Generic answer would be no threads (threadless) 1 1/8 headset set from Cane Creek or Chris King...depends on your budget...but why not just ask the bike manufacturer to make sure? If you carbon fork...then you will need a compression nut instead of a star nut.
I just went through this. Got a headset on the way but not sure it's the right one or not.
Looks like an integrated headset. Best thing is to go to the Cane Creek website - they have a headset finder and lots of info.
If it's not in their database then you will need to do some measurements. If the OD of the tube is 45mm and ID is 41mm then it's IS41. If the OD of the tube is 46mm and ID is 42mm then it's IS42.
Take this with a grain of salt since I'm working with integrated headsets for the first time but I've been looking into this for my frame.
A semi-integrated headset still uses a press in bearing cup. Spec shows there should be a 15mm deep spot for the cup to press into. You don't have that much room going by the picture.
I'd guess from your measurements that you need an Italian or Campy integrated headset. Also known as IS42. It uses a 42mm bearing. It will be a drop in fit but it should still locate on the 45 degree shoulder when tightened. That's what I've got ordered for mine - I've got the same problem, my headtube measures 43.95 with the top inset 5.90mm. Too big and too deep. Inset should be 3.2mm.
What kind of frame is this for?
Check the Cane Creek site for PDFs "headset-tech-specs-rev-e" and "headset-identification-and-specification-guide".
There is a 44mm integrated headset called ICBM. It was used by Shwinn around 2000 and has been totally obsolete since 2004. So I doubt that's what we have.
It looks to me that there is already cups in that frame? Is the frame blue and the cup is black? Is it an aluminium frame or is it a carbon frame? I would guess that it is just a standard 1 1/8" threadless headset so you would have a ton of options.
Those "cups" are bonded into the frame and are not meant to be removed looks like a 2003-4 era zero stack headset which has evolved into the ZS44 standard (where manufactures now use a 44 ID headtube without the angled ledge)
This is the whole reason for the creation of the SHIS. Due to the fact there was far too much confusion with different brands offering very similar headsets/headtubes, but made with different dimensions or tolerances.
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