Bicycle Mechanics - why is my new headset behaving like a worn out headset?

if i take my hands off the handle bars the bike immediately pulls left or right even with my hands on the bars it is still very unstable. the steering seems to be indexed too. . its a fairly new headset, i took it apart and cleaned it and look and i can find absolutely no signs of wear.

thank you

Haha indexed steering.
I imagine that you just adjusted it too tight, and when you ride you lean, and it resists moving back because is it too tight, and 'stuck' kind of.

When you adjust it (with the hex bolt at the top of the steerer as you probably know [that is assuming it's threadless]) tighten it until there is no play - ie. movement of the fork inside the headtube when you hold the front brake and move the handlebars back and forth - while still moving freely - ie. when you lift up the front of the bike by the toptube (not the handlebars) the handlebar/fork/wheel etc. should be able to turn to one side or the other freely.

[edit:] if the steering seems indexed then perhaps you overtightened your headset enough to pit the bearing races. Does it have notches/a notch in which the steering stays, kind of? It's hard to explain.

From the Park tool website:

"All bearings on a bike have some friction as they rotate. This is normal and does not affect the ride. Better quality bearing surfaces are ground smoother and will have less friction and resistance to turning. Adjustable type bearing systems use two opposing races which can be moved relative to one another. If the adjustment is too tight there will be too much pressure on the bearing surfaces and balls and the system will quickly wear out. If the adjustment is too loose there will be movement or "play" between the parts. This will cause a knocking in the bearing surfaces and again they will wear out prematurely. Generally, the bearings should be adjusted as loose as possible without play or knocking in the system."


For adjustment instructions see Park's page for:

Threaded headset service: http://www.parktool.com/repair/readhowto.asp?id=127

or

Threadless headset service: http://www.parktool.com/repair/readhowto.asp?id=65

thanks guys. its a new head ste and inspected it so i already knew there was no pitting or wear of any kind. also it was adjusted proper tightness. as it turned out my brake cables were the culprit.