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Explain Like I'm 5: Don't I need a compression plug to oppose the stem bolt forces?

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Explain Like I'm 5: Don't I need a compression plug to oppose the stem bolt forces?

Old 09-20-19, 02:34 AM
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Pulsify
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Explain Like I'm 5: Don't I need a compression plug to oppose the stem bolt forces?





I'm 3 years new to cycling. I've had this bike (Canyon Endurace AL Disc 7.0) for 1 year with NO problems. I have, however, been doing some research and it seems like compression plugs are very much recommended for carbon steerers, as they provide a necessary opposing force to the stem bolts, thus preventing carbon crimping/failure over time. In fact, it seems that compression plugs that cover the entirety of the steerer (in this case 40mm in length) seem pretty standard on bikes. It doesn't look like Canyon ships their bikes with these plugs; they just come with this short (15mm) wedge at the bottom of the steerer that is only good for loading the bearings through tightening the stem cap. I'd like my carbon steerer to be safe. Should I remove this 15mm wedge and replace it with a 40+mm compression plug that covers the length of the stem and stem bolts? Something like this?: https://www.pro-bikegear.com/global/...RO_HS_GAPEXPAN

Thanks in advance.

Thanks

P.S. please correct me if I'm wrong with any of this...

Last edited by Pulsify; 09-20-19 at 03:03 AM.
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Old 09-20-19, 02:56 AM
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znomit
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Since you're 5...
  • The grown ups that built the bike probably know what they were doing
  • You're going to outgrow that bike in 6 weeks anyway so time to buy another.
  • If you have a torque wrench and know how to use it you probably aren't going to squish that carbon tube anytime soon.
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Old 09-20-19, 06:12 AM
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Originally Posted by znomit View Post
Since you're 5...
  • The grown ups that built the bike probably know what they were doing
  • You're going to outgrow that bike in 6 weeks anyway so time to buy another.
  • If you have a torque wrench and know how to use it you probably aren't going to squish that carbon tube anytime soon.
This is all accurate.

However, I believe in better safe than sorry, and if a compression plug can add additional support and strength and reduce the risk of a snapped steer tube, then I'm all for having one in there.
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Old 09-20-19, 07:42 AM
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There's also the option to remove that big spacer stack and what I assume is a -17º stem, and replace the lot with like a -5º or -6º stem right on top of the headset cap, which would put the bars in about the same place. Then the stem would be right over the expander.
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Old 09-20-19, 07:50 AM
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I confess to this form of weenie anxiety too. My Cervélo came with only a star nut.
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Old 09-20-19, 07:58 AM
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Timely thread considering the CF steerer/fork failure that is being talked about.
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Old 09-20-19, 08:08 AM
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Originally Posted by DrIsotope View Post
There's also the option to remove that big spacer stack and what I assume is a -17º stem, and replace the lot with like a -5º or -6º stem right on top of the headset cap, which would put the bars in about the same place. Then the stem would be right over the expander.
That's a good tip. With the stem lower on the steerer, it will also have less leverage to exert -- meaning the steer tube will experience less stress.

I think any compression plug is helpful, and buttresses the steerer pretty well if it's somewhere in the range where the stem clamps.

Make sure a carbon steerer is cut well with a good carbon saw, and there's no excessive clamping during the cut. I'm convinced some of these get cracked before they're ever ridden because someone clamps down the cutting guide like they're about to saw a 2x4.
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Old 09-20-19, 08:38 AM
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I wouldn't worry at all if your bike came factory set up like this. The video does also specify that if your bike didn't come with one, it's because it don't need one (which is logical, otherwise you would have one). I'd trust your manufacturer; its engineers are a little more educated than we are.

It's also funny how the guy in the video doesn't use a torque wrench. May be that's because the plug prevents the overtightening. Still, I would use one...

Last edited by eduskator; 09-20-19 at 08:44 AM.
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Old 09-20-19, 09:04 AM
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Where is the top cap? Does it have an extended length that fits snugly in the steerer tube? That provides the support needed as well and adds to the 15mm of the compression plug
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Old 09-20-19, 09:22 AM
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Originally Posted by Pulsify View Post
it seems like compression plugs are very much recommended for carbon steerers, as they provide a necessary opposing force to the stem bolts, thus preventing carbon crimping/failure over time.
It seems this compression plug-opposing force-carbon failure jibber jabber is just one more myth being passed around by the uninformed.

Try to find a statement from a manufacturer that specifies using one of these full length compression plugs. Go ahead. I've searched for years for such a statement and have come up empty handed.

If the manufacturers aren't publicizing compression plug warnings, a safe conclusion is that it's a made up myth.
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Old 09-20-19, 09:25 AM
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People have a lot of anxiety about this.

The handlebars and seat tube don't have compression plugs in them, and nobody seems to mind.
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Old 09-20-19, 09:49 AM
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Originally Posted by Seattle Forrest View Post
People have a lot of anxiety about this.

The handlebars and seat tube don't have compression plugs in them, and nobody seems to mind.
Stop with the micro-aggressions! I’m anxious about all that stuff.
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Old 09-20-19, 09:54 AM
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Originally Posted by Seattle Forrest View Post
The handlebars and seat tube don't have compression plugs in them, and nobody seems to mind.
Now you've done it.

Everyone, prepare yourselves emotionally for the new products that promise to keep your bars and and seat posts from "asploding".

Last edited by terrymorse; 09-20-19 at 03:22 PM.
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Old 09-20-19, 10:03 AM
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"asploding" really? I guess we are all just 5 yr olds
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Old 09-20-19, 10:49 AM
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Go ask your mother.............
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Old 09-20-19, 11:05 AM
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Could someone please link this/combine with the recent steerer tube asplosion video?
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Old 09-20-19, 11:07 AM
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Originally Posted by datlas View Post
Could someone please link this/combine with the recent steerer tube asplosion video?
https://www.youtube.com/watch?v=NQJU...od6KOUTZhHwTt8
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Old 09-20-19, 11:33 AM
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Originally Posted by Bigbus View Post
"asploding" really? I guess we are all just 5 yr olds
This forum is older than spell check, which gave us asploding frames from massive guads.
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Old 09-20-19, 11:36 AM
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Originally Posted by Seattle Forrest View Post
This forum is older than spell check, which gave us asploding frames from massive guads.
Not to mention droped hamers.
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Old 09-20-19, 11:51 AM
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Originally Posted by datlas View Post
Not to mention droped hamers.
With disc breaks and peddles
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Old 09-20-19, 12:34 PM
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Originally Posted by redlude97 View Post
Where is the top cap? Does it have an extended length that fits snugly in the steerer tube? That provides the support needed as well and adds to the 15mm of the compression plug
The top cap has no utility at all once the stem bolts are tighten to the proper torque... It can technically be removed. Your fork tube will not asplode if ridden without (your head might though if you continue overthinking the whole thing).

Last edited by eduskator; 09-20-19 at 12:41 PM.
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Old 09-20-19, 12:39 PM
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Originally Posted by eduskator View Post
The top cap has no utility at all once the stem bolts are tighten to the proper torque... It can technically be removed. Your fork tube will not asplode if ridden without.
the top cap used with those types of carbon steerer compression tubes prevent the tube from deforming on the open end where cracking generally occurs, it is necessary for proper function of the compression plug design
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Old 09-20-19, 01:10 PM
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Originally Posted by eduskator View Post
The top cap has no utility at all once the stem bolts are tighten to the proper torque... It can technically be removed. Your fork tube will not asplode if ridden without (your head might though if you continue overthinking the whole thing).
Originally Posted by redlude97 View Post
the top cap used with those types of carbon steerer compression tubes prevent the tube from deforming on the open end where cracking generally occurs, it is necessary for proper function of the compression plug design
These two statements are totally contradictory.

My understanding has been that the top cap is really only needed to set the preload, but I don't have any "proof" other than that's what everyone says.

Anyone know if there is proof/evidence to prove the first statement and/or disprove the second?
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Old 09-20-19, 01:14 PM
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Is this something that replaces star nuts?
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Old 09-20-19, 01:17 PM
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Originally Posted by datlas View Post
These two statements are totally contradictory.

My understanding has been that the top cap is really only needed to set the preload, but I don't have any "proof" other than that's what everyone says.

Anyone know if there is proof/evidence to prove the first statement and/or disprove the second?
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