Fork Steerer Length -- Is It Critical?

[TimDanaher]

I've got a hiddenset on my best bike used with dedacciai Black Drive forks / carbon steerer.

Think I can get the headset to fully compress? Can I fcuk. There's alway a tiny bit of residual play. It feels like the thread in the bung is running out before the stack fully compresses. I even bought a HeadLock, but the sodding forks don't have a hole under the crown...

In the past (alu steerer) I've been able to tighten the bung so that the steering becomes stiff -- not with this b@stard.

Anyway, I've got quite a bit of steerer above my stem (about 6cm). Would lopping this off make any difference? Common sense says no, the stack will still be pulled by the same amount, whatever the length of the steerer...anyone have an opinion?

Or can anyone recommend a bung that'll actually work? The one in the Dedas is a rubber-ring, knurled-leaf affair. It's hateful.

 

[mickle]

Methinks you need to install another washer above or below the stem. The stack needs to be a few mm clear of the top of the steerer.

 

[TimDanaher]

Thanks, Mickle, but there definitely is a good 3-4 mm of spacer protruding above the top of the fork steerer tube...I suspect the bung is crap.

 

[Proto]

I'd do as Mickle says. It's uUnlikely to be the bung in my opinion. If you need so much pressure to load the bearings that the bung is moving, then something isn't right.

You need 3 to 4mm even when the headset assembly is in it's fully adjusted position. The top cap will protrude inside the uppermost spacer by approx 3mm before it starts to put any tension on the steerer. So loosely assembled you need more, start with 10 and see what effect it has. If it works clamp up the stem, remove the top cap and see how much clearance the top cap has. Adjust the uppermost spacer accordingly.

 

[mickle]

have you lubed the thread and under the head of the bolt? The bung might be turning before the bolt gets a chance to bite.

 

[TimDanaher]

Cheers, Mickle, Proto ---

I stuck another 5mm spacer on the stack... no joy. It seems to be fine, but when I ride it over a cobbled street nearby, I can feel that tell-tale play...

The threads are greased... that's another problem with this fecking bung: every time I unscrew the top cap, the top half of the threaded expander comes out with it, the bottom expander falls into the steerer, and all the little gnurled leaf-plate thingies and the rubber rings fall apart, I have to turn the bike upside down to get it all out, and it takes me half an hour to put the bloody thing back to gether. I hate it. I just hate it.

 

[RedBike]

You can put a few cassette spacers ontop of the stem to give you that extra 3/4mm while you tighten everything up. Once the stem bolts are tight you can just remove them.

 

[mickle]

What an almighty pain in the arse! carbon steery tubes are usually quite rough (weave rather than gloss) on the inside, I wonder why the bung isn't taking. Are you sure the bastard is assembled correctly??

 

[TimDanaher]

Redbike -- spacers I got.

Mickle -- yeah, it's the right way round, n' all... I'll try and take a photie tomorrow. The only thing that's got me a bit suspicious is, it doesn't sit inside the steerer tube, like a star-fangled nut does. The top half has 'shoulders' that sit on top of the steerer tube.

 

[mickle]

Does the top half look like half a star-fangled nut? I suspect you might be required to bang it in. So to speak.

 

[Proto]

Have you got the correct sized bearings. Cane Creek standard are 41.0mm dia and Campag standard are 41.8mm dia. Just a thought.

 

[TimDanaher]

Proto --

I would hope so -- I actually sent them Campag's own engineering specs for the headtube (included with every hiddenset) -- and I checked it on the engineering drawings that they sent back as well, just to be sure... but as anyone who's ever done business with Chiang' Da / XACD will tell you, what you ask for and what you get are not necessarily the same thing...

 

[TimDanaher]

Well -- I've solved it...sorta.

So, the Bung won't compress stack...get something that will.

So I traipsed off to Domäne Haarste (our local swag shop) and got myself a 'Spanngurt' -- one of those straps with a ratchet buckle that you use to secure loads on your roof-rack.

I cut it to about 50cm length, threaded the strap under fork crown, rested the flat of the buckle on the top spacer, threaded the strap through the buckle...click, click, click. One fully-compressed stack.

It all seems to be fine now, except in the most extreme of situations (heavy cobbles, etc.) where I'm sure I can feel a tiny bit of movement.

This leads me to think that the headtube hasn't been machined properly. It may only be a fraction of a mm out, but it's there.