I share this incident to express what I learned from a recent flight. I was attending a local fly-in event last week-end and  was preparing to depart for my home field. I was in too much in a hurry to demonstrate my CH701's STOL capability to a largely non-pilot crowd and strapped myself in without first retrieving my ignition key from my pocket. I found the key after first digging out my very bulky personal key ring and leaving it on the cockpit floor and proceeding to start the engine. After a steep takeoff, I encountered very stiff resistance on applying forward stick. Increased forward pressure freed the controls, but roll control remained difficult. I soon discovered that my key ring with its collection of a dozen keys had lodged under the elevator/ flaperon torque tube where it passes through the seat front. I was able the dislodge the key ring by forcing it back into the center tunnel. Landing was fortunately uneventful. The forced push on the control stick bent the bottom edge of cutout in the seat front and also bent two keys and the key ring. Lesson learned: pre-take off checklist now contains "clear cockpit floor of loose objects!"