the top bearing is the same for the TCR and Tarmac (and most road bikes). The inner diameter is what is difference to fit the bigger steerer tube. I wonder if you could just buy a TCR headset assembly to make it work.
without counting the new TCR 2025...all previous TCRs have the seat for the steering the same up or down...so all TCR frames can mount OD2 or OD fork......You just have to install the appropriate bearings, up and down.
I have a Giant OD2 fork at home and I can place the fork on a Focus frame and on a Cube, with the OD2 lower bearing...the problem is at the top, although the bearing fits into the frame, when putting the adjustment wedge and the bearing cover, there is a lot of space between it and the frame
From what I have looked at, the superior OD2 bearing has an external diameter the same as other bikes with a 1 1/8 headset (the ones named Focus and Cube and many others...) but that bearing, the wedge and the cover are specific for OD2 forks.....There may also be a difference in the depth of the seat at the top of the frame.....
in short.....In the same TCR frame we could mount their OD2 and OD forks and other forks that have a 1 1/4" bottom, but the Giant OD2 forks with a 1 1/4" top tube would not be suitable for other frames....we would just have to check the Canyon and Scott using above 1 1/4"