UKC

Having a spot of bother with a internal headset on a bike I’m building.

When everything is grease and lined up,as soon as you tighten the star nut it all stops running smoothly and the lower bearing race  gets pitted.

Anyone with any idea?

In reply to ffati:

You haven't forgotten the crown part of the headset on the bottom of the steerer tube on the forks?

In reply to QRZBuddha:

No tried a split and a non split crown. 

 

Might see see if Bike shop can re face the bearing surface

In reply to ffati:

Hmmm.... I used to work in a bike shop years ago (pre aheadset days), trying to think of anything.....

Is it a brand new headset, or just replacing the bearings? Are they loose bearings, or caged?

If they're loose, are you sure they're the right size? Have you got the correct amount in each race?

If they're caged, is it worth checking the cages, make sure they're not pinching.. are they definitely the right ones?

I used to get a problem where the races would pit slightly and the steering felt like it was 'indexed' and return to the straight position with almost a click.. I used to get a bit more life out of the headset by tapping the cups out and turning them in opposite directions, but if it's an internal headset, I'm guessing you don't have that option...

In reply to QRZBuddha:

Brand new headset 45° Top and bottom. Seems stiff about 300° of the circle if that makes sense

In reply to ffati:

Over tightening the star nut was my first thought, now you've mentioned it's stiff through its turn I'm thinking bent steerer tube. 

In reply to thepodge:

Maybe but it’s a new fresh from the box fork which is not to say it can’t be

In reply to ffati:

Occasionally some headsets are not made to precise tolerances. If you have a bearing like this when the preload bolt is tightened the bearing will become tight to turn, but you will notice it still has a bit of play If that happens you need a shim which lifts the top ring away to stop the binding. It sits on top of the inner top race so the free play is taken up. Not sure how just tightening is causing pitting, this normally takes many miles of riding.

In reply to Crofty:

It’s the bottom set that get pitted

Shouldn't pit by just tightening unless the race is made of something very soft or the bearings are pitting something else (ie alloy part of fork). Is it a race that fits on the fork crown or the race that is pressed into the lower steered tube that is pitting? What make of bearing have you got? What frame and fork? Where did you buy the parts from? Did the seller recommend that combination? Sorry for all the questions. I am Cytech qualified and just need to know all the facts b4 making a valid suggestion

In reply to ffati:

It's nearly always the lower race that will pit as most weight carried there and also suffer more water damage if not greased well. If yours is new it shouldn't be pitting by tightening.

In reply to Crofty:

Gt bmx

Insight chromoly fork 

fsa headset

In reply to ffati: Sorry can't help. On paper stuff like this seems really simple. My first suggestion is one that occurs a lot. Even an out of the box £700 bike sometimes needs a headset shim to make a headset work smoothly. I'd take it to your LBS and ask a mechanic to take a look. A friendly mechanic will should be able to point you in the right direction esp if you offer to purchase a shim if required. Just double checking but are the bearings sealed?

 

In reply to ffati:

Worth checking the bearing race is the right way up.  It should feel very smooth even when you have cinched all the play away.  If it is feeling slightly rough then this could be the problem.

I've done this a couple of times: sometimes the race looks like it should be the other way round.