Pedal Power

I hopped down the exterior steps into the sunny brick courtyard. Leaning right against the stone wall was a full-sized bicycle. Pure mechanics! I marched straight over to the crankset. The heavy steel chain looped across a massive toothed cog, just waiting. I stepped onto the lowest curb, reached out both hands, and shoved down on the rubber pedal with all my weight. Clack-clack-whirrr! The sprocket spun forward, pulling the chain along every single tooth, and the spokes of the rear wheel hummed in a fast, breezy circle. Direct mechanical drive! One solid push sets the whole gear train rolling.