Columba Foldable Pedals A pair of foldable pedals. It can be simply pushed in to be folded to save storage or shipping space. The pedal size is 9/16 inch. These pedals fit our Columba 20 inch and 26 inch folding bikes. To measure your pedal size. You can unscrew left pedal from crank arm. (remember the left one has a left-hand thread), turn wrench clockwise to take the left pedal off from crank. Then measure the diameter of the threaded end with a vernier caliper. A bike pedal size is either 9/16"(14.3 mm) or 1/2" (12.7 mm). Most bikes have 9/16 inch pedals.