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In the case of the Wilson, like it happened with the GT RTS for example, the chainstays are not directly connected to the frame but the seatstays are, and their pivot point on the frame is the precise pivot point of the rear wheel, which is also what defines it as a single pivot type design even if there are other pivots and linkages. It's true that any non-single pivot type design ends up having a virtual pivot point for the wheel's path. But it shouldn't be difficult to identify a so-called "vpp" design, the outland's design isn't that different...

Yes that's true... But fsr has a typical chainstay directly connected to a pivot point on the frame, which vpp doesn't. And neither did the Outland.

The Outland IS the original VPP, how can you ask if it is even a vpp? It was a FSR-type design but in which the chain stay was linked to the bottom bracket with two extra links which created a virtual pivot point (VPP). Santa Cruz then switched the fsr type design for a unified rear triangle, and relocated those two links. But it's still a vpp system, where the wheel's pivot point is virtual and defined by the size and location of those two links.

There is also at least another vpp bike which has an additional linkage insted of a rear triangle, maybe a Marin or something.

It's true that double the bearings equals to double the bearing "play", but there is another, crucial factor here, which is the width of the pivots themselves. A pivot located immediately behind the bottom bracket can be as wide as the bb itself, usually it has an axle with bearings at each end. This is also why pivot bearing play on single pivot bikes is usually not noticeable at all. The pivots of a fsr setup on the other hand are only about a centimeter wide. They are far from the bb but are close to the wheel axle, which...

Virtual pivot point systems nowadays are actually the most rigid, or the potentially most rigid designs. Because you basically have a one-piece rear triangle like on a single pivot, but which is connected to the frame not only on one place but on two. There is an extra link on each of those connections instead of a direct attachment like on a single pivot frame but it's usually a short and stout one that doesn't introduce extra flex into the system. I have seen some vpp systems that don't use the one piece rear triangle but most of them do...

No, the rope is the chain. The chain IS the pedaling force. The bb has nothing to do with this. Going by the analogy, the bb is your feet, and your hands are the edge of the chainring that is pulling the chain. It doesn't really matter how high or low you place your feet, as far as the effects on the rope and pole are concerned.

Think of a pole that is laying on the ground. One end is tied to a fixed point on the ground, another end is tied to a rope with approximately the same length as the pole. The analogy is that the pole is the chainstay, the rope is the chain and the end that is tied to the ground is the pivot. If you pull the rope alongside the pole, all the force will be converted to a compression force on the pole, against the point that is tied to the ground. There will be no actual "work" done. If...

"A concentric BB pivot actually does NOT affect the suspension. Yes, it bobs like hell, but that is not because of the chain forces themselves. It's because of the inertia of the body and it's high position." Wrong. What affects the suspension is the chain force, not the bottom bracket placement. The bottom bracket could be anywhere and the force be transmitted through a secondary chain, it doesn't matter. A bb-concentric suspension pivot squats a lot because it stands much lower than the chain line, that's all. The farther the chain line is from the rear triangle pivot, the easier...

I think you have some concepts wrong here. A concentric BB pivot is all but neutral regarding the influence of pedaling on the suspension. What matters is only where the suspension pivot stands in relation to the line of force, and the line of force is the chain line from the top of whatever cog it is in to the top of the chainring. If the pivot stands along this line, or in the virtual continuation of it, then pedaling has no influence on the suspension. If it is above the line, pedaling will extend the suspension (the so-called anti-squat)...