Headset constantly coming loose
This one has me stumped. The headset on my bike constantly comes loose. All components are ok and installed correctly.
What happens is, i correctly install the fork, preload the top cap (which takes more tightening than I would like, though the top cap is not hitting the steerer), and it is all solid. I torque up the stem, its all good. Then usually after the first ride, it is all loose again; sometimes i can make it come loose simply by doing the 'hold front brake and rock bike' test. At this point the top cap has magically become very loose, and the spacers can be moved around below the stem.
Its a full carbon fork, and the bearings are all good. My options are;
Replace the expander bung, as it may be that, even though i cant detect movement; have added carbon paste.
Make sure the stem isnt slipping up the steerer even though i am torquing it up (alloy stem onto carbon)
Add another shim underneath the conical spacer, as maybe the split washer thing underneath isnt being driven down far enough into the head tube+bearing to hold everything right
Another thing i note; no matter how hard i tighten the top cap during installation, the steering never binds tight, which i think is a bad sign. Tells me maybe things arent being compressed as they should.
Its a fiddly problem this. Anyone?
What happens is, i correctly install the fork, preload the top cap (which takes more tightening than I would like, though the top cap is not hitting the steerer), and it is all solid. I torque up the stem, its all good. Then usually after the first ride, it is all loose again; sometimes i can make it come loose simply by doing the 'hold front brake and rock bike' test. At this point the top cap has magically become very loose, and the spacers can be moved around below the stem.
Its a full carbon fork, and the bearings are all good. My options are;
Replace the expander bung, as it may be that, even though i cant detect movement; have added carbon paste.
Make sure the stem isnt slipping up the steerer even though i am torquing it up (alloy stem onto carbon)
Add another shim underneath the conical spacer, as maybe the split washer thing underneath isnt being driven down far enough into the head tube+bearing to hold everything right
Another thing i note; no matter how hard i tighten the top cap during installation, the steering never binds tight, which i think is a bad sign. Tells me maybe things arent being compressed as they should.
Its a fiddly problem this. Anyone?
0
Posts
You can either chop down the steerer a bit more or if not possible just slip a 2mm or so spacer under the top cap: no need to put something huge under there because you already have part of a gap under the top cap.
De Sisti wrote:
This is one of the silliest threads I've come across.
Recognition at last Matthew, well done!, a justified honour
There is no secret ingredient - Kung Fu Panda
London Calling on Facebook
Parktools
I think its an fsa, as the top cap and spacers are all fsa. When i checked it, the part that you refer to had indeed dropped clear of the threads; i have rectified it now, but oddly i dont think thats the issue. I note that the expander isnt knurled so it may slip, and even a quarter of a mm would be enough to make the headset go loose i think.
There is about 5mm of spacer under the top cap; I did that deliberately to remove that as a potential issue
I wonder if maybe there is residual grease on the steerer where the stem grips it, which i need to completely remove....?
I have never tried to tighten the top cap until the steering binds. That sounds like a real bad idea but with bearings in good condition I would not think it was possible.
Exactly; thats the.thing, you Should be able to overdo the top cap, so that the fork wont turn freely, from which point you can then work out how far to back it pff again.
You cant do that with my bike!
So, the bung is slipping or the stem is slipping, or both.
You guys are not getting your heads around the mechanics of how this headset system works.
the topcap/bolt/bung set preload, but it's the stem holds things in place
barring something broken, or incorrectly installed, the problem is that the stem is slipping
remove stem, degrease clamping surfaces of stem and steerer, refit, set preload, clamp stem
fwiw i use 6Nm on stem bolts, but different stems may need different torque
Many manufacturers like you to leave the bung in too, especially if it's a carbon steerer. It gives some extra support to the steerer tube in case of stem overtightening as may well happen here given some of the advice above. We used to remove them in the olden days to save some weight which seems comical now, along with drilling holes in everything
+1, highly recommend you check this. I have had this problem and it took two shop visits to work it out. steering was "interesting"
This is a different issue and is the bung not gripping tightly enough. Not a good idea to overtighten the top cap too much as you could damage the bearings.
Marin Nail Trail
Cotic Solaris
Invariably this is the issue/solution in my experience.
Guys like you are so funny. Idiot.
I will not comment as to whether dennisn is an idiot or not but he does have a valid point.
Bikes: Donhou DSS4 Custom | Condor Italia RC | Gios Megalite | Dolan Preffisio | Giant Bowery '76
Instagram: https://www.instagram.com/ben_h_ppcc/
Flickr: https://www.flickr.com/photos/143173475@N05/
If you follow bike radar forum much you'll see this all the time. "I just bought a new blah blah model blah 1000, did all the work myself, followed all the instructions perfectly, doesn't work, must be faulty parts." Not trying to brag but I've been around a while and I've met plenty of people who, even with the proper tools, let alone the wrong ones, just aren't capable of doing a mechanical or electrical job correctly. How many times on this forum have you heard someone advise another that "No, all you need to build a wheel is an old fork, a spoke wrench, and a good ear. All that fancy stuff is just fluff." Sure, you can BUILD one that way. Having any trust in it is another story. Nothing wrong with trying your hand at things but resign yourself to the fact that if YOU did it and it doesn't work, it's most likely your fault.
You might be right, but you still come across as a right pedantic smartarse with nothing constructive to add. Some kind of weird forum troll. I came asking for help, and the best you could do is snipe at my words. I dont remember the part where you suggested constructively how i might fix my problem.
Just stick another (or bigger) spacer on top to test it.
In the second paragraph of the opening post the OP says,"I torque up the stem, its all good".I assume this is correct and the OP is not talking rubbish.
Therefore there is no problem with spacers , the bung or the top cap.The top cap and the bung have done their job.
If he had a problem with the spacers,the bung or the top cap it would not be possible to adjust it and it could never be "all good".
This really is simple!
The other 5% are "mechanics errors" , like lower race not being in place 100%, wrong model of bearings, steerer top too high, centering ring damaged or similar.
Not a shadow of rocket science...