BMX Freestyle Assembly Guide

Visit the Help Center

This guide contains important information regarding bicycle assembly. It is intended to be a convenient general reference only. It is not intended to be a complete or comprehensive manual covering all aspects of bicycle assembly or safety. Please reference the BMX Product Manual for more information.

The tools you will need to assemble the bike include: 

  • Socket wrench 
  • 15 mm and 17 mm socket  
  • 4, 5, 6, and 8 mm Allen wrenches 
  • 15 mm open-end wrench or adjustable wrench 
  • Wire cutters or scissors 
  • Grease 
  • Phillips and Slotted screwdrivers
  • Box cutter or knife
  • Air pump

Step 1: Unbox the Bike 

Remove the bike from the box. Be careful of the staples in the box when removing the bike.  Cut any zip ties that are holding the parts together and remove packing material that’s wrapped around parts. I would lay all the parts out so that you can see each one.

It’s a good idea to make sure all the parts are there before starting to assemble the bike. Note: You can use the empty box to build on, so you don’t scratch your floor.

Step 2. Attach the Handlebars 

If you have a bike stand, this is the time to clamp in your bike. Although it’s easier to assemble using a stand, you certainly don’t need one. To attach the handlebars, unscrew the stem bolts and set aside along with the top cap of the stem. Put the handlebar in the stem, making sure it is centered. Apply a small amount of grease to the bolt threads. Replace the top cap and hand thread the bolts back into the stem. Next, using your 6 mm allen wrench, tighten the bolts evenly in an x-pattern making sure you keep the stem cap even as you tighten the bolts. It is suggested that you line the handlebars up with the angle of the forks. Lastly, torque the bolts to make sure they are tight.

Mongoose Freestyle BMX Bike Assembly Guide

Step 3. Install the Seat Post 

Now it’s time to install the seat post.  Apply a small amount of grease on the inside of the seat tube, and insert the seat post into the seat tube. Align the seat so the nose runs parallel with the frame and tighten the bolts on the seat clamp. You can always adjust your seat into the perfect position later on, but always make sure the minimum insertion mark is not visible above the seat clamp.

Freestyle BMX Bike Assembly Guide

Step 4. Install the Front Wheel 

If you’re not using a stand, flip the bicycle over and inset the front wheel into the fork dropouts. Slide the safety washers onto the axle and put them into place by pressing the tab on the washer into the tab hole on the dropout.  Next, apply a small amount of grease on the axle. Now thread the axle nuts on by hand, and then finish tightening them with either a 15 mm wrench or the socket, making sure the wheel is centered in the fork.

Freestyle BMX Bike Assembly Guide

Step 5. Install the Pedals  

To install the pedals, start by greasing the threads of each pedal. Use either a 15 mm wrench or pedal wrench to attach one peddle to the corresponding crank arm. You can use an open-end or adjustable wrench if you don’t have a pedal wrench. Look for an "L" and "R" on your pedals to determine which one is for the left and right side. Screw in the pedals in the direction of the front wheel – right pedal will tighten clockwise and left pedal will tighten counterclockwise.

Freestyle BMX Bike Assembly Guide

Step 6. Pre-Ride Assembly 

Now it’s time to flip the bike back over to do some pre-rides tests and fine tuning. Let’s start with the handlebars. Looking straight down on your stem to make sure it is lined up with your front tire. With the side bolts on the stem loosened, you can gently tap the tire with your foot to line the tire up with the stem. Once they are lined up, tighten the bolts on the side of the stem. You can test your assembly with a couple tests: A push test, by applying pressure in both a downwards and upwards direction on the handlebars. And a twist test, by holding the bike and twisting both the handlebars and stem laterally.

Freestyle BMX Bike Assembly Guide

Check that the seat is secure by pulling up and down on the nose and back of the saddle, then twisting laterally. Check your brakes to make sure that they don’t pull back too far. There should be a gap between a fully compressed brake and the grip. Ensure that the brakes are working.

Now let’s pump the tires up. You can find the recommended PSI to inflate the tires on the side of the tire. Never go over this recommended pressure because it can damage the tire. 

Freestyle BMX Bike Assembly Guide

Lastly, go around your bike and torque all of the bolts to the manufacturers specifications to make sure everything is tightened properly. The pressure needed to properly torque the bolts should leave a mark on your hands. Lastly, reference the pre-ride checklist to make sure you covered each step. Now it’s time to enjoy the bike you just put together yourself!