Specialized SJ 15 ALLOY Frameset BRSH/LQDMET/CSTBLU S4

The Specialized Stumpjumper 15 Alloy Frameset is a unisex trail mountain bike frameset built for riders building a highly tunable trail bike around Specialized's current Stumpjumper 15 suspension platform. This S4 frameset provides the core chassis and rear suspension rather than a complete bicycle, giving the builder freedom to choose fork, wheels, drivetrain, brakes, and cockpit. Component selection should follow Specialized's frame standards and approved travel ranges. The design keeps the focus on predictable handling and a clear purpose rather than chasing a single headline number, making it easier to choose the product for the terrain and skiing or riding style it was designed to cover.

The M5 alloy chassis uses the GENIE rear-shock system and adjustable trail geometry to let the finished bike be tuned around terrain, wheel choice, and rider preference. The resulting platform is intended to balance support where power is transferred with enough compliance and mobility to stay useful through long days and changing conditions. Fit, mounting, setup, and component compatibility should be confirmed for the individual user before heading out.

• M5 alloy Stumpjumper 15 chassis
• GENIE rear suspension system
• Adjustable trail geometry
• Internal frame storage integration
• Frameset platform for a custom build