DMF 

I'm on a 2003? Raleigh Professional with Columbus carbon fork. I believe it uses a Columbus-style headset.

The problem is that the thing rattles. The streets in this part of Dallas are like the surface of the moon. I get what sounds like something tapping thin carbon fiber.

I adjusted the pre-load by slacking off the stem clamping bolts and taking the cap down to about 5 Nm. (There are spacers so it isn't bottomed on the stem.) That helped - the rattle is of a higher frequency and doesn't happen as often - but it isn't cured. I'm afraid to crank down on the cap much harder. Interestingly, I get no bearing bind when taking it down that even tighter. Should I get some bind?

Is there a chance the something else is out of whack, like the star nut working out?

TIA

Dennis

alcjphil

Once your headset is adjusted and the stem tightened, your top cap serves no further function, you could remove it if you felt like it. The top cap is only there to set the preload on the headset bearings to remove play. Tightening the pinch bolts on the stem is what holds the headset in adjustment. If you are unable to tighten down the top cap enough to remove the play in the headset you may need an additional spacer. If you don't want to affect bar height, install the additional spacer above the stem

HillRider

Are you sure it's the headset? If the headset adjustment is good and there is no play in it when you lock the front brake and rock the bike fore and aft, the rattle is probably somewhere else. Shift or brake cables are a distinct possibility.

DMF 

I don't need an additional spacer. The cap is not bottomed on the stem (I mean the fork tube, not the stem clamp - is hard against that.)

Another odd thing is that although it rattles, I can't feel any play in the bearings, either static or on the road. I have also tried damping other things that might rattle, like the shifters - no effect. And I can't think of anything else that would have that carbon fiber sound.

So how tight can I reasonably take this cap down?

Dennis


Hi HillRider! Long time no see.

hueyhoolihan

don't worry about tightening it down. just remove it altogether, as mentioned, it serves no purpose. it's a tool for assembling only. people just like to keep them on there for some reason. i guess they are thinking about old quill stem bolts or something.

alcjphil

If the steer tube is even with the top of the stem clamp you may not be able to adjust preload. The top cap has to push the stem down on the steer tube to preload the bearings. Once the top of the steer tube gets up far enough, you can no longer tighten the headset. If your top cap has a recess that fits down inside the top of the stem as many do, you cannot tighten the headset even if the steer tube does not quite reach the top of the stem. It is entirely posible that you do actually need a spacer above your stem
A picture of your top cap and of your stem/steer tube could serve to clarify this

DMF 

Apologies. The clearance is smaller than I remembered. I'll get another spacer. Hope that does it.

Dennis

DMF 

That helped! It's still not as quiet as I'd like but it's a lot better.