IFF the 108mm measurement for the taper is correct then the reason your modifications work is that the top bearing ID is larger than 1 1/8th so your bearing is actually sitting over the taper.

Stating the measurements:

Head tube: 90 mm
Lower stack (inc. crown race): 14 mm
Recess of bearing in upper cup: 6.5mm

This leaves us with 97.5mm (90 + 14 – 6.5)

Fork tapered section: 108 mm

ie there is 9.5 mm deficit – I’d like a few mm on top of that for peace of mind.

But – as the bearing is actually bigger than 1 1/8th then we can steal some height from the bearing depth depending on the split ring that goes into it that Pete modified.

To fix it properly you need to ensure that the split ring is not bottoming out or deforming on the taper. The ring is not the full height of the bearing so you can steal some height from the bearing fitting over the taper but only a couple of mm.

5mm may ‘just’ sort it but I would like to see 8-10mm to be safe.

Have you heard anything back from BETD?

Not a sausage. O-O are the bset bet methinks. 🙂

so your bearing is actually sitting over the taper.

Yep! But not by much, the taper seems to end in the space of the bearing, so the split taper ring in the headset is squased too tight between the bearing and the taper

Whatever the maths say, there’s not much in it. Maybe production variances will have na effect between different forks and frames, but I reckon 3mm will fix mine, 5mm for sure.

They’ll get it sorted.

One thing they could do to remedy the problem on new frames is make a new upper headtube insert (the bonded in one) that protrudes from the top of the headtube a bit more and is then painted with the rest of the frame.

Would then mean any tapered headset (eg the Hope etc) will still fit.

Edit: other factors are:

1. is the front end as torsionally stiff as it should be if the top tube is lower down?

2. It is still very annoying to have to use a silly amount of spacers unless you want to cut your steerer down an extreme amount. I was meaning to post asking for suggestions on things to use to reduce the mass of visible spacers.

On the plus side the lower top tube gives slightly better standover.

Do fork manufacturers make the steerer tubes themselves or buy them in?

probably made elsewhere but to their specification – hence the proliferation of (and lack of) standards

Would also be worth checking the tapers on carbon steerers before a solution is decided on as they may be even longer.

Sorry to drag up an old thread, thinking about getting the carbon 456 but have a headset Q for the experts. Currently got a standard 1 1/8″ hope headset – will I need a new complete headset or is there just the 1.5″ part I can buy and still fit “normal” 1 1/8″ steerer forks?

I have just built mine up and when i was putting the headset smoothie into the headset, it was that slack i could nearly push it in with my fingers, all i actually had to do was tap it in with a hammer, and i mean tap, havnt rid this one yet so will have to see this weekend

UPDATE:

Stevo from On One has sent me 2 thicker crown races, +3mm and + 5mm, as he said he would. They’re chunky wee things:

IMG_1078 by PeterPoddy, on Flickr

Bike with standard crown race:

IMG_1075 by PeterPoddy, on Flickr

Bike with +3mm crown race:

IMG_1079 by PeterPoddy, on Flickr

I’ve just fitted the +3mm one and it fits fine. The headset has tightened down fine and there’s no play at all in a ‘garage test’. Sadly it’ll be at least a week before I get to take it for a ride, but it looks promising and I’ll report back again.

🙂

UPDATE

Managed to get a ride in yesterday and the +3mm crown race seems to have fixed the problem. 🙂

Thanks to Stevo at On One for the help! 🙂

Great stuff. What happens if you want to upgrade to your usual CK headset? 😉

CK won’t fit Dez. Well not my usual £45 used ones at least. Do they even do tapered headsets? I don’t think they do semi integrated either, like the top race….

Bit of a bump in case anyone’s is interested in the new crown races 🙂

I notice that Hope list a +3mm crown race for their version of this headset – probably more for crown/downtube clearance issues but might solve this problem too.

Pete, is there an O ring on the bottom of the lower cup to fit into the outer groove on the crown race?

Andy, I can’t say I’ve noticed one to be honest. There certainly isn’t a separate one, put it that way…. I guess there might be one fitted somewhere, but sorry, I’m not taking the forks off to have a look! 😀

Just got my external bearing upper cup from On One (thanks guys).

I now realise the groove in the On One crown race is a labyrinthine seal with a lip on the bottom of the lower cup as they have this set up on the top cup instead of a rubber seal or o-ring.

The new upper cup will easily sort the problem so just have to knock out the upper cup now and fit it. It has a massive 1.5″ bearing which makes me wonder if a 1.5″ straight steerer could be used with a different upper cap and compression ring (what is it called again?). I guess this will let them use tapered or 1.5″ steerers on their new steel frames with 44mm ID head tubes.

Andy the simple answer is Yes

If you put a top and bottom external cupped head set onto a 44mm id headset a 1.5 inch strait steerer can be used.

Nuke proof make head sets like this currently with extended inner lips but i was lead to believe by brant they will be releasing standard length headsets similar to the cane creek ones in the not to distant future.

back to the tread, does this now mean On One have now come up with a second solution to the issue with a re-worked top hedset section or the extended lower crown race?