Neco Headset Expander Top Cap Star Nut Plug Bolt Stem Expanding Nut Bolt Carbon Fiber Cap Cover Long Large Size

Buy the long one. Trust me. My Marin gravel bike has a carbon steer tube. The expansion plug that came with it only went about 1 inch (25mm) into the steer tube. My stem sits well below this and was therefore clamped onto an unsupported area of steer tube. The long option is about 3 inches long and goes well past the top bearing. Exactly what I wanted. No worries about crushing carbon steer tube. Expansion plug comes dry, not greased. Pull it apart and add some heavy duty/wheel bearing grease on THE INSIDE sliding/metal to metal contact areas of plug to improve installation. Do not put grease on outside of plug. Use a torque wrench.

Ok, to be honest, it’s also your only real choice for carbon steerer tubes in 1”. There are a few alternatives for 1 1/8”, but this is all I could find for 1”. That being said it really does work well. It catches the sides with enough force to wedge itself in without deforming the tube, which would result in a fork that will be headed to the trash heap. Keep in mind that you still need to torque the bolt carefully. Applying too much force would be catastrophic. I was careful and on the second go I got it perfect . All I had left was to tighten the top cap screw down correctly to get rid of all the play in the fork.

ALWAYS USE A TORQUE WRENCH, mixed review, I did return for two reasons. 1) has a lip so it stays at the top of the steering tube, I wanted it down a little for fitting purpose. 2) slipped up when I tried to preload the steering bearings to 1.8 Nm, I should have tightened the plug to 8-9 Nm, NOT 6-7 Nm. These plugs with more surface area require more torque, not in the instructions. Smaller plugs require less torque to hold, too much torque on a small plug could distort the steering tube.

These are a great value for expander plugs especially for modern day carbon steerers. I like the availability of different sizes but for most, the middle or large options is more than suffice for most applications. I prefer these expander plugs because of the larger surface contact it makes with the steerer.

I wanted a more secure top cap for my carbon Niner gravel bike with 1 1/8" steerer tube. the Original one only gripped a small part of the inside of the steerer tube and left the area underneath the stem unsupported. The 2" version extends well below where the stem bolt onto and now the carbon steerer tube there is supported. It was a simple 5 minute job.