<![CDATA[The growing use of electric bicycles for urban transportation creates a need to select motor capacity according to performance and energy requirements. Motor power affects speed, electrical demand, battery operating duration, and travel range; therefore, a higher-rated motor does not necessarily provide the most efficient configuration. This study compares 350 W and 500 W brushless direct current motors installed alternately on the same electric bicycle platform. The objective was to evaluate the relationship between motor power, rider load, speed performance, mileage, battery discharge time, terminal voltage, current consumption, and electrical power consumption under controlled comparative conditions. Experiments used the same Selis Murai bicycle platform, 48 V 12 Ah battery, 48 V 500 W controller, and 16 x 2.5 wheel size. Five rider loads of 60, 70, 80, 90, and 100 kg were tested on a relatively flat route repeatedly traversed until the battery discharge limit was reached. Maximum speed, average speed, mileage, battery operating duration, terminal voltage, current, and electrical input power were evaluated using descriptive comparison and linear trend analysis. The 500 W motor achieved 20.89% higher maximum speed and 5.5% higher average speed than the 350 W motor. However, its battery operating duration was 16.51% shorter. Across the five load conditions, the 350 W motor provided an average load-wise mileage advantage of 13.08% and consumed approximately 35.5% less current and 37.3% less electrical power. Increasing rider load reduced speed, mileage, battery operating duration, and terminal voltage while increasing current and power demand. These findings demonstrate a clear trade-off between speed performance and electrical energy use. The 500 W configuration is preferable when higher speed is prioritized, whereas the 350 W configuration is more suitable for longer range, longer operating duration, and lower electrical consumption in daily urban use]]>
