The idea for the springs is that it helps eliminate some of the harmonics and provides a little "Give" when a pothole, bump in the road or some other irregularity in the road is encountered. It prevents the shock from being transmitted directly to the thin wall tubing, and susequent welds. The mount that attaches to the frame near the rear wheel should also have a rubber mount incorporated. If it's good enough for the pounding that Moto X bikes receive, then it I think is certainly engineered well enough for these applications. There must be a small amount of movement available or there will be breakage.
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