A four-link does away with leaf-spring-style axle wrap, and the quarter elliptical springs flex like mad. Excessive droop travel is a common problem with a quarter-elliptical rear suspension, and can push you over face-first on steep descents. Brian limits the droop using chains in place of fabric limit straps. They're effective, but they'll likely break their mounts in time. There's no cushion when the chain slack is taken up, so all the energy goes right into the frame and the mounting tabs on the axle.