dmanthree

I noticed today that my front wheel/headset has a "click stop" right about dead center. Rather than smoothly progressing across dead center when I turn the bars, there's a definite hitch right at the middle. What could cause this?

Russ Roth

Your headset is indexed, it comes from general wear and tear. You can pull apart the headset and clean and grease the bearings and races which will make it better but the best solution is to replace it. Most modern frames use an integrated system with cartridge bearings set into the frame and the only real solution is to replace the bearings.

cxwrench

It's wore out. As Russ posted it's time to replace it.

Juan el Boricua

As said before, your headset is worn and the indexing described is called brinelling. Besides replacing (and if your headset is of the caged bearing design), you can: clean cups and races and see if besides the indentations of the bearings there is also heavy pitting ( if pitted, discard and replace headset). If only indented, you can replace the caged bearings with loose balls of the same size, filling the cup minus one ball. This should help for a couple more years depending on were you ride, as harsh conditions ("single tracking", mountain biking, randonneuring, etc.) will be more detrimental than road, leisure, bar hopping or light commuting to the headset.

andrewclaus

Funny you say this. I was taught that road bikes are more susceptible to brinelling than MTBs, since road bikes will ride for many miles without course correction. Randonneuring of course will be harder than leisure riding. I may have been taught wrongly, of course.

My "solution" to brinneling once was rotating cups 180 degrees.

JohnDThompson 

Fretting damage from lubrication failure. The balls push grease away, and in the absence of significant rotation (as opposed to hubs, bottom brackets, etc., which are in continuous rotation), road shocks create microscopic welds between the lower cup and crown race, which are then torn out when the handlebar is turned. Over time, this creates pits that the balls will fall into, thus the "click-stop" you describe. The fix is headset replacement, although it's only the lower cup and crown race that get damaged. Ultimately, balls are not the best type of bearing for the thrust loads headsets must handle. Roller bearings are better suited for that purpose.

davidad

It's not brinelling, it is caused by fretting. "Indexed Steering" by Jobst Brandt (sheldonbrown.com)
Replace the bearings.

dmanthree

Thanks, appreciate all the answers. I'll contact the LBS to see if I can get it done quickly.

JohnDThompson 

Another option that can buy you some time is to remove the crown race and re-install it in a different orientation so the pits no longer line up between the crown race and lower cup. This will minimize the "click-stop" effect until the fretting takes hold in the new orientation.