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How to Build a BMX Bike - A Comprehensive Guide
This is our guide to BMX building and maintenance. When it comes to mounting the different parts on a BMX bike, there’s a learning curve to climb. All the parts of a BMX must be mounted correctly since a faulty assembly decreases the lifespan of your parts and represents a potential safety issue as well.
If you’re a kid new to the sport, we recommend building your bike under the supervision of an adult or an experienced rider. Remember that a local bike mechanic will be able to help you out if something proves to be too difficult.
Overview
How to Build Your Own BMX Bike?
In our BMX bike build video, Marcus and Lasse have fun showing you how to put a BMX bike together from scratch. Watch it to get in the zone before assembling your own BMX, or to learn the order in which to mount the different BMX parts.
The video above is a quick and dirty BMX bike assembly. Further down in this guide, we provide more detailed instructions on installing some of the most important BMX parts.
SkatePro’s Advice for Building BMX Bikes
Always follow these recommendations when building your new BMX:
- Kids should not assemble a BMX without supervision from an adult or an experienced rider.
- Always use the right tools for a given purpose to avoid damaging parts and to ensure proper installation.
- Always tighten all nuts and bolts before you take your new bike for a ride.
- Be patient and take your time to do things properly - for your own safety and for the longevity of your parts.
BMX Bike Parts - The Anatomy of BMX Bikes
A complete BMX bike is made up of the following parts:
- Frame
- Bar
- Grips
- Stem
- Headset
- Headset Spacer
- Fork
- Wheels
- Rims (Rim strips)
- Tires (Tubes)
- Spokes w/ Nipples
- Front Hub
- Pedals
- Cranks
- Sprocket
- Bottom Bracket
- Chain
- Rear Hub
- Driver / Freewheel
- Seat
- Seat Post
Further down in this guide, you will find instructional videos on how to mount many of these parts.
What BMX Tools Do I Need?
Only a few essential tools are required to assemble and maintain a BMX bike. A standard BMX tool kit usually contains the tools needed to assemble a partly assembled complete BMX bike fresh out of the box. Having a BMX tool kit with you when you are out riding is always recommended, so you don’t have to end an otherwise awesome session because of a loose part.
We recommend having the following tools at your disposal when building, maintaining, or repairing your BMX:
- Hex keys/Allen wrenches: 4, 5, 6 & 8 mm
- Wrench sockets: 15, 17, 19 mm (deep socket for pegs)
- Open ended 15 mm wrench for pedals
- Chain breaker
- Tire levers
- Spoke wrench
- Air pump
- Grease / lubricant for threads
- Tire levers
- Adjustable wrench
- Brake cable wire cutter
- Bottom bracket installation tool or a hammer with soft head
In the long run, you will need more tools for proper maintenance and disassembly of parts. You'll likely want to expand your collection of bike tools as the need for more specialized tools arises.
At SkatePro, we always stock a selection of BMX Tools for basic maintenance and assembly:
Building a BMX Bike Step-by-Step
Getting an experienced bike mechanic to assemble your BMX isn't always an option. If you follow the instructional videos below, you'll have a good starting point, but if it proves too difficult, we recommend getting help from someone who has experience working with bikes. To make it even easier for you, we've listed all these videos in order, providing you with step-by-step instructions on building a complete BMX bike from scratch.
BMX Crankset Installation
In the video below, we show you how to install a three-piece crankset. Three-piece cranksets are the most common type of cranksets, and the installation of a two-piece crankset works in a similar way – the main difference being that in two-piece cranksets, one crank is pre-attached to the spindle.
Compatibility-wise, you should pay attention to matching the spindle diameter with the inner diameter of your bottom bracket bearings. The inner diameter of your bottom bracket bearings is either 19 mm, 22 mm, or 24 mm, with the most common spindle size being 19 mm.
If you need a new crankset, you can browse our selection:
BMX Bolt-On Sprocket Installation
Installing a BMX sprocket is fairly simple. The most common type of freestyle BMX sprockets are installed via bolts that attach to the sprocket and thread into the crank arm. Simply align the bolt-hole in the sprocket with the threads on the crank, and thread it on.
If the diameter of the hole in the spindle hole is larger than the crank spindle, you’ll need a spacer.
BMX Rim Tape Installation
Before mounting tires and tubes, always remember to install rim tape. While not much can go wrong, it's essential to keep one thing in mind: align the hole in the rim tape with the hole in the rim where the valve will pass through.
Find BMX rim tape:
BMX Tires and Tubes Installation
Begin by mounting half of the tire onto the rim, leaving the other half free. Slightly inflate the tube before installation to prevent twisting or pinching between the tire and the rim, and always ensure that the valve sits straight before you fully mount the tire.
Note: When installing the tire on the rear wheel, remember to pay attention to the direction of the tire pattern.
BMX Front Wheel Installation
When mounting the front wheel, slide it into the fork and gently tighten it with your fingers. Ensure it's completely straight before proceeding to tighten the wheel from both sides. Also, pay attention to the direction of the tire pattern. Simply, flip the wheel if it is on backwards.
BMX Rear Wheel Installation
Before mounting the rear wheel, release the chain from the front sprocket to provide enough slack for fitting it onto the rear wheel sprocket. Slide the wheel into place and reattach the chain onto the front sprocket. Adjust the wheel position to ensure the chain is neither too loose nor too tight. Finally, get your wrench and tighten the bolts securely on both sides..
- BMX chain tightness: Aim for a slight amount of play where the chain can move up when touched, but not more than half an inch.
BMX Chain Installation
Installing a new BMX chain entails shortening your chain to fit your setup precisely. To shorten the chain, you need a bike chain breaker, which you will find here:
In the video below, you will learn how to properly install a half link chain:
BMX Pedals Installation
When mounting the BMX pedals, two things are important:
- Be absolutely sure that you have identified the left and right pedals and mount them on the correct side.
- Add grease to the threads to ensure proper tightness and to facilitate future dismantling.
The following video demonstrates precisely how to install your BMX pedals:
BMX Headset Installation
When installing an integrated headset, it's always recommended to apply grease to the bearing cups. Ensure that the bearings are correctly oriented within the cups, and don't forget to install the C-ring.
BMX Fork Installation
Installing the BMX fork is straightforward. One potential issue is forgetting the C-ring, so remember to include it for a secure fit.
BMX Stem Installation
When installing the compression bolt and stem bolts, always apply grease to facilitate a snug fit and to make it easier to unscrew them later on.
During stem installation, ensure there's a gap between the top of the steerer tube and the top of the stem, allowing room for compression. If the steerer tube extends beyond or sits flush with the top of the stem, a spacer is necessary.
After tightening the compression bolt, verify that the stem aligns with the fork before securing the side bolts, effectively tightening the stem to the fork.
BMX Handlebar Installation
Once you've unscrewed the four bolts on your stem, you're ready to install the handlebars. It's crucial to ensure that the knurled middle section of the handlebar is centered within the stem. Tighten the bolts gradually in a cross pattern to ensure that the bolts are evenly tightened across the stem.
Discover our selection of BMX Bars if you are on the lookout for an upgrade or a replacement:
BMX Grips Installation
Spraying alcohol-based window cleaner on the handlebars makes it easier to slide the grips onto the handlebars. The alcohol content aids in evaporating the cleaner, ensuring the grips adhere firmly to the handlebars without any sliding off the handlebar.
BMX Bar Ends Installation
Plastic bar ends are typically hammered into the handlebars using a rubber mallet, while metal bar ends are screwed in securely using an Allen key.
BMX Pivotal Seat and Seat Post Installation
Pivotal seats are mounted onto the seat post through a hole on the top of the seat. It's crucial to ensure compatibility between seats and seat posts to ensure proper fitting and functionality.
Find everything you need for perfect BMX seating right here:
