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📐 What Is the Ideal Stack-to-Reach Ratio for Comfort?

on May 09, 2025

📐 What Is the Ideal Stack-to-Reach Ratio for Comfort?

The stack-to-reach ratio is one of the most valuable — yet overlooked — tools in bike fitting. It tells you how upright or aggressive your position will be on a given frame and helps compare geometries across bikes of different sizes, styles, and brands.


📐 What Is Stack-to-Reach Ratio?

  • Stack = Vertical distance from bottom bracket to top of head tube

  • Reach = Horizontal distance from bottom bracket to top of head tube

Stack-to-Reach Ratio = Stack ÷ Reach

This gives a normalized indicator of a bike's fit posture — useful across brands and frame sizes.


🧠 Why It Matters

Higher ratio → More upright, comfort-oriented geometry
Lower ratio → Lower, aggressive, race-style fit
Great for comparing road, gravel, endurance, or touring bikes
✅ Eliminates confusion between inconsistent size labels (like "54 cm" or "M")


🔢 What’s the Ideal Ratio for Comfort?

✅ General Guidelines by Bike Type

Bike Type Stack-to-Reach Ratio Fit Style
Aero Race Bike 1.35 – 1.45 Low, stretched, aggressive
Standard Road Bike 1.45 – 1.55 Balanced performance
Endurance Road Bike 1.55 – 1.65+ Upright, comfort-focused
Gravel / Touring 1.60 – 1.75+ Relaxed and upright
Flat Bar / Hybrid 1.70 – 1.90+ Maximum upright comfort

💡 For long-distance comfort, aim for 1.55 or higher — ideally 1.60+.


🧩 Real-World Examples

🛣️ Example 1: Endurance Road Bike

  • Stack: 580 mm

  • Reach: 370 mm

  • S:R = 1.57 → Comfort-oriented for long rides

🏁 Example 2: Race Road Bike

  • Stack: 520 mm

  • Reach: 390 mm

  • S:R = 1.33 → Aggressive, efficient but less forgiving

🏕️ Example 3: Touring Gravel Bike

  • Stack: 610 mm

  • Reach: 360 mm

  • S:R = 1.69 → Ideal for relaxed posture and long touring days


📏 How to Use This Ratio When Buying a Bike

🔎 Check geometry charts before buying — don’t rely only on frame size labels
📊 Use S:R ratio to compare bikes across brands
🔧 Helps guide decisions on stem length or bar height adjustments
🚲 Especially important for gravel, endurance, and touring riders


🧾 Conclusion

If comfort is your top priority — whether for commuting, endurance rides, or multi-day touring — aim for a stack-to-reach ratio of 1.55 or above. It promotes a more upright position that reduces strain on your neck, back, and wrists, especially over long distances.

⚙️ While low-ratio frames work for racing, most riders benefit from a fit that balances performance with all-day comfort — and S:R ratio is the key.

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