Making sense of ICR headsets

Question

The bike in question is a Focus Atlas 6.8. It comes with an Acros IS52/28.6-IS52/40 headset. In the interest of future-proofing this bike (in case I'm not gonna be able to find these exact bearings), I was wondering what other headsets might be compatible, specifically the upper part, through which the cables pass.

Am I correct in assuming that, as long as the OD (~52 mm), contact angle (45°), and depth (7 mm) of the upper bearing matches, then pretty much any IS52/28.6 upper headset should work? This one for example (though the bearings are 8 mm deep, not 7 mm). Is there any reason it wouldn't work?

Answer 1

As for bearing replacement, yes generally speaking any replacement with the same OD, angles, and height should work. The 45x45, 52mm, 7mm height size is very common and all the usual suspects for headset bearings (Cane Creek and FSA) have them, so that shouldn't be a problem. Acros also has them.

As for what you would do if you needed to replace the entire headset upper, that requires more detail about how exactly the routing scheme inside the head tube area of this bike works. To my awareness there aren't really dimensional standards for where the upper plate outputs the housings/hoses, but some frames do need them in an exact location, so it's possible to have a bike that's married to a specific headset unless modifications were involved. Acros sells a replacement set that consists of two bearings and an upper, so it might make the most sense to just get that, since the bearings are the expensive part of it anyway and you know you'll likely need that. Having a whole replacement top plate in reserve should be enough of a contingency plan.