How To Build Your Own BMX Bike From Scratch- Complete Guide

BMX Bikes are known for hardcore sports and aggressive riding, these bikes are a gateway to the wild side of bicycling. Although sometimes getting a complete BMX bike from the retailers can be a very expensive experience, and for that, this guide will help you build your own custom BMX bike from scratch. Since you will know and install each component yourself you will have complete power over the bike and will know how to master it without any kind of problems. 

When it comes to the bike industry, manufacturers cannot meet every single demand and trend out there, and that leaves a lot of people heartbroken. People have different demands when it comes to bikes, some want a different type of braking mechanism and some want a more comfortable saddle, most of the time keeping up with these demands can be very troublesome.

After experiencing these problems, have you ever had the thought that apart from buying a complete BMX Bike, why not build your own from scratch? A Custom-Built BMX works even better for street riding and that is a well-known fact!

Complete BMX Bikes don’t cater to a lot of people’s needs, sometimes you need a bike that is fully distinct from others. 

Why Build A Custom BMX Bike?

Custom Bmx Bike
Custom Bmx Bike

If you want to have a really good challenge and test your skills as a BMX rider, then build a bike on your own. This is a serious challenge, and the end results are going to be very satisfactory since you will be making the bike out of love. 

Being a bike rider, there are many responsibilities that we need to take care of, this includes bike maintenance and assembly. Using a normal BMX Bike that you got from the store gets outdated just in a few months if you are a seasoned rider and getting a new bike whenever this happens is definitely not the right way to go, that is why it is always recommended to build a custom BMX from the ground up if your needs vary from time to time.

Building a BMX from scratch will be the ultimate test but this is why we have made this guide for you, we will make sure that you have all that you need for the perfect bike construction. Let’s get started!

The Components Needed For BMX Bike Construction

Building a BMX Bike is going to be tricky, but that is why this guide is here. I wish I knew these things before I got started but still, glad to help out others. We have split the main components into different categories, and you need all of these components/tools to build the perfect BMX Bike for yourself!

  1. Main Body
  2. Bearings
  3. Stem, Handlebars, and Seat
  4. Crankset
  5. Bearings and Axle
  6. Pedals and Sprockets (Both Front and Rear)
  7. Chain and Braking Structure
  8. Optional Tools/Components

1. Main Body

Here are all the components needed for the main body of the BMX:

  • A BMX Frame (You Can Choose Feely)
  • BMX Fork

2. Bearings

Here are all the components that you need for the bearings section of the BMX:

  • Bearing Race
  • Bearings
  • Top Bearing
  • Top Cap
  • Spacer
  • Top Gyro Plate
  • Gyro Piece

3. Stem, Handlebars, and Seat

Here are all the components that you need for the Stem, Handlebars, and Seat section of the BMX:

  • BMX Stem
  • Handlebars
  • Stem Bolt
  • Seat Post and Seat 
  • Seat Clamp
  • BMX Seat
  • BMX Grips

4. Crankset

Here are all the components that you need for the Crankset portion of the BMX:

  • Crank Arms
  • Crank Bearing Spacers
  • Cranks
  • Sprockets
  • Crank Spacers (2-3)

5. Bearings and Axle

Here are all the components that you need for the Bearings and Axle portion of the BMX:

  • Bearings
  • Axle
  • Washers
  • Axle Nuts

6. Pedals and Sprockets

Here are all the components that you need for the Pedals and Sprockets portion of the BMX:

  • Sprocket Bolt
  • Pedal Bolts (2)
  • Two Sets Of Wheels
  • Socket Pegs
  • Primo Jewels (2)
  • Washers (2)
  • Sockets (2)
  • Back Sprocket
  • BMX Pedals
  • Double Wall Rims (Optional)

7. Chain and Braking Structure

  • Chain
  • Chain Tensioners (2)
  • Axle Nuts (2)
  • Washers (2)
  • Brake Levers (1-2)
  • Brake Cable 
  • Brake Arms (2)
  • Tri-Flow

8. Optional Tools To Get 

Here are some optional tools to get:

  • Bike Tool Kit
  • Bike Stand
  • Dried Rags 
  • Grease

Tools Needed For Bike Assembly

Here are the necessary tools needed for bike assembly:

  • 1*5mm Allen Key 
  • 1*6mm Allen Key
  • 1*15mm Spanner
  • 1*19mm Spanner
  • Bike Air Pump
  • Side Cutters

How To Build A BMX Bike

Bmx Bikes
Bmx Bikes

Many people have this misconception that building a BMX Bike is a really tough job, although, in reality, it is not. You just need to have a bit of knowledge about bike assembly, experience, and confidence in yourself. That is why we have made this guide for you so that you can build your BMX Bike from scratch without any kind of problems or delays.

Each critical step of the BMX Building process has been made separate, make sure to read through the guide fully. Let’s start!

The BMX Frame Comes First

Let’s start with the foundation of every bike- the overall construction, which includes the frame and fork. If you want a bike that will last you for a very long time then make sure that you invest in a really good frame. The choice of frame will depend on what kind of BMX you plan to build. Here are the types of BMX Bikes:

  • All-Around Racers
  • Freestyle
  • Jumpers (Dirt Jumpers)

If you have some knowledge of bike building and assembly then you can start welding the frame tubes all by yourself or you can take the frame to a professional and let them do the fitting for you. You should go for a frame that fully satisfies all of your needs, you will be needing that for an amazing experience.

Let’s talk about the measurement of the frame now, this needs to be according to your height otherwise the performance of the bike won’t be good enough. 

Rider Height Tube Frame Size (Inches)
4’9’’-5’2’’ 18-19.5’’
5’2’’-5’5’’ 20-20.5’’
5’6’’-6+ 20.5’’-21’’

Check the above chart to find out the best tube frame size for yourself for an amazing experience.

Another thing that you need to know about is the components of the bike frame, make sure to do your research well and choose the frame material according to your needs the nature of the BMX riding. BMX Bike frames are made from the following materials:

  • Chromoly Steel
  • Hi-Ten Steel
  • Aluminum
  • Carbon Fiber

The Headset, Stem, and Fork Come Next!

For the next step, we will be installing the headset, stem, and fork. When it comes to these components, there is a certain trick. Most of the frames that you will purchase will already have an integrated head tube (Measure the tube length accordingly), you just need to add a BMX headset to it. 

The next thing that you need to look for is the headset race, either the fork of the bike will have it or you will have to look in the headset box. What you are actually looking for here is the lower race, before you install it, make sure to apply a little grease on the headset surface, this will make installation easier. Install the headset bearing now, just make sure that its seal is facing downwards, you don’t want a problem here afterward.

In the next step, you have to apply the grease again but on the head tube’s bearing surface, later slide the fork to the head tube’s bottom. Now, install the upper headset bearing, unlike the previous step, the rubber seal should be facing upwards.

Now, we have to install the space ring, which isn’t that hectic. The bearing that we are looking for is the compression ring, like the previous steps, apply grease here as well and install the dust cover above the bearing. This will make sure that the headset is tight enough.

All that is left here is to make sure that the bike’s fork is tight enough, you will need a compression bolt for that. In order to keep the bike’s handlebar straight, we need to tighten all the pinch balls.

Now Install The Bottom Bracket and Crankset

The big next step in our guide is to install the bottom bracket and crankset. In order to get started, flip the bike carefully so that it rests on the seat and handlebars, now we can get started. Let’s start with the bike’s bottom bracket first, the bottom bracket consists of the crankset, internal spacing, and two bearings.

The spacer will need to be installed through the bracket shell, which is where the seat tube and down tube are attached. If you have a friend with you then they can make the whole process easier, otherwise, you will have to keep one side of the spacer steady till you install the bearing on the other side of the shell. When one side is done, install the bearing on the other side too.

Now comes the bike’s crankset. We hope that you have chosen a really good-quality crankset because this is the component that attaches both the chain and pedals to the bike. A crankset doesn’t contain much, other than a sprocket and a spindle, we will be working with them.

Generally, people get confused about the spindle when building a bike but that’s okay! A spindle is that attaches the crank arms and sprocket, it is in the shape of a rod. The spindle needs to be attached to the right side of the crank arm, people get easily confused and attach the whole thing to the left side. Make sure to push the spindle in, otherwise, the whole process will fail. Tighten the bolt, also, slide a crank spacer ring on the top of the spindle, this will make sure that the spindle remains intact.

After doing all of these steps properly, the spindle will almost be done with. From here on, you need to insert the spindle into the bottom bracket, it needs to go all the way to the end. Use a rubber mallet here, this will make the crank be firm, it won’t get loose this way. 

You will need to install the other crank too, just follow the steps mentioned as before. In the end, the cranks need to be facing upwards vertically and form a straight line. Both the cranks need to have the same amount of clearance between them, if that is not the case with you then you can use spacers to rectify the situation. You will need to use bolts to lock the cranks in place.

Now, you are fully done with the bottom bracket and crankset.

Time To Attach The Pedals

Now that the crankset has been installed, it is time to attach the pedals. Although before you get started, apply some grease on the threads of the pedals. By using a pedal wrench, attach the pedals to the crank arms. Don’t be worried about which pedal to attach, they always have a Left and Right label on them.

For the right pedal, you will need to tighten it by moving the wrench clockwise and for the left pedal, it needs to move anti-clockwise.

Attach The Wheelset Now

In the next step, we will be installing the front and rear wheels, both are installed in separate areas of the bike. The first thing that we need to make sure of, is that the safety washers are active. The front wheel will be attached to the bike’s fork.

Once you have installed the wheel, tighten each nut carefully, this makes sure that the wheels don’t get crooked. Using pegs will make the whole installation process easier. The rear wheel will be installed in the bike’s frame. This is a two-part procedure, the next part will be discussed in the portion of the chain.

Bmx Bike

Installing The Bike’s Chain

We are nearing the end of construction, now we will be installing the bike’s chain. The back sprocket comes in very handy here, wrap the chain around it first. After wrapping the chain around the rear sprocket, we need to wrap it around the front sprocket now, now carefully both the ends of the chain together.

An important piece of advice concerning the chain is that each master link needs to be connected to an end of the chain. For example, with each plate, two pins of the master link will be attached.

Using a flat-head screwdriver, you need to snap the clip to the right place after sliding the clip over the plate. The pegs also need to be installed but make sure that they aren’t that tight.

Install The Brakes and Levers At The End

In the last part of the guide, we will be installing the brakes and levers. The levers will be installed on the handlebars, just slide them in. The position of the levers will depend on you, make sure that you use a position that is comfortable to use. Once the perfect position has been sought, just tighten the levers.

Now you have to deal with the brake arms but before you install them, make sure to apply the grease on the mounts of the brakes, this will make installation very easy. Now all you have to do is slide the brake arms and springs to the brake mount.

The next part is to install the brake cables. The cables need to be inserted into the lever, make sure that the barrel adjuster is left on the brake lever, we will need that later on. The brake cable needs to go to the brake arms of the bike but through the top of the crossbar, wheel, and the fork’s front. The cable needs to be optimal, neither it should be tight nor loose.

Now that the cable is attached, cut the extended part of the cable by pulling it and with a wire cutter. The cable needs to be attached to the brake arms now, once it is attached, tighten it. The spring tension also needs to be adjusted, loosen the spring bolt first and then adjust the tension, it needs to be balanced.

Test the brakes, make sure to apply a whole lot of pressure on them, take a small test ride to check the brakes of the bike. 

The last part over here is to adjust the brake pads, and for that, we need to loosen them first. The brake pads need to be parallel with the rim, when they are parallel, just tighten the pads. MAKE SURE THAT THE BRAKE PADS DON’T TOUCH THE RIM!

That is the end, you have successfully built a BMX Bike from scratch, make sure to give it a test ride! When you are done, your hard work will speak through your own bike that you built from your hands!

Recap

BMX Bikes have been inspired by the amazing Motocross Bikes from the 1970s and since their advent, they have attracted a lot of riders. These bikes are used for hardcore sports, including stunts and tricks. With the number of riders growing, everyone wants a BMX Bike but with their own set of features, they don’t want something generic.

Sometimes getting a complete bike doesn’t do the job and for that purpose, we made this guide for you. In this guide, we discussed how to build your own BMX Bike from scratch and the various components/tools that you will be needing. 

We hope that after going through this guide, every question of yours regarding BMX Bike Construction is answered. If you still have problems or questions then do reach out to us in the comments below!

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