Every component in a BMX bike will matter because they affect your performance considerably. Many bikers like to customize their bikes to achieve the most outstanding efficiency. How about you?
Manufacturers can’t satisfy all of your requirements for the bike. So, you can choose to build a complete BMX by collecting and assembling components.
If you plan to upgrade your experience, do not miss this post. We will show you how to build a BMX bike from scratch. Let’s read on to discover!
How to Build a BMX Bike?
Building a BMX bike is challenging because you have to work with all the parts. Moreover, once you do something wrong, the whole system will fail.
We will split the assembly process into eight steps. Please scroll down and take notes to get everything done properly.
Step 1: Gather the components
There are eight parts in a BMX bike body, each coming with numerous components as follows:
| Part | Components |
| Main body | – BMX frame – BMX fork |
| Bearings | – Bearing race – Bearings – Top cap – Top bearing – Spacer – Gyro piece – Top gyro plate |
| Stem system | – BMX stem – Stem bolt – Handlebars – Seat and seat post – Seat clamp – BMX grips – BMX seat |
| Crankset | – Cranks – Bearing spacers – Sprockets – Crank spacers |
| Axle | – Bearings – Axle – Axle nuts – Washers |
| Pedals | – Pedal bolts – Sprocket bolt – Wheels – Socket pegs – Washers – Primo jewels – Sockets – BMX pedals – Back sprocket – Double wall rims |
| Braking structure | – Chain – Chain tensioners – Washers – Axle nuts – Brake cable – Brake levers – Brake arms – Tri-Flow |
| Optional parts | – Tool kit – Bike stand – Dried rags – Grease |
When selecting the components for your bike, please pay attention to these points:
Fork
The fork will endure a lot of stress, so you don’t want it to break on you as you’re completing a performance. Choosing a fork with the appropriate characteristics for your riding style is vital.
When buying a BMX fork, there are many different features to take into account, including Investment Cast dropouts, taper, offset, and heat-treating.
Headset
There are two main types of headset systems in a BMX bike:
- Integrated system: The bearing holder, which sits in the frame, supports the bearing ring.
- Push-in system: With the bearing sitting above the frame instead of into it, a push-in method secures the headset bearings.
Most riders prefer the integrated system because it gives a high-quality solution at an affordable price, and the design is more appealing
Cranks
BMX cranks usually have a 3-piece structure with two crank arms and one spindle. Some of them come in 2- or 2.5-piece designs. The 2-piece design is easier to install, but sometimes you can’t use Spline Drive sprockets with it.
Chain
The regular BMX chain is available in full-size and half-link types in a 1/8-inch size. Riders have opposing ideas about the superior option between these two, so it depends on your personal preference to opt for the better.
Step 2: Build the frame
Fork and frame together make up the overall structure of your BMX bike. Make sure to invest in a solid frame if you want your bike to last for a long time.
A frame could give a BMX bike a completely different experience from another one because of the various geometry and dimensions involved.
If you are confident or have experience in bike assembly, you can weld the bike frame tubes on your own. Alternatively, you might take it to a mechanic and have him handle the fitting.
No matter which method you choose, consider the following three things when building the frame:
BMX frame types
Your choice of BMX frame depends on the riding style you perform. Here are the three main options:
- Race frames are lighter to increase speed and work best for Olympic-style racing. They can’t assist you in doing tricks and are unsuitable for hard hits on concrete.
- Freestyle/street frames are flexible, making them a good choice for vert ramp riding, dirt jumping, and skatepark riding.
- Cruiser frames are more extensive than regular BMX frames and can accommodate 24″ wheels instead of 20″.
Frame height
Take the frame’s dimensions into consideration too. Decide on its size based on your height, or the bike’s performance will disappoint you.
- For riders that are 4’9″ to 5’2″, the frame should be 18 to 19.5 inches in height.
- If you are about 5’2″ to 5’5″ tall, the frame height should be from 20 to 20.5 inches.
- And if you are taller than 5’5″, choose a frame that is 20.5 to 21 inches tall.
Material
The material of the bike frame is another thing you should be aware of.
Take the time to thoroughly research your options and select the frame material according to your requirements and the kind of BMX riding.
Often BMX riders prefer these materials for their bike frame:
- Hi-Ten steel
- Chromoly steel
- Aluminum
- Carbon fiber
Geometry
Different BMX frame geometries have an impact on how the bike rides. Some essential factors to consider are:
- Head tube angle
You will tend to lean more over the front part of your bike for speedier steering when the head tube angle gets steeper (75 to 75.5 degrees). This angle makes it easier for you to perform technical tricks.
When the head angle is slacker, about 74 to 74.5 degrees, you will stay farther back on your bike. This position can improve stability and help you handle well at high speeds.
Bike frames for freestyle and technical rides come with steeper head angles. Meanwhile, racing, dirt jumping, and park jumping frames have slacker angles.
- Seat tube angle
The seat tube angle is often between 69 and 71.5 degrees. Sometimes, it gets slacker, about 69 degrees, for more stability.
Similar to the case of the head tube angle, most riders need to find their own “right fit” between the two. Steep is better for technical precision, while slack means stability when accelerating.
- Chainstay length
It will be simpler to jump up on the back wheel for tricks and manuals with a shorter wheelbase and chainstays. On the other hand, a larger wheelbase and chainstays aid in balance at high speeds.
Although racers choose longer wheelbases for security and stability, technical street riders prefer short bikes.
Step 3: Install headset, fork, and stem
This step sounds complicated because of the multiple components. However, the process becomes a piece of cake once you find where to attach them.
- Install the headset
Most of the BMX bike frames you buy already have a built-in headtube. You just need to install a BMX headset there.
The headset race is the next component to search for; it rests on the bike’s fork, or you may need to check the headset box for the lower race.
Add some grease to the headset surface to simplify the installation. Then, attach the headset bearing. If there is a seal on it, make sure it is pointing down to avoid further problems there.
- Attach the fork
Use the grease once more, this time on the bearing surface of the head tube, and then insert the fork into the tube.
Attach the upper headset bearing so that the rubber seal is pointing up, unlike the direction of the lower bearing.
- Install the space ring
Perform this step like the two previous ones. You need to apply oil and install the bearing to the compression ring. Don’t forget to add a dust cover over it so the headset can be tight enough.
- Tighten the fork
Tighten the fork with a compression bolt. Also, tighten the pinch balls to keep your bike’s handlebar straight.
Step 4: Attach the bracket and crankset
This step is important, so do it carefully. You need to flip your bike so that it can stand on the handlebars and seat stably. It would be best to have a friend help you at this stage.
Attach the down tube and seat tube on the bracket shell. Then, install the spacer through the shell. Your friend can help you secure the spacer while installing the bearing on the two sides of the shell.
Simply repeat the previous steps to attach the other crank. In the end, the cranks must be in a straight line and be vertically pointing upward.
The distance between the two cranks should be the same. You can use spacers to fix the spacing problem. Once everything is in place, lock the two cranks tightly using bolts.
Step 5: Insert the pedals
Apply a little oil to the pedal threads when you start to make things easier to handle. After that, use a pedal wrench to attach the pedals to the crank arms.
You won’t need to worry about which pedal to tie because there are always “Right” and “Left” labels to distinguish.
Tighten the right pedal by rotating your wrench clockwise. For the left pedal, turn it anti-clockwise until it locks in place.
Step 6: Attach the wheelset
In this stage, you will install the rear and front wheels in different areas of your bike. But before you start, ensure that the safety washers can work.
Attach the front wheel to your bike’s fork. Remember to tighten the nuts carefully and securely so your wheels won’t get crooked. You can use pegs at this stage to simplify the installation process.
Then, move to the rear wheel. You have to install it on your frame’s bike. This installation involves the bike’s chain, so we will discuss it in the next section.
Step 7: Install the chain
Your BMX is almost complete when we reach this step. Now, you will be installing the chain. Wrapping the chain around the back sprocket is the first thing to do.
Next, wrap the bike’s chain around the front sprocket too. You must connect each master link to one end of your bike’s chain. If the master link has two pins, attach them to each plate.
Slide the clip over the plate and use a flat-head screwdriver to snap it to the right position. Install the pegs, too, but they shouldn’t be tight.
Step 8: Finish with the brakes and levers
It’s time to install levers and brakes to finish your project. You will attach the levers to the handlebars by sliding them in.
You can choose their positions but make sure they will be comfortable for your hands. When you find the perfect spot, tighten your levers.
Apply some oil on the brake’s mounts to install them easily. Then, slide the springs and brake arms to the mounts.
Insert the brake cables into the lever, leaving the barrel adjuster on the lever.
The cable should access the brake arms across the wheel, crossbar, and fork’s front. Tighten the cable properly. It shouldn’t be too loose or tight.
There may be an extended cable section. You can cut it with a wire cutter.
Now, attach the cable to the brake arms and tighten it. Also, release the spring bolt a little to adjust the spring tension and ensure balance.
The brakes are crucial when riding. Hence, test them carefully. Apply pressure on the brake to see if they can stop immediately.
Adjust the bike’s brake pads too. Loosen the pads first, adjust them until they are parallel, and don’t touch the rim. Once they are in good condition, tighten them.
Video Tutorial for Assembling a BMX Bike
Is It Better To Build Or Buy A BMX Bike?
You can build or buy your bike. The two options are different in the cost you pay and your experiences.
Generally, buying a complete BMX bike is better for beginners, whereas seasoned riders like to build and customize their bikes.
Cost
It may be more cost-effective to buy a complete BMX bike from the store rather than build one. BMX bikes often cost between $300 and $1,500, and in some situations, they can come at a high price tag.
On the other hand, if you want to construct a BMX bike, you will need a budget of $1,000 to $2,000 on average. Finding the right components for your bike is essential.
You may be lucky enough to find secondhand products in great condition. Constructing your own BMX bike out of old parts is not a terrible idea unless the parts get broken.
Experience
It is challenging to make your own BMX, but the outcome will be well worth the work. Everything about the bike is precisely how you want it to be when you gather the components.
However, this factor depends on your skill level as well. Investing in a store-bought BMX bike will be a better idea if you are a newcomer. You don’t have to pay much for your first bike.
Besides, beginners don’t have enough knowledge of bike assembly. You will ruin the structure. What’s worse, the bike can’t perform as you expect, causing problems and even accidents.
On the contrary, if you are a professional, customizing your bike will give you a fantastic experience. You know what you need for your bike and choose the right component to satisfy your needs.
Tips For Building A BMX Bike To Make It Faster
You can build your BMX correctly following our instructions. But you will need more than that to bring out the best of the structure.
These tips will help you make your bike faster and conquer more challenges.
Lubricate the chains
Regular maintenance is essential for the bike chain. After installing all the components, don’t forget to lubricate the chain with the right bike lubricants.
Once you have a properly-oiled bike chain, you will achieve two things:
- First, your BMX bike can run smoothly and help you reach high speeds.
- Second, lubrication will prevent debris accumulation in the chain, extending its lifespan.
Check the gears
A well-maintained BMX bike may work efficiently for stunt driving and racing. Adjusting your gears is crucial for this efficient biking.
You can learn how to shift the gears on your BMX bike by yourself, even though it may seem like a complicated job.
Otherwise, rely on an expert to adjust them if you don’t want to deal with the difficulty. Usually, the cost is not very expensive.
Adjust the brakes
It can seem confusing to need to correctly adjust a BMX bike’s brakes to improve your speed. But you can take slopes and curves more smoothly if you properly set the brakes.
Drop the front
Your BMX bike’s model and maker greatly affect its speed. It does not exclude you from taking action, though.
Physics, or more specifically aerodynamics, suggests that lowering the front end of a BMX bike can aid in maintaining speed.
You can find it hard to handle your bike sometimes since the speed shift after lowering the front end is so substantial. But removing one of the spacers and adapting to the new position may prevent injuries and accidents.
Adjust the saddle height
If you are a seasoned rider, you will know what saddle height feels right for you. If you are a beginner, adjusting the saddle for comfort and speed will be vital.
Sometimes, you need a properly positioned bike saddle for a comfortable ride.
You can get the best with the least effort. For your feet to easily reach the paddles, set them around 10cm lower than the inseam.
This video will show you more hacks and tricks to upgrade your bike. Please check for your bike to perform at its best:
FAQs
Why do some BMX bikes have no brakes?
Furthermore, BMX riders don’t often rely as heavily on stopping ability as riders of other bikes. Since they are not moving very fast, they don’t require powerful brakes to slow them down.
Is it easy to build a BMX?
Nevertheless, professional BMX riders like to build their bikes because it allows them to customize their constructions. It’s a kind of satisfaction.
Is it cheaper to build or buy a BMX bike?
Often, you need $1,000 to $2,000 to build a BMX bike on your own. But if you buy one, it will cost you about $300 to $1,500.
What are BMX bikes made of?
What sprocket size is best for BMX?
Conclusion
Building a BMX bike is challenging yet rewarding. You need knowledge and skills to do it correctly. Even if you are confident about the outcome, test it carefully before joining the race.
Please feel free to ask if you have any problems following our guide. We are always eager to assist you. Also, do not forget to share your experience with us.
Thank you for reading!
