So, I have a Cannondale Six-13 with carbon steerer tube. The frame came with a compression plug (first pic) but is missing the top cap. I went to the LBS, and bought a Reynolds OUZO compression plug, but the way it's designed, only one end expands, which seems like it will give a pretty small contact area inside the steerer tube because it will not expand evenly. The plug I have expands from both ends and the expanding part is about 30 % more surface area than the Reynolds. Is the Reynolds safe ? I think something like the Pinarello (bottom link) would be the best.

Thoughts ? Can I find a cap for whatever brand plug I have ?



Reynolds:


Pinarello:

I don't have any idea. It's a good post, with lots of info and pics, try positing in the mechanics forum.. they'll love this.

i wouldn't worry about the strength of the plug. it is only really used when you load the bearings. once that is done and the stem bolts are tightened, you could undo the top cap and plug without harm. the expansion force is not that great that the integrity of the steerer requires it to avoid getting crushed.

That's not the case with the third option shown -- the plug is left compressed (you can see the hex head used to compress it, with the threads for the top cap bolt inside that). The tension on the top cap bolt doesn't affect the compression within the plug.

All those plugs stress the carbon fibres evenly in tension without any point loads, which is the direction they are incredibly strong. Even with the stem not installed I doubt it would be possible to damage the steerer tube with the plug no matter what you did.

I suspect you'd strip the bolt before damaging the tube.