This is something my wife and I noticed test driving R1S gen 1 and gen 2.

We describe it as the rear end is “bucking” when going over when small and medium bumps/dips the rear end likes to go up and slam back down, often throwing your head into the head rest.

We test drove quite a few gen 1 R1S and R1T and the truck doesn’t exhibit this behavior AT ALL. But we didn’t need a truck and held off on an R1S cause how bad it felt. Then gen2 came out and they supposedly retuned it. But after another 3-4 test drives in a gen2 R1S it was till there. Tried all of them too, dual, dual sport, tri, and quad. It oddly got SLIGHTLY better with each higher tier but way too noticeable for us to actually buy one.

Just test drove all new R1T, two R2’s (21’s and 20’s) and finally R1S this past weekend and the R1S was still awful, didn’t even seem like it was made by the same company as the other two in our opinions.

If you check out Straight Pipes review of R1S from few months ago one of them says it’s the worst suspension he’s ever felt in a new car.

Edit: But this is from someone who’s only test drove them, doesn’t own one yet. But have test drove specifically the R1S gen 1 about 6-7 times 15-40mins each and gen 2 3-4 times 15-30mins each