1987cp

I recently came into possession of a bike with a threadless headset for the first time, and pondering this and that I found at least two idle questions I don't know the answer to.

One, that doohickey inside the steer tube - I see people calling it a "star nut" or "star fangled nut" - that seems to be used only to secure the decorative steer-tube cap to - if you want that out, do you just grab a socket extension and mallet and drive it out the bottom? And if you do that and wish to reinstall it, do you usually have to get a new one?

(yes, I have in mind to experiment with something vaguely along these lines - and yes, my bike is steel and not carbon)

The other question is, I had a bike shop employee once tell me that at least on a certain model of bike (the one in question at the time was a '12 Trek FX, IIRC - sorry, don't remember what brand headset it had) that the star nut arrangement is what actually secures the fork to the frame and holds the headset tight, and that it would not be necessary to re-adjust the headset by leaning hard on the handlebars whilst tightening the stem clamp in the event of a stem swap. Whether true or not on that bike, it doesn't seem to be true on mine, and I can't conceive of a way in which it might be true - so is it more likely that I misunderstood the statement?

fietsbob

Actually the cap is NOT decorative, it is the headset bearing Preload adjustment.
it presses down on everything below it, and tightening the stem clamping bolts
around the steering tube, holds the adjustment.

Wilfred Laurier

the top cap is not exactly decorative

when assembling the top cap pulls the stem down to preload the bearings

after the headset bearings are adjusted and the stem is clamped tight
the top cap is optional
until you want or need to adjust the stem or headset again
but until you need to readjust you are perfectly fine riding without a top cap

you can also preload the brearings with a long bolt and some washers
or a long bar clamp
or a ratcheting tie down strap or some sort of winch and cable arrangement
or by slightly tightening the stem bolts and hitting the top of the stem with a mallet

there are also removeable headset adjustment wedges made by several companies
that are commonly used on carbon steerer tubes
this might be the best way to go about your silly project

Kimmo

Pounding it out the bottom is all you can do, a lot of the time. Sometimes you can screw a bolt into it, and wiggle it around to bend the arms of the star more and loosen it up enough to pull out.

You can just bend it straight and use it again, until it breaks.

Not sure what the LBS guy was raving about, but the nut and top cap serve to apply the proper preload to the headset bearings before the stem's steerer clamp is tightened. Once you have the bearing preload right and the stem aligned with the wheel you don't need the top cap and star nut again until the stem is loosened.

It's hard to imagine a good way to apply preload without it, either... hanging off the bars while tightening the steerer clamp sounds pretty dodgy.
Edit - heh, Wilfred's just pwnt me with a bunch of ideas.

HillRider

Go to the Park Tool web site and look up the tutorial on adjusting threadless headsets.

The star nut is not just to hold the "decorative" top cap, both are necessary parts of the mechanism used to set the headset preload. Do NOT remove it.

Once you remove the top cap you should see the top of the steerer tube is a few mm below the top of the stem or the top of any spacer above the stem. If it is flush, add spacers until there is 2-3 mm gap as that is essential. To adjust the headset set you:

1. Loosen the stem's steerer clamp bolts
2. Tighten the top cap's center bolt until all play is removed from the headset. (The gap mentioned above allows the steerer to move up relative to the stem to remove any headset play.)
3. Center the stem and tighten the stem's cteerer clamp bolts.

At that point the top cap is indeed decorative as the headset adjustment is locked in by the stem clamp.

fietsbob

I found the center of the 2 stars on Mine, was Aluminum, riveted essentially, joining them to the threaded center.

so I forced it upward (in the steel steerer fork) it, the aluminum, is the weak spot
you could further weaken it , by drilling off the edge, some,
then Pulling against the top by the flat-washers I put across the top of the fork

once the star nut comes apart, I turned the stars edge on, and they came out easily..

suspension fork crown cast on the steerer tube would not allow pushing it through.

HillRider

Maybe some of those work but several years ago Easton included their "Beartrap" rotating wedge headset adjuster with their carbon forks. The thing was a total failure and would vibrate loose during every ride. After two or three tries at using one, I called Easton and they sent me an expander plug gratis. The Beartrap disappeared from their offerings soon after.

Wilfred Laurier

rattling loose while riding is not a problem for the op
as he would likely use it to adjust and then remove for riding

still available as far as i know

https://harriscyclery.net/product/pro...d1409-qc49.htm
https://harriscyclery.net/product/fsa...d4666-qc49.htm
https://harriscyclery.net/product/pro...d9911-qc49.htm

DX-MAN

That link proves that even the late, great Sheldon can have a silly idea from time to time. But, when you've done as much with bikes as Sheldon, did, what else is left?

The star nut is an idea that's been used for a long time; but it can be replaced with a 'Headlock", either from Azonic ($22) or Sette ($12). For those, the star nut must be removed, but they do a BETTER job of holding the works together, IMO. My daughter's AND my nephew's new bikes both have headlocks in them -- I don't have one because I can't right now clear the steerer tube.... The headlocks won't work with this idea, though, since the through-bolts aren't long enough.

1987cp

Hm, Headlock concept looks interesting, but I can see where it'd interfere with attaching racks and fenders (and maybe brakes? LOL) to the fork crown! Still, that arrangement may be quite viable for convenient headset adjustment (as with the "long bolt and some washers" suggestion!). Interesting.


So I guess I probably misunderstood the bike-shop guy; very likely he was trying to fix my misconception that it's at all usual to adjust the headset just by pushing down on the handlebars (as described here).


Thanks for all the helpful replies!

HillRider

OK, I misunderstood your above posting. I thought you were referring to those concentric ramped ring headset adjusters that were available for a time with the Easton Beartrap being the most common.

Those expander plugs you linked to do work and work well and are essential for carbon steerers. There are similar models available for steel steerers too (larger in diameter due to the steel steerer's thinner walls) and they also work but aren't as essential since a starnut won't harm a steel steerer.

onespeedbiker

If the sole purpose of your post is to inquire about the star fangled nut being necessary, then the answer is yes as indicated by the above replies. Yes, there are alternatives, but since you already one installed in your fork, then it makes little sense to switch it out for a different style. If you intent on using a carbon fork, then you will need one of the alternative methods like the expander plugs; other wise you may be looking for solution in search of a problem.

1987cp

The main point was to clarify what the starnut actually does do and doesn't do, and what would be lost if I were to knock it down or out and install a quill stem. One doesn't learn about newfangled technology from riding older bikes with threaded steerers.

Wilfred Laurier

new fangled threadless headsets started showing up on bikes almost twenty years ago
at what point do fangles get old

1987cp

20 years? Wow! Didn't realize my head was that far under a rock! And I'm probably a punk kid compared to some of you. But, my newest previous bike was a 1991 model.

I guess old fangles might include cottered cranks, Ashtabula cranks, 21.1mm stem quills, and 590 and 597mm tires. And 630mm, maybe, though I know there are plenty of folks who like their tires no fatter than 32mm.