How to Disassemble a BMX Bike

Hi. My name is Ben Farthing

I have been racing BMX for about 12 years. All through my childhood I was taught by my dad how to build and disassemble BMX bikes for racing. I have been building all my BMX race bikes since I was 10 years old. It is quite a simple task if you follow the correct steps.

I am going to teach you how to take apart a BMX bike step by step. There are a few techniques to disassembling a bike like this one. After this, you will be able to have the skills you need to disassemble one yourself.

With my years of experience, you will learn how to take apart a BMX bike in a few simple and easy steps.  

Size 5mm, 5/32mm, 8mm, 4mm, 6mm Allen Wrenches

Firstly, locate the grips of the bike. They are going to be the rubber on the handlebars. To take these off, grab a 3/32 Allen key and locate the small screw on the left and right side of the grip. In the event of the screws not wanting to break loose, just spray some WD-40 and it should loosen right up. To take the screws out, just turn them to the left until they come out. After that, pull the grip off the handlebar, it should just slide off since it’s a lock on.

Moving forward, to remove the brake handle, grab a size four Allen key. Locate the top screw on the piece that mounts to the handlebar. Use a size three Allen key and loosen the screw just enough until the brake handle is loose enough to slide off the end of the handlebar. We are not going to fully take the brake handle off the brake line, that’s for another day. 

To begin with removing the handlebars, use a size five Allen key. The screws that need to be removed, are going to be at the base of the handlebars. There are four screws that hold it in place. As soon as the screws are removed, the handlebars will come right off. Set them to the side to a place they will not be in the way. Make sure to put the top back on and screw the bolts back in so they will not get lost.

Next the front wheel will need to be removed. Now this is self-explanatory but take the size six Allen key and find the one bolt on both the right and left size and turn them counterclockwise until they are just loose enough to slide the wheel off the forks. Also make sure to put all the parts that have been removed into a secure place, so they do not get lost or misplaced.

First thing to remember when taking the stem off, is beginning with the top bolt that is connected to the headset on top of the stem. Take a size five Allen key and locate the bolt at the top of the stem. The stem is what the handlebars were originally connected to before it was removed. Take the size five Allen key and loosen the top bolt to the headset until it comes all the way out. At the same time, this will also loosen the tension associated with holding the forks on. Continuing, find the bolts on the back of the stem and remove those also. This will then allow the stem to be removed.

To take the forks out is a simple step. Since the stem was removed and the front wheel was removed, the forks will come right out. For the most part, there will only be 1 or two spacers on top of the forks that were under the stem. It depends on the size of bike and how tall the rider is. In this case, there is only a single-double size spacer. To finish this step, pull the forks out from the bottom and set them aside. Also take the top of the headset and connect it to the bottom of the headset that ran through the forks. One thing to remember, some bikes will have integrated bearings. Those will need to be kept in specific order to work properly.

The seat latch and seat are going to be the next item to remove. Pull the latch open underneath the seat to pull the seat out. Moving forward locate the bolt on the side of the latch. Use a size 5 Allen wrench to loosen it and pull the latch off. 

When going to remove the cranks and the sprocket, it is a two-part deal. This step is going to have to be started with taking the sprocket off first. That is going to be towards the bottom of the bike, the part that looks like a gear. It is in the same area as the pedals and cranks. Now there are two sprockets. One is connected to the back wheel also. We are going to focus on the front one first. To begin removing it, take a size four Allen key and find the 4 bolts holding on the sprocket. A quick tip to successfully taking these off is to put a finger behind each bolt with pressure while the bolt is being unscrewed. This will prevent the bolt from falling and possibly losing it. After each bolt has been removed, make sure to screw the backs onto the front of the bolt and place them in a secure place or a bag. To take the sprocket (or gear) off, pull the chain off each side of the gear, while still pushing back the gear and eventually the chain will come off the gear, allowing for the gear to be taken off. 

Cranks will be the next item to take off. Locate the two tension bolts on the top and bottom of the left crank. These two tension bolts will need to be removed with a size 4 Allen wrench. The bolts won’t need to be necessarily taken out; they can just be loosened. Furthermore, locate the crank bolt which will be on the left side of the left crank. It should be flush with the side of the crank. Remove this to loosen the left crank. The crank should just come off with a little bit of wiggle. After the left crank has been removed, there will be part of the spindle inside the bottom bracket sticking out on the left side. Take a flat sided object and pound the side of the spindle to the right to loosen the right crank. After doing this, the right crank will come out with a little tug. Before the cranks are put away, push the left crank onto the spindle and insert the crank bolt back into the crank and tighten it and the tension bolts. The pedals do not need to be removed in this case but if that is something that would be removed in the future it just takes a size 8 Allen wrench.

Continuing on, the back brakes will need to be unlatched, but not fully removed. To do this, locate the silver piece that is connected to the rubber piece on the top. To unlatch these two, push the top of both sides together and pull up on the silver piece. Doing this will allow for the back wheel to easily come out.

The last step to disassembling a bike, is to take off the back wheel. This is a simple step. Locate both bolts on the right and left side. To remove these, find a size 8 Allen wrench. Turn the bolts until they both come all the way out. After this, pull the wheel backwards to remove it.