Do you need to replace your R9100 Left STI dual control lever? We do carry it individually in case of a bad fall, or damage of some kind. Dura-Ace R9100 is the second generation 11-speed version of this legendary nameplate. Shimano worked at serious refinement of the cable-actuated mechanical dual control lever 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.

Start with the ergonomics, as the ride begins when you place your hand on the left side 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 Left Lever is 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.