Specialized Stumpjumper 15 EVO Alloy Frameset

Specialized Stumpjumper 15 Alloy Frameset

M5 Aluminium | 145mm Travel | FOX FLOAT GENIE Performance | Adjustable Geometry

The Specialized Stumpjumper 15 Alloy Frameset provides a strong and highly adaptable foundation for a custom trail-bike build. Its M5 aluminium chassis combines 145mm of rear travel with a GENIE-equipped FOX FLOAT Performance shock, six geometry settings, SWAT storage and compatibility with either a full 29-inch or mixed-wheel setup.

M5 Aluminium Construction

The M5 aluminium chassis and rear end provide the durability required for regular trail riding while retaining the carefully tuned ride characteristics of the Stumpjumper platform. Specialized has engineered the front triangle, rear end and suspension link to work together rather than simply making the frame as stiff as possible.

This gives the bike the support needed for accurate handling without creating an unnecessarily harsh ride through rough terrain.

GENIE Suspension Included

The frameset includes a Ride Dynamics tuned FOX FLOAT Performance shock with Specialized GENIE technology. The air spring provides a supple, coil-like feel through the early and middle portions of the travel, helping the rear wheel maintain contact across roots, rocks and braking bumps.

As the shock moves deeper into its travel, the spring rate becomes more progressive to provide support and reduce harsh bottom-outs. Mid-stroke and end-stroke support can also be tuned independently to suit the rider and terrain.

145mm of Versatile Rear Travel

The Stumpjumper 15 Alloy delivers 145mm of rear-wheel travel. This is enough to provide confidence on rough and technical descents while retaining the responsive handling and pedalling efficiency expected from a versatile trail bike.

The suspension kinematics balance climbing support with active bump absorption, making the frame suitable for everyday trail rides as well as more demanding terrain.

Six Geometry Settings

The adjustable head angle and bottom-bracket height provide six geometry configurations. Riders can choose a lower and slacker setup for greater stability on steep trails or a higher position for additional pedal clearance and more responsive handling.

This allows the finished bike to be tuned for different trails and riding styles without changing the complete frame.

Choose Your Wheel Setup

The frameset can be configured with matching 29-inch wheels or a mixed-wheel setup using a 29-inch front and 27.5-inch rear wheel. The mixed configuration creates a more responsive and playful feel, while matching 29-inch wheels provide maximum rollover performance and stability.

An appropriate aftermarket shock link is required when changing wheel configuration on applicable frame sizes.

Practical Frame Details

Internal SWAT downtube storage provides space for tools, a tube and other trail essentials. The threaded bottom bracket, SRAM UDH compatibility and conventional internal cable routing make the frame practical to build and maintain.

Unlike the carbon frame, the alloy version supports internal routing for mechanical derailleur cables as well as brake and dropper-post lines. This gives riders greater freedom when choosing a drivetrain.

Key Features

• Frame: Specialized M5 aluminium chassis and rear end
• Rear travel: 145mm
• Rear shock: FOX FLOAT Performance with Specialized GENIE technology
• Shock tune: Specialized Ride Dynamics Trail Tune
• Shock adjustments: Two-position lever and low-speed rebound
• Shock size: S1: 210 x 52.5mm; S2–S6: 210 x 55mm
• Geometry: Six adjustable configurations
• Head angle: Adjustable
• Bottom-bracket height: Adjustable
• Wheel compatibility: Full 29-inch or mixed wheel with the appropriate link
• Storage: Internal SWAT downtube storage
• Bottom bracket: Threaded BSA
• Rear spacing: Boost 12 x 148mm
• Derailleur hanger: SRAM UDH compatible
• Cable routing: Internal
• Drivetrain compatibility: Mechanical or electronic
• Seatpost diameter: 34.9mm
• Claimed weight: 4.31kg in size S4
• Product ID: 221699
• Frame support: Lifetime replacement suspension pivot bearings for the original owner, subject to Specialized’s terms

Why Riders Choose the Specialized Stumpjumper 15 Alloy Frameset

The Stumpjumper 15 Alloy Frameset suits riders who want to select every component around their terrain, budget and preferences. It provides the suspension technology and adjustability of the Stumpjumper platform in a durable aluminium package.

Build It Your Way

Starting with a frameset allows you to choose the fork, drivetrain, brakes, wheels and cockpit rather than paying for components you intend to replace.

GENIE Suspension

The included GENIE shock provides small-bump sensitivity, useful mid-stroke support and progressive resistance near the end of the travel.

Adjustable Handling

Six geometry settings allow the finished bike to be tuned for stability, agility or additional ground clearance.

Wheel-Size Flexibility

The option to run matching 29-inch wheels or a mixed setup gives riders another way to alter the character of the bike.

Mechanical or Electronic Gearing

Internal cable routing means the alloy frame can be built with a mechanical drivetrain or a wireless electronic system.

Useful Frame Storage

The SWAT compartment provides convenient storage for tools and essential spares without requiring a frame bag.

Straightforward Servicing

A threaded bottom bracket, UDH compatibility and conventional cable entry points make the frame easier to build and maintain.

Who Is This Frameset For?

Perfect For

✔ Riders planning a custom trail-bike build
✔ Riders transferring parts from an existing bike
✔ Technical trail riding
✔ Long rides across varied terrain
✔ Riders wanting adjustable geometry
✔ Riders choosing between full 29-inch and mixed wheels
✔ Riders who prefer aluminium durability
✔ Riders wanting mechanical drivetrain compatibility
✔ Anyone who wants control over the complete build specification

Our Thoughts on the Specialized Stumpjumper 15 Alloy Frameset

The Stumpjumper 15 Alloy Frameset makes the most sense for riders who already know how they want their bike built. The frame provides the important parts of the Stumpjumper platform, including its adjustable geometry, SWAT storage and GENIE suspension, without locking you into a complete-bike component package.

The included FOX FLOAT Performance shock is a worthwhile starting point. It gives the frame the traction and support the suspension design was developed around, while still providing enough adjustment for a practical trail setup.

At 4.31kg including the shock, this is not aimed at creating the lightest possible build. Its strengths are durability, versatility and compatibility. If you want a dependable aluminium trail frame that can be configured around your own riding, it is a very solid foundation.

What Is Included?

• M5 aluminium front triangle and rear end
• FOX FLOAT Performance GENIE rear shock
• SWAT internal downtube storage
• Seat binder
• Sealed cartridge-bearing suspension pivots
• SRAM UDH-compatible derailleur hanger
• Integrated geometry-adjustment hardware

Fork, headset components not supplied with the frameset, wheels, drivetrain, brakes, crankset, bottom bracket, cockpit and seatpost must be selected separately. Contact Chain Reaction and we can help confirm compatibility before ordering parts.

Why Buy from Chain Reaction?

✔ Official Specialized Dealer
✔ Frameset professionally inspected before collection or dispatch
✔ Rear shock checked and initially set according to rider weight
✔ Expert component compatibility and build advice
✔ Custom bike-build services available
✔ Expert frame sizing and geometry advice
✔ Lifetime workshop support from experienced mechanics
✔ Nationwide New Zealand delivery
✔ Finance and WorkRide options available

Frameset

• Frame: M5 alloy chassis and rear end, Trail Geometry, SWAT Door integration, head-tube angle adjustment, threaded BB, internal cable routing, 12 x 148mm dropouts, sealed cartridge-bearing pivots, SRAM UDH compatible, 145mm travel
• Seat binder: Alloy, 38.6mm
• SWAT: Internal downtube storage

Suspension

• Rear shock: FOX FLOAT Performance with Specialized GENIE Shock Tech, Ride Dynamics Trail Tune, two-position lever with low-speed rebound adjustment
• Shock size: S1: 210 x 52.5mm
• Shock size: S2–S6: 210 x 55mm

Frame Standards

• Bottom bracket: BSA, 73mm, threaded
• Rear axle: 12 x 148mm Boost
• Derailleur hanger: SRAM UDH compatible
• Seatpost diameter: 34.9mm
• Cable routing: Internal
• Rear brake mounting: Disc-brake compatible

Product Details

• Product ID: 221699
• Frameset weight: 4.31kg
• Weight size: S4

Geometry

The Stumpjumper 15 Alloy Frameset offers six geometry configurations through its adjustable head angle and bottom-bracket height. Measurements vary according to frame size, wheel configuration and selected setting.

Contact Chain Reaction if you would like help selecting a geometry position, fork travel or wheel setup for your intended riding.

Size Guide

• S1: Approximately 150–160cm
• S2: Approximately 157–173cm
• S3: Approximately 165–180cm
• S4: Approximately 173–188cm
• S5: Approximately 178–193cm
• S6: Approximately 188–203cm

Rider height is only a starting point. Body proportions, riding style and preferred handling can influence the ideal size, particularly where recommendations overlap. Contact Chain Reaction for personalised sizing advice.

Frameset Preparation and Delivery

Every Specialized Stumpjumper 15 Alloy Frameset purchased from Chain Reaction is inspected by our workshop before collection or dispatch.

Your frameset receives:

• Full visual inspection
• Frame and suspension-pivot check
• Rear-shock operation checked
• Shock pressure initially set when rider details are supplied
• Derailleur-hanger alignment checked
• Threaded interfaces inspected
• Geometry hardware checked
• Secure packaging for transport
• Nationwide New Zealand delivery
• Click & Collect where available

Chain Reaction can also help plan or complete a custom build using components selected for your riding, budget and preferred setup.

Specifications are based on manufacturer information and may change without notice.

Specialized Stumpjumper 15 Size Guide

The Stumpjumper 15 uses Specialized’s S-Sizing system. Instead of choosing a frame from height alone, S-Sizing allows many riders to choose between two sizes depending on whether they prefer a more agile bike or greater stability at speed.

Rider Height Recommended Size Traditional Equivalent Wheel Setup

S1 XS Mixed 29"/27.5"157–173cm

S2 Small Mixed 29"/27.5"165–180cm

S3 Medium 29-inch 173–188cm

S4 Large 29-inch 178–193cm

S5 XL29-inch 188–203cmS6XXL29-inch

How Specialized S-Sizing Works

The height ranges intentionally overlap. This gives many riders the option of choosing between two frame sizes based on their proportions, local terrain and preferred handling.

As a general starting point:

• S1 is similar to a traditional Extra Small
• S2 is similar to a traditional Small
• S3 is similar to a traditional Medium
• S4 is similar to a traditional Large
• S5 is similar to a traditional Extra Large
• S6 is similar to a traditional Extra Extra Large

Choose the Smaller Size If You Want:

• Quicker and more responsive handling
• A bike that is easier to move around on
• More confidence through tight corners
• A more playful feel on jumps and technical sections
• A shorter and more compact riding position

Choose the Larger Size If You Want:

• More stability at speed
• A roomier riding position
• Greater confidence through rough or steep terrain
• A longer wheelbase for high-speed descending
• More space for riders with longer arms or torsos

What If You Are Between Sizes?

If you sit within the overlap between two sizes, consider your body proportions as well as your riding style.

Riders with a longer torso or arms may feel more comfortable on the larger size. Riders with shorter arms, a shorter torso or a preference for agile handling may be better suited to the smaller option.

For example, a 178cm rider could potentially choose an S3, S4 or S5:

• S3 will feel compact and manoeuvrable
• S4 will provide the most balanced all-round fit
• S5 will feel longer and more stable at speed

Most riders should begin with the middle or traditionally equivalent size unless they have a clear preference for a more agile or more stable bike.

Wheel Size and Frame Size

The S1 and S2 use a mixed-wheel setup, with a 29-inch front wheel and 27.5-inch rear wheel. This provides the rollover ability of a larger front wheel while keeping the rear of the bike compact and easy to manoeuvre.

Sizes S3 through S6 use 29-inch wheels front and rear for stability, momentum and smoother performance over rough ground.

Standover height is useful, but it should not be used as the only measurement when choosing a Stumpjumper. Reach, arm length, riding position and handling preference are equally important.

Need Help Choosing Your Stumpjumper Size?

Contact the Chain Reaction team with your height, inside-leg measurement and current bike size. Let us know whether you prefer a more agile bike or greater stability, and we can help narrow down the best S-Size before you order.

Every Stumpjumper purchased from Chain Reaction is professionally assembled and safety checked, with expert suspension and setup advice available.

This guide applies to the 2026 Specialized Stumpjumper 15 range. It is intended as a starting point, as rider proportions, terrain and handling preferences can affect the best size.