Something going "bunk" in the front end

[dave thompson]

If the upper cup and bearing cap are uneven as in the pic, it would indicate to me the head tube wasn't faced 'square'. I would pursue this as a strong candidate for your recurring noise.

[Black Dog]

Originally Posted by dave thompson

If the upper cup and bearing cap are uneven as in the pic, it would indicate to me the head tube wasn't faced 'square'. I would pursue this as a strong candidate for your recurring noise.

This or the cup has not been pressed fully and is not completely seated. Is there an even line between the cup and top of the head tube? Veloo, is this bike your Linskey Helix?

[Veloo]

The cups look to be in the right position with no space. I'll run some shims to see if it's consistent.
Yup BD, it's on my Helix.

[Black Dog]

Originally Posted by Veloo

The cups look to be in the right position with no space. I'll run some shims to see if it's consistent.
Yup BD, it's on my Helix.

Check the gap for sure. If it is consistent then it is a facing issue and on a Ti frame not super easy to face with conventional tools due to the hardness of the Ti. A lot of shops will not want to subject their tools to Ti surfaces. However, Truenorth Cycles makes Ti bikes and they are just down the road from me and my be willing to face the head tube for you, if needed. Non, he less if the fork spins freely and there is no binding when the bearing preload is set then you should be ok. I have a King headset that has an uneven gap like yours and it spins freely and I just ride it as is and have had zero issues for years. Did you check the spacers to make sure that they are parallel? A bad spacer could also cause this.

[Tony T]

Originally Posted by Veloo

One thing I noticed when I first got the bike was that the gap between the upper cup and the bearing cap wasn't consistent. When viewed from the side, the gap at the front is just a tad tighter than the gap at the back. You can see it in the pic. Never could get it seated level.

I have the same "gap" issue (see: http://forums.thepaceline.net/showthread.php?t=122661).
Re-faced the tube, fixed the gap a bit , but still have a very small uneven gap. (No "bunking" though).
I would be surprised if the gap is causing the problem if the headset is moving freely …but it could still be the headset causing the "bunk". Not cheap, but installing a new headset is a relatively easy task.

Check that there is no movement. With the from brake engaged, move the bike back and forth — there should be no movement in the headset. — As Tihsepa suggested, make sure that there is enough space between the top-cap and stem. Easiest way to check is to put a 1/8" larger spacer between the stem and headset.
CK says to tighten only btwn 4-10 in lbs (15 in lbs max) — don't overtigten

[Veloo]

Fixed.

Leveled and no more "bunk" sound.
Had to reface the head tube. I could feel a sharp spot as soon as we took the top portion off. You'd think you spent a few thousand on a Ti frame they'd do it properly at the factory.

[oldpotatoe]

Originally Posted by Veloo

Fixed.

Leveled and no more "bunk" sound.
Had to reface the head tube. I could feel a sharp spot as soon as we took the top portion off. You'd think you spent a few thousand on a Ti frame they'd do it properly at the factory.

yup

[Mikej]

I've found that greasing the top split wedge device thing inside and out helped. It actually stated to do that in the instructions-degrease stem clamp area after.

[Ken Robb]

When I bought my Rambouillet frame I had it built with Ultegra 9 speed group including headset. Everything was brand new. There was a wee bit of drag when turning the fork. Shop owner/tech removed fork and headset, faced the head tube at both ends and installed Chris King headset. Absolutely perfect ever since. This was a quill stem fork.

While you are trying different cures I think it would be wise to make sure HT is perfectly faced/aligned.

[seanile]

wow. 2 year old follow-up.

[Veloo]

Yeah, the bunk noise was getting louder and more frequent.
ie it annoyed me enough to fix it.

Originally Posted by seanile

wow. 2 year old follow-up.

[dddd]

I had a case where there was a plastic wedge washer that had worn/distorted to the point where it's conical outer face had become very convex, and replacing this part solved an identical-sounding problem.

On yet another bike, the Aheadset had come loose during a very rough ride, and the bearing actually had sort of hogged out the lower cup enough that the headset could no longer be adjusted to a click-free state.

The King headsets I've used (and acquired used) have been super-durable, some even enduring severe over-tightening before being re-adjusted to perfection.

[dustyrider]

Originally Posted by Veloo

Yeah, the bunk noise was getting louder and more frequent.
ie it annoyed me enough to fix it.

I love it!

[bitpuddle]

Originally Posted by Veloo

You'd think you spent a few thousand on a Ti frame they'd do it properly at the factory.

No, I wouldn’t think that, ever. Always face surfaces and chase threads.

[fignon's barber]

Originally Posted by Veloo

Yeah, the bunk noise was getting louder and more frequent.
ie it annoyed me enough to fix it.

I'm glad you did. One of my bikes has had this same problem for a year and a half. Drives me crazy. The only thing I haven't tried is refacing the headtube.