The driving force behind Shimano's ascent to the top of the component world was their development of the Shimano Total Integration (STI) concept and their Dual Control shifter/brake lever system. The levers, referred to colloquially and officially as STI levers, are just the start of that story, but proudly wave the flag for Shimano. Through eight generations since 1990, and several inline changes, when Dual Control was first released with the Dura-Ace 7400, the evolution of the mechanical Dual Control road system has been fluid, progressive and the benchmark of the industry with performance and capability that every competitor is measured against.

Dura-Ace R9100 is the second generation 11-speed version of this legendary nameplate and while some cyclists had hoped for 12-speed and a 1x drivetrain, Shimano opted for serious refinement of the cable-actuated system, greater range and applied some of the lessons learned from parallel development of the Di2 electronic shifting system. The ST-9100 STI Levers actually manifest some important changes that may seem incremental to some folks, but required considerable overhaul of the internals. The end result: backwards compatible 11-speed shifting and braking controls that reduce lever throw and effort for faster more efficient shifts, greater brake lever reach adjustability, advanced ergonomics, and a new standard for performance. Whether you are building a full Dura-Ace 9100 drivetrain or just want to update or replace your 9000, 6800 or 5800 11-speed STI lever, the ST-9100's deliver on Shimano's dedication to engineering excellence and ultimate performance.

Start with the ergonomics, as the ride begins when you place your hands on the lever. The body feels slightly less bulky than 9000 (though it is the same size), and the lever top and hood set-up naturally on contemporary handlebars with a flat, wrist-friendly profile if desired. You will immediately recognize and feel that Shimano has moved to a textured hood for the first time. The rubber material Shimano uses has long been effective in wet or dry conditions, but as it wears, it can get a bit slick. Pro riders tend to wear thin, simple gloves, and the grid-like pattern offers more grip, with channels for water and moisture release. The material used is new, and the overall effect is that the hood feels more natural in the hand, with better grip. Dura-Ace 9000 series levers offered 10mm of reach adjust for the brake lever. With R9100 you now get 14mm, and Shimano pre-sets this at the 10mm mark, so if you large hands or long fingers, you can move the lever out 4mm, a substantial difference. Of course those with smaller hands can also take advantage and shorten the reach by 10mm. The final ergonomic refinement comes in the form of a larger surface for the paddle on the secondary, or release lever. This simply makes the paddle easier to find, especially when in the drops, and offers more room for errors, especially with gloved hands.

The most important change has come with the length of the lever throw and shift actuation itself. Shimano's mantra for 9100 has been "Optimal Input-Maximum Output", and though it applies throughout the groupset, it is most obvious in the shift levers. The throw and actuation of the main (outer) lever has been reduced by 24%, and the throw of the release (inner) lever by 14%. The action feels more precise and requires less effort and reach resulting quicker, more responsive shift action. Taking a cue from the XTR mountain shifter, the inner lever now delivers Instant Release, with no hesitation from the lever in engaging the shift. Previously there was what could be called a dead spot, which was intentional. Now that is gone and the results are both obvious and welcome when dropping a gear. On the braking side of the equation, the lever feels smoother and when used with the new 9100 dual pivot caliper brakes, the action feels smoother and much more linear, which is largely a function of the new brake, but is aided by the lever pull. For both shifting and braking, the actual cable pull ratios are the same as the previous generation 11-speed components, so there is full compatibility backwards and forwards.

Mechanical shifting and braking is hugely impacted by friction within the cable and housing system. The OT-SP41 Polymer-Coated Derailleur Cable Housing has lightweight silicone grease inside the lining and sealed end caps to allow the cable to glide smoothly and remain free from contaminants. The cables themselves are high-grade SUS stainless steel, which is highly anti-corrosive, exceptionally strong and lightweight. Shimano coats the cable with a polymer treatment to prevent the cable from taking in any grime or even grease that can impact its performance. With the coated cable gliding through the flexible, greased housing, the overall reduction in friction, even with tight bends, is impressive and clearly noticeable. This combination debuted with Dura-Ace 9000 and has carried over to the 9100, where the shifter and derailleur changes truly allow the cable system to perform to its capabilities.

Of course, the ST-R9100 STI Levers are Dura-Ace, so the components, hardware, and finish are top-notch. The main body is CFRP composite, which is lightweight, exceptionally strong, and utterly reliable. The lever blades are carbon fiber, and the mechanical systems ride on 4 super smooth bearings. Shimano only uses their most reliable materials in Dual Control shifters, which is why longevity, durability, and supremely consistent performance are not only expected, but realized. If you are riding 9000, 6800, or 5800 STI now and want or need to upgrade, you can do so with no problems. You can enjoy the benefits of Shimano's endless scientific research and tireless approach to optimal efficiency. For those seeking more drastic changes, you should keep two things in mind: Shimano never changes for the sake of change, only when the the engineering and testing demonstrates a new group exceeds current performance, reliability and overall quality, and second that while innovation is clearly part of the company's history, every Dura-Ace level product that is released has spent years in development to ensure that cyclists, from pro's to Fred's has the best experience possible on the bike. That means impeccable performance and the highest level of rider confidence in the components are two concepts that married together. This is patently obvious in the progressive evolution of Shimano's Dura-Ace nameplate over the years, as it is in Dura-Ace R9100 overall, and wonderfully evidenced by the ST-R9100 STI levers.