An S and S Coupling also known as a Bicycle Torque Coupling or BTC is a
coupling
A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end mov ...
which enables
bicycle
A bicycle, also called a pedal cycle, bike or cycle, is a human-powered or motor-powered assisted, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A is called a cyclist, or bicyclist.
Bic ...
frames to be separated into smaller pieces, usually to facilitate packing and transporting. Couplings can be built into the frame by the frame manufacturer when the frame is made or can be added to a frame after it is finished. A special
spanner
A wrench or spanner is a tool used to provide grip and mechanical advantage in applying torque to turn objects—usually rotary fasteners, such as nuts and bolts—or keep them from turning.
In the UK, Ireland, Australia, and New Zeala ...
is available for tightening and loosening the couplings.
Applications
The couplings are usually installed in the
top tube
A bicycle frame is the main component of a bicycle, onto which bicycle wheel, wheels and list of bicycle parts, other components are fitted. The modern and most common frame design for an upright bicycle is based on the safety bicycle, and consis ...
and
down tube
A bicycle frame is the main component of a bicycle, onto which wheels and other components are fitted. The modern and most common frame design for an upright bicycle is based on the safety bicycle, and consists of two triangles: a main triangl ...
of a single-rider diamond frame. This enables the bicycle to be boxed small enough to avoid the extra fee most airlines charge to check a bicycle as luggage.
They can also be installed in
tandem
Tandem, or in tandem, is an arrangement in which a team of machines, animals or people are lined up one behind another, all facing in the same direction.
The original use of the term in English was in ''tandem harness'', which is used for two ...
and
recumbent
Recumbent may refer to:
* Recumbence, the act or state of lying down or leaning
* Recumbent bicycle, a bicycle, tricycle or quadricycle which places the rider in a reclined or supine position
* Recumbent effigy
A tomb effigy, usually a ...
frames. Santana manufactures a "triplet (or quad) that can be transformed into a tandem by simply removing the center section of the frame."
Characteristics
The couplings are available in stainless steel, cromoly steel, and titanium and in different sizes, from to match the frame tubing in which they are installed.
They weigh about per pair, and arc as strong as uncoupled tubing. They use a
Hirth joint
A Hirth joint or Hirth coupling is a type of mechanical connection named after its developeAlbert Hirth It is used to connect two pieces of a shaft together and is characterized by tapered teeth that mesh together on the end faces of each half sha ...
to resist
torsion
Torsion may refer to:
Science
* Torsion (mechanics), the twisting of an object due to an applied torque
* Torsion of spacetime, the field used in Einstein–Cartan theory and
** Alternatives to general relativity
* Torsion angle, in chemistry
Bi ...
.
It takes a few minutes to separate the couplings.
Alternatives
In order to support the ovalized tube
Santana Cycles
Santana Cycles is the world's leading manufacturer of tandem bicycles. Santana was founded in 1976 by Bill McCready, an Associate Editor at ''Bicycling Magazine'', and is located in La Verne, California. In the 1970s "Santana virtually re-invented ...
uses between the
bottom bracket shells of their tandems, they have developed their own oval couplers.
See also
*
Folding bicycle
A folding bicycle is a bicycle designed to fold into a compact form, facilitating transport and storage. When folded, the bikes can be more easily carried into buildings, on public transportation (facilitating mixed-mode commuting and bicycl ...
*
Recumbent bicycle
A recumbent bicycle is a bicycle that places the rider in a laid-back reclining position. Most recumbent riders choose this type of design for ergonomic reasons: the rider's weight is distributed comfortably over a larger area, supported by ba ...
*
Tandem bicycle
A tandem bicycle or twin is a form of bicycle (occasionally a tricycle) designed to be ridden by more than one person. The term tandem refers to the seating arrangement (fore to aft, not side by side), not the number of riders. Patents relat ...
*
Touring bicycle
A touring bicycle is a bicycle designed or modified to handle bicycle touring. To make the bikes sufficiently robust, comfortable and capable of carrying heavy loads, special features may include a long wheelbase (for ride comfort and to avoid pe ...
References
{{reflist
External links
* http://www.sandsmachine.com/ S and S Machine Bicycle Torque Couplings (BTCs)
* http://www.bikecad.ca/boxes Determining the placement of couplings in BikeCAD
Coupler