You don’t know squat: what is anti-squat in mountain biking and why does it matter?

“Anti-squat” was not a well-known term outside engineering departments until recently. As the search for mountain bike performance has advanced, engineers have delved deeper and deeper into the details of how your suspension works to offer riders an edge. Today, these kinds of terms have become important to explain how one bike is different from the next. This short guide will walk you through what anti-squat is and why it makes such a big difference to how your mountain bike feels on the trail.

Anti-squat is the suspension force that helps stop your full-suspension bike from bobbing up and down as you pedal. You have probably felt yourself being gently pulled back into your seat as a vehicle accelerates. This is called mass transfer. On your bike, each pedal stroke you take is actually a small acceleration, so every time you pedal, each small acceleration is pushing your weight backwards and compressing the rear suspension a little. This is called squatting in engineering terms, and anti-squat is the force that helps counteract these compressions.

The simplest way to think about anti-squat is to think about trading off between downhill performance and pedalling efficiency. A bike with a high anti-squat percentage would be very efficient and fast to pedal, but the suspension would be less comfortable and find less traction. A bike with low anti-squat would be very comfortable with very plush, active suspension that would feel great on the way down, but it would bob up and down a lot on the way back up.

In the grand scheme of things, humans don’t generate a lot of power. Even an elite athlete can only briefly put out around 2.5 horsepower; for the rest of us, it is more like 1.2. With so little power on tap, making sure all of it is used to propel you forward is important. If your bike is bobbing up and down, it means that some of your energy is being used to do that, rather than driving you forward. By reducing how much the bike bobs up and down, a bike with high anti-squat values will help you put more of your power into speed. 

Anti-squat comes from the suspension design of your bike. It is a combination of the placement of the pivots, the chainstay length and the chain line that work together to give the characteristics of the suspension.  

You may hear of many different suspension designs like “four-bar”, “single pivot” or “VPP” and how these have different features. These terms refer to different ways of building a full-suspension bike to fine-tune the various suspension forces and make the bike ride well. There are small differences between the layouts, but what matters more is how the bike’s designer has interpreted their system to give their desired characteristics.

Have you heard riders talk about their “anti-squat percentage”? This is because anti-squat is measured as a percentage of the chain force. A bike with 0% anti-squat would have no resistance at all, and each pedal stroke would fully compress the suspension. At 100%, the mass transfer and suspension forces would be in balance, and the bike would not move as you pedal. Beyond 100%, the bike actually extends a little bit with each pedal stroke because the suspension force is stronger than the mass transfer. In other words, the higher the number, the more anti-squat a bike will have.  

To make this all more complicated, your anti-squat percentage changes as you go through your suspension travel. The most important anti-squat value is at the sag point of your suspension, and this is the percentage most manufacturers will talk about. Sag is how much travel your suspension uses to support your bodyweight. This is the point that your suspension will sit at when you are pedalling in the saddle - when anti-squat is most needed. For most bikes, the sag point sits between 20 and 35% of the total suspension travel. This is one of the reasons why getting the right suspension setup is so important - because you need to be at the right sag point to get the correct amount of anti-squat. 

From this sag point, the anti-squat value will normally decrease as you go through the suspension travel. This allows you to use all of the suspension travel. On bikes where the anti-squat stays high, you would struggle to use all of your suspension, and the bike would be very efficient but harsh. Most bikes try to find a balance where they are efficient for pedalling, but still allow riders to use the full stroke of the rear shock comfortably.

Chain line is one of the elements that helps create the anti-squat, and you can alter your chain line with the size of your chainring and cassette. This means you can make small changes to your anti-squat. For everyday riders, this can be a fun experiment, but for racers, the size of their chainring is really important to their overall performance, which means this is not a great option.

If you are digging into suspension design, you may have come across the terms anti-rise and pedal kickback alongside anti-squat.  

While anti-squat deals with acceleration forces, anti-rise deals with deceleration forces - braking, in other words. If you are familiar with being pushed back into your seat by a vehicle accelerating, you are hopefully also familiar with the feeling of being pushed forward by hard braking. This is called rise. Anti-rise is the suspension force that allows the suspension to resist this forward shift. The downside is that it restricts the movement of the suspension. A low anti-rise bike would not resist the braking forces, which would mean the suspension would stay active. The problem is that the geometry would shift, which could be very disconcerting at such a critical moment.

A bike with 100% anti-rise would remain neutral under the braking forces, keeping the bike’s geometry consistent, but it would effectively lock out the rear suspension while braking. The downside is that if anti-rise gets too high, it can interfere with the action of the rear suspension, making the bike feel harsh and inconsistent.

Most suspension designs cause the rear axle to get further from the main frame of the bike as it compresses, pulling on the chain. This is called chain growth. When the suspension is compressed, this can cause the cranks to rotate backwards, giving the rider an unpleasant feeling of their pedals being pulled backwards and restricting the movement of the suspension. This is more of an issue on bikes with high anti-squat.

The challenge in designing a great bike is to balance anti-squat, anti-rise and pedal kickback. Often, altering one of them can affect the other two, so designers need to think long and hard about what compromises are suitable for the rider they have in mind.

There are some signs to look for if you are worried that your bike might have too much or too little anti-squat: 

Does your bike feel harsh on rough terrain? Do you feel like your suspension is locked out all the time and doesn’t really absorb the impacts from the trail? If this is the case, then you might have a bike with high anti-squat.

Can you feel yourself bobbing up and down as you pedal your bike? This is the classic sign that your anti-squat is low.  

The size of your chainring affects your anti-squat. This means that you can adjust your anti-squat a little by changing your chainring size. A larger chainring will decrease your anti-squat, and a smaller chainring will increase it. The downside to this is that your chainring size is now dictated by your suspension, rather than your needs for pedalling, which can be a problem for some riders. 

In modern cross-country racing, the performance edges are in the details, like anti-squat. Working with our elite athletes, we developed a simple flip chip system for the Lux World Cup to allow them to fine-tune their anti-squat levels to the course in front of them, without having to compromise their gearing. This means that for technically demanding tracks, they can dial out the anti-squat to get maximum traction and control from their suspension, while on faster tracks, they can crank up the efficiency for ruthless speed.

As modern cross-country racing demands bikes with more suspension travel, how the bikes deliver that travel becomes more and more important. To make it more complicated to find the ideal balance in suspension characteristics, those needs can change from track to track. We believe that anti-squat is the key to these challenges, and by building a bike that can let riders tune their levels of anti-squat, we have built a formidable race weapon for modern cross-country racing.

If you would like to explore what makes a great cross-country bike in more detail, we have a dedicated buyer’s guide to cross-country bikes. For beginners, our best entry-level MTBs guide highlights great options to get started, while our comprehensive MTB guide covers all categories, components and key considerations. We also offer guides across the full spectrum of riding styles - from downcountry to hardcore downhill - so you can better understand the differences and find the right fit. If you are not sure what sort of bike would suit you best, our bike finder tool will help you figure out what works for you and your riding.

We hope this has helped demystify anti-squat for you a little. See you out there on the trails!