Trek's Mino Link of Doom - beware the lost spacer (Trek Fuel EX mountain bike)

Update Oct 18, 2021: I wrote Trek a paper letter (!) about my experience and they are working on removing any references to trailside Mino Link maintenance.  They are also sending me some nice swag for my troubles. (Lastly, yesterday I found the lost Mino Link spacer in the dirt of my driveway. So now I have an extra!)

----

The Trek Mino Link is a feature of the Fuel EX. It lets you raise or lower the bottom bracket depending on whether you prefer fewer pedal strikes or a lower center of gravity. Trek says: "Mino Link lets you quickly and easily make small geometry adjustments to suit your riding style or terrain." 

As of Sept 2021 Trek's Mino Link video claims you can even swap your geometry on the trail.

I am here to tell you that you we would be insane to touch the Mino Link over dirt. If you're going to mess with the Mino Link do it over light carpet so you can see what falls out and pick it up -- especially the critical spacer/washer. A sterile environment would be nice.

The 2021 Mino Link is a problematic design. (The YouTube videos I've seen describe an earlier version that the nut and the bolt, I can't speak to that design.) That doesn't mean you should avoid the Fuel EX -- I really like mine. It does mean you should treat the Mino Link cautiously. If you aren't mechanically inclined have your local shop swap it. If you are then do it over that light carpet. Check that it's secure each time you ride (I do before and after).

The problem is the washer:

SUSPENSION PART GENERIC WASHER 10 X 16 X 3.0 Item: 601479594559

Those two black washers fit are supposed to fit on the inside of the bearing race shown below. The race that's scarred up because the washer fell out when I was adjusting the Mino Lake and it took weeks for me to figure out what had happened:

Here's the other eroded part of the Mino Link hinge:

It doesn't look as bad with a replacement washer in place (it was a bit tricky to get it to stay in during assembly). You can see the black outer washer between the assembled frame components:

If you swap the Mino Link and unknowingly lose the washer two things can happen:

1. Everything assembles and seems fine but the bolt will work loose. You may have the Mino Link come apart on one side. I don't know how long the assembly will hold with just one bolt, but if it fails you'll have an unpleasant mechanical.

2. Number 1 happens so now you tighten it to spec and because you have lousy vision and it's dark you don't notice that one side of the assembly has very little to no space between two hunks of aluminum. It starts to squeal when all the nice paint and gloss wears off. Then you figure out WTF happened and buy a replacement.

Both of these are bad in their own way. I like my Trek Fuel EX. I like Trek. Just be careful about the Mino Link.