I feel a bit silly for asking, but I have no idea what’s going on here. I’ve had this bike since 2014 (Scott CR1), and just had the headset replaced earlier this year. I noticed some play in the headset earlier this week, and tried to adjust it. I’ve pre-loaded plenty of headsets with steerers that have a star nut. When I loosen the stem clamp bolts on this one and tighten the bolt at the top cap, it maxes out at like 3NM. There is still play, and the steering isn’t even binding yet. Any idea what gives. I’m not even sure what I’m looking at, as the compression plug looks to be integral with steerer. I have another bike with a carbon steerer and compression plug, but it doesn’t look like this. Any advice?

Maxed at 3NM with no positive sense that there's solid binding going on I'd say there's a bad match in size down where things are supposed to be snugged up once proper torque has been applied to the star nut on top.

You put a mic to the OD bits down inside?
Know the ID of the tube you're trying to get a grip in?
Trust the folks who sold you the new headset to put the right stuff on?

I trust them. I have the old headset. I’ll compare the markings.

That is functionally no different than a star nut. Make sure your spacers are doing what they are supposed to be doing and addd a couple of NMs...

the odd part is, I can’t add a couple of NM. The wrench won’t turn anymore. It’s like the screw is bottomed out. It’s really odd, I know.

Ok, assuming the headset is intact and properly assembled (check that), and that you have the proper bolt and cap (ditto), sounds like your stem (or stem plus spacer above it) is not protruding enough above the top of the steerer tube. Go!

Did you tighten the Allen head that the bolt passes through? That secures the compression plug in the steerer tube.

Was there a bolt in the center that you've removed? I wonder if you just need to loosely put it back in and tap it down with a mallet, similar to how we use to do with quill stems that were difficult.

Either the lower part of the plug is moving up (pulling out), or the steerer is too long for the combination of stem and spacers you have, so the cap bottoms out.

See if the bottom plug is tight, then put your stem and all your spacers back on and take a picture. With the top cap off you should see the plug be at least 3mm down inside the top spacer or stem. If it isn't, add a spacer.

That mismatched spacer in the photo shows that something changed since when the bike was first built.

sounds like I need to pull out the plug and inspect it. You are right, the shop did change the spacer stack when they swapped the headset. I’ll dig on it some more tonight. Somebody asked, and yes, there was a bolt (through the top cap). What I don’t understand is why there is a hex shaped countersink within the plug, since you load the headset once the top cap is on. So what is the hex shaped slot for?

The hex slot is for tightening the plug in place inside the steer tube.

Dear God, make it stop!...

ps: we are a Scott dealer.

Scott Foil 10 carbon fork steerer cap - how do you remove to cut down the steerer?

okay, thanks, so that being the case. Any thoughts on why I can’t get the headset to load enough to take out headset play (or even load enough to cause the steering to slightly bind?) The play I’m trying to take out is pretty mild, not super sloppy, but tightening the top bolt to any degree seems to have almost zero impact.

As previously stated, the steerer is likely too long compared to the stem and spacer stack, so it bottoms out on the plug instead of putting pressure on the spacers and bearings

I believe that your new headset has less stack height than the old one. You will probably have to add a spacer either below or above the stem in order to be able to take out the play

Man, I feel sheepish posting this. I assumed that since a mechanic swapped out the spacers all was good. I just compared the top cap from the new headset to the old one (still in a bag with old parts). The new one is deeper and doesn’t taper quickly. I just installed the old one and voila! , no more bottoming out. I apologize for the fire drill, I really assumed it must be something more complex!!!

You shouldn't feel sheepish not assuming your mechanic is incompetent.

Your mechanic is incompetent. Let the store know, and maybe get your labor costs back. They will never learn unless it hurts a little.