This article's tone or style may not reflect the encyclopedic tone used on Wikipedia. |
Mini choppers first existed as a cheaper version of custom-built motorcycles.
Components
Frame
Mini chopper frames are generally constructed from 1" steel tubing or 3/4" steel black pipe. The tube or pipe is bent and then welded together to get the desired angles and shapes of the frame, which is usually custom made. While there may not be an apparent difference between tubing and pipe, tubing is measured by taking the outer diameter whereas pipe is measured by taking the inner diameter. Different tools are also required to bend the different types. Tubing benders are very expensive and pipe benders are not. Although it can be rigged to bend tubing only a few have had success bending tube in a pipe bender.
Engines and Transmission
There are a variety of engines used to power mini choppers. The most typical engine is a Briggs & Stratton or Tecumseh horizontal shaft industrial engine with a non tapered shaft. Other engines include small motorcycle engines and powersport engines such as ATV and dirtbike engines. If an industrial engine is used, some sort of transmission also needs to be used to apply power to the rear wheel. Centrifugal clutches, which allow the engine to idle without moving the chopper, are cheap and easy to find on the internet; the downside to such an arrangement is that you are fixed into one gear ratio for both low and higher speed operation. So, it is very important to choose the best combination of these components to suite your goals. However, some people opt to make a jackshaft, which allows the builder to change the gear ratio to his liking or to change which side the axle sprocket is on.
There is also a transmission called a torque converter, or CVT (Continuously Variable Transmission). The torque converter is essentially an automatic transmission that changes gear ratios according to the RPM of the engine. When the engine is at low RPMs, the gear ratio is at 1:x, depending on the ratio the torque converter has (This allows for more lower end torque). As the RPMs rise, the gear ratio changes to 1:1. As the higher end RPMs are reached, the gear ratio reaches X:1, which allows for a higher top speed.
Wheels
Mini choppers often use bicycle or mpoed rims and tires up front and large pneumatic wheels in the rear. Commonly golf cart wheels or 205/50-10 style tires are used in the back. The rear also needs something to let the wheel spin,and that's where that axle comes in. There are 2 different types of axle setups used, a live and a dead axle.
A live-axle is probably the most common axle setup used on mini choppers. The "live" term indicates that the axle spins along with the wheel, sprocket, and other pieces anchored to the axle. Since the axle spins, bearings are mounted to the swing arm frame. This is a very simple axle setup, and components are relatively easy to change. Each piece, such as wheel hub, disc brake rotor, sprocket, etc, are slid onto the axle and are held in place by set-screws or locking collars. The components can also be separated by bushings that are cut to the desired length. Since the axle spins, the wheel, brake, and sprocket components must be locked to the axle. This is accomplished by using a square key that fits into a groove on the axle and the components.
A dead-axle (or hub and bearings) is much less common than the live-axle setup used on most mini choppers. As opposed to a "live" axle, where the axle spins along with the wheel, this axle does not spin. The wheel or hub has built-in bearings to allow it to spin. Depending on the setup, all spinning components are attached to the hub or to the rim itself. The bearings and hub spin on the axle. This is the type of setup that is used on most motorcycles. Often, the axle is inserted into slotted dropouts and the chain is adjusted by moving the wheel forward or backward within the slots. solid, This allows the engine to be mounted which makes the bike's drive-train much more rigid and reliable. There are also other advantages to this type of axle, including the possibility of a cleaner and more attractive rear axle area, but this setup is often more expensive than a live-axle and custom parts are much more difficult to locate.
Custom Parts
Custom parts are what make choppers art. Whether it's coming up with a new frame design or thinking out of the box and using a car rim for the rear, there are tons of different ideas and parts. A lot of builders build their own gas tanks that are similar to fullsize motorcycle gas tanks, but scaled down to fit the bikes. Sheet metal parts such as laser cut gussets are also used as accent pieces on the bike.
More Info
- Hardcore Mini Choppers Huge Mini Chopper Forum
See also
External links
- Baileigh Industrial Popular manufacturer of pipe, tube, and exhaust benders.
- Rooke Customs Jesse Rooke's Customs site.
- Twisted Minis Custom mini builder and parts.
- Custom Mini Bikes Kits and parts.
- Nebraska Custom Cycles Custom midsized builder.
- BmiKarts Huge inventory of mini parts.
- West Coast Mini Choppers Custom built from the ground up, also parts including rolling chassis and kits
- Howron Industries USA manufacturer of metal benders
.