Bicycle trailer - AbsoluteAstronomy.com

A bicycle trailer is a motorless wheeled frame with a hitch system for transporting cargo

Cargo

Cargo is goods or produce transported, generally for commercial gain, by ship, aircraft, train, van or truck. In modern times, containers are used in most intermodal long-haul cargo transport.-Marine:...

by bicycle

Bicycle

A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....

. It can greatly increase a bike's cargo capacity, allowing point-to-point haulage of objects up to 4 cubic yards (3 cubic metres) in volume that weigh as much as half-a-ton.

Types

Different types of trailer are designed for various purposes, cargo requirements and riding conditions:

By number of wheels

Single-wheel: a single rear-mounted wheel. Though of limited towing capacity, this design tends to be more stable (when moving) than trailers with two or more wheels. The single wheel can tilt from side to side when cornering (as the bicycle itself does,) allowing for coordinated turns at relatively high speed. The Bob series of trailers and the Extrawheel all have a single wheel.
Two-wheel: A two-wheel design makes possible much greater load carrying capacity and a wider cargo bed. Though not suitable for high speed, they are ideal for everyday cycling (very much like towing a trailer behind a car). Two-wheel trailers tend to be as wide or wider than the handlebars of the bicycle, therefore care needs to be taken when riding through narrow spaces.

By intended cargo

General Cargo: for transporting cargo of all kinds. The load capacity of commercially-available cargo trailers ranges from 30 to 300 pounds (14 to 140 kg), but much larger loads have been transported by custom-built trailers or by multi-trailer "trains" attached to a single bicycle.
Child passenger (as cargo): constructed to enhance the comfort and safety of one or more small human passengers. These usually have a low centre of gravity and widely-spaced wheels to increase stability when cornering, and often have integrated rain-proof covers, seat padding, and safety belts
Seat belt
A seat belt or seatbelt, sometimes called a safety belt, is a safety harness designed to secure the occupant of a vehicle against harmful movement that may result from a collision or a sudden stop...

. A lot of the trailers designed for transporting children can also be converted to strollers.
Child passenger (as rider): Trailer bike
Trailer bike
Trailer bike is a one-wheeled bicycle trailer designed to carry one or more small riders in positions that closely resemble that of a bicycle rider...

s and pedal trailer, one-wheel trailers (tandem trailers) with integrated seat, handle bars, and drive train, that normally attaches to the bike via the seat post (and operate very much like a tandem). These allow small children who can't yet ride a bicycle alone to accompany adult riders as participants and motive-power producers. These trailers are by far the most popular style.
Canoe and Kayak: designed for towing long, thin, relatively light-weight loads such as canoes, kayaks, or wind surfing rigs.
Disabled passenger: made for safely towing wheelchair
Wheelchair
A wheelchair is a chair with wheels, designed to be a replacement for walking. The device comes in variations where it is propelled by motors or by the seated occupant turning the rear wheels by hand. Often there are handles behind the seat for someone else to do the pushing...

s with persons in them.
Pets: for carrying small domestic animals, especially dogs, that weigh less than 100 lb (45 kg).

Frame

Metal: usually steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

or aluminum alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

tubing, assembled by brazing
Brazing
Brazing is a metal-joining process whereby a filler metal is heated above and distributed between two or more close-fitting parts by capillary action. The filler metal is brought slightly above its melting temperature while protected by a suitable atmosphere, usually a flux...

, welding
Welding
Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...

, or nuts and bolts.
Wood: seldom seen but sometimes used in make-shift and home-built trailers, fastened with glue, nails, screws, bolts, or a combination thereof. bamboo and other improvised materials.

Axle

Most trailers have a separate axle for each wheel, like those used on a bicycle. These separate axles usually mount directly on the frame using either threaded nuts, or a quick-release mechanism, or some press fit arrangement. The use of separate axles for two-wheel trailers allows the load carrying area to be between the wheels with its base below the axles, so as to keep the centre of gravity relatively low.

Some trailers support a normal axle on two sides, others mount the wheel off one side with a stub axle (a one sided axle).

Wheel

Traditional spoke
Spoke
A spoke is one of some number of rods radiating from the center of a wheel , connecting the hub with the round traction surface....

d bicycle wheel
Bicycle wheel
A bicycle wheel is a wheel, most commonly a wire wheel, designed for bicycle. A pair is often called a wheelset, especially in the context of ready built "off the shelf" performance-oriented wheels....

in various sizes. Has the advantage of being light, strong, readily available. Pneumatic tires
Bicycle tire
A bicycle tire is a tire that fits on the wheel of a bicycle, unicycle, tricycle, quadracycle, bicycle trailer, or trailer bike. They may also be used on wheelchairs and handcycles, especially for racing...

provide some suspension
Suspension (vehicle)
Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose — contributing to the car's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants...

for the load, larger diameters ride smoothly and have much less drag than many other types of wheels.
Solid metal wheels with solid tread
Tread
The tread of a tire or track refers to the rubber on its circumference that makes contact with the road. As tires are used, the tread is worn off, limiting its effectiveness in providing traction. A worn tire tread can often be retreaded. The word tread is often used incorrectly to refer to the...

s, such as dolly
Hand truck
A hand truck, also known as a Hannibal lectern, two wheeler, stack truck, dolly, trolley, trolley truck, sack barrow, sack truck, or bag barrow, is an L-shaped box-moving handcart with handles at one end, wheels at the base, with a small ledge to set objects on, flat against the floor when the...

wheels. Extremely durable but rough riding and usually slow due to small diameter.

Fender/mud guard

If included, the fender

Fender (vehicle)

Fender is the US English term for the part of an automobile, motorcycle or other vehicle body that frames a wheel well . Its primary purpose is to prevent sand, mud, rocks, liquids, and other road spray from being thrown into the air by the rotating tire. Fenders are typically rigid and can be...

(or just a mud flap) helps to protect the cargo and the towing bicycle from road spray and dirt. On heavy-duty trailers, the fender may be designed to be capable of bearing heavy loads.

Hitch

There are various types, from home made to those supplied by the trailer manufacturers.

Hitch positions:

Seat-post: Temporary or permanent clamp
Clamp (tool)
A clamp is a fastening device to hold or secure objects tightly together to prevent movement or separation through the application of inward pressure...

assembly attaching trailer hitch to the seat post.
Rear axle: Special attachment points, integral to the rear quick release skewer
Quick release skewer
A quick release skewer is a mechanism for attaching a wheel to a bicycle. It consists of a rod threaded on one end and with a lever operated cam assembly on the other. The rod is inserted into the hollow axle of the wheel, a nut is threaded on, and the lever is closed to tighten the cam and secure...

or bolted on to solid axles, hold dropouts
Dropout (bicycle part)
A bicycle dropout is a type of fork end that allows the rear wheel to be removed without first derailing the chain. The more inclusive term fork end refers to a slot in a frame or fork where the axle of the wheel is attached....

cut into the trailer hitch.
Chainstay: Two-piece sandwiching clamp screws tight over left rear triangle, with protruding socket-and-pin receiver.
Rear cargo or pannier rack: Some improvised hitches attach to the rear cargo rack or pannier
Pannier
A pannier is a basket, bag, box, or similar container, carried in pairs either slung over the back of a beast of burden, or attached to the sides of a bicycle or motorcycle. The term derives from the Old French, from Classical Latin, word for bread basket....

frame. Since rear racks are not structural parts of the bicycle they cannot handle much weight or torque
Torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....

loading.
Improvised: Ropes, bungee cord
Bungee cord
A bungee cord , also known as a shock cord, is an elastic cord composed of one or more elastic strands forming a core, usually covered in a woven cotton or polypropylene sheath...

, chain, cable, etc. Usually not dependable, often dangerous to rider and cargo.

Single-wheel trailers generally use a special frame hitch which attaches to both sides of the rear axle, and which incorporates a vertical hinge to allow cornering. Attaching the trailer at the seatpost can (dependant on the design) place the load at a lower point relative to the longitudinal pivot axis of the attached trailer. This can make it possible to wheel a loaded single-wheel trailer around while disconnected from the bike, as the seatpost hitch is a natural height for grasping while walking upright.

Hitches for two-wheel trailers must incorporate some form of universal joint or flexible coupling. If the joint relies on a certain amount of play to give the required movement, then there is the possibility of resonance at certain pedalling speeds and trailer loads. The effect is that the trailer feels as if it is 'bumping' the bicycle. However, there are other methods such as spring with a nylon tube inserted through the middle to provide rigidity and flexibility, allowing the bicycle to lean while the trailer remains upright and isolates the bicycle from any resonance.

Two-wheel trailers which attach to the rear axle or chainstay generally have an angled towbar to help keep the trailer central behind the bicycle.

External links

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