RockShox Suspension Calculator

This rockshox suspension calculator provides a reliable starting point for setting your fork or rear shock air pressure and rebound. Fine-tune your settings on the trail for optimal performance based on your riding style and terrain.

Sag Measurement Guide

Desired Sag (%)	Required Sag Measurement (mm)

Use a ruler to measure sag on the stanchion and match it to these values.

What is a {primary_keyword}?

A {primary_keyword} is a specialized tool designed to simplify the complex process of setting up your mountain bike’s air suspension. Instead of relying solely on generic manufacturer charts, this calculator provides a personalized starting point for your air pressure (PSI) and rebound settings based on your specific weight and bike’s travel. Correct suspension setup is arguably the most important adjustment you can make, directly impacting traction, control, and comfort on the trail.

Anyone with a mountain bike equipped with a RockShox air fork or rear shock should use a {primary_keyword}. From beginners who want a safe and reliable baseline to experienced riders looking for a consistent starting point for further tuning, the calculator removes guesswork. A common misconception is that the pressure printed on the fork is the final word; in reality, it’s just a guideline. A proper {primary_keyword} like this one gives you a more nuanced recommendation.

{primary_keyword} Formula and Mathematical Explanation

The logic behind this {primary_keyword} is based on established starting points used by mechanics and the RockShox TrailHead app. The goal is to balance the spring force (air pressure) against the rider’s weight to achieve a desired “sag” level.

1. Air Pressure Calculation: The primary starting point for many RockShox forks is a 1:1 ratio between rider weight in pounds and the required air pressure in PSI. It’s a simple, effective baseline.
2. Sag Calculation: Sag is the percentage of suspension travel used when the rider is stationary on the bike in a riding position. It’s crucial for allowing the wheel to track the ground. The formula is: `Sag (mm) = Total Travel (mm) * (Desired Sag % / 100)`.
3. Rebound Calculation: Rebound controls how fast the shock returns to its full travel after a compression. Our calculator uses a simplified algorithm where the rebound is adjusted relative to the air pressure. Higher pressure requires slower rebound (fewer clicks from closed) to control the higher spring force.

Variables Table

Variable	Meaning	Unit	Typical Range
Rider Weight	Fully geared-up weight of the rider.	lbs / kg	100 – 250 lbs
Suspension Travel	The maximum distance the suspension can compress.	mm	100 – 200 mm
Sag	Percentage of travel the suspension compresses under rider weight.	%	15 – 35%
Air Pressure	The force of the air spring inside the suspension.	PSI	50 – 250 PSI
Rebound Damping	Speed at which the suspension re-extends.	Clicks from Closed	0 – 20

Practical Examples (Real-World Use Cases)

Example 1: Cross-Country (XC) Rider

An XC rider on a bike with a 120mm fork wants a firm, efficient setup.

• Inputs: Rider Weight: 150 lbs, Suspension Travel: 120 mm, Desired Sag: 15%.
• Calculator Outputs:
  • Air Pressure: ~150 PSI
  • Sag Measurement: 18 mm
  • Rebound: ~8 Clicks from closed
• Interpretation: This setup provides a firm platform for climbing and sprinting, minimizing pedal bob. The lower sag keeps the bike in a more aggressive geometry. For more related information, you might be interested in our {related_keywords} guide.

Example 2: Enduro Rider

An Enduro rider on a bike with a 170mm fork needs a plusher setup for rough descents.

• Inputs: Rider Weight: 190 lbs, Suspension Travel: 170 mm, Desired Sag: 30%.
• Calculator Outputs:
  • Air Pressure: ~190 PSI
  • Sag Measurement: 51 mm
  • Rebound: ~5 Clicks from closed
• Interpretation: The higher sag percentage allows the suspension to absorb large impacts and maintain traction over rocks and roots. The slower rebound (fewer clicks) controls the powerful return force of the high-pressure spring. This is a key part of any {primary_keyword}.

How to Use This {primary_keyword} Calculator

Using this {primary_keyword} is a straightforward process. Follow these steps for an accurate baseline setup:

1. Enter Your Weight: Put on all your regular riding gear (helmet, shoes, pack with water) and weigh yourself. Enter this value in the “Rider Weight” field.
2. Enter Suspension Travel: Find the travel of your fork or shock. This is often printed on the side or can be found on your bike manufacturer’s website. Enter it in the “Suspension Travel” field.
3. Enter Desired Sag: Choose a starting sag percentage. For an XC bike, 15-20% is good. For a trail or enduro bike, 25-30% is more common.
4. Read the Results: The calculator instantly provides your starting air pressure, the physical sag measurement in mm, and a rebound setting. Our guide to {related_keywords} can offer more context.
5. Apply and Test: Use a shock pump to set the recommended air pressure. Then, check your actual sag and fine-tune pressure until it matches the “Sag Measurement” value. Set your rebound dial. Go for a ride and adjust as needed!

Key Factors That Affect {primary_keyword} Results

The {primary_keyword} gives you a starting point, but several factors can lead you to deviate from these numbers for a personalized tune.

• Riding Style: Aggressive riders who hit jumps and drops may need slightly more pressure and slower rebound than smoother, more ground-based riders.
• Terrain Type: If you ride mostly smooth, flowy trails, you might prefer less sag for better efficiency. If your trails are rocky and technical, more sag will improve traction and comfort.
• Volume Spacers (Bottomless Tokens): These plastic tokens reduce the air volume in your fork or shock, making the suspension more progressive (harder to bottom out). If you have tokens installed, you may be able to run slightly lower pressure for better small-bump sensitivity. Check out our deep dive on {related_keywords}.
• Temperature: Air pressure can change with ambient temperature. A setup dialed in on a cold morning might feel different on a hot afternoon. Always set pressure at the riding temperature if possible.
• Leverage Ratio: Every bike frame has a unique leverage ratio that affects how the rear shock compresses. This is why a {primary_keyword} is a starting point, as your specific frame may require more or less pressure than another bike with the same shock.
• Low and High-Speed Compression: Higher-end RockShox dampers have external compression adjustments. These settings can be used to fine-tune support without altering air pressure, a topic we cover in our {related_keywords} article.

Frequently Asked Questions (FAQ)

1. What if my measured sag doesn’t match the calculator?

If your measured sag is too high (e.g., 35% when you want 30%), add more air pressure in 5 PSI increments. If it’s too low (e.g., 25% when you want 30%), release air pressure. Always cycle the suspension a few times after adjusting pressure to equalize the air chambers.

2. How do I know if my rebound is too fast or too slow?

Too fast (too many clicks from closed) will feel bouncy and uncontrolled, like a pogo stick, especially after big hits. Too slow (too few clicks) will cause the suspension to “pack down” on successive bumps, feeling harsh and failing to use full travel. Finding a great setting is what makes a {primary_keyword} so useful.

3. Should I use the same sag for my fork and shock?

No, typically you run less sag in the fork (15-25%) and more sag in the rear shock (25-35%). This helps maintain the bike’s intended geometry and balances the feel of the front and rear wheels.

4. Can this rockshox suspension calculator be used for other brands?

While the principles of sag are universal, the 1:1 weight-to-PSI rule is a specific starting point for RockShox. Other brands like Fox or Marzocchi may have different recommended starting pressures. It’s best to use a calculator specific to your suspension brand.

5. How often should I check my suspension settings?

It’s good practice to check your pressure before every ride, as air can slowly leak over time. You should re-evaluate your entire setup using a {primary_keyword} if you change your riding weight, install volume tokens, or move to drastically different types of trails.

6. What does “clicks from closed” mean for rebound?

This is the standard way to measure rebound. Turn the rebound dial all the way clockwise until it stops (this is the “closed” or slowest setting). Then, turn it counter-clockwise and count the number of distinct clicks. This calculator gives your starting point from that fully closed position.

7. Does bike type (e.g., hardtail vs. full suspension) change how I use this tool?

For a hardtail, you only need to use the {primary_keyword} for your front fork. For a full suspension, you should run the calculation twice: once for the fork’s travel and desired sag, and a second time for the rear shock’s travel and desired sag.

8. Where can I find my suspension serial number?

RockShox often places the serial number on the back of the fork’s crown or on the shock’s air can. You can use this number on the RockShox TrailHead website or app for model-specific info.

Related Tools and Internal Resources

Expand your knowledge and dial in your ride even further with these resources:

• {related_keywords}: A detailed guide to understanding and installing volume spacers to tune your suspension’s progressivity.
• Advanced Tuning Guide: Learn about low and high-speed compression and how to use them to your advantage.
• Maintenance Schedule: A comprehensive look at how often you should service your RockShox suspension to keep it running smoothly.