SF-B2618 How to Replace the One-Piece Crank
STEP 1: Remove the left lock nut (Part 40) using an adjustable wrench and a spanner by turning clockwise. Once the nut has been removed, you will be able to remove the pedal (21L) and the connecting rod (Part 23).
Remove the right lock nut (Part 43) using an adjustable wrench by turning counter-clockwise. Once the nut has been removed, you will be able to remove the pedal (21R) and the connecting rod (Part 23).
(NOTE: Please do keep in mind that the left pedal is reverse threaded. Also, be mindful when removing the pedal, the handlebar post may swing down.)
STEP 2: Remove the covers of the unit by removing the screws (Part 64) using a Philips screwdriver. Turn the crank arm at a 45-degree angle and guide the covers across the crank arm to remove.
STEP 3: Carefully remove the chain from the bike.
STEP 4: Using an adjustable wrench, loosen the hexagon nut (Part 58) from the one-piece crank. Using a flathead screwdriver, remove the washer (Part 57) from the one-piece crank as well.
STEP 5: Remove the Slotted Bearing Nut (Part 56) using a flat head screwdriver and a small mallet or hammer to loosen it, then turn the nut until it is removed from the crank.
STEP 6: Once the nut has been removed the ball bearings will be able to be removed. Then you will be able to remove the one-piece crank by guiding it through the mainframe.
STEP 7: Reinstall the one-piece crank back into the unit.
For more information, please see the video below.