The Shimano Deore XT CS-M8100 is a 12-speed mountain bike cassette tuned for wide-range, close-step gearing. With a 10-45T spread it delivers tight, usable jumps between gears for efficient cadence on climbs and flats alike, built on Shimano's HYPERGLIDE+ tooth profile for fast, seamless shifts under load.

Freehub compatibility: Mounts on a Shimano Micro Spline freehub body — required for the 10T smallest cog. It is not compatible with a standard HG freehub. Pairs with a Shimano 12-speed HG chain.

Key Specifications

• Model: Shimano Deore XT CS-M8100 (M8100 series)
• Speeds: 12-speed
• Gear range: 10-45T (450% range)
• Cog combination: 10-12-14-16-18-21-24-28-32-36-40-45T
• Freehub type: Shimano Micro Spline (not HG compatible)
• Shift technology: HYPERGLIDE+
• Compatible chain: Shimano 12-speed HG (CN-M8100 / M9100)
• Construction: Beam Spider — alloy carriers + alloy lockring
• Material: Steel cogs / aluminum carriers & lockring
• E-bike rated: Yes
• Weight: 461 g (16.3 oz)
• Color: Silver / Black

Technology Highlights

• HYPERGLIDE+: New shift-ramp design for the fastest, smoothest shifts under full pedaling load.
• Beam Spider: Light, stiff construction reduces cassette inertia for faster acceleration and better chain security.
• Micro Spline 10T: New freehub body realizes a 10-tooth smallest cog and a wide, close-step 12-speed range.
• E-MTB durable: Meets Shimano's durability requirements for e-MTB drivetrains.

Who It's For

Mountain and e-MTB riders on a Shimano 12-speed Micro Spline drivetrain (XTR M9100, XT M8100, SLX M7100, Deore M6100) who want tighter gear steps than a 10-51T while keeping a versatile climbing range.

What's in the Box

• 1 x Shimano Deore XT CS-M8100 12-speed cassette (10-45T)
• 1 x alloy lockring

Condition & Shipping

• Condition: Brand new in retail packaging
• Ships from: Ontario, California (US domestic)
• Estimated delivery: 3–5 business days
• Returns: Free 30-day returns