Hope Headset 8 seal problems

I’m trying to fit a new, Hope headset to my Titus Goldrush – V2, I think (with through axles and flat mount brakes, but predating the swinging dropouts). I’m pretty sure I’ve got the right one (8 + J for 42mm and 52mm head tube inner diameters). However I’m having trouble fitting the seal on the top part, and there don’t seem to be specific instructions from Hope on how to put it together. All I can find is an exploded diagram on this page: https://www.hopetech.com/_repository/1/documents/Upper_Headset_Compatibility_2022(1).pdf

The top cap has come with a lose o-ring which I think is supposed to be stretched around the bearing cartridge to fill the gap between the top of the head tube and the anodized top cap of the headset.

When installed with 2 of the supplied shims, the o-ring fits the gap nicely at the back, but at the front of the headset, it won’t go into the gap – it’s too tight and the o-ring sits proud.

With 3 shims, it fits nicely at the front, but at the back of the headset, it slips in from where I think it should be sittng and disappears into the space between the top of the bearing and the topcap.

With the o-ring removed, you can see the gap is slightly closer at the front (0.8mm by my calipers while the rear is 1.2mm). The previous headset had a spring “skirt” type of seal, so I suspect was more forgiving to the varying gap.

I’m pretty confident that everything is settled – there’s no play and I’ve ridden to the end of the street and back. I’ve also reinstalled the old headset and confirmed that the gap isn’t fully even with that, so I don’t think my new headset’s been bent in shipping or anything.

Am I right that I need to take a file to the top of the headtube to get this gap more even, or am I trying to fit the o-ring in the wrong place?

Update: After a cuppa tea, I decided to give it one more go. Eventually found that by leaving the bearing proud of the headtube, I could stretch the o-ring round that then pull it all into place by tightening the top bolt down. On the second or third try, I’ve ended up with the o-ring where I think it should be, so I will see if it stays in the right place after a few rides.

I noticed this yesterday but thought someone else might pop up with an opinion! From the second picture it does look like something isn’t seated correctly, difficult to see with the spacers and seal cap in place and another photograph might prove different. However, forcing it together by over tightening the top cap will just be masking the problem, take your stem, spacers and cover off and post another photo?

Thanks for the reply, you’ve reminded me I should have made another update yesterday, but I was far too hot after a test ride…

From the second picture it does look like something isn’t seated correctly, difficult to see with the spacers and seal cap in place and another photograph might prove different.

As far as I can tell, the issue is that the top face of the headtube hasn’t been faced, I’m not sure it needs to be as unlike an external headset, it has no effect on the bearing surface – the important part is the alignment of the champfered faces inside the head tube. I’m not sure if the Hope headset is still relying on this being a square surface though.

However, forcing it together by over tightening the top cap will just be masking the problem

Sorry, I’ve not overtightened the topcap or foced it. All I did was left the bearing proud of the frame, with the o-ring stretched around it, then assembled the rest of the parts then pushed the whole assembly down into the head tube (and hence the o-ring up the bearing) by gently screwing in the top cap bolt, so that it all ended up where (I think) it is supposed to end up. However…

Update 2: After a short ride last night, the o-ring has migrated from where it looks right (between the headset and the frame) and is now up inside the gap between the headset and bearing cartridge (so more or less where it was in the first photo). This doesn’t strike me as right (there’s no groove for it to locate in, and it’s loose inside the outer lip). I’ve emailed Hope to ask where it is supposed to end up.

I’m presuming that it’s an integrated headset where the bearing sits in the frame? I can’t quite see in the picture, if it is then check that the angle on the cartridge bearing is the same as inside the headtube otherwise it won’t sit “square” and tend to cockle over to one side. Also check that the cone type thing (I’m working from memory) is correctly located on the steerer and hasn’t stuck at a slight angle. If it’s semi-integrated with a cup pressed into the head tube then check that the top face of the cup is flush with an even/no gap all the way round. Sorry if you know all this but it’s not clear…

You do get integrated seat cutters that cut the seat and face at the same time.

OK, another update. Yes, it’s a fully integrated headset. This is how the bearing sits in the frame:

As far as I can tell, the angle on the bottom of the bearing is right and matches the old one. It looks like there’s definitly about 0.4mm more headtube above the bearing surface at the front than the back, I suspect the tool that @bigyan posted would have avoided this, but I’m reluctant enough to start filing things, let alone re-facing the bearing surface!

Reply from Hope is that if there isn’t enough of the bearing cartridge sticking out the headtube to make a lip to hold the o-ring (as in my case), it’s fine to leave the o-ring out, which I’ve done and removed the spacers to minimise the gap between headtube and headset. I actually prefer the look now, but having one fewer seal doesn’t strike me as ideal – hopefully the main seal in the bearing is enough to keep winter glop away from the bearings.

My o-ring doesn’t seem to have anywhere to sit properly either, I just lay it on top and push the cap down. Doesn’t seem to have caused any issues.