[Gadzooks Mike]

That was me that started this - the trotting horse affect.

I've still got it. I had changed from a setting of 4 to 5 for the trip to Michigan (loaded down pretty good) and it's still there with a setting of 5, although it does help quite a bit. I hadn't noticed it made a difference until you mentioned it, and then I realized that it did.

I'm pretty sure that just about any thumper will do this at certain RPMs unique to the machine. There just isn't anything to cancel out the sympathetic vibrations caused by that single cylinder moving up and down. I'd be curious to know if anyone riding as S40 has experienced this.

There are a couple of examples I could use, but since this is a family board, let's try this one: jumping up and down on a trampoline will get you the same sort of affect, and you don't notice it while jumping up and down on a wooden floor, although the floor is moving very slightly. Two people jumping on the trampoline in opposite directions (one going up with the other coming down) also dampens the vibration, just like a second cylinder will.

At least, that's my theory, and I'm sticking to it (until proven wrong, in which case I will blame it on space aliens and skunky beer).