The new Chorus crankset is a true concentrate of technology and versatility. It is technically advanced because it uses unidirectional carbon fibre construction technology, which is obtained directly from the mould without surface coating and, like the Record crankset, uses the Ultra-Torque steel bottom bracket axle. It is versatile because its new 123 mm pitch circle, although offering a structure with extreme performance, ensures a wider variety of application segments. The new reduced pitch circle of the Chorus crankset, available with crank arm lengths of 170, 172.5 and 175 mm, makes it compatible with 52/36, 50/34 chainrings and the latest 48/32 rims.
LIGHT WEIGHT, STIFFNESS, SIMPLIFIED ASSEMBLY AND MAINTENANCE: ULTRA-TORQUE.
THAT'S CAMPAGNOLO'S ANSWER TO INTEGRATED CRANKSETS.
6 years after its introduction, Ultra-Tourque is still recognized as the most powerful crankshaft in terms of strength, weight savings and power transmission.
Campagnolo has made sure that the two halves of the bottom bracket axle are inseparably linked to each crank arm. This new development has made it possible to significantly reduce the lateral protrusion of the frame at axle height, thus preventing unwanted contact with the ankle when pedaling.
Their assembly is extremely simple, a single oversize screw is used to firmly connect the two halves of the axle. In terms of the effectiveness of torque transmission, this system can stand up to comparison with a one-piece axle.
Campagnolo has also succeeded, despite the narrow side profile, in placing the bearings outside the bottom bracket housing, so that the axle, which has a larger diameter, becomes stiffer thanks to the increased support width. Campagnolo was able to achieve these characteristics by using the Ultra-Torque, based on the Hirth spur gear, an ingenious mechanical system derived from many years of experience in engine construction in the field of couplings for rotary axles and motor shafts.
It is basically a self-centering and self-aligning spur gear coupling located in the centre of the bottom bracket axle where the ends of the axle halves fixed to the crank arms are in contact.