Building a tandem requires a highly individual approach, especially in its geometry and design. It requires the combination of two frame sizes so that the result suits both riders. Thanks to our custom production and our extensive experience of many years with tandems, Duratec, can design and fine tune frame geometry, manufacture the frame and assamble complete bikes to our customers satisfaction. Duratec tandem bikes are used by many national teams of disabled athletes around the world. Representatives of Australia, the Netherlands, Brazil, Ireland, Greece, Russia, Belgium, Austria, Germany, Spain and many other countries are the best references for our products. Duratec prides itself on building high quality tandems for very tallented riders. Many international and national track medals have been won on Duratec bicycles.
Big Bang T9 is a racing tandem specially intended for sprint and pursuit. Large-diameter tubes made of 7020T6 aluminium alloy are used for construction of the frame. The large diameters of the tubes ensure the rigidity of the frame and effectively resists stress in the direction of torsion. For track disciplines the conversion of force from pedalling to acceleration is a core requirement. Overall this is an extremely high quality frame concept in terms of strength and rigidity. The riding position and position of the riders in terms of each other is an important parameter, in particular for track disciplines. Duratec offers 14 basic sizes in the standard offer. The geometry is designed according to the height of the riders so that the length of the rear rider's top tube is shorter and they adopt an aerodynamic position without excessive space between each other. If requested, it is possible to make the frame to order according to the individual requirement of the riders.
DURATEC F02 front fork is made of 7005T6 aluminium alloy and has conical post 1-1/8“-1-1/2“, crown diameter 50 mm, weight 720 g. The fork is offered in many variants according to the individual disciplines and selected types of brakes. For example road fork for calliper brakes, road fork for disk brakes, track fork etc. The crown diameter seamlessly blends with the frame head and the transition between these parts is very compact. The fork is certified for tandem use.
One of key challenges with tandem bikes is the sourcing of appropriate cranks. We very often use GEBHARDT cranks which are customed machined to the client's requirements in the Czech Republic. It is possible to choose the lengths of the cranks for pilot and passenger separately or depending on the frame size (167.5 , 170, 172.5 , 175, 180mm). The 1:1 coupling gear is most often 39-39, rear chainring size 51 teeth (or 47-56T), pinion 16 teeth (or 13-17T). Possible colour versions black, red or silver. ISIS or 4-edge axle. More info and pictures available at www.gebhardt.cz
Very frequently discussed topic in the tandem cycling is the stiffness and resistance to torsion. Frame Big Bang T9 achieves high torsional rigidity mainly due to the usage of oversized tubes made from highest quality alloy 7020T6 in their construction. The lower and central tubes have a diameter of 52 mm and the middle of the frame tubes are specially shaped to resist high loads.