I have an older 1" (25.4mm) carbon fork from Nashbar. The inner diameter of the carbon steerer is 20mm at the max. My two options are to use a 1" compression plug or a start nut, but I need some advice.

Since the steerer is carbon, I have always been under the impression that a compression plug is better, versus using a star nut for a steel steerer. Is this thinking wrong?

Should I use a compression plug? I am trying to search for ones that are 1 inch but it has been tricky.

I also have some star nuts that are for 1-1/8th forks, but I am hesitating before hammering them in the carbon steerer. That seems like the wrong thing to do. Should I use a 1" star nut?

pics below. thanks

Inner diameter is a maximum of 20mm

If you don't like the answers you already have, you'll like the answers you receive here even less.

My understanding is on a carbon steerer a compression plug is REQUIRED. A star nut is a spring, loaded under tension that pushes outward on the inner wall of the steel steerer tube and as such can damage a carbon steerer tube.

It's never a good idea to hammer a sharp metal object into a carbon steerer. Find an appropriate compression/expander plug or epoxy in a threaded aluminum insert. https://www.modernbike.com/cinelli-e...arbon-steerers

1" compatible compression plugs are available but I agree - they are most likely scarce. I seem to recall that I bought one from ti cycles ebay store for like $12. I'm going to check and see if they still have them.

Update: I just went to the ticycles.com website and found the 1" plug "headset compression plug". It comes with a top cap that says Portland Titanium and it sells for $18. The only down side is that it is not very long so it may not give full support for the stem.

OP, you might want to see what you think of DaveSSS's method in this thread: Compression plug for oval carbon steerer. It would avoid the need for a rare 1" plug, which will be even harder to find in a version that extends below the base of the stem clamp, while potentially being even better at resisting crushing forces (important, and a star nut will be useless in this function). I'm going to put my fork through the process soon, if you'd prefer a guinea pig.

Hammering a star nut into any carbon fork will ruin it. If you can't find a 1 inch plug, then gluing a tee nut into the steerer may be your only choice.
I found a 1 inch carbon plug with one quick search.

1 inch compression plugs are out there.
Don't use a star nut.
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I use this

Neco 1" 25.4mm Top Cap Key Expander Compressor Plug Bike Threadless Headset (Silver) https://www.amazon.com/dp/B077JYV6Z4/ref=cm_sw_r_cp_apa_i_80AtEb19P25NC

Cheap, nice and long to cover the length of a stem, knurled for solid grip.

I haven't had to retighten my headset in the 2 years since I got it. Prior to that with a rubber plug type, it would come loose every few rides.

I put a cooler top cap on mine.

Yeah, it is kind of scary to see "hammer" and "carbon steerer" in the same sentence.

Thanks for the recommendations on these compression plugs! It's the kind of info I was looking for. I went ahead and ordered the longer one to make sure that the stem is supported.

It's been about a year since I shopped for one so I can't remember details. But I wanted a long one so I ordered a couple different ones from Amazon and eBay just to compare. Give that a look-see. Order a couple of different ones and return the one that you don't use.

Also from my experience (below), I know that Chain Rraction sells - or used to- a very nice, long 1" plug.

​Turns out the full carbon fork I bought (Columbus Minimal- beautiful fork) came with a plug which wasn't clear on the product description on the Chain Rraction website. So I just returned the other ones is ordered while waiting for the fork to come.



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