Plug-in locking mechanism, rotary locking assembly, lock catch assembly and foldable bicycle

The invention provides a foldable bicycle, which comprises a front wheel part, a rear wheel part, a front wheel part and a rear wheel part, and is characterized in that the front wheel part comprises a front fork frame; the rear wheel part comprises a rear fork frame, and the rear fork frame is used for being connected with a rear wheel; the lower beam part comprises a head pipe and a lower beam; the front fork frame is connected into the head pipe in a sleeved mode and can coaxially rotate relative to the head pipe. The first rotating assembly is connected with the upper beam part and the head tube, so that the front wheel part and the lower beam part can jointly rotate relative to a pivot of the upper beam part; the second rotating assembly is connected with the upper beam part and the rear wheel part, so that the rear wheel part can rotate relative to a pivot of the upper beam part; the folding structure of the foldable bicycle is suitable for a full-size bicycle, folding or unfolding can be completed only through three steps, the operation time consumption is short, and the occupied space is small after the folding structure is folded.