Solving The Mystery Of The Carbon Fork Compression Plug

In this video, I run through the function of a carbon bicycle fork compression plug, and how to correctly install it to get a good headset adjustment. I also run through a few mistakes if seen in the past couple of years and how to correct them.

[@denis_roy_7]

Hey Joey, good to hear from you! Hope you are well. Thanks for the tips. Good job!

[@JoeyMesa]

Hey, thanks Denis! I'm well, but I've just been super busy these days and my video making free time has gotten limited. I appreciate you taking the time to leave a comment!!!

[@ozgurinsan]

The only thing about expander plug is not to preload the headset bearings as i know. It also supports the steerer from inside of the clamping force of the stem bolts.

[@yonglingng5640]

Yes. This is the reason why some riders deliberately use longer expander plugs, which allows them to lower their stems without having to cut off any excess steerer tube first.

[@jeffbrunton3291]

My Cannondale headset bearings come in a set that includes the top cap, so I change it at the same time. Key learning for me is that Cannondale require there be NO spacers above stem. Seemed odd, but supported by industry experts, key is to have the plug support the upper part not the bottom part, against the load on the fork from the stem

[@JoeyMesa]

Yes, I've owned many Cannondales that use this type of preload cap/compression plug system. I like the fact that you can thread the preload cap partially not the compression plug, drop the assembly into the steerer tube, tighten the compression plug into the ideal position because the hex key size is always a size smaller than the preload cap.

[@wafflechatanddrone1638]

At last I understand. Thank you!

[@mancello]

Welcome back. What are your thoughts about clamping the stem slightly above or below the midline of the compression plug. Some people say that the plug will take some of the load off the steerer tube when you tighten down the stem bolts and that the stem bolts should always lie within the length of the plug. I tend to use longer compression plugs in my carbon steerers just to be safe.

[@JoeyMesa]

Yes, I'd agree with the plug being somewhere within the steerer tube where the stem clamps for added support. I prefer the longer compression plugs as well.

[@pgreenx]

Well done - I understand it now. Was always afraid of messing with this

[@JoeyMesa]

I'm glad the video was helpful! Thanks for taking the time to comment!

[@Newtttton]

thankyou. my orbea aluminum frame bike has a carbon fork. and it comes with star nut stem plug and not compression plug like this. should I change it? is orbrea perhaps being cheap when they put the star nut? does it make a difference? thank you mate

[@peterbedford2610]

Good info. Thanks

[@Godspeed961]

my top cap of compression plug doesnt fit well on steerer tube by factory( it has some gap ) . should i untighten and fix it? (aim not sure what kind of compression plug has inside) . Also 10:50 when i tighten up these bots it makes noise. Like somthing you hit.

[@Cykelmyggen72]

Do you tighten up the compression plug up to 9-10 nm or? 😉

[@andrewlipsiner9791]

FINALLY.. Someone shows that the compression plug when inserted and tightened to the fork adjusts the bearind preload THEN ..the top cap allen bolt is lightly tightened ..

[@markifi]

i know this is not how it's done anywhere, but how much more would a 16 cm long bolt weigh with an almost identical bottom-cap as the top cap? not very elegant but it would do the job (except with non-direct-mount rim brakes)

[@Laserpico1985]

Hi there, thanks for the great explaination! My plug is installed (stuck) in the steerer. When turning the compression bolt counter clockwise, it doesn't loosen the plug, it just feels like it is spinning in place. After several turns of the bolt, the steerer tube heats up slightly indicating some friction. When turning clockwise, similarly the compression bolt never becomes tight and spins in place, heating up the steerer after a few turns as well. My suspicion is that the compression bolt is seized to the bottom wedge, and when the compression bolt is turned either direction, it merely spins the bottom wedge around and does not push/pull (loosen/tighten) the bottom wedge. Any suggestions on how to get the plug out in this case? If it matters (i.e. I'm just plain doing something wrong), this is for the carbon fork of a 2014 Merida Reacto 400. Thanks!

[@JoeyMesa]

The wedge lower section is probably stuck into the actual compression sleeve, or the outer portion. With the main bolt portion loose, give it a little smack, or at least the wrench engaged into the bolt and try to break it loose. If that's the issue, it should come right out. if not, it's difficult to speculate exactly why it's not budging without actually seeing it in person.

[@Laserpico1985]

@@JoeyMesa Many thanks for the reply Joey, definitely appreciate that it would be impossible to diagnose the issue over a single comment. You were right, the lower wedge was stuck within the compression sleeve and thus holding the entire plug in the steerer tube. The root cause was that the lower wedge was seized to the compression bolt (cross threaded as it turns out), and therefore I could not get "the main bolt portion loose" (I think this is what you meant) as the compression bolt could only turn together with the lower wedge within the compression sleeve, whereas it should ordinarily turn with respect to the lower wedge and thus pull or push the lower wedge (tightening or loosening the entire plug respectively). Many taps with my mallet did not help because the compression bolt would bottom out against the top wedge before the lower wedge was out of the bottom of the compression sleeve. The break through for me was to bring the stem up to the approximate level of the lower wedge and tighten the stem to the max torque specification for the steerer tube. This squeezes the steerer tube slightly, which in turn squeezes the compression sleeve against the lower wedge and gives more resistance to break the compression bolt loose from the lower wedge. Once loose, I smacked the compression bolt with 4 days worth of pent up frustration as you said and the plug loosened right up! Thanks again for the great video, knowing the workings of the plug really helped me to come up with the solution!

[@kidgugstev6406]

Hey Joey, I don’t know if you’ll see this but I just got a new bike(specialized Allez E5) and wanted to remove a few spacers to slam it and place the remained of the spacers above the handlebar. Will I have to cut the steering tube to adjust the height or install compression plugs so that I don’t crush my bike? I’m new to all of this so I’ve been left a bit confused as to what to do.

[@JoeyMesa]

Sorry for the late reply, but thanks for the question! You can definitely move the spacers above the stem to experiment with different sizing. Once you've found the spot you like, cut the steerer tube so that the top cap is flush with the stem. A 5mm above the stem is fine as well. When cutting the steerer tube, you'll need to remove the compression plug. Long term, having a bunch of spacers above the handlebar stem is bad (smacking into it if you crash, little to no support on a carbon steerer tube), But it's fine for the short term to find what works for you. An experienced bike fitter can be helpful if you have the funds, plus someone good in your area. Hopefully this is helpful!

[@kidgugstev6406]

@@JoeyMesa More than helpful! Thank you so much🙌

[@freddyVelo]

I literally avoid bikes that come with carbon steerer tubes, or immediately replace those forks. Nothing wrong with the alloy tubes that worked wonderfully

[@JoeyMesa]

Aluminum steerer tubes work great, until they don't!

[@freddyVelo]

@@JoeyMesa Carbon steerer tubes are 1 nm away from cracking and having to replace.

[@patiorio1538]

I remove the spacers trying to get better feel for riding . sometimes everytime I remove spacers long bolt comes up along with compression plug . this is been so frustrated can you give me any advice .

[@JoeyMesa]

Just make sure the compression plug is secure and leave a few millimeters (4 or so) below the top of the stem before trying to adjust.

[@patiorio1538]

@@JoeyMesa I have Colnago V1R kindy crappie design . The tech at the bicycle shop told me some high end frames are just built that way . Thanks for the tip I appreciate .

[@georgewilson19]

always loosen the stem before you undo the topcap!

[@MaxiFau]

omg thanks.

[@JoeyMesa]

You're welcome!

[@solocyclist3993]

These things are a stupid invention and i have had trouble with 5 road bikes built over the years and nothing but trouble with movement before you pull your hair out until it clamps down properly.

[@rickdoehler502]

In a few words. WYF