I have a 2010 Giant Defy 3.0 with broken lower headset bearings. It's a tapered 1 1/4 and 1 1/8 fork but the lower part of the headset seems to have a non-standard extra fitting that only allows a band type bearing ring:
I tried adding a sealed bearing but it won't fit with with the extra part welded to the frame:
The existing bearing ring broke when I serviced the headset so need to find a new one.