Redbullet

Thanks.
No. My steerer is under built. It is a 6.5kg bike L size, with some weight savings coming from very light frame and fork. The expander is thick and correctly installed and the torque was always 5Nm - max allowed. I can see some pressure signs on it at the level of stem edge, which means that the steerer bents imperceptible under the forces.

That would result in longer reach, which my back and arms can not manage for a 2-3 hrs ride...

SoSmellyAir

All the more reason not to add adapters and shims.

Assuming that your current stem rises from back to front, and has certain length L and a certain angle A, which give you both a horizonal distance X and a vertical distance Y to your handlebar. With a new stem, keeping L the same and increasing A (to increase rise), the horizonal distance X decreases while the vertical distance Y increases. This should allow you to install the new stem at a lower spot on the steerer, because that lower spot is also further from you. What length you need depends on the stem angle and how much lower on the steerer you want to go. Use the stem comparison tool posted above to figure out unless you want to do the trigonometry yourself.

Redbullet

If that tool correctly calculates, considering available angles of stems similar to mine, it would mean increasing angle from 6 to 17 degrees in order to decrease spacers height from 30 to 15 mm. I don't know, I'll think about...
Thanks.

squirtdad

pictures of the actual stem and steerer and damage will be much more helpful than drawings

delbiker1 

I wish you well.

Redbullet

I should disassemble the system I am not sure that I can take such a quality picture to show a dent of 0.1 mm, but "rm-rf" posted a link above with the general issue. My issue is very similar with the one in picture below, with the main difference that the dent is much smaller at this moment. It only appears at the contact with bottom edge of the stem.
Thanks
.

Iride01 

What's this that looks like a crack? Maybe you should go to a bike shop and get some one's opinion that can examine it closer than any of us can.

Redbullet

No, that one is missing in my case. I only have the shape of the stem sculpted, only at the bottom edge of the stem and only in front of the steerer. One shape of 0.1mm depth made during the period when the spacers height was 35mm. A second similar shape but only as a scratch now lower down, made last year after I removed a 5mm spacer. I intend to stop it to evolve, otherwise it will continue to dig until it will compromise the steerer.

Thanks

Camilo

In other words, it is irrelevant. Please post a damn photo of your issue if you want meaningful help. Otherwise there's nothing to be said, imho.

Redbullet

Ok, I disassembled for pictures.
- 3 pictures (taken from right, front and left).
The arrow above shows the mark of stem bottom edge when I had 35mm spacers. The arrow below shows the new scratch after I removed one spacer of 5mm. Steerer diameter front - back in the section marked with a red point (between the arrow above and the circular mark of the stem), is with 0.1-0.13 mm smaller than the diameter left-right measured in the same section. It is smaller with roughly the same amount than the diameter measured in other sections.
- 1 picture of the compression plug: the top edge stays around 0.5-1 mm below steerer edge. The bottom edge of the ACTIVE part stays around 3-5 mm below the region of stem edge.

Thanks.

Iride01 

Is the clamp on the stem rough around the edges and around the hole where the actual stem meets the clamp part of it? That's about all I can think of to explain the curved marks. Some almost a complete circle. My Specialized and Easton stems are pretty smooth and rounded edges in those areas of the clamp. They haven't made marks like that on my steerer tube.

Even so, I still say take it and let someone experienced see it in person.

Redbullet

No, the stem edges are not quite sharp, it is brand stem - Ritchey. I am sure that the reason of the issue is the high flex of the steerer forward, during stand-up pedaling and strong brake on descents. The flex is aggravated by big height of the spacers - 35 and then 30 mm. Also by the fact that fork and frame have minimum material - it is rated as 6.5kg bike overall and it probably really is below 7kg without pedals. I'm pretty sure that it is not yet catastrophic especially that the new marks with 30mm spacers are only scratches. But I think I should protect and reinforce the steerer somehow, before it goes too bad. Removing most of the spacers is a technical solution, but I can't face a very big drop to handlebars...

Iride01 

You had 65 mm of spacers under that stem? Geesh! You really need to get a different model bike with a higher frame stack, IMO.

Now that you've gotten the pictures for us, let us know what the guy at the bike shop says after they look at it in person.

There is still too much here to digest and is probably yet unknown to us to render a decision. Other than currently, I'd say don't ride it and that you might want another fork that has a steerer in better shape. Though I'd definitely yield to the opinion of someone that can see it in person.

Others might disagree and that's okay.

Redbullet

No, I said I had 35mm and got this issue within around 3 years - some 25000+ km. Then I reduced to 30mm and I got some new scratches within around 1 year - some 5000-10000 km, but it looks to me that the new scratches will transform in a new similar issue and I want to avoid it.
65 was 6.5 and it was kg - the rated weight of the bike.
I don't really think I can get a valuable advice from the bike shop. I bought the bike over the internet directly from the producer, well known in the "second tier" level. Just changing to a new fork is not a solution, as it will probably evolve in the same way...

squirtdad

picture help..... it seems like the whole for the stem making marks on the steerer ( ovale/circle) this is past my hands on experience, but it almost looks like the steerer expanded into the stem.

So only thing i can add are a couple of questions, that I don't think I saw details on

1) was torque wrench used and torque at spec for the installation of the compression plug?
2) was torque wrench used and torque at spec for the stem pinch bolts?

Camilo

The picture helps.

You know, 30 and 35mm of spacers is not unusual. Yeah, maybe for racers. but a lot of (most?) cyclists use 30-35, even 40 (which is the maximum I've seen spec'd for a CF steer tube). I really don't think the spacer height is the problem, especially since it happened again with 30. I would bet good money that if a fork manufacturer spec's 35mm, it's well within engineered safety, probably significantly below. I'd look for another cause.

Andrew R Stewart 

This, as I tried to say before. The photos sure look like the steerer is being compressed by the stem. Were it only a rocking action the lower marks would be far deeper than the upper ones. To also pull up on the bars with similar force as they see when you ride over a bump is asking a lot from a human body.

I forget how old the bike is, this is one reason why forks are becoming a component and no longer considered a frame WRT warranties by many brands.

I have some conflict with this situation. The proactive will either monitor the steerer often (with all the effort to see it as frequently as your risk management says is acceptable) or replace the fork. Others will do as they wish, and pay those "costs" if they don't sell the bike first. There are a few applications of carbon construction which I don't agree with and steerers are one. Andy

Redbullet

Thanks.
Lower marks are deeper: the difference of 0.1-0.13 mm in diameter exists only at the level of the red point, generated during previous period of using 35mm of spacers, 3-4 years / 25000 km. Upper marks are scratches, there is no decrease in diameter. Lowest marks are also scratches for the moment and were generated within 1-1.5 years / approx 10000 km with 30mm spacers. Torque was always 5Nm, for plug and for stem. The plug was the first tightened and the stem was the second.

Since normal maintenance or costs and hassle of sending the bike abroad to producer for a new fork would not eliminate the reason of the issue, I want to make a change. I am tented to proceed with changing of the stem from 28.5 to 31.8 mm clamping and use aluminum shim adapters that go down 1-2 cm below the stem edge. That would distribute clamping forces to a much larger area of the steerer, see the sketch at the 22nd post in this thread.
But I am wondering whether the stem might easily slip at 5Nm torque in this setup, since I shall have 2 surfaces of friction instead of one: one between the stem and adapters and another between the adapters and the steerer. I also wonder whether some other issues (unidentified by me) might be generated by this change...

Camilo

Why would you have to send the bike abroad to get a new fork? Why not just buy an aftermarket fork that is similar in axle-crown length and rake? They're readily available.

You're talking about the connection between the stem and the steer tube, not the stem and the handlebars. If you do what you're thinking of, you will experience no slippage unless you hold the front wheel with your knees and forcefully twist the handlebar side to side - this is how you'd test it. And I'll bet it wouldn't slip at all. Certainly won't slip just riding. There is little or no force exerted on the handlebars when turning the bike and therefore virtually no force causing slippage in that plane. Even so, if it would slip, it would slip slightly and not dangerously. But, just put gritty assembly paste between the inside of the shim and the steer tube as well as between the outside of the shim and the stem. I have done this and there is no slippage at 5nm bolt torque.

Now, if you were talking about shimming up a small diameter handlebar to a larger diameter stem clamp (which I have done), the chance of slippage would be greater and more dangerous. This is because, especially in the drops, but also on the hoods, you are forcing the bars downward just because of your body weight, exacerbated when you go over a bump. This can slip, for sure, and if it does, could be catastrophic. But again, using gritty assembly paste eliminates this, and you can test ahead of time by forcefully pushing down on the drops or the hoods.

rm -rf

Your steerer photos look okay to me. The carbon doesn't look damaged. But it's hard to see in photos compared to in person.
I think your nice lightweight steerer is way more reflective than my standard carbon steerer, that shiny surface makes it look worse than it is?

I don't use the full 5 nm torque on my stem. It holds fine at a range of around 3.5 nm to 4 or so. I have a 20mm of spacers below, and 5mm above the stem.

Sonofamechanic 

1) shimming a steerer tube is often done when putting 1 1/8” stem on a 1” steerer tube—and its a cheap fix, so I think its a smart solution. An aluminum shim will help spread the load. Jus tighten it all up to spec and see if it slips when you hold the front wheel in place and pull on the handlebars. 2) your pics if the fork steerer tube look like you caught it in time—not too much grooving to worry over. I saw your other post asking about a new fork but I don’t think you should give up on this one just yet—it looks like a great fork. 3) a couple of commenters have mentioned you could try dropping the stem lower (fewer spacers below) and make up for the ‘lost’ height by getting a steeper stem…you seem to have passed up on that suggestion a bit too quickly in my opinion—its a good and practical solution to reducing the torsion on your steerer. When you get your 31.8 clamp stem, get it with a steeper angle at the same time—double up on your solution.

Redbullet

Thanks.

I am balancing between a new fork and preserving the actual… But what about the mark at the contact with headset? Wall thickness here was reduced with 0.1-0.15mm.
If this does not mean critical reduction in resistance, I could cover the area with a thin layer of epoxy. Not to increase resistance, but only to protect against further reduction of wall thickness…

Sonofamechanic 

Good concern to have—IF (per your drawings above and earlier posts) that wear mark is under your stem’s clamp area (so ABOVE your headset bearings) then your stem contact area is big enough that a narrow depression like that is manageable—there are stems out there with much lower stack heights (and thus contact area) than the one you have and they still manage just fine. But if (as I’m reading your latest post above) the wear mark is IN the headset area, that’s a whole different issue as your headset bearing (race) would be what wore that groove and will no longer be tight to your fork—you’d have a gap (‘slop’) in your top bearing area. No epoxy will help there as it would wear out faster than the carbon before it. That’s a much more difficult issue to solve for—the most direct solution would be to go with a different fork. Since your preferred set up is putting so much torsion on this, maybe opt for an aluminum steerer in the replacement fork?

Redbullet

Sorry for insisting, it looks that I just start to learn some things about the forks and headsets .
The part in the photo below is the one that grove in the fork at that level - I understand it is named "headset bearing (race)". In my case id does not stay tight, it has a very small play if you put it anywhere along the steerer (even at 28.6 mm diameter, not only in affected area). I can't see how it can be tightened to the fork, especially that it has a cut as shown by the arrow, which prevents it to be really tightened. So: is it normal that the headset bearing (race) to rotate free around the fork?

Thanks

Sonofamechanic 

ok—got it! That helps explain things!
1) what you have there is not the bearing race but is the collar that needs to be pressed down from the top firmly between the bearing and the steerer tube to ‘fill in’ any gap between them—if you don’t/didn’t do this then that would leave it loose to slide around and completely explains the groove that you have! No problem—that’s an easy fix… 2) the ‘cut’ as you call it is there so that as you push the collar down it can wedge in tight and constrict (get smaller) around the steerer tube. So as you push it down you will see that ‘cut’/gap get narrower. 3) So!…put your fork back on and tap that collar down into place (you can see how it slides in and tightens up) and then put on your stem (if you put spacers in first, make sure they are narrow/thin enough to ONLY touch that collar and not the bearing—you want those spacers to push that collar down into place ( to “seat” the collar). 4) Before you tighten the stem bolts, install and tighten your steerer (expander) bolt—that will ‘pull’ the stem (and spacers) down and push the collar tightly into place. THEN you tighten the bolts on the stem.

>>given the fork steerer wear, etc, your smartest move is to take this to your local bike mechanic to show you how to do what I’ve outlined above (once you see it done it will make sense). He/She may say you need a new fork—maybe you do, maybe you don’t—but have them show you how to do it regardless of that. IF that was loose that would explain most of your issues!