Hope headset crown race and carbon fork steerers

silentbutdeadly

has some good things to say
Have had a issue with the Hope headset on the cross bike. I've just swapped the original alloy steerer fork out for a new Kinesis PureCX straight steerer full carbon fork.

One of beaut things about Hope headsets is the split crown race which makes both removal and fitment to a fork an absolute doddle. And so it was here. Popped easily off the old fork and fitted snugly to the new fork requiring only a light tap with the PVC tube to seat snugly and seemingly square.

The drama came about with the fork was installed back in the frame and the whole shebang is quite tight - the steering is no longer free and easy. It is tight with some hydraulic like resistance.

Now it all seems square but it appears that there is incredibly tight tolerance between the crown race and the inside of the bottom bearing which may well be the source of the resistance.

My query is though is whether the issue is the split crown race has expanded ever so slightly due to tolerances in the carbon steerer and made the bearing contact tighter or whether I've actually managed to get the thing ever so slightly out of square (still and despite doing the assembly twice). The other question is of course...does it matter? It still steers very well...just with some resistance.
 

takai

Eats Squid
Sounds like too much pre-load on the bearings with the top cap. Loosen off the top cap and see if you can find a pre-load tension that doesnt have any axial or radial play but allows for smooth steering movement.
 

mitchy_

Llama calmer
given the bottom race is tapered, unless you have over tightened the headset, it will work fine even if it is slightly expanded.

what i had with a previous carbon fork, was that the fork itself was contacting the bottom headset cup, the face where the lower race sits on wasn't perfectly flat, and the outside edge touched the cup when correctly tighened. the hope race also uses a rubber seal, that not contacting anything it shouldn't?
to me it sounds like you may need a shim or similar under the lower race though.
 

silentbutdeadly

has some good things to say
Sounds like too much pre-load on the bearings with the top cap. Loosen off the top cap and see if you can find a pre-load tension that doesnt have any axial or radial play but allows for smooth steering movement.
It's tight even without any pre-load applied...top cap not even fitted.
 

silentbutdeadly

has some good things to say
what i had with a previous carbon fork, was that the fork itself was contacting the bottom headset cup, the face where the lower race sits on wasn't perfectly flat, and the outside edge touched the cup when correctly tighened. the hope race also uses a rubber seal, that not contacting anything it shouldn't?
to me it sounds like you may need a shim or similar under the lower race though.
Now that is worth checking...when in doubt, re-start from scratch.
 

takai

Eats Squid
Yeah. Start from scratch, check bearings by hand (out of round head tube can cause bearings to be squeezed) and then check for an overlap lip on the lower cup and then the upper.
 

silentbutdeadly

has some good things to say
Started again and found that a tiny section of the steerer just above the crown race had the same diameter as the ID of the bottom cup. So it was sticking. A quick and careful sand of the covering epoxy with some wet & dry and it freed up nicely. All went back together and now turns sweet.
 
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