What About the Tyres? Self-Damping, etc.
Strictly speaking, all possible components of a mountain bike "spring" and "absorb shocks". First of all are the tyres, which flex as they roll, so they constantly deform while in motion and then return to their original shape. The deformation itself counts as a spring function, while the so-called self-damping of the material slows down the movement in both directions. When frames or handlebars bend under load (often called "flexing"), this is basically also a spring function. Nevertheless, one usually only speaks of suspension in the case of suspension forks and shock absorbers. There are good reasons for this: Firstly, the "pseudo-travel" of the components results from their respective material properties and can hardly be controlled and adjusted externally. Secondly, the "travel" that tyres, wheels, frames or handlebars can provide is extremely limited. If the material deforms beyond a certain limit, it fails. Nevertheless, on a road bike or gravel bike, the deformation of the tyre and carbon fork or frame is often already the entire suspension travel. However, that’s a different topic altogether.