Shimano Caliper Fixing Bolt (Rear)

Factory Thread Precision. Unyielding Caliper Alignment.

The engineering hallmark of Shimano Flat Mount Caliper Fixing Bolts is their calibrated frame-thickness sizing paired with an integrated anti-loosening snap-ring channel. Because rear flat mount calipers bolt upward through the chainstay directly into the caliper body (or flat mount adapter), bolt length must match your frame’s exact chainstay thickness. Shimano CNC-machines each high-tensile steel bolt with precise under-head seating washers and pre-applied micro-encapsulated threadlocker to prevent vibration-induced backing out, ensuring perfectly centered rotor clearance and noise-free braking under heavy heat and torque.

Why Genuine Shimano Fixing Bolts Belong on Your Build:

• Frame-Specific Length Calibration: Offered in dedicated lengths (from 23mm up to 48mm under-head length) to match chainstay dropouts, ensuring optimal thread engagement into the caliper body without bottoming out.

• Integrated Snap-Ring Safety Groove: Features a precision-cut groove beneath the head designed to accept Shimano’s anti-loosening safety clip, preventing the bolt from backing out under rough gravel chatter or high-heat vibration.

• Pre-Applied Factory Threadlocker: Coated with Shimano’s micro-encapsulated threadlock compound to create a secure, vibration-resistant bond right out of the packaging without contaminating hydraulic bleed ports.

• High-Tensile Heat-Treated Steel: Resists head stripping, thread galling, and lateral shearing when torqued to Shimano's recommended 6–8 N·m specification.

• Precision Flat-Seating Washers: Includes dedicated conical/flat friction washers to distribute clamping force evenly against carbon and alloy frame dropouts, protecting delicate frame paint and carbon layups.

• Universal Shimano Caliper Compatibility: Direct OEM fit for all Shimano road and gravel flat mount calipers across Dura-Ace, Ultegra, 105, GRX, and Tiagra series.

Technical Specifications:

• Interface: Flat Mount Rear (Chainstay-to-Caliper Mounting)

• Drive Interface: 4mm Hex (Allen Key)

• Thread Pitch: M5 x 0.8 mm

• Material: High-Tensile Heat-Treated Steel w/ Anti-Corrosion Black Oxide Coating

• Hardware Included: Bolt, Friction Washer, and Anti-Loosen Snap-Ring Clip

• Torque Spec: 6.0 – 8.0 N·m

The Alegro Perspective: Bolts are one of the most overlooked details on custom builds and frame swaps. If a bolt is just 2 mm too long, it bottoms out inside the caliper body before fully clamping, leaving the brake loose and rattling. If it’s too short, you risk stripping the delicate aluminum threads out of a $100+ caliper under heavy panic braking. We always insist on using genuine Shimano bolts with the factory snap rings: they give you exact thread depth, protect your carbon chainstays from clamping damage, and ensure your caliper stays dead-center no matter how rough the road gets.

Factory Thread Engagement. Absolute Caliper Security. Build with Precision Using Shimano.