Bicycles have a short
wheelbase relative to the height of their
center of mass, when compared to other vehicles such as cars. Because bicycles are pedalled, their forward acceleration tends to be in surges while each pedal is under power. Because the driving force at the rear wheel is not aligned with the center of mass, the bicycle experiences a torque, according to
Euler's second law. This torque is partially responsible for the compression of the rear suspension under power known as squat. Squat which occurs in time with pedalling is known as "suspension bob."
Suspension bob has three main causes:
- Rider weight shift due to their pedalling stroke
- The chain tension acting on the suspension
- The suspension squatting or jacking due to acceleration forces.
On bikes which are subject to bob, the following two techniques can reduce it.
However, neither of these solutions are ideal as they hinder the suspension's ability to absorb small bumps or low-speed impacts while the bicycle is coasting (Note: "low-speed" does not refer to the velocity at which the vehicle is traveling, but the speed at which the suspension is compressed). In the case of excessive compression damping, this problem is known as
overdamping.
The DW-link uses an anti-squat suspension design to counteract forces responsible for "suspension bob" and consequently removes the need for excessive compression damping. This allows the suspension to be much more active over low-speed impacts, allowing more traction.