Hayes Dominion A4 Disc Brake and Lever

Hayes Brake

219.99 $ 229.99


Making Power is easy. Making Power with the right feel... that is the real challenge. Hayes was able to accomplish this by creating an all-new system.

The Dominion four-piston hydraulic disc brake was developed specifically for the rigors of DH and Enduro riding and optimized for the world’s most demanding conditions and riders. It was designed with a specific lever pull curve to balance on-demand pressure modulation and provide firm engagement between the pads and rotors.

With a motorsports-inspired Two-Stroke dual port bleed system, industry-leading DOT 5.1 fluid, and Kevlar hose, the hydraulic system is engineered for ultimate performance across all temperatures and easy maintenance.

The Dominion A4 features the proprietary QuickBite system for fast and consistent burnish, coupled with Hayes D-Series Rotor to manage the heat with less braking noise.

MASTER CYLINDER: LoFi (Low input / High Fidelity) – Speaks to the overall system feel - Master cylinder dead stroke tech, cam profile, and feel
  • Cartridge-bearings used in the brake lever
  • Aluminum piston operates smoothly across operating temperatures
  • Piston glide ring - technology pioneered in suspension forks
  • Two Stroke – Dual caliper bleed ports for maximum bleed integrity
  • KingPin – Structural caliper pad pin

Crosshair Caliper Alignment System – Dramatically simplifies caliper installment and alignment

  • Patented Crosshair caliper alignment screws
  • Allows mechanics and end users to quickly and accurately set brake caliper with no rubbing of the rotor on the pads
  • Eliminates guesswork and trial and error
  • Makes set up process quick and easy for ‘out of the box’ build
D-SERIES ROTOR: MRC (Modal Resonance Cancelation) – Rotor harmonic design
  • All objects have a resonant frequency
  • The FEA-optimized modal shapes of D-Series rotors is intentionally designed to oppose that of Semi-Met T106 and Sintered T100 pads; this cancels out noise and vibration translating into more consistent braking
  • 1.95mm material thickness enhances heat dissipation
QuickBite – Offers riders the shortest path to high performance
  • Fast, consistent burnish
  • Predictable performance
  • Quiet

Additional Features:

  • Low-effort lever input (LoFi), coupled with high-fidelity power output for optimum braking feel and control
  • Pre-bled and assembled with Hayes K2 hose: Constructed from woven Kevlar to provide the stiffest hose possible for maximum power transmission
  • QuickBite2 specific pad compounds paired with the Hayes D-series rotors deliver fast, consistent braking performance across all temperature and speed conditions
  • Both pad compounds are included: Semi-Metallic T106 (standard) and Sintered T100 (wet conditions)
  • Uses DOT 5.1 brake fluid due to its high boiling point and consistency

    *D-Series rotors, caliper adapters, and bleed kit sold separately



    • Weight: 310g (Front) 320g (Rear)
    • Caliper: 74mm
    • Color: Black/Bronze
    • Pad Material: T106 Semi-Metallic (Included), T100 Sintered Metallic (Included)
    • Rotor: D-series (180, 203) w/ QuickBite and MRC
    • Reach Adjust: Tool Free
    • Pad Contact Adjust: Tooled
    • Lever Pivot: Sealed Cartridge Bearings
    • Pad Retention: King Pin
    • Bleed: 2-Stroke Dual Port Bleed System
    • Brake Lever Actuation: Hydraulic
    • Hydraulic Hose Length: 1000mm (Front) 1800mm (Rear)
    • Fluid: Hayes DOT 5.1
    • Graphics: Laser Etch
    • Alignment: Crosshair