* Low traction surfaces (ice, snow, loose gravel): Locking up the front wheel on a slippery surface will cause a loss of control and a likely fall or skid. The bike will tend to go straight ahead, regardless of handlebar input. The increased stopping power of the front brake becomes a liability in these conditions.
* Steep descents: On steep descents, excessive use of the front brake can lead to a loss of control, especially at high speeds or if the surface is uneven. The increased weight transfer to the front wheel further reduces the available traction.
* Sudden stops at low speeds: While less of an issue than the other conditions, a sudden, hard application of the front brake at low speeds could also cause the front wheel to lock and lead to a loss of balance.
Proper braking technique involves using both brakes, modulating the pressure, and adjusting the application depending on the conditions. Generally, the front brake should provide the majority of stopping power (around 70% in good conditions), but this ratio should be reduced significantly on slick surfaces. The rear brake helps stabilize the bike and prevents skidding, especially in low traction conditions.
