Difference between revisions of "BMW Paralever"

Now to be truly accurate, and get to the real nitty-gritty of the design: the geometry of the Paralever isn't an exact parallelogram.  As shown below and in the original picture, the forward pivots are closer together, somewhat negating the theoretical benefit.  Consider the two extremes: if the two forward pivots were in the same place, forming a triangle out of the rear drive, swingarm and torque arm, all three of those components would rotate around that point exactly like a Monolever. If the linkages form a true paralellogram, like some of my illustrations show, the rear drive won't rotate at all, which would be like having a swingarm of infinite length. By moving the forward pivots closer together (going partway back to being a Monolever) they create the effect of having a much longer swingarm than they really have.  The "virtual pivot point" of this system is somewhere around the steering head - a very long swingarm indeed, which resists the shaft effect as mentioned. Additionally, moving the pivot points closer together changes a few things. For one, they gain ground clearance: with the true parallelogram arrangement I described earlier, the forward pivot would just be too low when the suspension compressed over a bump. Primarily, though, they reintroduce enough "shaft effect" to counteract the squat that would otherwise happen under acceleration.