Post #4775697 · Elektrine

2026-08-13 13:16 UTC

*Why bicycles are surprisingly stable* A common myth is that bicycle stability comes mainly from the spinning wheels acting as gyroscopes. Gyroscopic effects help, but they are actually not the dominant factor. The major sources of bicycle stability are: 1. Steering geometry (trail) • The front wheel naturally "falls into" a turn when the bike leans. • This automatically steers the contact patch underneath the rider's centre of mass. • The bike performs a kind of continuous self-correction. 2. Large wheel diameter • Large wheels roll smoothly over imperfections. • Small steering disturbances produce gentler changes in direction. 3. Long wheelbase • Reduces sensitivity to perturbations. • Creates slower, more manageable dynamics. 4. Rider position • The rider's mass is located relatively high and centred between the wheels. • Subtle body movements can effectively influence balance. At speeds around 10-20 km/h, many bicycles are remarkably self-stabilizing. If you've ever seen a bicycle coast for a surprising distance riderless, that's evidence of these effects.

Replies (1)

@adub@beige.party 2026-08-13 13:21

* Why e-scooters are less stable* Most e-scooters move in the opposite direction on several of those factors. 1. Tiny wheels This is probably the biggest issue. • Typical bicycle wheel: ~66-74 cm diameter (26-29 inches) • Typical e-scooter wheel: ~20-30 cm diameter (8-12 inches) if that A bump that's trivial for a bicycle can represent a significant fraction of a scooter wheel's radius. Consequences: • Easier to be deflected by cracks and potholes. • More sensitive to rough pavement. • Higher likelihood of "catching" on obstacles. • Faster steering reactions. This alone accounts for much of the subjective feeling that scooters are twitchy. 2. Short wheelbase An e-scooter's wheelbase is often around half that of a bicycle. The result: • Quicker pitch motions. • Greater sensitivity to weight shifts. • More rapid response to steering inputs. In control-theory language, scooters tend to have faster unstable modes and less passive damping. 3. Higher steering sensitivity The handlebars are directly above the front wheel. On a bicycle: • Hands are farther from the steering axis. • Steering motions are somewhat filtered by body posture. On a scooter: • Small hand movements can create substantial steering angles. This is one reason inexperienced riders often exhibit slight "wobbling" on scooters. 4. Standing posture Standing has advantages, but it changes the dynamics. The rider's center of mass is: • Higher above the deck than a cyclist's center of mass is above the bike frame. • Less constrained by a saddle. This means: • Greater potential leverage on the vehicle. • More body sway. • More active balancing required. The rider becomes part of the control system in a stronger way.

Open ##4775696