“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.
What is anti-squat in mountain bike suspension?
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.
Why anti-squat matters for mountain bike performance
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.
Pedal bob: why efficiency matters on climbs and how anti-squat helps
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.
Where does anti-squat come from?
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.
How linkage designs affect anti-squat
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.
How is anti-squat measured?
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.