Good evening, folks. This post was inspired by a question from @Manofinterests asking about Boba U4 Thocks vs the silent ones (and their bumpers). I decided to compare the two stems close-up and share what I found.
Edit; more discussion including the Holy Boba below.
[ TL;DR: Tactile bump is the same, but I don’t recommend removing the bumpers. ]
Let’s start with some side-by-side visual comparisons at a few different angles:
The U4 bottoms-out on those soft bumper pads, while the U4T bottoms-out on the center post.
As you can see, the tactile bumps / legs are basically identical, while the center post on the Thock stem is lengthened to make it the bottom-out point - and of course there’s no silicone bumpers.
The bumpers are indeed quite easy to remove (and re-install, thankfully) - however, removing them does change how the stem interacts with the housing:
So - my conclusions are as such:
U4T’s are un-silenced U4’s, but with shorter travel (and of course THOCKNESS) thanks to the post.
U4’s without the bumpers aren’t the same as U4T’s without the long post; they technically work but not as intended, with the stem resting higher and having some weird-feeling pre-travel before otherwise normal function.
One more thing to note about silenced Outemu stems in general: while removing the bumpers is easy, the plastic rails that hold them aren’t meant to be bottomed-out on, and will likely wear out and collapse pretty quickly without the bumper there to support them.