I have a 2002 Giant OCR-3 that I'm looking to put a carbon fork on. The steerer is 1" threaded and it's got a Giant adjustable quill stem (which I'm also looking to replace).

I guess the simplest thing to do would be to find a 1" threaded fork thats the same size but I've heard a few different things about the integrated headset that Giant used on these bikes. I've been told by one person online that they went with a 1 1/8" steerer. I questioned this and they advised that the only reason the bike has a fork with a 1" steerer is because Giant uses some kind of headset that acts as a reducer.

I've seen the latest OCRs which now all have 1 1/8" FSA integrated headets. I've spoken to Cane Creek via email and they told me that Giant has never really been specific about what the setup is (!!!!????). I spoke to a few LBS guys... and they just look at me funny. I've looked around for an email link for Giant but have come out emptyhanded. I know how the people at Chris King feel about the whole system.... I'm starting to agree.

I'm wondering if anyone has any experience with converting this kind of bike and what they used.

OK,the trick about the headset that Giant uses is that it's a fake integrated headset, it's an internal headset, the headset can be replaced.

If you are going to get a new stem and fork go ahead and get a threadless headset, stem and fork.
I can't remember the deal for 2002 OCR3 but I will call my guys monday and let you know what you need.(I am pretty sure in 2002 they used a conventional headset for the OCR

I'm doing this swap right now...did anyone ever figure out which headset will fit? Integrated or traditional?

I'm in this situation now with an '03 Giant OCR3. Were you able to get yours swapped? what headset did you end up with?

After three headsets, I settled with a Cane Creek IS-8 and a ton of spacers. The internal race seats are to deep for the bearings so it took a lot of trial and error to eliminate any rubbing (particularly on the bottom end where the spacers don't fit). I'm still having issues with the headset getting loose when I ride (if I tighten it enough to stop this I get rubbing btwn the fork and the head tube). I hate to sound cynical, but if I had known what a PITA this was going to be, I would have gone with an new bike and saved myself the frustration.