BUCKLOS Zoom 4-Piston Hydraulic Disc Brake Set, Rear only, 1550mm Hose, Pre-Bled Mineral Oil

BUCKLOS Zoom 4-piston hydraulic disc brake set is a ready-to-install upgrade that delivers stronger, quieter stopping power for mountain bikes, e-bikes, fat bikes and many other cycles.

If you're replacing worn mechanical calipers or improving control on steeper terrain, this pre-bled hydraulic kit from BUCKLOS provides a plug-and-play solution. The pair includes a left lever and caliper for the front (850 mm hose) and a right lever and caliper for the rear (1550 mm hose), aluminum-alloy levers, mineral oil inside, and four pistons per caliper for more even pad pressure. The system is compatible with a wide range of bike types — from MTB and fat bikes to e-bikes and folding bikes — as long as the hose lengths match your frame layout.

How do these 4-piston calipers improve braking feel?

Having four pistons increases the surface area pressing the pads to the rotor, which spreads braking force more evenly and helps you modulate speed with less lever travel. This can feel more progressive than single- or two-piston calipers, especially under heavy or repeated braking.

• Four pistons for broader pad contact and steady braking force
• Aluminum-alloy lever for responsive feel and reduced weight
• Resin-metal composite pads reduce noise while preserving rotor life

Are these brakes easy to install on my bike?

The kit ships pre-bled with mineral oil, so you won’t need to bleed lines before first ride. Installation requires mounting the calipers and routing the hoses to the levers — check that the 850 mm front and 1550 mm rear hoses reach your frame’s routing points.

• Pre-bled with mineral oil for immediate installation
• Follow manufacturer note: do not remove the yellow pad spacer before mounting
• Adapters included for common IS/PM mounts and many e-bike setups

How quiet and durable are the pads and seals?

The brake pads are a resin-metal composite designed to cut noise without sacrificing braking performance on rotors. The integrated hydraulic cylinder design minimizes leak risk, and the sealed system helps protect internals from dirt and moisture for longer life between services.

• Resin-metal pads balance low noise with strong bite
• Integrated hydraulic cylinder reduces potential oil leaks
• Sealed caliper construction for improved reliability in varied conditions

Will these brakes work with my e-bike or fat bike?

Yes — the BUCKLOS Zoom set is intended to be versatile across many bike categories. It’s suitable for mountain bikes, electric bikes, fat bikes, BMX, scooters, folding bikes and more, provided hose length and mount compatibility are checked before purchase.

• Compatible with most common bike types and rotor standards
• Longer rear hose (1550 mm) fits frames with rear routing or larger e-bike frames
• Includes mounting options for IS and PM adapters where needed

Who is this for: This hydraulic brake set is aimed at riders upgrading from mechanical disc brakes or worn hydraulic units who want stronger, smoother braking without a complicated bleed procedure. It suits trail riders, commuter e-bike owners, fat-bike users and DIY mechanics comfortable with standard brake mounting and hose routing. If you need factory-quiet stops, broader pad contact, and a pre-bled kit to minimize setup time, the BUCKLOS Zoom 4-piston kit is built to fit those needs.