Typical bicycle pedals have a threaded rod that is made from case-hardened steel. Most pedal cranks arms are made from aluminum alloy that is bored and threaded to accept the pedal rod. The difference in density and strength of the two metals can lead to problems, such as a loose pedal. This may be resolved by rethreading the pedal rod or the port in the crank arm. If you are familiar with a simple metal tap and dye, you can troubleshoot the problem and rethread a bicycle pedal in the workshop.
Step 1
Inspect the threads on the pedal rod. If the threads are consistent and not damaged, the problem is most likely the threads in the pedal crank arm. If the threads are damaged, the rod may be rethreaded after the pedal crank threads have been serviced.
Step 2
Loosen the compression fitting bolts that hold the pedal crank arm to the bottom bracket using an Allen wrench. Pull the pedal crank arm off the bottom bracket. Determine the size of the threaded port on the end of the arm and insert the correct metal tap into the threaded port.
Step 3
Thread the tap through the threaded port on the crank arm by hand. If it will not thread completely though the port, use an open-end wrench at the square end of the tap and attempt to thread the tap completely through the port with minimum effort. If the tap binds at any point, remove the tap.
Step 4
Secure the pedal crank arm in a bench vice with the threaded port up. Apply several drops of lightweight oil to the threads on the tap. Thread the tap into the port on the crank arm and turn it with the wrench to rethread the crank arm. Back the tap out and run it through the threads a second time to clear any metallic debris.
Step 5
Remove the tap from the pedal crank arm. If the pedal rod threads are not damaged, thread the bicycle pedal into the crank arm by hand. Use a pedal tool or open-end wrench to tighten the pedal to the crank arm. If the pedal rod is damaged or will not thread properly, proceed to the next step.
Step 6
Refer to the size of the tap and use the same size dye to rethread the pedal rod. Secure the pedal in the bench vice with the threaded pedal rod up. Put several drops of lightweight oil on the pedal rod threads.
Step 7
Thread the dye onto the end of the pedal rod by hand until the threads catch. Make sure the dye is not cross-threaded. Attach a pedal tool or open-end wrench on the pedal rod nut to prevent the rod from turning.
Step 8
Thread the dye onto the pedal rod threads using open-end wrench. If the dye binds and will not turn, back the dye off the threads and apply more lightweight oil to the rod threads. Thread the dye onto the end of the pedal rod and rethread the rod again using the open-end wrench.
Step 9
Repeat the procedure until the pedal rod rethread is successful. Remove the pedal from the vice and thread the pedal rod into the pedal crank arm. Tighten the pedal onto the crank arm with the pedal tool. Reattach the pedal crank to the bottom bracket and tighten the compression bolts with the Allen wrench.
Tips and Warnings
- Rethread nylon or composite pedal rod threads in the same way. Replace the pedal or crank arm if either rethread did not correct the problem.
Things You'll Need
- Metal tap and dye
- Allen wrench
- Open-end wrench
- Bench vice
- Lightweight oil
- Pedal wrench
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