instant expert: ANTI-SQuat
What is it?
Just as braking pushes your weight forwards, acceleration pushes it back. Every pedal stroke causes the suspension to squat into its travel and then re-extend. Known as ‘pedal bob’, this wastes pedalling energy. Savvy designers can use chain tension to restrict this – a force known as ‘anti-squat’.
What affects it?
On most designs, the main pivot is above the bottom bracket. That means the rear axle moves away from the BB slightly as the suspension compresses. This adds to the tension created in the upper part of the chain as you pedal, countering the suspension’s tendency to compress. The more a linkage moves the axle away from the BB, the more effective this is.
What effects does it have? Anti-squat can be used to reduce pedal bob significantly, but there are drawbacks. Because the axle moves away from the BB when the suspension compresses, the chain can pull on the chainring, causing the cranks to rotate backwards. This is known as ‘pedal kickback’, which can feel harsh through your front foot. All that tension on the chain can also make the suspension less able to absorb bumps while pedalling.