E-bikes can reach speeds well beyond what's possible on a regular bicycle. However, their top speed depends on several factors that can either enhance or limit performance. Understanding these influences will help riders optimize their e-bike's velocity and better control it based on varied conditions.

1. Motor Wattage

Perhaps the biggest determinant is the motor's wattage rating. More powerful motors in the 500W-750W range will yield faster acceleration and higher maximum speeds. While legal limits restrict motor wattage on public roads in some places, off-road higher wattage can be utilized. Riders seeking outright speed should look for bikes equipped with Bafang or Bosch Performance Line CX motors rated at least 500W.

2. Pedal Assistance Level

Pedal assist acts as an e-boost multiplier for a rider's manual power input. Its scale typically ranges from 1 to 5, with level 1 providing the lowest extra torque and level 5 engaging the motor the most. Cruising at max pedal assist will naturally be faster than keeping it at the lower end. Most ebikes top out the motor's input around level 3 for safety and to conserve battery.

3. Terrain and Weight

Going uphill requires more energy to maintain speed due to gravity. Heavier loads like with cargo or passengers also increase rolling resistance against forward motion. Steeper slopes and excess weight will naturally cause velocity to drop unless the motor compensates. Riders seeking consistent speed should prioritize lightweight aluminum frames and low-gear sufficient hill climbing ability.

4. Tire Size and Air Pressure

Larger, wider tires offer better traction but also increase rotational mass and rolling resistance inhibiting acceleration potential. Ideal performance tires will maximize grip while minimizing unsprung weight effects. Keeping them properly inflated helps minimize this drag. 26 inch tires will roll quicker than bulky fat 20 inch variants in most cases.

5. Brake Type

Hydraulic brakes provide strong, predictable stopping power better suited for higher speed riding scenarios. Their braking feel also allows motor control with less risk of accidental wheel lockups. Mechanical brakes can warp rotors when overheated from repeated hard stops at faster paces that hydraulic discs withstand better.

6. Battery Charge Level

A drained or low battery will shorten the maximum possible range and top speed capabilities. Maintaining batteries between 20-80% state of charge optimizes voltage output and performance longevity over time. Carrying additional charged battery packs extends top speed ride duration by swapping out when one gets depleted.

7. Gearing

Proper gear selection matching cadence to motor power output enhances speed potential. Higher end ebikes with more focused performance applications often come equipped with efficient multi-gear transmissions. Internal hub motors with fewer gears will require carefully matching gearing to the terrain. Upgrading to wider chains and cassette sprockets multiplies overall mechanical advantage.

8. Wind Resistance

Headwinds literally push against forward motion like applying brakes. Even moderate breezes can visibly decrease velocity, so riding position, protective aero accessories, and conditions all factor in. Taller riders experience more drag than low-set frames. Aero bars, tight-fitting helmets, and ram-air front covers help maintain top-end speeds in less than ideal wind conditions.

In conclusion, optimizing these various factors through bike setup choices, rider techniques, and elemental conditions unlocks greater e-bike speed performance. But safety should never be compromised for the sake of velocity - operating within legal limits and personal skill level ensures responsible enjoyment. Understanding what governs maximum pace empowers riders to better self-regulate based on any given scenario.