Chris king headset

[Monkeeee01]

Headset with the channel

 

[baron von greenback]

Nice guys good info as always

 

[Monkeeee01]

CK in and forks, stem now on.

Need to cut the steerer a bit as the massive red spacer irk’s me!

 

[ishaw]

Someone may have to explain this channel. There's still a significant part of the cup the same size as it was that needs pressing into a known fragile head tube. I figure the top and bottom of the head tube won't have the cup pressing against it once fitted, I'd that the fix for the problem then, Les stress on the extreme ties?

 

[Frankenorange]

Someone may have to explain this channel. There's still a significant part of the cup the same size as it was that needs pressing into a known fragile head tube. I figure the top and bottom of the head tube won't have the cup pressing against it once fitted, I'd that the fix for the problem then, Les stress on the extreme ties?

A crack will start at the end of the head tube, top or bottom, so the channel is machined into the cup and this lessens the stress at the ends of the tube. I think that is the reasoning behind it and as mentioned up thread CK cups are on the upper limit of sizing so are a problem for some frames.
Adding rings to the outside of the top and bottom of head tubes are also another way of adding strength to the tube and these also help to stop the ends of head tubes from going oval on rigid front ends from the wheel banging into stuff. This is a common problem with retro cyclocross frames that have been raced a lot.