If you’re planning on building your mini bike, you must understand the various frames. This article will help you choose the perfect frame for your needs.
Most manufacturers will quote reach and stack numbers when discussing their frames; these measurements refer to how far away the bottom bracket axle from the head tube lies.
Basics
Every mini bike can be made faster with just a few tweaks to its engine and aerodynamic modifications, like frame modifications. A frame modification can drastically decrease air resistance; if you have or can learn welding, custom frames may prove cost-effective as an investment in time and effort spent learning welder skills.
Frame choices vary considerably, but the critical element in finding your ideal bike frame is finding one that fits you properly. In a perfect world, both feet should remain flat on the ground while being able to reach both handlebars without strain on either leg. A seat height that is too high could place additional pressure on the legs; too close an axle could increase the frontal area and drag significantly.
The shape of the tube also matters significantly. A round steel tube will have much higher drag than one with more aerodynamic lines; although low-drag pipes may be possible to create, they are usually costly and don’t always arrive from directly ahead; there are often additional factors at play that increase total drag.
Example: Riding a TT bike at 25mph in the wind tunnel will produce a headwind that reduces your speed and increases drag due to wind having to pass over more distance for its forceful effect to be felt on your bike.
Those looking to improve their bike can turn to Aeroweenie as an invaluable tool. Here, they can compare frontal area and drag for various configurations of wheelsets, frames, cockpits, and helmets, as well as estimate power savings per dollar spent – an incredibly helpful metric when shopping for upgrades.
Design
One of the critical elements of any mini bike is its frame. It must be sturdy, strong, and capable of withstanding high speeds; in fact, some frames are specifically designed with strength in mind.
An essential consideration in selecting a frame is how much space there is for components like engine and control components, as well as crucial essentials like brake pads. Furthermore, light enough material must be used so the rider can maneuver at high speeds safely.
Honda GX200 engines are widely favored among mini bike enthusiasts, serving multiple functions ranging from compressors and generators to log splitters and go-karts. Producing an initial stock output of 6.5 horsepower, they can also be tuned up to pay double that amount if desired.
To get the most power and speed out of a GX200, it requires a large rear wheel and brake, a powerful controller, and a battery that can withstand the voltages and current required by its motor, and all these elements are packed into a sturdy mini drag bike frame; fortunately, its design makes this task relatively simple even for beginners welders.
Assembly
Don’t be daunted by the complexity of this project; its frame is flexible enough for beginners. Just take your time following the templates provided by your welder to stay on course.
A jig is an effective way of making sure the frame remains perfectly straight during welding, then use it afterward to cut out front fork mounts with ease and create an ideal curve for the front fork – it makes cutting out horses more efficient than grinding or filing out each peak individually!
I also added a cross-member tube in the center of the rear half to reinforce it further. This piece is just an offcut of 1″ tubing notched on both ends, then slipped into place + welded into place.
Finally, I painted the frame using a standard rattle can of Hammerite smooth/rust-oleum paint. While it appears satisfactory so far, I still need to find that perfect finishing touch!
This kit contains an assembled bare chassis, wheels, bearings, bearing retaining clips, wheels bearings, and holding clips, as well as the assembled motor and rear axle drive sprockets, drive belt, wheelie bar, and precise body set – everything that’s needed to build your mini bike is included – you add motor leads wires guide braid, and you’re good to go! A great way to begin custom building mini bikes.