Sumart UBB-20 Bleed Block & Piston Spreader, 2-Piston

The block that goes in the caliper whenever the pads are out: it pushes the pistons back so new, thicker pads slide in, and holds them in place during a bleed. Built for 2-piston hydraulic calipers; it also works as a piston spreader on 4-piston calipers. Adjusts by hand or with a 3 mm hex key.

From Sumart, a tool and parts maker in Taichung, Taiwan. Ships from a US warehouse.

Why we carry it: it makes a home brake job clean and repeatable instead of a fight.

See it in use: our Aventon brake pad guide shows where it fits in the job.

Details from Sumart

Protect pistons, set the correct pad gap, and make 2-piston brake bleeding cleaner and more consistent.

The Sumart UBB-20 Universal Bleed Block is designed to simplify hydraulic brake maintenance on 2-piston calipers. Built to help hold pistons in the correct position during bleeding and service, the UBB-20 protects delicate ceramic pistons, supports proper pad spacing, and helps mechanics achieve a more consistent brake setup with less guesswork.

This tool can also be used on 4-piston calipers as a piston spreader, though it is primarily intended as a bleed block for 2-piston systems. Whether you are servicing brakes in a professional workshop or maintaining your own bike at home, the UBB-20 is a practical tool for safer, cleaner, and more repeatable brake bleeds.

Key Features & Benefits

• Ceramic Piston Protection: Helps protect delicate brake pistons during bleeding and maintenance.
• Designed for 2-Piston Calipers: Built specifically for 2-piston hydraulic brake systems found on many bicycles.
• Also Useful as a Piston Spreader: Can be used on 4-piston calipers for piston spreading, even though it is not intended as a 4-piston bleed block.
• Adjustable by Hand or 3 mm Hex Key: Easy to fine-tune for a more precise fit during service.
• Broad Hydraulic Brake Use: A practical tool for brake bleeding, piston resetting, and general brake maintenance.
• Multiple Color Options: Available in several finishes to match your tools or bike build.

Why Use a Bleed Block?

A proper bleed block helps keep brake pistons correctly positioned during maintenance, which can improve bleed consistency and reduce the risk of accidental piston damage. On 2-piston brake systems especially, using the correct block can make brake bleeding faster, more repeatable, and less frustrating.

Specifications

• Model Number: UBB-20
• Product Type: Universal bleed block / piston spreader
• Primary Use: 2-piston hydraulic brake calipers
• Secondary Use: 4-piston calipers for piston spreading only
• Adjustment: Hand-adjustable or 3 mm Allen key
• Available Colors: Black, Red, Blue, Gold, Purple, Orange, Pink

Ideal For

The Sumart UBB-20 is ideal for bike shops, home mechanics, and riders servicing 2-piston hydraulic disc brakes. It is especially useful for brake bleeding, piston resetting, and routine hydraulic brake maintenance where piston protection and consistent pad spacing matter.

If you want a cleaner, more controlled way to service 2-piston brakes, the Sumart UBB-20 Universal Bleed Block is a smart addition to your maintenance toolkit.