Steering dampers are very important on mountain bikes, especially for trail riders. Steering dampers allow slow-speed steering movement and can resist high-speed deflections such as rocks. Steering dampers stabilize your mountain bike and help to preserve energy when going up and down hills.
Step 1 – Remove Star Nut
You need to remove your star nut form the mountain bike’s steerer tube. A star nut consists of a couple of spring steel stars that are coupled together by a threaded steel sleeve. The sleeve’s collar located on each end, is folded back to form a rivet that retains the star. Instead of drilling out the full length of the threaded sleeve, just remove the folded collar to break the top star free from the rest of the assembly. The damper cartridge has a 12-mm nut located on the bottom of the assembly. This must be tightened from below once the damper is inserted into the steerer, which is why you have to remove the star nut.
Step 2 – Remove Upper Headset Cup
Next remove the upper headset cup, install the adapter, and replace the cup. The threaded post hole located on the adapter needs to center on the top tube. The threads at the top of the steering damper assembly are not supposed to sit perfectly within each other or come out on the stem. When tightening the 12-mm nut that binds the damper to the steerer tube, the damper needs to be allowed to pull down into the steerer component. If the stem limits the damper’s movement, the damper may be improperly secured to the steerer or the unit may become damaged. To fix this, leave 5 mm of steerer exposed above the stem and put a 10-mm spacer over it.
Step 3 – Load Headset Bearings
When the star nut has been removed, a star nut substitute is needed to tighten the bearings. Tighten the plug to get rid of any residue, but not so tight that the bearings bind when the handlebars are turned. Once the headset bearings are satisfactorily loaded, tighten the stem and the adapter pinch bolts. Next, take out the star nut substitute from the top of the steerer tube.
Step 4 – Cut the Posts
Cut the posts with the Dremel so they end 8 mm below the top of the stem assembly. Make sure you measure twice, so you only cut once! Mount the post into the adapter then grease the upper end where it interfaces with the damper arm. Screw the 35-mm bolt towards the bottom of the threads. The damper rests on this bolt once it is inserted into the steerer. Before inserting the steering damper assembly, locate the centering mark and ensure it is aligned 180 degrees from the damper arm. It needs to point straight ahead when the damper assembly is set into the steerer tube.
Step 5 – Tighten the Bolts
Use a 12-mm socket and extension arms to reach the 12-mm bolt through the bottom of the steerer tube. Removing the front wheel might be needed for this step. The 12-mm nut needs to be hand tight. Unscrew the 35-mm nut to the top of the threads to allow the damper assembly a bit of wiggle room to pull down into the steerer. Then torque the 12-mm nut down to 18 to 24 foot-pounds.
Step 6 – Double Check
Verify that the alignment divot is pointing straight forward. If the cartridge is off center, loosen the 12-mm nut and start over. If everything is centered correctly, then tighten the 35 mm nut down. Enjoy the ride with your new steering damper!