db143

Hello all.

Short problem: is the locknut of my headset (threaded) digging into and damaging my quill stem?

Long description: I have noticed that as I ride over bumps (steel frame, 90s campag headset, nitto quill stem) I often hear what can best be described is a "clink" sound of metal on metal coming from the front end. (I also notice this noise on my 70s Peugeot beater and put it down to a quirk of quill stem setups). Upon recently raising the stem on the first bike mentioned, I noticed that there are markings where the headset locknut appears to have dug in to the front of the quill stem. I have scoured the internet and these forums but not found a phrase which describes this so therefore not found any help.

Is it normal for the flexing of the quill stem to bring it into contact unevenly with the locknut, and if so, am I eventually at risk of catastrophic failure of the aluminium quill stem should this contact dig in further and further?

Many thanks in advance.

Rick

That is not normal. Is your quill stem very low were the shape of the stem shaft is not round running into the nut. Is the quill stem or headset loose. Are the headset pressed in cups no longer pressed in tight. How about some pictures. I know you are new so get creative with some posts.

Iride01 

Unless you have an undersized stem for that bike I'd not think that's your issue. Though those type stems do get marred somewhat, but not anything to worry about as far as damaged and unsafe. I'm even wanting to say there were some steering tubes on some that required a slightly smaller diameter on the quill side of the stem. But I may just as well be imagining things again. So if that's your stem, but in the wrong fork and steerer... whoops.

I'm wondering though if you have a loose headset. If you've mucked around loosening and tightening that big nut, then you might have messed up the bearing adjustment.

You do know that big nut does not need to be loosened to remove your stem and visually check for damage..... right?

Mad Honk 

I have thought about this for a few hours and I think you are experiencing what happens with every quill stem. The binder nut is deep inside the steerer tube and the stem is free to move a bit inside the tube and within the diameter of the lock-ring for the head set at the top of the tube. Most every time I remove a quill stem I find a small ring of damage to the stem from flexing due to the movement of the handlebars. I have had racers who threw their weight from side to side when riding and came in complaining that they heard a creaking sound when this happens. It is really from the flexing of the stem at the top of the stem when the stem is anchored at the bottom by a wedge holding the stem in place.
I doubt there is enough damage from this flexing to harm the stem as it is only surface contact between the two surfaces. Smiles, MH

Rolla

Straddle the bike with your feet on the ground, squeeze the front brake lever, and rock the bike forward and back.

1. Does the front end make noise? If so, probably a loose headset.

2. If you put your hand around the top of the headset while you rock it, do you feel it move? If so, definitely a loose headset.

3. Watch the stem quill where it meets the locknut while you rock it. Does it flex enough to bang against the locknut? If so, it's probably the stem. Is the stem inserted past the minimum insertion line?

Andrew R Stewart 

A good term for what I think is happening is "scoring". A scratch or mar from repeated contact. Happens to many quill type stems. BYW quill stems have a minimum amount of their length that needs to remain in the fork. There is usually a stamped indicator mark and/or a "min insertion" reference. About 2.5" is typical. failure to keep enough stem in the fork will result in what this thread has suffered with. Front fork - Bike Forums Andy

db143

Good morning all, and huge thanks for some very thoughtful answers since I've been asleep!

To address some questions:

Rick - Could be the cups - I actually run the quill stem quite high. It's a 190mm nitto. The insertion limit just needs to be below the locknut... right?? (I'll get creative!)

Iride01 - What do you mean by the bearing adjustment? I have tightened the upper threaded race part to a satisfying level (no play but bars turn reasonably) and then tightened down the top locknut. I am a novice but I think I've read that this is correct. When installing and subsequently moving the stem up and down I didn't touch the headset.

Mad honk - thanks for your hours of thought! To be honest this is what I expected. When I first learned how quill stems worked it baffled me that such a crucial point of the bike is held together by a seemingly crude anchor point. Of course I'm aware this has worked troubled free for decades - let's hope you are right.

Rolla - I'm aware of the rocking, wobbling technique, and I believe my headset is tight enough as there's no movement. I can't get the stem to noticeably hit the edge of the locknut like this (your third point). Occasionally, it will have worked itself loose after a ride, though, so I'll investigate this third point again if this happens again.

Andrew - Thanks for the reassurance. I think I am ok on insertion as I there is a min line on the stem and it is nowhere visible when installed.

Thanks again all, pictures will come in due course.

cjenrick

you could put 1/2 a turn of black electrical tape around the front of the stem so that it barely protrudes a few thousandths above the headset nut (don't want people to notice) then ride the bike a bit, then pull the stem and see if there is an indentation or wear mark on the tape. your weight is pushing the stem forward, thus the tape on the front.

if so, then you are probably smacking the stem with the headset nut, what to do next i do not know.

is the wedge rusty? steel on steel can cause rust, maybe clean the fork tube and wedge. scotchbrite , particles could be underneath the wedge causing mis-allinment, but you should be able to eyeball this by seeing if the stem is centered in the headset.

me i screwed up and bought a 21mm stem for a 22mm hole. being cheap and unable to find a 22mm in the same length, i simply shimmed the stem with black tape and try not to sprint like Sagan. seems ok so far,

Iride01 

I was just making certain you didn't think that big nut had to be loosened to remove or install the stem. If you had loosened it in the belief it allowed you to adjust the stem, then your bearings would likely be misadjusted.

The thing about the stem not being inserted far enough into the steerer tube seems to be the question now as another ask. You somewhat addressed that, but seems to gloss over it with your answer. So was or is your stem not inserted far enough to hide the line that marks it's max extension?

190 mm is an abnormally long stem to me. That extra unsupported length would have me worried about it just snapping from fatigue if you ride your bike like a sprinter yanking the bike side to side to get more power to the pedals. But I guess that's not you, is it? For leisurely slow pace it's probably good enough.

But then the question becomes is this really the right frame for you? Wouldn't something with a higher stack be a better fit?

Mr. 66

It does not happen often, I have a bike that the steer tube is not in center with the threads. Making for a situation that I can't install the stem with the headset locknut set. I need it loose to install stem then tighten locknut which scores the stem in the process. At some point I will grind the locknut for clear install.

Ive only heard of one other bike that has this issue.

db143

CJenrick - I like the electrical tape idea. The stem was brand new and the fork was barely used.

Iride01 - The minimum insertion line on the stem is and always has been completely out of sight. In fact, I can't even see it in my adjustments unless I undid the front brake cable, as the stem won't come out that far. And you're right, I'm not a sprinter. I bought the long stem so that I could sit more upright (stiff back, not a racer) without having to lower the saddle (I get knee issues with low saddles). I ride the frame because I like how it looks and it is large. A touch too large, if I'm completely honest.

Mr. 66 - interesting that this is a possibility. Barring the snapping from wrenching the bars that Iride01 suggests, it sounds as though this gentle scoring shouldn't be too much cause for concern.

joeruge

This is out of left-field and quite unlikely. You mentioned your 'beater Peugeot.' Up until about the mid 70's Peugeot, a French bike, used a 22mm quill stem. Most bikes, even back then used 22.2mm stems. Obviously, the Peugeot stem would fit in the place of a 22.2mm stem and the expansion nut or wedge would take up the difference and hold it tight, leaving the top of the stem a little less supported.

Any possibility that over the years you tossed the Peugeot stem into the newer bike?

db143

I appreciate your consideration but this has never happened - the stem in question is brand new nitto bough for my new bike. The peugeot's stem has only come out once for a headset overhaul and went straight back in.

bark_eater 

I've seen this line scored on a lot of old stems. The next one I am tearing down had a score mark on the front side of the quill when I raised the stem. I've been curios about the cause. Im going to look at the alignment of the wedge and the actual diameters of the quill and the the stearer id. The previous owner was a big guy and the bike has steep angles and other signs of being ridden hard. The stem is a budget oem model and the rider could have had a lot of weight on the bars, which would certainly be pushing the stem forward. What I worry about is this being influenced by a loose headset and being an indication of an ovalized headtube. I think most stems could be salvaged by sanding out the scores to limit stress risers.
I'll ad one bit of mechanical trivia. When you have a slip fit of a cylinder in a tube, the longer your over lap, the less posible angle for movement or slop. Quill stems are looser than a slip fit and I am inclined to use a longer quill to get as much bury in the stearer as possible.

thook

many "taller" quills are 180mm. heck...the technomic is 225mm...pretty sure. so, 190's not abnormal. a fellow BF member, merziac (usually over at C&V), runs technomics to max on most of his bikes no prob

db143

That's interesting bark_eater - could you let me know what the result of your investigation is? It sounds a similar situation to mine.

Thanks thook for the reassuring words on longer stems!