Serotonin: Joy and Satisfaction Serotonin is known for promoting happiness, contentment, and serenity. The E-bikes of the Serotonin series are designed to enhance your mood on every ride, featuring a sleek design and strong performance. These bikes are perfect for anyone seeking a joyful urban riding experience, offering options from single-speed to advanced Pinion gearing. PINION 1.9 Equipped with a sporty carbon fork, providing a dynamic and powerful riding experience for all those seeking thrills.