The axle of a mountain bike pedal screws into the crank. Replace this axle when you replace the pedal. The left pedal axle is reverse threaded. Former "Bicycling Magazine" technical editor Jim Langley notes that to remove and attach a left pedal, turn the wrench in the opposite direction that you would turn it for a right pedal. Nearly all mountain bike pedals will take a 15 mm pedal wrench, but if that is not the right size, get a 9/16-inch pedal wrench. Park Tool warns that a cone wrench is not sufficient for the task.
Step 1
Rotate the left crank until it is parallel to the ground, halfway between the top and bottom of its rotation, with the pedal pointing toward the rear of the bike. Put the pedal wrench around the flat sides of the left pedal axle, between the pedal and the crank, with the handle forming an angle less than 90 degrees above the crank.
Step 2
Hold the crank with your left hand and turn the wrench clockwise with your right hand until the pedal axle comes out of the crank.
Step 3
Drip a few drops of chain oil onto the axle where it screws into the crank, if you cannot loosen the axle. Let this sit for three minutes and try again. For extra leverage, place the pipe length over the pedal wrench handle and turn the wrench via the pipe.
Step 4
Rotate the right crank until it is parallel to the ground and the pedal faces the front of the bike. Place the pedal wrench on the axle flats with the wrench handle pointing toward the rear of the bike. Turn the pedal wrench counterclockwise until the pedal comes off of the crank, or use Step 3 to treat a stuck axle.
Step 5
Apply a thin layer of grease to the threads on the axles of your new pedals.
Step 6
Place your fingers on the flat sides of the right pedal axle and screw it clockwise into the right crank by hand until you feel resistance. Use the pedal wrench to finish screwing in the axle; rotate the wrench until the axle no longer moves.
Step 7
Repeat Step 5 with the left pedal, turning counterclockwise to tighten.
Tips and Warnings
- If your pedals feel stiff, grind or click when rotated, you may be able to maintain the pedal once you've removed it, rather than replace it. Pedals contain small ball bearings held in by the pedal axle and its threaded cones and nuts. Manufacturers do not design all pedals to be maintained, particularly cheap or old pedals. However, if you can pry off the axle cap facing out from the bike, you or a bike mechanic can probably service the pedals. Some mountain bike pedals, particularly clipless pedals, do not have axle flats for a pedal wrench. Instead, insert an Allen wrench, typically the 8 mm size, into the back of the axle on the inside of the crank. Look at the pedal from the outside of the crank as you turn the wrench in the same direction as you would for axles with flats.
Things You'll Need
- 15 mm pedal wrench
- 2-foot length of pipe that fits over pedal wrench handle (optional)
- Bicycle chain oil
- Bicycle grease
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