Designing a full suspension MTB

What’s inside this week:
1. Ever wondered how a full suspension mountain bike goes from a sketch to the trail?
2. Gadget of the week, a staple in the newsletter.
3. Shorts.
4. Industry Insight - setting SAG correctly.
4. MTB video of the week.

What goes into designing a full suspension MTB?

Since part of what I do is design bicycle frames, I thought this would be a great opportunity to share what really goes into creating a full suspension bike from scratch. From idea to production, it’s a deeply layered process — and while this issue only scratches the surface, it should be eye-opening if you’ve ever wondered how your dream bike comes to life.

Let’s dive into it 👇

🛠️ From Idea to Production: A Bike is Born

1. The Spark (Idea):
It always starts with a need — a gap in the market, a terrain-specific problem to solve, or a performance target (e.g. “a more pedal-efficient long-travel trail bike”). Sometimes the spark is as vague as "what if we could make something more confidence-inspiring on big mountain descents and good at climbs?"

2. Research:
What do riders want? What’s trending in geometry, drivetrain standards, wheel sizes, suspension platforms? This step includes benchmarking against existing bikes, riding competitor bikes, collecting feedback from riders, racers, and dealers — and aligning the bike's purpose with its end user.

3. Spreadsheets (Yes, Really) :(
Before anything is drawn, numbers get crunched. Travel, leverage ratios, anti-squat curves, seat tube insertion, fit windows, stack/reach—this is where suspension curves and frame layout begin to take shape through formulas, plots, and loads of pivot point calculations.

4. Brief & Design Intent:
Now the project has shape: what category it serves, what rider it suits, travel, wheel size, kinematic behavior, and design goals (e.g. “must fit both air and coil shocks,” “high anti-squat for pedaling,” or “compatibility with UDH and T-Type drivetrains”).

5. Geometry:
A good bike rides on numbers. Head angle, seat angle, reach, chainstay length, BB height — geometry influences stability, agility, traction, comfort, and control. We balance static numbers with how the bike moves dynamically through its suspension travel.

6. Suspension Kinematics:
This is the heart of performance. We model how the bike responds under load, braking, and pedaling. Key terms here:

• Anti-squat: Reduces pedal bob.

• Anti-rise: Manages how the rear reacts under braking.

• Axle path & leverage ratio: Impacts small bump sensitivity, bottom-out resistance, and progression.
  A well-tuned kinematic layout keeps things supple off the top but composed under load — and inspires confidence at speed.

7. 3D Design & Modeling (CAD):
This is where the bike begins to look like a bike. Suspension layout, pivot placement, clearance for shocks, water bottles, routing, dropper posts, tire clearance — everything gets modeled and checked virtually.

8. 3D Printing:
Rapid prototypes allow for ergonomic checks, bottle fitment, and component integration testing before committing to costly tooling.

9. Prototyping (Real Frames):
Depending on the material (alloy, carbon, or titanium), we build test mules. Sometimes it's welded by hand, sometimes CNC’d or 3D printed. These are for suspension tuning, geo validation, and real-world feedback.

10. Testing & Refinement:
Frames are sent out to test riders and team members. We gather ride feedback, monitor wear points, check cable routing, and sometimes go back to CAD if something doesn’t feel quite right.

11. Tooling & Moulds:
Once the frame design is locked, production moulds are cut (especially for carbon). This is a huge investment, so you want zero surprises.

12. Pre-Production Samples & ISO Testing:
Test frames go through stress testing: impact, fatigue, and safety compliance to meet ISO standards. Failures here mean going back a few steps.

13. Graphics:
Now the fun part — designing paint schemes, decals, and visual identity. We also refine finishes for welds, polish, anodizing, or raw frames depending on material.

14. Spec & Production Planning:
Parts are selected: suspension, brakes, drivetrain, wheels. Sizing options are finalized. Compatibility is double-checked. Then comes the supply chain, production timelines, and the final go-ahead.

15. Production Launch!
After 18–24 months, the bike hits the market. What started as a sketch now flies down trails

🔧 Gadget of the Week (NEW)

OneUp EDC Lite Tool
A super-minimal multi-tool that hides in your steerer tube — no need to cut threads or carry a saddle bag. Includes 9 essential tools (hex, Torx, flathead) and installs in minutes with a star nut or included plug system. It’s light, rattle-free, and always where you need it.

✅ Available from: Bruce Reynecke cycles.

📏 MTB Shorts (Real Quick)

What does “travel” mean in MTB design?
It refers to how far the suspension can move. A 160mm fork, for example, can compress 160mm under load. More travel = more capability for rough trails, but can come at the expense of pedaling efficiency.

🧠 Industry Insight: Set Sag at the Wheel, Not the Shock

Why measuring sag at the shock can be misleading
Many riders check their sag using the rubber O-ring on the shock shaft — but that doesn’t tell the whole story. Sag should be set based on how much the wheel travels through its total range, not just how far the shock compresses. Why?

Because the leverage ratio of your frame affects how much shock stroke equals wheel movement. For example, on a frame with a 2.5:1 ratio, 15mm of shock sag equals 37.5mm of wheel sag.

✅ A better approach:

• Prop your bike against a wall (or use a friend).

• Measure axle-to-seat collar distance (or use a travel indicator).

• Sit in full riding gear, bounce once, then settle.

• Measure again — the difference is your true wheel sag.

🎯 Target sag (by wheel travel):

• XC Bike (100-120mm): 20 - 25%

• Trail bike (130–150mm): 25–30%

• Enduro bike (150–180mm): 27–33%

• DH bike (180–200mm): 30–35%

🎥 MTB Video Pick

"Behind the Scenes at Devinci’s Quebec Factory: From Raw Aluminum to Trail Ready"
Go behind the scenes at a frame factory to see the cutting, welding, jigs, and testing involved in getting a full susser to market.
▶️ Watch on YouTube

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About the author:
Hello, I’m Francoin, an Industrial Designer in the cycling industry based in Somerset West, South Africa.

Tools, lights, accessories and bicycle design is my daily graft.

This newsletter is to share some of the experience & industry insight that I pick up along the way, with fellow cyclists. If you are new to the sport, or been riding for many years, I plan to give you something of interest in every edition.

Thanks for subscribing and Happy trails!

FV

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