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.
