Hi helpful people, I have a three-part question.

First, I bought a Specialized multi-stem on Ebay. My bike does not have a carbon steerer so I know to use grease on the steerer before installing. But do I grease the shim before installing in the stem? It is a very tight fit. I would assume no, but want to be sure.

Second, the instructions for this stem that I looked up online indicate the top cap is sloped and has two directions, and that it should match the shim installed. Mine does not appear to be sloped- instead it is slotted. I’m assuming the slot makes the sloped cap unnecessary? Seems like the slot would be a path for water/sweat though.

Third and finally - I’ve adjusted plenty of threadless headsets but always by feel (hold front wheel, rock bike to make sure there is no play in headset). Is there another trick? This bike is sitting on a direct drive trainer and has neither a front or rear wheel currently. I can remove it and install some wheels if that is the only way to really adjust the headset, but thought I would consult experts first though.

Thanks!

i cannot find any place the recommends putting grease on your steerer tube/stem interface. most people install it dry and I have never heard of a stem really seizing from this. perhaps some "friction paste" would be appropriate here if you're using a fork with a carbon fiber steerer tube.

I would not grease the steerer, even a steel one. I've also never heard of a threadless stem seizing on a steerer. As to the slotted cap, yeah, it does look like a good place for water leaks so perhaps a piece of electrical tape over it would be useful.
I also adjust the headsets on my bilkes by rocking them against a locked front brake but some headset makers recommend a tightening torque for the top cap bolt and that works too. Typically its 5 to 20 inch-pounds depending on the manufacturer.

Thanks! Apparently there is a washer that is supposed to go between the bolt and cap. Appreciate the advice here!

As far as correct preload without a wheel, I'd just keep tightening the top cap, wiggling the steerer to make sure things are seated, until you can no longer twist (steer) the fork blades easily with your fingers, and then back off until it's clearly turning without any binding. That should get you close. If you'll continue to use it on a trainer, then the preload isn't all that critical anyway. If you eventually take it back to the road, you could double-check your preload using your usual method of rocking the bike with the front brake engaged.

I put one on my wife's bike a number of years ago. It is pretty simple.

I didn't grease anything where the stem contacts the shim or the shim to the steerer. I have had the aluminum "spacers' below the stem get stuck on a steel mountain bike steering tube, so I have put a bit of grease just where the spacers sit. I think that is personal preference and how much water/rain the stem is subjected to.

There is no washer between the cap bolt and the cap. It is just like any other threadless stem cap except the slot allows for the cap bolt to properly align with the slanted insert. You pre-load it the same way.

I has worked well. Since you have one, you know that you start with a 12*, 17*, or 24* stem angle and then adjust that angle in 2* increments to fit.

John