Shimano XT Disc Brake BR-MT805 Flat Mount (K04S Metal Pad)

Overview

The Shimano XT BR-MT805 is a hydraulic 2-piston disc brake caliper designed for mountain bike rear wheels with flat-mount compatibility. Featuring heat-resistant plastic pistons, K04S metal disc pads, and low-viscosity mineral oil, this caliper delivers responsive, consistent braking performance across cross-country and trail riding conditions.

Key Features

• Hydraulic 2-Piston Design — Dual pistons provide balanced braking force and modulation; lighter weight alternative to 4-piston systems while maintaining adequate stopping power for XC and trail use
• Flat-Mount Compatibility — Modern flat-mount standard ensures compatibility with current mountain bike frame and fork standards; simplifies installation and maintenance
• K04S Metal Disc Pads — Sintered metal friction material delivers strong stopping power and consistent performance in varied weather; more durable than resin pads under extended use
• Heat-Resistant Plastic Pistons — Engineered plastic resists thermal expansion and maintains consistent braking feel across temperature ranges; prevents piston stiction in cold conditions
• SERVO WAVE ACTION — Optimized power curve manages pad-to-rotor friction throughout lever pull; delivers better balanced braking and improved modulation
• Low-Viscosity Mineral Oil — New formulation maintains consistent braking power across wider temperature range; improves performance in cold and hot conditions
• Flexible Lever Compatibility — Pairs with BL-M9200 brake lever for cross-country use or BL-M9220 lever for enduro/trail riding; allows customization for riding style
• Lightweight Construction — 2-piston design minimizes overall weight compared to heavier 4-piston alternatives; benefits weight-conscious XC riders

Technical Specifications

• Brake type: Hydraulic disc (2-piston)
• Mount type: Flat-mount
• Pad type: K04S metal sintered
• Fluid type: Low-viscosity SM-LVOIL mineral oil (required)
• Piston material: Heat-resistant plastic
• Rotor compatibility: Standard 6-bolt and 2011+ ISO mount
• Lever options: BL-M9200 (XC) or BL-M9220 (Enduro/Trail)
• Series: Shimano XT (mid-to-high-end)

Compatibility & Ideal Use Cases

Compatible exclusively with flat-mount brake frames and forks and 6-bolt/ISO rotors. Requires low-viscosity SM-LVOIL mineral oil; standard DOT or other mineral oils will damage seals and reduce performance. Designed primarily for mountain biking, not BMX use. Ideal for cross-country and trail riders seeking consistent, modulated braking without excessive weight. The 2-piston design and metal pads make this caliper well-suited for riders prioritizing responsive braking and extended pad life on technical terrain. Pair with BL-M9200 lever for weight-conscious XC setups or BL-M9220 for more demanding enduro/trail conditions. Not suitable for BMX, road, or casual cycling applications.