Set Your Mountain Bike Shocks: A Complete Guide

Last Updated on October 26, 2026 by Jaxon Mike

Setting your mountain bike shocks is easier than you think. You can find the right shock settings by using a suspension calculator and then making fine-tuning adjustments based on how your bike feels on the trail. Getting this right means you’ll have a much more comfortable and capable ride.

Your bike’s suspension is key to control and comfort. Properly set shocks absorb bumps and keep your tires in contact with the ground. This helps you maintain speed and confidence on rough terrain. We’ll help you dial in your sag percentage and rebound damping.

• The main goal is proper sag.
• Use an online calculator first.
• Test and adjust on the trail.
• Focus on sag and rebound.

Ready to make your ride smoother and more controlled? Let’s walk through how to set your mountain bike shocks step by step.

Dialing in Your Mountain Bike Suspension Settings

Getting your shocks set up correctly is one of the best ways to improve your mountain bike’s handling and your overall comfort. You don’t need to be a professional mechanic to do it. We’ll guide you through the simple steps to make your bike feel like an extension of you on the trail.

Understanding Sag: The Foundation of Good Suspension Setup

Sag is the amount your suspension compresses under your weight. It’s the most important starting point for setting up your shocks. Too much sag means your suspension might bottom out. Too little sag means it won’t absorb bumps effectively. Finding the sweet spot is key.

What’s the Ideal Sag Percentage?

For most mountain bikes, research suggests a sag percentage between 20% and 30% for the rear shock. For your front fork, 20% to 25% is a common recommendation. This range allows your suspension to work well on various terrains. It balances plushness with support. Many experts recommend starting at 25% for both front and rear and adjusting from there (MTBR).

How to Measure Sag on Your Bike

This is where you’ll need a few simple tools. Grab a ruler or measuring tape, a pen or marker, and a zip tie. You’ll also need to know the total travel of your fork and rear shock. This information is usually in your bike’s manual or on the manufacturer’s website.

Steps for Measuring Rear Shock Sag

• Prepare the shock: Make sure your shock is clean. Locate the rubber O-ring or a similar marker on the shock stanchion (the shiny sliding part). Slide it down to rest against the shock seal.
• Get on your bike: Carefully swing your leg over the bike. Stand on the pedals as you would when riding. Try to keep your weight centered and avoid bouncing. Have a friend help you hold the bike upright if needed.
• Mark the travel: While you’re holding your weight on the bike, carefully dismount without disturbing the O-ring. The O-ring will have moved up the stanchion. Mark this new position with your pen or marker.
• Measure the distances: Now, measure the distance from the shock seal to your O-ring mark. This is the amount of sag your shock experienced.
• Calculate the percentage: Divide the sag distance by the shock’s total travel. Multiply by 100 to get your sag percentage. For example, if your shock has 150mm of travel and you measured 30mm of sag, your sag is 20% (30mm / 150mm * 100 = 20%).

Steps for Measuring Fork Sag

The process for your fork is very similar. Look for a rubber O-ring on the fork stanchion. Slide it down to the seal. Carefully get onto your bike, maintaining a neutral riding position. Dismount and measure the distance the O-ring moved. Divide this by your fork’s total travel and multiply by 100 for the percentage.

Adjusting Air Pressure for Sag

Most modern mountain bike suspension uses air springs. This makes adjusting sag straightforward. Your fork and rear shock have air valves, usually covered by a small cap. You’ll need a shock pump, which is specifically designed for high-pressure, low-volume air chambers.

Using Your Shock Pump Correctly

A shock pump attaches to the air valve. You can then add or release air pressure. To increase sag, you’ll need to reduce air pressure. To decrease sag, you’ll need to increase air pressure. Always attach the pump slowly and avoid losing air when connecting or disconnecting it. Some pumps have a gauge for precise readings.

The Recommended Method: Suspension Calculators

We highly recommend using an online suspension calculator. These tools are a fantastic starting point. You’ll enter your bike’s make and model, the travel of your fork and shock, and your weight (in riding gear). The calculator will then suggest a starting air pressure for both your front and rear suspension to achieve your target sag percentage (SRAM).

After you’ve used the calculator, you’ll still need to check your sag with the ruler method. The calculator gives you a great baseline, but it’s essential to confirm it on your actual bike.

Adjusting Pressure Based on Calculator Results

Let’s say the calculator recommends 150 psi for your fork. After setting it and checking your sag, you find you have too much sag. This means you need to increase the air pressure. Add a few psi at a time, re-check sag, and repeat until you hit your target.

Conversely, if you have too little sag, you need to decrease the air pressure. Let out a few psi at a time, check sag again, and keep going until it’s right. It might take a few tries to nail it perfectly.

Understanding and Adjusting Rebound Damping

Sag gets your suspension compressing correctly. Rebound damping controls how quickly your suspension extends back out after hitting a bump. This is just as important for control and comfort as sag.

What Does Rebound Damping Do?

Think of rebound like a spring stretching back. Without damping, it would snap back too quickly, kicking you around. Too much damping, and it feels slow and packed down. The goal is to have the suspension extend fast enough to be ready for the next bump but slow enough to keep you in control. We found that most riders benefit from a moderately fast rebound setting for general trail riding (Fox Racing).

How to Adjust Rebound

Your fork and rear shock will have a rebound adjustment knob. It’s usually a red or black dial with +/- markings. Start by turning the knob all the way clockwise to the slowest setting (fully damped). Then, slowly turn it counter-clockwise, opening it up one click at a time. You’ll feel and hear clicks as you turn it.

Testing Rebound on the Trail

After setting your sag and adjusting rebound based on the calculator or manual recommendations, it’s time to hit the trail. Find a section of trail with moderate bumps and jumps. Ride through it several times, making small adjustments to the rebound knob between runs.

• Too Fast Rebound: If the bike feels like it’s bucking you off or the wheels are skipping over bumps, your rebound is too fast. Turn the knob clockwise a few clicks.
• Too Slow Rebound: If the bike feels like it’s packing down after hits, or the suspension doesn’t seem to extend fully, your rebound is too slow. Turn the knob counter-clockwise a few clicks.

You’re looking for a feeling where the bike stays planted and the suspension extends smoothly. It should feel controlled, not bouncy or sluggish.

Fine-Tuning and Trail Testing Checklist

Setting your suspension is an ongoing process. The best setup might change depending on the trail conditions, your riding style, and even the weather. Here’s a quick checklist to ensure you’ve dialed it in:

• Measure and set your sag to the recommended percentage (20-30% rear, 20-25% front).
• Use an online calculator for initial air pressure recommendations.
• Adjust air pressure in small increments, re-checking sag each time.
• Set rebound damping to a moderate speed, avoiding packing or bucking.
• Test ride on familiar terrain, making minor adjustments as needed.
• Listen to your bike and how it feels; trust your instincts.

Conclusion

You’ve now learned the essential steps to properly set your mountain bike shocks. Remember, achieving the right sag percentage and dialing in your rebound damping are key. Using an online calculator gives you a solid starting point, but real-world testing is where the magic happens. Don’t be afraid to make small adjustments on the trail; it’s how you’ll find that perfect balance of comfort and control.

Your next step? Grab your shock pump and a ruler, then head out for a test ride. Pay attention to how your bike feels, and you’ll soon enjoy a smoother, more capable ride on all your adventures.

Frequently Asked Questions

How do I know if my mountain bike suspension needs adjustment?

You’ll notice a few signs. If your bike feels harsh, bottoms out easily, or bounces excessively on descents, it’s time to adjust. A poorly performing suspension also impacts your control and can lead to fatigue more quickly.

Can I adjust my suspension without a shock pump?

While it’s not ideal, you can make very rough adjustments using a standard bike pump. However, you risk losing air quickly and won’t get precise readings. A dedicated shock pump is inexpensive and makes the process much easier and more accurate.

What happens if my sag is too high or too low?

If your sag is too high (too much compression), your suspension may bottom out on big hits and feel overly plush. If your sag is too low (not enough compression), your suspension won’t absorb smaller bumps effectively, leading to a harsher ride and less traction.

How often should I check my suspension settings?

It’s a good practice to check your sag and rebound settings at the beginning of a riding season or after any major maintenance. You may also want to make minor tweaks if you change the type of trails you ride or notice a change in performance.

Is it okay to use different sag percentages for my front and rear suspension?

Yes, it’s very common and often recommended. Generally, your front fork might have slightly less sag than your rear shock to maintain front-end support and prevent diving. The percentages mentioned (20-25% front, 20-30% rear) are good starting points.