Titanium Bolt M5x30 35 40mm Bicycle Seatpost Screw for Bicycle Replacement Parts, 1 Set, by Tianswer

Ultra-lightweight Aerospace Ti-6Al-4V Grade 5 titanium M5 bicycle seatpost replacement hardware kit featuring an integrated articulated cylindrical barrel nut and spherical concave washer, engineered for two-bolt micro-adjust saddle clamps on road, gravel, and mountain bikes.

Articulated Barrel Nut & Spherical Concave Washer Geometry

Unlike rigid standard nuts that introduce bending stresses into long bolt shanks when adjusting saddle tilt, our seatpost kit includes a precision CNC-machined 16mm long × 8.5mm diameter cylindrical barrel nut and a 2.0mm thick spherical concave washer. As you fine-tune saddle angle, the barrel nut and curved washer pivot fluidly inside the seatpost yoke and cradle pockets, ensuring 100% axial tension alignment and eliminating lateral bolt fatigue bending loads.

Extreme Dynamic Cantilever Load Support

Bicycle seatpost clamp hardware carries the full dynamic weight of the rider under continuous cantilever loading. Every road dip, trail root, and gravel bump translates into violent cyclic shock through the saddle rails. Manufactured from certified Aerospace Grade 5 Ti-6Al-4V titanium with a tensile strength exceeding 950–1050 MPa (matching Class 10.9 high-tensile steel), this kit eliminates the sudden catastrophic shearing risks associated with fatigue-compromised stock hardware.

Sweat & Road Spray Corrosion Immunity

Positioned directly beneath the saddle and directly behind the rear tire, factory steel seatpost clamp bolts are notoriously plagued by rider sweat dripping down the seat tube and gritty road water spray. Factory bolts frequently rust solid, seize, or strip their hex drives during height adjustments. Certified titanium alloy forms a permanent ceramic-like passivating oxide layer that is 100% immune to perspiration acids, road salt, and harsh wash detergents.

Weight Optimization

At approximately 6.5 grams per complete set (bolt + barrel nut + concave washer), this titanium hardware kit sheds roughly 50% of the weight of factory steel assemblies—saving grams at the highest point of the bicycle to improve out-of-the-saddle climbing dynamics.

Bicycle Seatpost Compatibility

• Two-Bolt Micro-Adjust Seatposts: Direct replacement for Thomson Masterpiece / Elite, Specialized S-Works, Trek / Bontrager, Cannondale, Giant Contact, ENVE, Canyon, 3T, Ritchey, Deda, and aftermarket carbon seatposts utilizing M5 barrel nut clamp mechanisms.
• Saddle Rail Compatibility: Suitable for both standard 7mm round metal rails (titanium, hollow chromoly, stainless) and 7×9mm oval carbon fiber saddle rails.

Specifications & Dimensions

Material: Certified Aerospace Ti-6Al-4V (TC4) Titanium Alloy, Grade 5
Thread Size: M5
Thread Pitch: 0.8mm (Standard Metric Coarse)
Bolt Dimensions: Head Diameter 8.5mm, Head Height 5.0mm
Drive Type: 4mm Allen Key / Internal Hex Drive
Barrel Nut Dimensions: Length 16.0mm, Outer Diameter 8.5mm (Cross-drilled M5 threaded center)
Washer Dimensions: 2.0mm Thickness, Spherical Concave Alignment Profile
Available Bolt Lengths: 30mm, 35mm, 40mm
Total Weight: ~6.5g per set
Package Contents: 1 × M5 Titanium Bolt, 1 × Titanium Barrel Nut, 1 × Titanium Concave Washer
Available Finishes: Natural Titanium, PVD Vacuum-Coated Gold, Rainbow, Burn Blue, PVD Deep Black

Installation & Torque Guidelines

Clean the seatpost yoke and cradle holes thoroughly. Apply a generous smear of anti-seize paste or synthetic grease to the bolt threads, barrel nut exterior, and concave washer surface to ensure smooth articulation and eliminate creaks. Alternately tighten front and rear clamp bolts in half-turn increments to set saddle tilt and fore/aft position. Torque to 5.0–6.5 N·m (44–58 in-lb) using a calibrated manual torque wrench, taking care never to exceed the maximum torque stamped on your saddle rails or seatpost clamp. To learn more about selecting high-stress fasteners and avoiding common fatigue failures, read our Ultimate Guide to Choosing Titanium Fasteners.

Price is for 1 complete set (1 Bolt + 1 Nut + 1 Washer). For seatposts requiring twin bolts, order quantity 2.