How to Fix a Moving Seat on a BMX Bike

The acronym BMX (bicycle motocross) has come to represent several styles of two-wheeled bikes. Some bikes have motorized components, while others do not. Which type of BMX bike you own is inconsequential, as they are all made with seats that are adjustable. Even if you have securely adjusted the hardware holding the seat in place, over time it may become loosened due to riding on rough terrain, whether on a street, track or off-road.

Things You'll Need

  • Adjustable wrench
  • Ratchet set
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Instructions

  1. Seat Tilt

    • 1

      Locate the wing nut on the underside of the seat where it mounts to the seat post. Some BMX bikes have a wing nut that allows you to tilt the seat slightly upward for a more comfortable ride. If the wing nut becomes loose, you may find that the seat is tilting up or down during the ride.

    • 2

      Loosen the wing nut by unscrewing it to the left until you can easily move the seat. This usually done by hand, however, if it is caked in mud or too tough, use an adjustable wrench.

    • 3

      Reposition the seat so the front is slightly pointing upward.

    • 4

      Tighten the wing nut by turning it to the right until secure. Again use your hands or adjustable wrench to complete the task.

    Seat Post

    • 5

      Locate the pinch bolt on the seat post. Seat posts are long, round posts in the shape of a cylinder that fit into the round frame post. Therefore in order to secure a round object inside another round object a pinch bolt is used on the seat post itself. If loose, the seat may swing slightly from side to side while riding.

    • 6

      Locate the proper tool for the pinch bolt. Depending on the shape of the pinch bolt, you may need common tools, such as a simple adjustable wrench, or more specific tools such as a hexagon ratchet. If possible, match the shape of the head of the bolt to the tool for the tightest fit.

    • 7

      Secure the tool around the head of the bolt. If the tool is adjustable, tighten until you have a good grip.

    • 8

      Turn the ratchet to the right and tighten the pinch bolt repeatedly until secure.

    Seat Rails

    • 9

      Locate the bolts on the seat rails. Some BMX bike models have a set of rails that the actual seat is secure to with bolts. These rails, several inches in length, allow you to adjust how far or how close you wish to be to the bottom bracket. While riding over course terrain, these bolts may loosen.

    • 10

      Match the tool to the bolts. Use adjustable wrenches or ratchets that fit the head of the bolts.

    • 11

      Slip the tool over the bolt head and turn to the right repeatedly until tight. Repeat until all bolts on the rails have been adjusted.