The pilot reported that during landing touchdown with all three wheels “down,” and the airplane “tracking fine,” he removed his feet from the lower rudder pedal bars to apply braking via the upper braking pedal bars. The pedals then fell rearward toward the pilot and his right foot got wedged between the lower rudder pedal bar and the upper braking pedal bar. The pilot reported this action caught him by surprise and he applied “heavy” right rudder, thinking it was braking application. The airplane departed the right side of the runway, nosed over, and came to rest inverted in the grass next to the runway. The airplane sustained substantial damage to the top right wing and the empennage. The pilot reported there were no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation. The pilot reported that he had recently purchased the airplane and did not know that the rudder pedal return springs were not installed. The investigation revealed that the airplane was previously modified for aerobatic competition with the addition of a large rudder and that due to cockpit spacing limitations, the rudder pedal return springs could not be installed. The pilot concluded that the accident could have been prevented by performing a “very thorough” inspection and understanding all the modifications made to the airplane before flying it.