Rigid MTB, headset eternally working loose.

vinnn

Hey folks,

Have an annoying issue regarding my headset coming loose on trails.
I've carbon rigid forks with an alloy steerer tube, star nut's about 1cm below the top of the steerer tube and the spacers top out about half a cm above the top of the steerer tube. All is as it should be but soon as I take the bike out on rocky trails the headset comes loose. For example I took it out on Coed Llandegla red route (11 miles) today, had to tighten the bugger up 4 times!

Common sense would suggest that I'm not tightening up the stem clamp enough but I feel that I am doing the stem bolts up pretty f'in tight, any tighter and I'm concerned I might strip the threads. Switched from a run of the mill Bontrager stem to a beefier 'Pro' stem but no difference.

So rigid riders, any tips? Do you really have to hang yourself off the allen key to tighten up your stem or will a headlock save the day?

Chz...

sethy

Assuming you have a threadless headset, it is the allen key on the very top (in the cap, pointing down the steerer tube) that will keep everything together. You doing that one up right?

vinnn

Yes of course.
When I say I have to tighten the headset I do mean...
>loosen the stem
>preload the top cap
>tighten the stem bolts

Just to clarify, I'm a experienced cyclist btw, mainly road riding over the past 6 years but have owned hardtail & full-sus MTBs before. Never had this problem so acutely though. This rigid MTB is a recently finished project.

cooldad

sethy wrote:

Assuming you have a threadless headset, it is the allen key on the very top (in the cap, pointing down the steerer tube) that will keep everything together. You doing that one up right?

No it isn't, it just preloads the bearings. The stem bolts hold everything together. Once they are tight you can take the topcap off - it does nothing.

supersonic

Headlocks do the same as star nuts, will make no difference. As above once is adjusted and the stem clamp bolts done, the adjuster can be removed.

Sounds like the bearings are taking a while to settle, or the headset cups are not pushed in correctly and are settling too. It usually goes away after a while.

vinnn

supersonic wrote:

Headlocks do the same as star nuts

Ah OK, that answers my question.
Well I just think I'll tighten the stem as much as I can (overtighten in my opinion) and go back to the trails to test it out tomorrow.
Must get my torque wrench back too!

supersonic

Overtightening the stem will not solve- it won't be moving. What is moving is the headset after. Justdo up as normal, and keep readjusting. If it doesn't go away after a few goes, take to a bike shop or replace the headset.

vinnn

What I should've said is that I'll do this as a test to rule out stem tightness.
It's not a new headset so I'll look into this also. There are no gaps between headset cups and the ends of the headtube and the amount of times I've had to re-tighten (way too many) rules out bedding in.

Chz, I'll let you know how it goes.

YeehaaMcgee

Could also be the crown race on the forks bedding in -as Sonic said, it should settle after a while.
Rigid makes no difference - apart from taking the fun out of riding

386ka

YeehaaMcgee wrote:

Rigid makes no difference - apart from taking the stone out of your kidney.

Also, it can be pretty fun.

vinnn

When testing on the trail this morning it came loose again.
Took my tool box with me though so got back to the car and got to the bottom of it, and it wasn't the kind of thing you'd expect.

Turned out the root cause was the star nut was not properly straight, causing the headset to be not evenly preloaded, wasn't way out but out enough. Even though it seemed tight under preload and I could ride it around just fine on flats, as soon as it came to rough stuff that's when the problems occured.

Smacked the star nut in a tad further making it straight and tightened it all up again. Was able to give it 15 miles of trails after this and all seems OK.

.. and to the rigid haters, it's all about lines and technique. You should try a bit of finesse sometime as opposed to the usual clumsy crash-down-and-hang-on style I see out there which is not necessarily faster. Nothing wrong with suspension but it's not the be all, end all.

nicklouse

A not straight star nut makes no difference.

Sounds more like he top cap was bottoming out on the steerer.

YeehaaMcgee

vinnn wrote:

.. and to the rigid haters, it's all about lines and technique. You should try a bit of finesse sometime

Many of us did, about 20 years ago!

vinnn

nicklouse wrote:

A not straight star nut makes no difference.
Sounds more like he top cap was bottoming out on the steerer.

Think what you like, that is what fixed it and the star nut and top cap is crucial to the preload before tightening the stem. In this case an uneven preload was the issue as the top of the headtube was being forced slightly forward when tightening down the top cap. As said in my first post...

vinnn wrote:

star nut's about 1cm below the top of the steerer tube and the spacers top out about half a cm above the top of the steerer tube"

Thread closed.

cooldad

vinnn wrote:

Thread closed.

That's what you think.