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Discussion Starter · #1 ·
Hi all
How about some collective advice with regard to carbon steerer tube expander plugs?
I've just bought a replacement carbon fork for my Specialized Allez. The new fork has a carbon steerer tube and I now need to buy an expander plug to allow for setting of the pre-load on the headset bearings.
I'm new to carbon steerer tubes and would appreciate your recommendations for an expander plug. I'm interested in your reasons for your preference as there seems to be a number of designs available, varying lengths, materials and construction.
Haven't been able to search any concise thread on this so hope to create one here.
Appreciate your response!
 

· century rider
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Best you bring your fork when you shop for carbon plugs. Apparently the inside diameter of carbon steerers are not standard in size. My reynolds ouzo comp fork fits great with FSA compressor plug, but is a bad fit with other generic taiwan forks.
 

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Discussion Starter · #4 ·
Thanks Battaglin, appreciate your reply and take your point regarding generic forks. I should have stated that my new fork is a Specialized Carbon 4; maybe someone can tell me which plug Specialized used as original equipment with this fork?
 

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Try a Columbus "Gap Cap"...

jefflyng said:
Thanks Battaglin, appreciate your reply and take your point regarding generic forks. I should have stated that my new fork is a Specialized Carbon 4; maybe someone can tell me which plug Specialized used as original equipment with this fork?
I don't know what specialized use but I have the columbus "gap cap" in 3 carbon steerer tubes (despite the name it's a compression plug). They have a knurled outer surface that prevents slippage in the steerer tube without needing heaps of force, and they're 45mm long which gives a bit more support inside the steerer if you want to move your stem up and down a bit. Highly recommended.

see this from columbus' website - scroll down to "Gap Cap"

http://www.columbustubi.com/eng/4_2_1.htm
 

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Discussion Starter · #6 ·
Thanks Armchair, thought the Colombus Gap Cap looked like a good option from what I've seen of it.
It certainly appealed because of its length. It looks more capable than most I've seen of resisting any crushing forces on the steerer tube ( due to pressure from the stem clamping bolts I presume).
Is the typical clamping torque recommended for stem bolts sufficient to crush carbon steerer tubes ie without an expander plug fitted??
 

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unlikely

jefflyng said:
Is the typical clamping torque recommended for stem bolts sufficient to crush carbon steerer tubes ie without an expander plug fitted??
unlikely, if treated with care and the stem's steerer clamp is free of burrs. Good carbon fibre is incredibly strong stuff but needs to be treated with respect. Every set of manufacturer instructions I've seen for carbon steerer installation recommends having the plug under the stem clamp. I have seen a carbon steerer tube ruptured as a result of torquing up the expansion plug too high - an expensive mistake.

For all that, I find the extra support from the long plug comforting, but that's me.
 

· fifth time's a charm
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The best compression plug I have found is the Reynolds. Just remember that like the torque setting on a standard preload cap you are only snugging the play out of the headset. You are not trying to hold the fork on the frame with this.
 

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Discussion Starter · #10 ·
Thanks rkb, take your point re the pre load on the headset bearings. I was more concerned I guess with the potential for crushing the steerer tube with tightening of stem bolts, but seems unlikely if tightened to appropriate manufacturers torque value. All good, appreciate your interest!
 

· fifth time's a charm
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jefflyng said:
Thanks rkb, take your point re the pre load on the headset bearings. I was more concerned I guess with the potential for crushing the steerer tube with tightening of stem bolts, but seems unlikely if tightened to appropriate manufacturers torque value. All good, appreciate your interest!
For the stem bolts I highly recommend getting one of these-Ritchey torque key- It has a preset 5nm and a 4mm bit that will fit Thomson, FSA, Ritchey, and most other stems. Use it for the stem bolts on the carbon steer tube as well as the face plate bolts for your carbon bars.
 

· Unsafe at Any Speed
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The radial force exerted by the (not overtightened) compression plug is negligible compared to the clamping force delvered by the stem IMHO.
But it sure is still reassuring to have the plug in line with the stem....
 

· Matnlely Dregaend
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IMHO carbon steerer compression plugs are basically worthless. They don't really do anything (they certainly suck at compressing the headset significantly) and once you tighten the stem are just added weight, because if the stem comes loose, the plug sure isn't going to hold the stem onto the steerer. They need something more effective, maybe a carbon version of a star nut? Or better yet, a stem that has a bolt to draw it down onto the steerer. Then the cap is just there to make the steerer solid where the stem clamps down.
 

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Discussion Starter · #16 ·
Thank you all, appreciate all your thoughts.
Now have a better good understanding of relevant considerations!
Will drop a Columbus plug in (like the length), take care to tighten stem to manufacturers torque recomendation and enjoy being back on my bike!
Ride on!
 

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recommend the fsa compressor plug. do a google search prices vary wildly also be sure you know which size to use. This will not scratch the interior surface of the carbon steer and will hold tight. It is also easly removable.
 

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battaglin said:
Best you bring your fork when you shop for carbon plugs. Apparently the inside diameter of carbon steerers are not standard in size. My reynolds ouzo comp fork fits great with FSA compressor plug, but is a bad fit with other generic taiwan forks.
So glad to find this thread. The ass hole I bought my Merlin Agilis from, among other things, put a standard compression nut inside the Reynold Ouzo. I have gone over the inside and outside of the steerer tube and it's smooth as silk so I'm not concerned it's been damaged.

However, I was completely unaware that some of the carbon plugs have different lengths? The traditional plug it came with is maybe 2" long at most so no way would it reach below the stem bolt.....at least until I cut the rest of the extra fork off....which I don't want to do for resale issues which have hurt me in the past not having any extra steerer tube to work with for the next guy.

How long do these plugs get?
 
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