When it comes to mountain bike shocks, one term you’ll hear frequently is “spring travel.” For those looking to upgrade their bike’s suspension or understand how their 185×55 shock functions, knowing the ins and outs of spring travel is essential. This guide breaks down everything you need to know about spring travel on a 185×55 shock, covering critical aspects to optimize your setup.
What is the Spring Travel on a 185×55 Shock MTB?
The spring travel of a 185×55 mountain bike (MTB) shock typically ranges from 47.5 mm to 55 mm. This measurement reflects how far the shock can compress when the spring is fully engaged. Getting the spring travel right is crucial, as it directly impacts your bike’s ability to handle rough terrain effectively.
But what does “185×55” actually mean?
- “185” refers to the eye-to-eye length of the shock, measured in millimeters. This is the total length of the shock absorber when fully extended.
- “55” denotes the stroke length or the maximum distance the shock can compress during use.
Why Spring Travel Matters
The spring travel defines the distance the shock can compress under load, which is essential for absorbing impacts and providing a smooth ride. If the spring travel is mismatched with the stroke length of your shock absorber, you could experience reduced performance or even damage to your suspension system.
Factors That Influence Spring Travel
- Spring Length: The spring length must match the shock’s stroke length. Springs that are too short may bottom out prematurely, while springs that are too long might not fit properly.
- Shock Type: Shocks can vary significantly depending on whether they have trunnion heads, which are 25 mm shorter, or eyelet heads, which take 8 mm bolts and are about 30 mm wide.
- Spring Compatibility: The inner diameter of the spring should fit snugly around the shock’s damper body for optimal performance. Always verify the compatibility of your shock and spring specifications.
What Is the Spring Travel on an 185×55 Shock Fox?
Fox is a leading name in suspension systems, and their shocks are widely respected for durability and precision. For a Fox 185×55 shock, the spring travel typically allows for up to 55mm of stroke length. The brand often focuses on providing highly tunable options, meaning you can adjust compression and rebound to suit different terrains or riding styles.
Fox shocks are engineered with progressive rates, meaning the resistance increases the further the shock compresses. This ensures stable control without bottoming out, even on aggressive rides. Pairing a Fox 185×55 shock with the correct spring rate can take your suspension setup to a whole new level, helping you hit the trails confidently.
Key Features of Fox 185×55 Shocks:
- High-quality materials for durability.
- Advanced adjustability (e.g., high-speed compression and lock-outs).
- Competitive spring travel for trail and downhill biking.
Understanding MTB Spring Travel on a 185×55 Shock
Mountain biking is all about tackling unpredictable trails and absorbing rough terrain, so spring travel is key for performance and comfort. For MTB enthusiasts using a 185×55 shock, the spring travel remains within the standard range of 47.5–55 mm, provided the spring and shock are correctly matched.
Key Measurements for MTB Shocks
- Free Stroke
- The unrestricted stroke of spring is the distance it can compress before it hits its mechanical limit, known as bottoming out. High-quality shocks and springs are designed to ensure that the unrestricted stroke matches the shock’s stroke length, allowing for smooth compression.
2. Bottoming Out
- This occurs when a spring compresses fully and can no longer absorb shocks effectively. Using a spring with the wrong stroke length may lead to this issue, damaging your suspension setup.
3. Shock Manufacturer Tools
- Many shock manufacturers provide compatibility charts to help you choose the right spring. Fox, RockShox, and other premium brands often include these guides on their websites.
Spring Length and Stroke Length Alignment
The key to seamless suspension performance is ensuring your spring’s length and stroke length align perfectly with the 185×55 shock specifications. Incorrect alignment may prevent the shock from achieving full travel or lead to inefficient suspension action.
What is the Spring Rate of a Shock?
Another critical factor to consider is the spring rate, which measures how much force is required to compress the spring by 1 millimeter. For example, a spring rate of 450 lbs/in means it takes 450 pounds of force to compress the spring by an inch.
Calculating Optimal Spring Rate
The spring rate depends on several variables:
- Rider Weight
Heavier riders typically require stiffer springs with higher spring rates, while lighter riders benefit from softer springs.
- Bike Suspension Design
The suspension kinematics of your MTB influence the ideal spring rate. Some bikes have more progressive suspension that naturally stiffens as the shock compresses, affecting spring selection.
Getting the Perfect Sag
Ideal spring rates allow for the shock to compress 40–50% of its travel when the bike is loaded with the rider’s weight, a measure known as the sag. Proper sag ensures optimal traction and better handling.
Example
If your shock travel is 55 mm:
- 40% sag = 22 mm of compression
- 50% sag = 27.5 mm of compression
Correct sag ensures a balance between responsiveness and support, reducing bottom-outs on rough terrain.
How to Choose the Right Spring for an 185×55 Shock
Spring selection for an MTB shock boils down to balancing compatibility, performance, and rider comfort. Here’s a checklist to help guide your decision-making:
- Match the Spring Length to Shock Stroke
An 185×55 shock should be paired with springs designed for 55 mm strokes.
- Check Compatibility
Verify the spring’s inner diameter fits the damper body of your chosen shock.
- Consult Manufacturer Resources
Brands like Fox and RockShox provide detailed setups for their shocks to ensure proper spring selection.
- Test and Adjust Sag
Measure your sag after installing the spring and adjust accordingly for a comfortable ride. If the sag percentage is too high or too low, you may need a different spring rate.
Final Thoughts on 185×55 Shock Spring Travel
Understanding spring travel and spring rates for an 185×55 shock is essential for optimizing your MTB’s suspension performance. From ensuring spring length compatibility to calculating ideal sag, each decision plays a pivotal role in creating a smoother, safer, and more efficient ride.
For those new to MTB suspension systems, consider consulting your bike manufacturer’s guidelines or visiting a local bike shop for expert advice. A properly tuned suspension can drastically enhance your riding experience, enabling you to tackle challenging trails with confidence.