Hi all,
I was swapping out the stem and bars on my Giant CRS and when tightening everything up again, there was play in the fork. Multiple reassemblies seem to have made matters worse and in the process I split the plastic seal/spacer. So, what I'd like is to buy the whole headset assembly and go in again. Maybe with a more knowledgeable friend watching. My question is, what do I need to buy to replace it? There's a bearing that sits round the tube and a black cap seems to push that against the frame as you tighten the pressure cap against the spacers. The bottom of the tube has a 45 degree bearing. The tube is not tapered as far as I can see. What do I even measure? The sealing cap that pushes against the top bearing has an inner diameter of just shy of 30mm or 1 1/8". Any suggestions welcome.

Some brands have used less common headset bearing designs then others. When i worked in a Giant shop (2003-2009) we had challenges keeping their odd headset size in stock. Some of these were essentially loose ball designed with the bearing element trapped by loose fitted seals. Other higher end bikes used a more cartridge like design that wasn't made to take apart. The former had really tiny ball diameters and thus didn't handle the peak loads as well as more traditional loose ball units with their classic 5/32" or 3/16" diameters. Both likes periodic servicing just the same.

If you don't have a local shop that sells (and services) Giant (and has done so since your bike was new...) to help determine the exact replacement then someone will have to take the headset apart and measure the various dimensions that headsets have. If you have the lower cost loose ball design and if the cup and cone surfaces are worn/damaged this measuring will include the cup/crown race fits to the frame/fork. Then the search for parts can start. Andy

Awesome detail. Thank you. I'm OK taking the headset to bits, fork off etc. So will take some measurements. I think it's a Press Fit and the play is in the lower bearing - according to my thumbs.

It sounds like you made mistakes reassembling every. If you care to try one more time, here's the Park Tool link: https://www.parktool.com/blog/repair...eadset-service

I suggest taking your existing parts to your local shop, having them measure everything, and having them order one.

Thanks for the link :_)

Unless the lower stack is not a proper press fit in the headtube and/or over the crown seat your thumbs are not right. The upper stack is not a hinged but can seem like one to the inexperienced. Just like a leaking tube whose air seems to exit around the valve hole but is actually coming from another location. It's that the valve hole is the path of least resistance. Another analogy is the leaking water dripping from the ceiling could be running along a joist from across the room. Where the slop can be felt is not always where the issue really is.

Since cartridge headset bearings have conical interfaces with their cups/races the bearing will self center if the preload is correct. One hinderance to this is a compression ring that is wrongly installed, broken, or binding on the steerer and can't be moved that little bit to affect adjustment just so. I generally lube the steerer's surface to reduce the build up of corrosion there. Andy

Thanks - it did strike be that the compression cap could be fatigued. I can get rid of play by going a little further on the compression. but then the bars don't turn freely.

No, I didn't reference the compression cap but the conical and "split" compression ring that is pushing directly on the top bearing. Sorry if I wasn't more clear.

The usual (but not only) issue concerning the top cap is it's bottoming out on the steerer's end before the bearing preload is achieved. Different problem with much the same effect. Andy