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A Thorough Guide to Constructing a BMX Bike
This serves as our manual for the construction and upkeep of a BMX. Proper assembly of the various components is crucial, as incorrect fitting not only shortens the life of your BMX parts but poses a safety hazard as well.
For beginners, especially children, it’s advised to build a BMX under the watch of someone more experienced. Local bike shops can also offer assistance if challenges arise.
Overview
Constructing Your BMX Bike: How to Proceed
Marcus and Lasse bring enthusiasm in our tutorial as they showcase how to start a BMX bike build from the ground up. Check out their video to catch the vibe before setting out to design your BMX or understand the sequence for assembling the essential parts.
The above tutorial provides a simplified approach to BMX assembly. More in-depth instructions on assembling crucial components are provided further below.
SkatePro’s Suggestions for BMX Assembly
Keep these guidelines in mind during the assembly of your BMX:
- Youths should not attempt assembly without adult supervision or guidance from a seasoned rider.
- Appropriate tools should always be used to prevent damage and ensure a successful build.
- Ensuring the tightness of all nuts and bolts is crucial prior to riding.
- Take each step patiently to prioritize safety and extend the lifespan of your components.
Anatomy of a BMX: Understanding Its Components
A complete BMX consists of the following components:
- 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
Instructional videos on mounting many of these parts can be found further in this guide under this section.
Essential BMX Tools
Minimal tools are necessary for both the assembly and upkeep of a BMX. A typical BMX toolkit encompasses the necessary implements to put together a partially assembled BMX right out of the box. Bringing a toolkit along while riding is a wise choice to avoid cutting sessions short due to loose parts.
We suggest equipping yourself with the following tools for the construction, maintenance, or repair of your BMX:
- Hex keys/Allen wrenches: 4, 5, 6 & 8 mm
- Wrench sockets: 15, 17, 19 mm (deep socket suitable 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 soft-headed hammer
In the future, acquiring more tools may be necessary for comprehensive maintenance and disassembling parts. A broader collection of bike tools can be developed as more specialized tools become necessary.
SkatePro consistently holds a variety of BMX Tools for fundamental maintenance and construction:
Comprehensive Steps for Building a BMX Bike
While having a professional mechanic assemble your BMX might not always be feasible, adhering to the instructional videos provided below can serve as a helpful guide. Seeking assistance from an experienced individual is advisable if needed. We have listed these videos sequentially for an orderly approach to building a complete BMX bike from scratch.
Installing the BMX Crankset
The video provided illustrates the process of putting in a three-piece crankset. Notably, the commonly utilized three-piece cranksets share similar installation methods with the two-piece kind. The key variance is that one crank in the two-piece varieties comes pre-attached to the spindle.
Compatibility is crucial, particularly the spindle diameter's alignment with the bottom bracket bearings' inner diameter. The sizes for the latter can be 19 mm, 22 mm, or 24 mm, but a 19 mm spindle is the most prevalent.
Looking for a new crankset? We offer a variety:
BMX Sprocket Attachment
Mounting a BMX sprocket is generally straightforward. Freestyle BMX sprockets are typically attached using bolts that fit into the sprocket and align with the crank arm's threads. Ensure the bolt-hole on the sprocket aligns with the crank's threads before securing it.
A spacer is required if the spindle hole's diameter surpasses that of the crank spindle.
BMX Rim Tape Attachment
Don't forget to attach rim tape before mounting tires and tubes. Though usually straightforward, ensure that the rim tape's hole aligns with that on the rim through which the valve passes.
Find BMX rim tape:
Installing BMX Tires and Tubes
Start by fitting half of the tire onto the rim, then slightly inflating the tube to prevent pinching or twisting. Ensure the valve remains straight before completing the tire's installation.
Note: Pay attention to the pattern direction when mounting the rear tire.
Installing the BMX Front Wheel
Fit the front wheel by sliding it into the fork and fastening it lightly by hand. Confirm the wheel's alignment before tightening securely on both sides. Ensure the tire pattern direction is correct and flip if necessary.
Installing the BMX Rear Wheel
Loosen the chain from the front sprocket to create space for fitting it on the rear wheel sprocket. Place the wheel accordingly, pull the chain back onto the front sprocket, and modify the wheel’s positioning until the chain is neither overly tight nor slack. Secure both sides with your wrench to finalise the installation.
- BMX chain tightness: Aim for minimal play such that it can slightly shift upwards, though not beyond half an inch when touched.
BMX Chain Assembly
For a new chain setup, adjusting the chain’s length to fit your BMX is necessary. Use a chain breaker tool to achieve the precise length, available here:
Below, a video guides you through the installation of a half-link chain:
Installing BMX Pedals
Two points are critical for pedal installation:
- Ensure pedal identification (left and right) before mounting.
- Apply grease to threads to aid in effective tightening and future ease of removal.
The video explains the procedure for pedal installation:
Installing the BMX Headset
For an integrated headset, grease the bearing cups for optimal results. Confirm the correct bearing orientation and ensure the C-ring is installed.
Installing the BMX Fork
Fork installation is typically easy; however, don't forget the C-ring for a secure installation.
Installing the BMX Stem
Greasing both compression and stem bolts is wise to ensure they fit closely and can be unscrewed more easily later.
When affixing the stem, ensure a gap remains between the steerer tube’s top and the stem’s top for compression purposes. Insert a spacer if the steerer tube extends past the stem. Align the stem with the fork before fully tightening the side bolts.
Mounting BMX Handlebars
After unscrewing stem bolts, position the handlebars ensuring the knurled section is centered in the stem. Gradually tighten the bolts in a cross pattern for evenness.
If you’re seeking a replacement or upgrade, view our BMX Bars:
Installing BMX Grips
Using an alcohol-based window cleaner helps slide grips onto the handlebars. The alcohol evaporates quickly, ensuring a firm grip once in place.
Installing BMX Bar Ends
Plastic bar ends are typically fitted using a rubber mallet, while metal ones require an Allen key for secure fastening.
Installing Pivotal Seat and Seat Post
Pivotal seats attach to the seat post via an opening at the seat’s top. Ensure compatibility for proper seat and seat post fit.
Discover a range of BMX seating options here:
