The main function of the eccentric bottom bracket is to adjust the tension of the chain or belt to get an optimal transfer for the cyclists power through the drivetrain to the rear wheel. Eccentric bottom hubs are used to adjust the chain or belt tension in single speed bikes, in bikes with an internal gear hub or in tandem bikes for adjusting the tension of the timing chain. Duratec uses an internal expanding design for the eccentric bottom brakes. It´s easy to adjust and it doesn´t need extra holes drilled through the frame (see video). Thus no external adjustment bolts are needed. External adjustment bolts need a lot of maintenance and are prone to wear down. Throughout Duratecs very elegant solution of tightening the chain tension, worn out adjustment bolts and loose bottem brackets with fatal chain derailment can be avoided. Thus, Duratecs eccentric bottom bracket grants a minimum of wear and maintenance.
Photos and video