With the new 105, Shimano is converting one of the world's most popular and widely used road bike groupsets to an 11-speed drivetrain, thus enabling 22 gears. The 105 5800 inherits the key technologies and features of the Dura-Ace and Ultegra groupsets introduced in previous years.
Key new features of the 105 include an 11-speed drivetrain that is designed to shift more precisely and smoothly than previous 10-speed groups, optimized braking performance, and numerous features that ultimately contribute to improved bike handling and control.
Like the two top-of-the-line groupsets from the Japanese manufacturer, the 105 is designed to be characterized by the same captivating smoothness combined with clearly defined indexing. This characteristic is due in part to the polymer-coated cables and in part to the new, optimized design of the brake/shift levers, front derailleur, and rear derailleur. Here, Shimano's philosophy of system engineering is evident . All components and parts have been individually developed to work together optimally and with maximum precision as a group, as a system.
The brake/shift levers of the new 105 groupset now feature a reduced diameter in the grip area, noticeably improving ergonomics, comfort, and control while riding. Furthermore, the levers can be adjusted by 10 millimeters in reach using a set screw, allowing for optimal adaptation to any hand size. This is a significant advantage, especially for women or men with smaller hands. At the front derailleur, the extended lever arm, combined with a new spring mechanism, delivers impressive performance. A new spring mechanism is also used at the rear derailleur, which, in conjunction with the optimized cable indexing system, offers excellent shifting performance and precise adjustment options.
The groundbreaking four-arm crankset design, also adopted from its big sisters Dura-Ace and Ultegra , has now found its way into the mid-range road bike segment . Excellent power transfer and the ideal balance between stiffness and low weight are thus achieved at a higher level. The standardized bolt circle diameter allows for all gear ratios to be implemented with just one base crankset; chainrings are available with 34, 36, 39, 50, 52, and 53 teeth.
The 11-speed cassette has lower gear steps or switching steps, which help to better maintain the cadence and thus the riding rhythm. It is available in 12-25 tooth, 11-28 tooth and 11-32 tooth versions. The new chain features Shimano's Sil-Tec coating for minimal friction values and maximum durability in all conditions.
Compared to its predecessor , the 105 5700 , the Japanese manufacturer has also made the braking system more efficient, increasing braking performance by 10 percent. This is primarily due to the new dual-pivot brake calipers with symmetrical pivot points. Thanks to the larger caliper arch, the new brakes are compatible with 28c tires, and special direct-mount brakes are also available. Two color options, black and silver, allow for visual customization of the groupset, which will be available from June 2014.
Alongside the new 105 groupset, Shimano is also presenting a mechanical-hydraulic brake/shift lever solution – the logical next step after last year's introduction of the Di2 variant at the Ultegra level. The engineers have managed to integrate a mineral oil cylinder, including the complete braking system, into the remarkably compact mechanical levers. The hydraulic disc brakes are characterized by consistently high braking performance regardless of weather conditions, thanks to innovative thermal management. Furthermore, the braking power can be precisely adjusted to suit the conditions, terrain, the rider's physical capabilities, and their skill level. Hydraulic disc brakes deliver more braking power with less effort. For optimal ergonomics, the brake lever reach can be adjusted by 10 millimeters, providing excellent control for riders with both small and large hands.
The BR-R785 hydraulic disc brake caliper presented last year will be replaced in future by the new, revised BR-RS785 brake caliper. In particular, the developers have once again optimized the wiring. Instead of using a banjo connection on the inside, as before, the brake line is now attached to the outside of the brake caliper with a straight connection.
The new brake solution is also compatible with the Dura-Ace and Ultegra groupsets.