Marin Frame Kit Alcatraz

The Marin Alcatraz Frame Kit is a purpose-built foundation for creating a custom dirt jump bike for jumps, pump tracks and skate parks. Built around a Series 3 6061 aluminum frame, it combines a lightweight feel with the stiffness and durability needed for repeated hard landings and aggressive riding. The frame uses 26-inch wheels and 135x10mm horizontal single-speed dropouts, making it well suited to dirt jump-style builds. Its short 395mm chainstays help create a responsive and playful handling character for manuals, jumps and technical tricks. The frame also features a 73mm threaded bottom bracket, ISCG 05 tabs and internal cable routing. The kit includes an FSA headset, Marin chain tension device and Marin bolt-type seat clamp, giving riders a solid starting point for a personalized build.

Key Features

• Frame Material: Series 3 6061 aluminum

• Wheel Size: 26-inch

• Frame Type: Dirt jump hardtail frame

• Dropouts: 135x10mm horizontal single-speed dropouts

• Bottom Bracket: 73mm threaded

• Chainstay Length: 395mm

• Cable Routing: Ambidextrous internal routing

• Headset: FSA No. 57E semi-sealed cartridge bearing headset

• Chain Guide Mount: ISCG 05 tabs

• Frame Sizes: Short and Long

• Seat Clamp: Marin bolt-type MTB seat clamp

• Chain Tensioning: Marin chain tension device

Product Specifications

• Product Type: Dirt jump frame kit

• Model: Alcatraz

• Brand: Marin

• Frame Material: Series 3 6061 aluminum

• Wheel Compatibility: 26-inch

• Rear Dropout: 135x10mm horizontal single-speed

• Bottom Bracket: 73mm threaded

• Headset: FSA No. 57E, 1 1/8" x 1 1/2"

• Head Tube Angle: 69°

• Seat Tube Angle: 69°

• Seat Tube Length: 320mm

• Chainstay: 395mm

• Bottom Bracket Height: 317mm

• Bottom Bracket Drop: 22mm

• Fork Offset: 42mm

• Head Tube Length: 115mm Short / 120mm Long

• Reach: 385mm Short / 430mm Long

• Stack: 575mm Short / 580mm Long

• Effective Top Tube: 600mm Short / 646mm Long

• Wheelbase: 1037mm Short / 1083mm Long

• Standover Height: 370mm Short / 400mm Long

• Seatpost Diameter: 30.9mm

• Intended Use: Dirt jumps, pump tracks, slopestyle and skate parks

Dirt Jump Design & Custom Build Potential

• Frame Construction: Double-butted aluminum tubing provides a balance of stiffness and durability for aggressive riding

• Chainstay Design: Short 395mm chainstays help make manuals, hops and quick direction changes more responsive

• Dropout Design: Horizontal single-speed dropouts allow precise rear-wheel positioning and chain tension adjustment

• Cable Routing: Ambidextrous routing allows the rear brake to be positioned according to rider preference

• ISCG Mount: ISCG 05 tabs provide compatibility with suitable chain retention systems

• Build Flexibility: The frame kit provides a foundation for selecting your own fork, cockpit, drivetrain and wheels

Easy Operation / Usage

• Wheel Installation: Install a compatible 26-inch rear wheel using the 135x10mm horizontal dropout system

• Chain Setup: Use the Marin chain tension device to help achieve proper single-speed chain tension

• Brake Routing: Route the rear brake internally according to your preferred handlebar setup

• Component Selection: Choose compatible drivetrain, fork, cockpit, wheels and finishing components for your custom build

• Maintenance: Regularly inspect the frame, dropouts, headset, bottom bracket and mounting points before riding

Why Choose This Product

• Dirt Jump Focus: Purpose-built geometry supports jumps, manuals, pump tracks and skate park riding

• Frame Strength: Series 3 6061 aluminum construction is designed for demanding off-road use

• Responsive Handling: Short chainstays create a playful platform for tricks and quick movements

• Custom Build: Frame-only design lets riders select components according to their riding style

• Single-Speed Ready: Horizontal dropouts provide a practical setup for dirt jump single-speed builds

• Cable Flexibility: Ambidextrous internal routing allows flexible rear brake positioning

• Mounting Support: ISCG 05 tabs provide an option for compatible chain retention equipment

• Complete Frame Kit: Includes important frame-building components to simplify the custom build process

In the Box

• Marin Alcatraz frame

• FSA No. 57E headset

• Marin chain tension device

• Marin MTB bolt-type seat clamp