dwhitlow

I have a China-made, eBay-purchased FM028 frame/fork that I've been riding happily since February. Lately, I've been noticing the front end has a 'notched' feeling when I lift the front wheel off the ground and turn the bars to the left or right. The 'notch' seems to settle in when the wheel is returned to straight ahead. I am using the integrated headset, bearings, etc. that came with the bike. There's nothing obvious just looking around the headset from the outside, and the stem and cap are both snugly on the carbon steerer tube with no excess play in any direction.

I don't notice it much while actually riding, but it does seem a little disconcerting just knowing it's there. I haven't had time to pull the front end apart and see what may be going on, but just wondering if this is a common thing and generally what may be the culprit. I'm guessing bearing wear or something like that, but figured I'd ask before tearing it apart.

Any thoughts what I may be looking at? Thanks in advance for any advice or pointers.

JohnDThompson 

"Indexed steering."

This usually results from fretting damage secondary to lubrication failure. Depending on the headset, you may need to replace the lower races.

kralizec

your headset might be too tight. i loosened mine just a tad and it stopped being indexed. you can loosen it too much though, to the point of the fork jiggling in the frame, which is not good.

2manybikes

It's easy to overtighten the headset bearings. This make a dent in the bearings. It might be ok if you loosen the headset, or you might have to replace the bearings.
It may also be from a hard crash, head on. Is it a used frame and fork set?

BCRider

If it doesn't "notch" at any other point it may be what John Thompson already mentioned or it may be that a race cracked. Either way your next step is to strip the fork out and clean and study the headset for unusual wear or damage..... Or a shop if you don't do your own work at this level.

If it feels "notchy" at a number of points in the rotation then you may just have too much preload in the bearing setup. Keep in mind that the center screw in the headset's cap only needs to be tight enough to remove any play and then just about a 1/4 to 1/2 turn more.

michaelnel

Given the bike's origin, it may be as simple as grossly underlubed steering head bearings. In any case, it needs to come apart for inspection and lubrication.

BobLoblaw

It sounds to me like a pretty classic case of loose headset leading to damaged races. Does it rattle when you bounce the front wheel? If so, the headset is loose and there's no solution to the notch apart from replacing the headset.

There is actually one possible solution but it requires completely removing the headset cups from the frame and crown race from the fork, rotating them 90 degrees and re-installing. Sometimes that works by moving the ding(s) in the race(s) out of the normal range of travel. Sometimes it doesn't. YMMV.

BL

fietsbob

new headset. they're available cheap , or expensive..

If they don't get out of adjustment, or lubrication, there is
little to make the divots.
The space for accelerating the balls into the race ,
before hitting it, to near zero.

yak

+1

prathmann

I've only had this problem as a result of the headset being adjusted too tight rather than too loose. When it's too tight the lubrication all gets squeezed out from the contact points between the bearing balls and the race resulting in fretting damage.

If the damage isn't too great you can frequently fix the problem by substituting loose bearing balls for caged ones or vice versa. Either way you change the spacing between the balls and therefore they no longer line up with the damaged spots in the race.

lostarchitect 

Worst case scenario.

First step is to take it apart, clean it, inspect it.