The Shimano Dura-Ace CS-R9100 is the pinnacle of Shimano's 11-speed road cassette engineering — built for competitive road cyclists who demand the lightest weight, the fastest shifts, and the lowest drivetrain friction available. Matched to a Dura-Ace or compatible 11-speed groupset, the 11-25T ratio gives racers a tight gear spread ideal for flat and rolling terrain where maintaining high cadence is paramount.

Highlights

• Titanium and steel construction: The five largest cogs are machined from lightweight titanium; the remaining six are steel — an optimal balance of weight savings and long-term durability.
• Carbon spider subassemblies: Carbon fibre spiders join the titanium cog clusters, adding lateral stiffness to resist flex under load while keeping mass to a minimum.
• Refined Hyperglide tooth profiling: Revised tooth geometry on the R9100 generation accelerates shift speed and improves shifting smoothness across all 11 gears, both under load and at high cadence.
• Minimal drivetrain friction: Nickel-plated steel cogs and precision tooth machining reduce chain wear and rolling resistance for sustained power transfer.
• 11-25T race ratio: Cog sequence 11-12-13-14-15-16-17-19-21-23-25T keeps steps tight for precise cadence control on fast, flattish courses.

Construction & Weight

Shimano engineers the CS-R9100 using a mixed-material approach: titanium for the five largest sprockets and nickel-plated steel for the remaining six cogs. Carbon fibre spider carriers bind the larger sprockets into rigid subassemblies, a construction method that eliminates unnecessary alloy hardware while maintaining the stiffness needed for precise indexing. The 11-25T variant has a claimed weight of 175g.

Compatibility & Fit

The CS-R9100 is an 11-speed road cassette designed for Shimano HG (Hyperglide) freehub bodies. It is compatible with Shimano 11-speed road drivetrains including Dura-Ace R9100, Ultegra R8000, and 105 R7000 series groupsets. Use with a Shimano 11-speed road chain (such as CN-HG901-11 or CN-HG601-11). A cassette lockring tool (TL-LR15 or equivalent) and chain whip are required for installation and removal.