Descriptions

The RISK RT146 / RA160 / RL256 / RL317 / RL247 Disc Brake Caliper Service Series is designed for road bike hydraulic disc brake caliper maintenance, piston replacement, seal replacement, piston resetting, and caliper side cover removal.

The RT146 titanium caliper piston features a lightweight titanium alloy outer shell with a polymer heat-insulation inner pad. The inner pad uses a ventilation groove design to help improve heat dissipation and reduce heat transfer during braking. It is suitable for compatible road hydraulic disc brake calipers including Shimano R7170, R8170, and R9270 series calipers.

The product range also includes RA160 piston sealing O-rings, RL256 hydraulic brake piston reset tools, RL317 caliper side cover removal tool with auxiliary block, and RL247 3/8″ ratchet wrench. These items can be purchased individually, making the series suitable for professional bike shops, home mechanics, and riders who perform brake caliper servicing and repair.

Key Features

Titanium Alloy Caliper Piston
- Lightweight titanium alloy outer shell
- Thin-wall design for reduced weight
- Suitable as replacement or repair part
Polymer Heat-Insulation Inner Pad
- Helps reduce heat transfer inside the brake caliper
- Designed for stable braking performance
Ventilation Groove Design
- Inner pad surface features airflow grooves
- Helps improve heat dissipation during braking
Compatible with Popular Road Disc Brake Calipers
- Suitable for R7170 / R8170 / R9270 hydraulic disc brake calipers
Replacement Sealing O-Rings Available
- RA160 includes 2 piston sealing O-rings per pack
Piston Reset Tool Available
- RL256 helps safely push hydraulic disc brake pistons back into position
Caliper Side Cover Tool Available
- RL317 includes side cover removal tool and auxiliary block
- Designed for R9270 calipers
Ratchet Wrench Option
- RL247 3/8″ ratchet wrench can be used with compatible bicycle repair tools

Compatibility

Suitable for the following road hydraulic disc brake calipers:

Shimano 105 R7170
Shimano Ultegra R8170
Shimano Dura-Ace R9270

Please compare the original caliper piston, seal, and tool interface specifications before purchase. Do not force installation if the size or structure is not compatible.

Product Specifications

Item	Model	Description	Main Size	Approx. Net Weight	Package Size	Approx. Package Weight
Titanium Caliper Piston	RT146	Titanium disc brake caliper piston set	Piston diameter 21 mm, thickness 8.7 mm including heat pad	12.4 g / 2 sets	15 × 9 × 2 cm	17 g
Piston O-Rings	RA160	Disc brake caliper piston sealing O-rings	Outer diameter 24.8 mm, thickness 2 mm	0.8 g / 2 pcs	10 × 8 × 1 cm	3 g
Piston Reset Tool	RL256	Hydraulic disc brake piston reset tool	106 × 30 × 16.2 mm	26 g / set	17 × 10 × 3 cm	30 g
Caliper Side Cover Tool	RL317	Caliper side cover removal tool + auxiliary block	Tool: 21.5 × 19 mm, 3/8″ interface; block: 65 × 25 mm	16.5 g / set	10 × 8 × 2 cm	20 g
Ratchet Wrench	RL247	3/8″ ratchet wrench	200 mm length, 3/8″ drive	316 g	25 × 12 × 3 cm	330 g

Product Options / Variants

RT146 — Titanium Disc Brake Caliper Piston

Model: RT146
Material: Titanium alloy outer shell + polymer heat-insulation inner pad
Piston diameter: approx. 21 mm
Thickness: approx. 8.7 mm including heat pad
Quantity: 2 sets
Net weight: approx. 12.4 g
Package weight: approx. 17 g

The RT146 is a lightweight titanium caliper piston designed for compatible road hydraulic disc brake calipers. It features a thin-wall titanium body and a polymer inner heat-insulation pad for improved heat management.

RA160 — Disc Brake Caliper Piston O-Rings

Model: RA160
Material: Rubber
Outer diameter: approx. 24.8 mm
Thickness: approx. 2 mm
Quantity: 2 pcs / pack
Net weight: approx. 0.8 g
Package weight: approx. 3 g

Replacement sealing O-rings for compatible disc brake caliper pistons. Recommended for caliper servicing or piston replacement.

RL256 — Hydraulic Disc Brake Piston Reset Tool

Model: RL256
Material: Tool-grade material
Size: approx. 106 × 30 × 16.2 mm
Quantity: 1 set
Net weight: approx. 26 g
Package weight: approx. 30 g

Designed to help reset hydraulic disc brake pistons safely and evenly without damaging the caliper body or piston surface.

RL317 — Caliper Side Cover Removal Tool

Model: RL317
Interface: 10 mm / 3/8″ drive
Maximum torque marking: 20 N·m
Tool size: approx. 21.5 mm diameter × 19 mm height
Auxiliary block size: approx. 65 × 25 mm
Quantity: 1 tool + 1 auxiliary block
Net weight: approx. 16.5 g
Package weight: approx. 20 g

Designed for removing and installing the caliper side cover. The auxiliary block helps support the caliper during operation. Suitable for R9270 calipers.

RL247 — 3/8″ Ratchet Wrench

Model: RL247
Drive size: 10 mm / 3/8″
Length: approx. 200 mm
Net weight: approx. 316 g
Package weight: approx. 330 g

A 3/8″ ratchet wrench suitable for use with compatible bicycle repair sockets and service tools.

Package Includes

Depending on the selected option:

RT146: 2 sets × titanium disc brake caliper pistons
RA160: 2 pcs × piston sealing O-rings
RL256: 1 set × hydraulic disc brake piston reset tools
RL317: 1 × caliper side cover removal tool + 1 × auxiliary block
RL247: 1 × 3/8″ ratchet wrench

Note: Product images may show brake calipers or other tools for demonstration only. The package includes only the selected product option.

Important Notes

Please confirm the caliper model and original part dimensions before purchase.
Do not force installation if the product does not match your caliper specifications.
Recommended installation should be performed by a professional mechanic.
Follow the recommended torque value when installing titanium alloy parts.
Minor measurement differences may occur due to manual measurement.
Product data is based on RISK laboratory measurements.