 Since truss members work primarily in tension and compression, there is no appreciable loss of stiffness due to the bending of the end flexures.Certain designs used by amateur telescope makers, specifically truss tube Dobsonians that use a single truss, are sometimes called "Serrurier truss" designs.These single truss designs are used for their rigidity and do perform the function of keeping the optical elements parallel, but since they lack the opposing truss that keeps optics on the same optical axis they are not technically "Serrurier trusses".