How to Set Up Your Trials Motorcycle Suspension for Better Performance
If you're aiming to better your technical riding, rider larger obstacles, navigate steeper climbs, and maneuver your bike with greater ease, this guide is for you. Effective suspension is a key component in a trials motorcycle's ability to tackle terrain, and tuning it is essential for optimal performance. While many riders might assume that the factory settings for their suspension are good enough, those who fall outside the average weight range or enjoy more technical terrains might beg to differ.
Why Suspension Setup Matters
Most trials motorcycles are set up for riders weighing between 170-190 pounds. But what if you're lighter or heavier? I've heard many people say that trials suspension works straight out of the box, but ask yourself: why do mountain bikers and dirt bikers spend thousands to tweak their suspension? There is a lot of added benefits to suspension tuning. Trials is no different—adjusting your bike's suspension allows it to help you rather than fight you.
Understanding Trials Suspension
Many new to trials riding perceive the suspension as overly soft and susceptible to bottoming out, leading them to opt for heavier spring rates. But it's crucial to understand that a softer suspension is fundamental for trials bikes, and overly stiff suspension can negatively impact handling by sacrificing grip and responsiveness.
A softer spring significantly enhances traction and simplifies the process of lifting or hopping the bike. As the spring compresses more, it stores more energy in its rebound. Its the rebound force that goes to lifting the bike and therefore making the bike feel more responsive and helps in lifting the wheels. You'll often observe top riders forcefully pushing down on their bikes. A soft suspension allows the bike to remain deeper into the travel, maintaining traction and storing energy in the spring for explosive moves. Conversely, a too-heavy spring resists this, rebounding too early and resulting int pushing the bike upwards too early and compromising grip. Another example comes to hopping, the common misconception is that it involves pulling up on the bike. In reality, riders push down, utilizing the rebound from the suspension to lift the bike with minimal effort. A softer setup permits greater compression and stronger rebound force, and easier for effective hopping as well provide more upwards energy on explosive techniques. However, if the suspension is too soft, it will be susceptible to bottoming out more often during high-impact activities like jump landings or high-speed travel over rough terrain.
Preferences for suspension stiffness can vary based on a rider's skill level and the specific terrain they tackle. However, most riders will find that a softer suspension setup will offers the best performance. Expert riders facing very large obstacles might choose a stiffer setup to manage the severe impacts, whereas those who mostly ride fast trails could benefit from a stiffer spring, which provides stability and speed but may reduce agility in technical areas.
Setting Up Trials Suspension: A Comprehensive Guide
Part 1: Setting the Correct Rider Sag
Getting the correct rider sag is the first and most important step in optimizing bike performance. Sag is just how much your suspension compresses with you on the bike. It's important to keep your wheels on the ground as well as lifting it off the ground. Proper sag keeps the bike from fighting you or the terrain.
To measure sag, you'll need to be in your normal riding gear and position on the bike. Have a helper measure from the rear axle to the rear mudguard for the rear sag, and use a cable tie around the fork stanchion for the front sag, measuring from the fork seal to the tie.
Measuring Front Sag - Ideally 30% of travel. Most trials forks typically have 170mm, with newer GasGas having 163mm.
1. Get the baseline - Measure the total length of the fork with the bike off the ground. This determines your baseline. Note there is usually 5-10mm of unused travel of a fork due to where your fork clamps are set.
2. Measure the dynamic sag - Rest the cable tie while the bike on the ground with a fully geared rider in a standard riding position. Carefully step off the bike and measure how far the cable tie has moved.
Calculation - (Baseline - Dynamic Sag) / Baseline.
Measuring Rear Sag - Ideally 45-50% of total wheel travel. Most bikes have between 165-170mm
1. Get the baseline - Measure the distance between axle and one point to the mud guard with the bike fully off the ground. This determines a baseline number.
2. Measure static sag - Measure the distance between axle and one point to the mud guard with the bike on the ground without a rider. The bike sags under its own weight without the rider determines the static sag. Correct Static sag number should be 9-18mm.
Calculation - Baseline - Static Sag
3. Measure the dynamic sag - Measure the distance between axle and one point to the mud guard with the bike on the ground with a fully geared rider in a standard riding position.
Calculation - (Baseline - Dynamic Sag) / Baseline
For example, for a bike with 170mm of rear suspension, aim for 75-85mm (44-50%) of sag with your weight on the bike. We recommend that more technical riders opt for a slightly softer spring combined with increased preload to maintain the same ride height, while less technical riders should consider a slightly harder spring with reduced preload.
Remember once you determine sag you may need to iterate to refine it by using preload or changing springs. Remember if you have too much or too little preload, you'll likely need to purchase a new spring.
Fork preload adjustment
Shock preload adjustment
Part 2: Rebound Damping
A spring will rebound after being compressed, rebound dampening is the suspension's system to control that rebound. Rebound damping is essential to prevent the suspension from behaving like a pogo stick after compression. Adjusting the number of clicks on your rebound damping adjuster can drastically alter the bike's handling. Less damping can make the bike feel bouncy and unstable, useful for lifting the wheels but can throw you off your line. More damping provides a slower, more stable ride, but can reduce maneuverability or traction. In some cases too slow of rebound can result in harshness due to your spring packing up over successive impacts. Remember when increasing spring rates (either by upping preload or switching to a stiffer spring), you should increase your rebound damping (turn clockwise) to manage the higher spring force. Conversely, decrease your rebound damping (turn counterclockwise) when lowering spring rates.
Part 3: Compression Damping
Not all suspension features compression damping, but for those that do, it adds a force that resists the compression of the suspension. Less compression damping allows for a softer, more supple ride, while more damping helps resist bottoming out and provides a more defined feel during compression. Too little damping can lead to frequent bottoming out, whereas too much can make the ride feel overly harsh.
Part 4: Bottom out support
If you are feeling harsh bottom outs for trials forks, you can try adding 5mm of oil at a time into the Spring (left) side of the fork leg. Similarly if you are not using enough travel, you can try removing 5mm of oil at a time from the Spring side. Remember to not go overboard as oil is used in the damper as well as the lubricant, removing too much oil may result in damage to the fork.
Here is the recommended oil levels in Tech forks.
Part 5: Bracketing and Customization
Optimizing your suspension typically involves more than just driveway adjustments; you may want to test and refine settings on the trail. Bracketing is an effective technique for this. Always start with the correct sag of your bike as this will be the right baseline. Begin by adjusting the rebound damping, two clicks / turns in one direction. Test the change; if it improves your ride, continue two more clicks of adjustments. If it worsens, back off one click in the other direction and repeat. This method helps you dial in on what feels best for you. Once you are happy, then adjust compression. But remember to adjust only one setting at a time and test across different terrains. It might take time to perfect your setup, but the effort is worthwhile for optimal performance.
In summary, don't settle for the factory settings if they don't suit your weight or riding style. With some adjustments, your trials bike can transform into a more responsive and capable companion on the trails. Happy riding!
Part 6: Advanced Tuning
In addition to basic adjustments, if you're significantly lighter or heavier than average, or simply seeking more performance, revalving your suspension might be the best approach. Suspension dampers work by allowing oil to flow through ports and shims, and altering this flow changes the damper's force. Tweaking these internal configuration can modify how the suspension reacts. Suspension tuning specialist such as Ben at Alba Distribution or Spencer at Arc Trials Motorcycles offer upgrade services. It's worth noting that some of these investments can often transfer between bikes. Generally, forks can be moved between bikes if they share the same aluminum/steel stanchions, and shocks can be transferred to another bike with compatible shock dimensions and suspension design.
Spring Rate Guide
These are general guidelines, different bikes may vary slightly. We recommend going one spring lighter with more preload for more technical riding and one heavier with less preload for less technical terrain.
Purchasing springs can be found here:
| Fork | |||||||||
| Springs | Soft | Standard | Stiff | ||||||
| Rider Weight (lbs) | < 165 | 165-200 | > 200 | ||||||
| Shock | |||||||||
| Springs (N/mm) | 60 | 62.5 | 65 | 67.5 | 70 | 72.5 | 75 | 80 | 85 |
| Rider Weight (lbs) (Gas Gas / TRS) | 100-110 | 110-132 | 132-143 | 143-165 | 165-177 | 177-187 | 187-210 | 210-220 | 220+ |
| Rider Weight (lbs) (Vertigo) | 110-128 | 128-136 | 136-144 | 144-152 | 152-160 | 160-168 | 168-176 | 176-192 | 192-210+ |
| TRS Standard | 70 | ||||||||
| GAS GAS Standard | 73.6 | ||||||||
| Vertigo Standard | 75 | ||||||||