How to Fix Broken Pedal Bearings on a Mongoose

The pedals on a bicycle have to withstand a high degree of pressure when the user is pedaling normally over flat ground. With a performance BMX or mountain bike, such as those made by Mongoose, the impact forces transmitted through the pedals and cranks can be huge, and it's not unusual for pedal bearings to get damaged. If there's a problem with your pedal bearings, then you're compromising your ability to transfer power to the rear wheel. It also risks damaging your cranks or bottom bracket.

Things You'll Need

  • 15mm wrench
  • Rubber mallet
  • 8mm hex wrench
  • Grease
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Instructions

    • 1

      Position the bike on a stable flat surface and rotate the cranks until they are parallel with the floor. Place the bike in first gear. Check your pedals to see if they can be serviced. Some models cannot, and others require a proprietary tool from the manufacturer in order to access the bearing races. If your pedals are of this second type, its advisable to take the bike to a repair technician, as you risk damaging them by trying to use an inappropriate tool.

    • 2

      Seat the 15mm wrench onto the axle between the pedal and the crank. Press down on the crank to reduce the chance of sudden slippage that could result in you cutting your hands on the teeth of the chainset. Apply gradually increasing pressure to the wrench to try and loosen the pedal. Pedals are notoriously stubborn to remove from cranks, so you may need to "persuade" them by giving the end of the wrench a sharp tap.

    • 3

      Remove both pedals and access the dust cap on the outer edge, opposite the threaded section of the axle that connects to the crank. With the dust cap removed, you should be able to see the locking fastener that holds the pedal onto the axle. An 8mm hex bolt is a common fastener. Remove the bolt carefully and turn the pedal over, so the axle is pointing vertically, with the crank threads at the top.

    • 4

      Slide the axle out carefully and look down into the pedal. The bearings may be in sealed cartridges, or they may be loose in their cups. Lift the upper cup out and ensure all the bearings are properly seated. Remove them and make sure none go missing. Clean the cups and the bearings, before piping some grease into the cup, and use it to hold the bearings in place while you reassemble the pedal. If your bearings are in sealed donut-shaped cartridges, you'll need to replace any damaged ones. Replace the axle and dustcap, then refit the pedal to the crank.