Shimano Ultegra CS-R8101-12 – 12-Speed HYPERGLIDE+ Cassette, 11-34T
The Shimano Ultegra CS-R8101-12 is a high-performance 12-speed road cassette designed for fast, smooth and precise shifting. Featuring Shimano HYPERGLIDE+ technology, it helps maintain seamless gear changes even during demanding pedaling efforts.
Its versatile 11-34T range combines closely spaced gears for efficient cadence management with easier ratios for challenging climbs. Developed for compatible Shimano 12-speed road drivetrains, it delivers Ultegra-level performance for training, racing and long-distance riding.
Key Features
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12-speed road cassette: Designed for compatible Shimano 12-speed drivetrains.
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11-34T gear range: Versatile gearing for flat roads, rolling terrain and climbs.
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HYPERGLIDE+ technology: Optimized shifting in both directions, including under pedaling load.
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Nickel-plated steel sprockets: Durable construction with corrosion-resistant finishing.
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Two aluminum sprocket carriers: Lightweight construction supporting the larger sprockets.
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Anodized aluminum lockring: Helps reduce weight.
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Road freehub compatibility: Designed for compatible Shimano HG road 11-speed and 12-speed freehub bodies.
Technical Specifications
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Brand: Shimano
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Series: Ultegra R8100
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Model: CS-R8101-12
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Manufacturer reference: ICSR810112134
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Product type: Rear cassette
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Number of speeds: 12
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Gear range: 11-34T
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Individual sprockets: 11-12-13-14-15-17-19-21-24-27-30-34T
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Technology: HYPERGLIDE+
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Compatible freehub bodies: Shimano HG spline L2 road 12-speed and compatible HG spline L road 11-speed
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Sprocket material: Nickel-plated steel
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Number of steel sprockets: 12
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Sprocket carriers: Two aluminum spiders
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Lockring: Anodized aluminum
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Compatible chains: Shimano HG 12-speed
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Average weight: 345 g
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Application: Road cycling and compatible 12-speed drivetrains
Fast, Smooth HYPERGLIDE+ Shifting
Shimano HYPERGLIDE+ technology uses specially designed sprocket profiles and shifting ramps to guide the chain smoothly between gears.
The system helps deliver quick, consistent shifts, including during sustained pedaling efforts and demanding climbs, when used with compatible drivetrain components.
Versatile 11-34T Gearing
The 11-34T configuration combines closely spaced smaller sprockets with a wide enough range to tackle challenging climbs.
Its twelve sprockets are arranged as follows:
11 – 12 – 13 – 14 – 15 – 17 – 19 – 21 – 24 – 27 – 30 – 34T
The 11-tooth smallest sprocket provides higher gearing for faster riding, while the 34-tooth largest sprocket offers an easier climbing gear.
Freehub and Drivetrain Compatibility
The CS-R8101-12 is designed for compatible Shimano 12-speed road drivetrains using HG 12-speed chains.
It fits compatible Shimano HG spline L2 road 12-speed freehub bodies and HG spline L road 11-speed freehub bodies.
Before installation, verify rear derailleur compatibility with the 34-tooth largest sprocket, total drivetrain capacity and chain length.
The cassette is not designed for Shimano Micro Spline freehub bodies or threaded freewheel hubs.
Installation and Maintenance
Install using the appropriate Shimano cassette tools and follow the manufacturer's specified lockring tightening torque.
Inspect chain wear regularly and verify drivetrain compatibility when replacing an existing cassette.
Package Contents
