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Evolution of the Humble Steering Tube Plug

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Evolution of the Humble Steering Tube Plug

Old 03-21-23, 05:11 PM
  #26  
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Originally Posted by SoSmellyAir View Post
If I understand you correctly, you have filled the entire internal volume at the top of your steerer down to the bottom of the stem clamp with epoxy and embedded a star nut (with its OD ground down) at the bottom of this epoxy cylinder, which is supported by a rubber plug. Do you then drill a hole through the axis of this epoxy cylinder so that you can thread a top cover bolt through the embedded star nut? How to set preload?
I screw a bolt that is covered with a plastic drinking straw or heat shrink tubing, into the star nut, before filling with epoxy. I slather the star nut first, insert the bolt and star nut, the add more to fill completely.

Preload is no different than an expanding plug. The top cap can't bottom out on the epoxy. I've had to use a countersink bit to add a bit of clearance.
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Old 03-21-23, 08:05 PM
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It is worth noting that no matter what sort of glue-in system you use (including the factory Cervelo alloy tubes), that you MUST let the epoxy cure with the stem loose. The clamping force does shrink the inner and outer diameter of the steerer tube, and when you loosen the stem bolts the steerer will expand and break the bond.

I experienced this with my first homemade plug and then saw it later when I started working in a Cervelo shop.

If you are doing the DaveSSS method, another approach is to use a long bolt with cap, grease the threads and screw it into the trimmed down starnut. Put the foam in the steerer, pour some epoxy, then insert the starnut assembly and pour the rest of the epoxy around the bolt with the cap held high. When you're you're several MM from the top, stop pouring an lower the also greased cap to the steerer to keep the bolt centered. When cured, the greased bolt is simply unscrewed from the starnut and the epoxy that formed threads around it. The threads in the epoxy aren't strong, but they don't need to be. The starnut will to do the work. You could add sawdust, chopped carbon, cotton or the like to the last epoxy poured if you want to decrease the weight.

Remember to sand and degrease the inside of the steerer to start.
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Old 03-22-23, 07:19 AM
  #28  
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It's easiest to do the epoxy plug during the initial build, before integrated bars and brake hoses are all in, but I just did it with the stem on, but of course loosened up. I masked off the stem, but its still hard to keep JB Weld epoxy off the top of the steering tube and the 1mm of exposed stem ID. I like to mask off the bolt so it drops right in, down to the star nut. For a 40mm depth, I mix about 35 grams of epoxy and don't use it all.

The bike also needs to be propped up so the steered is plumb.
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Old 03-22-23, 10:14 AM
  #29  
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You can always go with one of these: https://www.fairwheelbikes.com/extra...nder-plug.html
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Old 03-22-23, 10:18 AM
  #30  
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Originally Posted by Kontact View Post
In my experience the cap itself helps prevent creep of the stem that is tightened to only 5nm. It probably shouldn't work that way, but they do.

I’ve had mixed expereince with this. My mtb has the expander and top bolt completely removed, to facilitate the di2 wiring. That headset has never come loose.

We had a co-motion however that used an expoxied in sleeve in the steerer tube. That headset would never stay tight. Turned out the glue had failed, re glued and the headset stayed tight. So on that bike at least the top bolt was helping to keep the right load on the headset.
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Old 03-22-23, 05:13 PM
  #31  
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Originally Posted by merlinextraligh View Post
Iíve had mixed expereince with this. My mtb has the expander and top bolt completely removed, to facilitate the di2 wiring. That headset has never come loose.

We had a co-motion however that used an epoxied in sleeve in the steerer tube. That headset would never stay tight. Turned out the glue had failed, re glued and the headset stayed tight. So on that bike at least the top bolt was helping to keep the right load on the headset.
Assuming your MTB has a carbon steerer, I wonder if the current short stems make the forces neutral, while road bars and stems act as levers, inching up the steerer.

Last edited by Kontact; 03-22-23 at 09:55 PM.
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Old 03-24-23, 09:16 PM
  #32  
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Originally Posted by DaveSSS View Post
I have a picture from several years ago in my album, but I can't figure out how to add it to a post.
This one?

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Old 03-25-23, 07:01 AM
  #33  
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That's my picture. I used a countersink bit to add clearance for the top cap. This one probably used core foam to plug the steering tube and a 6mm thread insert that's normally used to add threads to wood, rather than a star nut. It's more difficult to get centered.
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Old 03-25-23, 10:04 AM
  #34  
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Originally Posted by DaveSSS View Post
That's my picture. I used a countersink bit to add clearance for the top cap. This one probably used core foam to plug the steering tube and a 6mm thread insert that's normally used to add threads to wood, rather than a star nut. It's more difficult to get centered.
To each his own, but that seems to be a rather elaborate and labor intensive solution to provide something as simple as bearing preload.
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Old 03-25-23, 02:43 PM
  #35  
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Originally Posted by terrymorse View Post
To each his own, but that seems to be a rather elaborate and labor intensive solution to provide something as simple as bearing preload.
Yes, it appears to be a somewhat labor intensive solution to a problem that doesn't exist.
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Old 03-25-23, 02:58 PM
  #36  
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There are people who have cracked the top of a steering tube, hence the suggestion to use a 5mm spacer and extend the steerer 2-3mm above the stem. There are also those who worry about over tightening the expanding plug, or leaving it too loose and slipping. The newest plugs sit on top of the steerer and force the use of a spacer on top. I like no spacer above the stem. This solves all of those problems. It might take 30 minutes to do, but I find it worthwhile. To each his own.

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Old 03-25-23, 04:04 PM
  #37  
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Originally Posted by tomato coupe View Post
Yes, it appears to be a somewhat labor intensive solution to a problem that doesn't exist.
It never can get loose and it can be lighter.

Not much labor. And it's cheap. The quick and dirty version would take 10 minutes to execute if you know what you're doing.
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Old 03-25-23, 10:08 PM
  #38  
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Originally Posted by Kontact View Post
It never can get loose and it can be lighter.

Not much labor. And it's cheap. The quick and dirty version would take 10 minutes to execute if you know what you're doing.
A bog-standard Wolf Tooth compression plug costs $15 and weighs 26 g. A plug of epoxy with the same dimensions weighs about 16 g, not including a threaded insert or star nut. Not much of a weight or cost savings, if any ...
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Old 03-26-23, 08:08 AM
  #39  
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I don't do this to save weight. I've used this same technique to extend the length of a steering tube by 10-15mm. 20mm would be stretching it. All you do is use a no-stop copper tube coupling, for 1 inch pipe that has an ID of 1-1/8. Lightly grease the ID of the coupling, slide it over the steering tube and tape it so it doesn't slide down. Fill with JB Weld epoxy and allow to cure.

I did this only once on a LOOK KG461. I rode it many thousands of miles with no problems.

Now you have fuel for more whining.
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Old 03-26-23, 08:33 AM
  #40  
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Originally Posted by DaveSSS View Post
I don't do this to save weight. I've used this same technique to extend the length of a steering tube by 10-15mm. 20mm would be stretching it. All you do is use a no-stop copper tube coupling, for 1 inch pipe that has an ID of 1-1/8. Lightly grease the ID of the coupling, slide it over the steering tube and tape it so it doesn't slide down. Fill with JB Weld epoxy and allow to cure.

I did this only once on a LOOK KG461. I rode it many thousands of miles with no problems.

Now you have fuel for more whining.
So, you used it once to extend the length. Why did you do it all the other times?
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Old 03-26-23, 09:06 AM
  #41  
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Originally Posted by tomato coupe View Post
A bog-standard Wolf Tooth compression plug costs $15 and weighs 26 g. A plug of epoxy with the same dimensions weighs about 16 g, not including a threaded insert or star nut. Not much of a weight or cost savings, if any ...
The ones I did were in 1 inch steerers where there were fewer plug selections.

10 grams seems like a very small number, but that's 10 grams for free. Compare that to most of the things people put on their bikes to save weight or decrease drag and it seem like a no-brainer.

No one is suggesting everyone should glue in their plug. But no one has really made an argument for not gluing it in.
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Old 03-26-23, 09:18 AM
  #42  
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Originally Posted by Kontact View Post
No one is suggesting everyone should glue in their plug. But no one has really made an argument for not gluing it in.
Itís not about making an argument against it, itís simply questioning why go to the trouble when there are easier solutions.
Originally Posted by terrymorse View Post
To each his own, but that seems to be a rather elaborate and labor intensive solution to provide something as simple as bearing preload.
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Old 03-26-23, 09:27 AM
  #43  
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Originally Posted by tomato coupe View Post
Itís not about making an argument against it, itís simply questioning why go to the trouble when there are easier solutions.
As previously stated: It is more reliable, lighter, reinforces the steerer tube, sometimes easier to source and really so little labor that calling it "labor intensive" is a bit ridiculous.

Do it, don't do it, whatever. If my headset works loose, I like knowing that I don't have guess whether the expansion plug slipped. (But it never gets loose.)
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Old 03-26-23, 09:36 AM
  #44  
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Reasons to do it:

1. Can't be over or under tightened.
2. Won't slip.
3. No 5mm spacer above stem needed.

This has all been stated before. Short memory?
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Old 03-26-23, 09:42 AM
  #45  
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Originally Posted by merlinextraligh View Post
You can always go with one of these: https://www.fairwheelbikes.com/extra...nder-plug.html
I had one of those. At recommended torque the steer tube bulged just enough that the stem wouldn't install with out extra, extra loosening the fixing bolts. Then for bike build reasons (trim extra steer tube length) I removed & replaced it. On the second application it self destructed at 4-5nm of applied torque.

I can think of a few confounding factors like maybe the presence of anti-seize on the threads acting like a lubricant or maybe a questionable torque wrench or limited duty cycles, or whatever...I think the lesson here is steer tubes are thin & extra support to keep inside/outside forces balanced on the steer tube is hardly a bad idea.

I have another one that came with another headset. I don't have any plans to use it on a unsleeved carbon steerer any time soon. The bulge in the steer tube from a 5mm tall plug, to me, says that there is too much force in too small of an area. A taller plug would have the same grip at a lower pressure over a larger area. Had I not hade a component failure following instructions & using proper tools & witnessed such obvious structural stress to the steer tube, maybe I'd have more confidence.
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Old 03-26-23, 10:08 AM
  #46  
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Originally Posted by DaveSSS View Post
Reasons to do it:

1. Can't be over or under tightened.
2. Won't slip.
3. No 5mm spacer above stem needed.

This has all been stated before. Short memory?
1 and 2 arenít really an issue for compression plugs (assuming you have some minimal mechanical aptitude), so it seems youíre mainly motivated to get rid of that 5mm spacer. What is the advantage of eliminating the spacer?
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Old 03-26-23, 10:37 AM
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Originally Posted by tomato coupe View Post
1 and 2 arenít really an issue for compression plugs (assuming you have some minimal mechanical aptitude), so it seems youíre mainly motivated to get rid of that 5mm spacer. What is the advantage of eliminating the spacer?
1. Aesthetics.
2. The stack limitations imposed by a previously cut steerer.
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Old 03-26-23, 10:52 AM
  #48  
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Originally Posted by Kontact View Post
1. Aesthetics.
2. The stack limitations imposed by a previously cut steerer.
You can't argue with aesthetics, if that's the motivation. But, the limitations from a pre-cut steerer tube are kind of throwing spaghetti at the wall. The 5mm spacer is only needed to accommodate 3mm of steerer tube that extends above the stem. With an epoxy plug, you could make the steerer tube flush with the top of the stem, and you'd gain 3mm of stack. That's a difference very few people would even notice, and it's a very low probability scenario.

Last edited by tomato coupe; 03-26-23 at 11:00 AM. Reason: typo
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Old 03-26-23, 11:07 AM
  #49  
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Originally Posted by tomato coupe View Post
It’s not about making an argument against [epoxy-affixed compression plug], it’s simply questioning why go to the trouble when there are easier solutions.
I have one problem with any epoxy method: it's permanent.

I have an aversion to anything that can't be unbolted, removed, and replaced. Stuff happens.

Originally Posted by base2 View Post
I had one of those [ultra-light compression plugs]. At recommended torque the steer tube bulged just enough that the stem wouldn't install with out extra, extra loosening the fixing bolts.
You can see that bulging of the steering tube with the more substantial compression plugs, too. Although it may seem that steering tubes are rigid, they are flexible. Everything flexes under load.
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Old 03-26-23, 11:29 AM
  #50  
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Originally Posted by terrymorse View Post
Why don't carbon seatposts come with compression plugs? They are:
  1. about the same thickness as a steering tube,
  2. clamped more tightly with the seatpost clamp,
  3. are subjected to much more stress during use.
Well this could have something to do with the fact that a broken steerer has the potential to be much more lethal than a broken seatpost.

Originally Posted by znomit View Post
Thats the whole point. The star nut is part of a calibration tool that is typically used a few times in the life of a bike.
BUT YOU CARRY IT UP EVERY STUPID HILL.
And they weigh soooooooooooo much.

Originally Posted by Kontact View Post
It never can get loose and it can be lighter.
Oh FFS, how much does an expander plug weigh?

Originally Posted by Kontact View Post
1. Aesthetics.
Yeah, everybody is looking at my extra spacer.

Originally Posted by Kontact View Post
2. The stack limitations imposed by a previously cut steerer.
Stack limitations are made for specific steerers regardless. The fork on the bike I'm currently building says no more than 35mm of spacers under the stem. So you're saying I can have more spacers under my stem with your method? I certainly wouldn't mind being higher up, but have to question the safety.

Last edited by Lombard; 03-26-23 at 12:22 PM.
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