Bicycle Mechanics - Headset bearing conundrum

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MKIV987
10-30-12, 08:40 PM
I'm installing a new cross check fork on my cx bike with a ~3-month old Woodman headset. When I first installed the headset on an aluminum fork, there was a bit of a gap between the lower headset cup and the fork crown race but I didn't think it'd be a big deal. Turns out it was enough of a gap that some mud and grime got into it during a particularly messy cx race a few weeks ago.

I removed the old aluminum fork (1" aluminum steer tubes make me nervous) and switched the fork crown race over to the cross check fork. When installing I noticed that there was an even larger gap between the lower cup and the fork crown race this time. I flipped the headset bearing over and the gap was significantly smaller, but when the bearing is "upside-down" I can tell it doesn't seat firmly in the crown race; I can easily tilt it so it doesn't sit level.

I've included pictures of how the bearing looks "right side up" and "upside down" as well as how the fork fits into the frame both ways. Am I missing something?

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reptilezs
10-30-12, 09:21 PM
match the angles to the crown race and cup. generally the way you have it "upside down" is the correct way
reptilezs
10-30-12, 09:22 PM
actually your crown race looks upside down

tomacropod
10-30-12, 09:30 PM
The "upside down" alignment is right. The chamfer on the bearing has to be the mirror image of the chamfer on the crown race - so the bearing is centralised. The writing is upside down, but as the bearing is also used in the top cup, it's correct half the time. If you have been running the bearing upside down, just check that it hasn't damaged the bearing. You should notice that the whole thing runs much smoother with it the correct way.

edit: Also, your crown race looks upside down as well.

- Joel
MKIV987
10-31-12, 06:20 AM
The "upside down" alignment is right. The chamfer on the bearing has to be the mirror image of the chamfer on the crown race - so the bearing is centralised. The writing is upside down, but as the bearing is also used in the top cup, it's correct half the time. If you have been running the bearing upside down, just check that it hasn't damaged the bearing. You should notice that the whole thing runs much smoother with it the correct way.

edit: Also, your crown race looks upside down as well.



Thanks for your input. I should mention that the other bearing looks identical but has a "Top" marking with an arrow pointing up--ostensibly to indicate which side of the bearing goes up. When I install this one upside down the gap disappears as well, even though the "Top" arrow is pointing down towards the fork.

Can you explain to me how I managed to put a fork crown race on upside down? Doesn't it only go on one way? Only one side of it is channeled to hold a bearing.

Thanks everyone.