Motorcycle frame

The motorcycle frame is the supporting chassis on a motorcycle. To him the major drive components such as engine, transmission and suspension, but also steering, energy storage are (fuel tank), seats, trim parts and optionally attached trailer hitches. In some embodiments, the motor-gear unit can be partially take over the supporting function of the frame. Modern motorcycle frames weigh from 8 to 17.6 KG including transfers the swingarm.

• 3.1 tubular frame
• 3.2 box frame
• 3.4 -cast frame

• 4.1 single-tube
• 4.2 Zentralrohrrahmen
• 4.3 Duplex frame
• 4.4 Double loop tubular frame
• 4.5 spar steel frame
• 4.6 Trellis frame
• 4.7 monocoque

• 5.1 Closed Frame
• 5.2 Open frame

• 6.1 Rigid
• 6.2 Geradewegfederung
• 6.3 swing frame

General

During the Daimler riding car of 1885 as a precursor of the motorcycles still had a wooden frame, quickly sat down with mass production and experience in the bicycle frame metal as a material through. The different performance and weight classes and the adaptation to a variety of applications require a variety of frame types, which are also organized differently depending on the perspective.

Breakdown by the supporting material

Wooden frame

Quality handcrafted in individual production and derived from the coach- bike frames made of wood only when Daimler riding car ( hickory ) and short time were to be found in Bekamo ( ash ).

Steel frame

Steel is still the most common material for motorcycle frame. High strength, easy processing and low cost in favor of this material. There sheet is used ( for central press frame) high-strength steel tube with round or rectangular cross -section ( for box sections ) or deep-drawn.

Aluminum frame

The first motorcycle frame consisting of die - forged aluminum had the Neander motorcycle from 1924. Aluminum frame can bring benefits by reducing weight. [Note 1] The processing, however, is more difficult, the starting material is more expensive. The parts produced can be joined together by TIG or MIG welding. It also complicated the casting, die-casting process or manufactured by forging parts with continuously cast sections or deep-drawn parts can be combined. One of the first bikes that came in large numbers with aluminum frame was the Suzuki GSX -R 750 from 1985.

Titanium

The first attempt with a motorcycle titanium frame was the site of BSA motorcycle from the year 1966. Husqvarna brought in 1971 a competition bike with titanium frame used, followed in 1998 by another single piece with grinding titanium frame.

Carbon fiber -reinforced plastic

Frame made of carbon fiber reinforced plastic (also called " carbon " or " carbon" called ) were previously found only in motorcycle racing. First race bike with a carbon fiber frame was the Tomos of 1978. 1983 appeared the Armstrong (250 cc ) with an 8 kg light carbon fiber frame, followed in 1985 by the Heron - Suzuki.

Magnesium

1988, again only in racing, parts of the frame at the Experimental motorcycle " elf -5 ' were used cast magnesium.

Composite frame

When composite frame different starting materials are combined. For example, be used by the steering head of steel pipes up to just before the engine mount / swing arm bearing ( front frame ), the swingarm pivot and the rear frame is made of cast aluminum. A prominent example is the Benelli TNT.

Aluminum frame Suzuki GSX -R 750 (1985)

Frames made of CFP Heron - Suzuki ( 1985)

Magnesium frame parts ELF -5 ( 1988)

Composite frame Benelli TNT ( 2011)

Breakdown by execution

Tubular frame

For metal frame usually round, but oval or rectangular (square tube ) are used frame profiles. In the early days of the bicycle oriented, standard round profiles were used. These were pre-bent and brazed or welded, reinforced at stress points with gusset plates or sleeves. The preparation was carried out manually at first, was expensive and time consuming. Today, handmade tubular frame are produced only for individual pieces or small series. For series production machine multi-point welding equipment or welding robots are used. This leads to a significant reduction of production time and human labor input in the same consistent quality and lower cost in mass production. In the 1950s, square steel tubes [note 2] in the 1980s, square aluminum tubes inserted into the serial production.

Box frame

As a special form of box frame can be viewed with a large cross section of square sheet profiles. First and prominent example is the White Mars by 1920. The bar-shaped frame box had a U-shaped profile and sat down next to the load-bearing function also further components, such as the tank. At the frame and the motor was screwed not pregnant and hanging.

In order to reduce production time and costs, mechanically pre-formed and die-cut frame parts made of sheet steel were used in presses. From the main parts that were symmetric in the horizontal longitudinal plane, the additional frame gusset plates or sleeves could be manufactured cost accounted. As one of the first motorcycles this design was applied in the Neander P3 from 1927 and the manufactured in Neander license Opel Moto Club from 1928. The prefabricated frame parts were riveted and bolted it, resulting in a significantly faster production enabled.

At the NSU Fox 1949 was offered as a central press frame machine made mass produced pressed steel frame with connected by welding the frame halves. Similarly, in the manufacture of the frame of the scooter Vespa (1946 ) with a shell frame made ​​of sheet steel, reinforced for rigidity with pipes was. The manufacturer Kreidler presented since 1957 in its foil models a folded central press frame ago. Even in the weaker models of small MZ ES, the central press frame was offered in large numbers. Today, steel frames can be produced inexpensively and in large quantities. For reasons of stability, this design is suitable for motorcycles and scooters with low engine power. In recent times, the central press frame found in the XV models from Yamaha.

Cast frame

One of the few examples of the type of frame in casting (aluminum ) is the Heinkel Perle by 1954. Combined with other frame materials ( composite frame ) supporting aluminum castings are used in the frame construction. Yamaha delivered from 2004 bolted cast aluminum frame on his FZ6 Fazer model.

Central press frame (Mars Monza )

Cast aluminum frame Heinkel Pearl ( 1954)

Cast aluminum frame Yamaha FZ6 Fazer (2004)

Breakdown by Frame Shape

Single-tube

The single-tube emerged from the diamond frame bicycles. It is characterized by a narrow tube guidance in the symmetry plane. The bottom of the frame profile of the motor is mounted. The fuel tank is semi-mounted on the upper frame tube ( saddle tank ). Cheap cost, especially when using a uniform cross-sections, but often weaknesses in stiffness. To improve this, the load-bearing the brunt upper frame tube of the joist is usually more powerful unit to the steering head, mostly forked. Single-tube today (125 cc ) or low-performance motorcycles, used almost exclusively in light motorcycles.

Central tube frame

In the central tube frame, the single upper frame tube is to increase strength more powerful unit and receives next to the bearing is often still receiving function. In the early days was called the central tube frame tank tube frame. 1924 was presented with a motorcycle tank tube frame in the TX motorcycle of the Berlin manufacturer Westendarp & Pieper. A thick tube served as the main frame and the fuel tank was mounted on the engine and passenger footrests. A central tube frame had the " Germany - drive model " by Ernst Neumann - Neander and the Nimbus " stovepipe " of 1924.

1947 Moto Guzzi of the tubular frame of the racing machine due cilindri provided with a large hollow carrier to the steering head, which originally served as the oil tank. After 1956, the last Vincent motorcycles were produced, the Swiss Fritz W. Egli acquired the rights and sales from 1969, the engines in its chassis. Egli improved the idea of ​​the central tube frame and drove the Egli- Central tube frame from 1975 -made, inter alia, with Japanese engines (eg Egli Kawasaki, Suzuki, Yamaha).

A designated as a curved spine tube frame Zentralrohrrahmen 1953 presented by NSU in the Rennmax. From Honda, this principle has been applied to the Honda CX 500 by 1978 in an amplified version. Today, the backbone tube frame is used only in few manufacturers.

Double tubular frame

By duplicate, spread out from the plane of symmetry joists from the steering head to a lower frame point not only results in a significant transverse reinforcement of the frame, but also a focus on favorable arrangement of the engine and transmission between the frame tubes. This both improves handling and safety. These frames form emerged in the 1920s. Leading the way was the Moto Guzzi model of 1921, the BMW R 32 of 1923 and the D- wheel. The twin- tube frame is still the basis of many motorcycle suspension kits. Currently (as of 2013) used Harley -Davidson, for its entire model range, twin-tube frame; Japanese manufacturers use this design especially for chopper models.

The stiffening effect of the closed loop splayed form was also used in many pressed-steel frame. Through their open pressing cross -sections are not tubular frame. In steel construction at BMW from 1928 on the BMW R 16 and R 11 BMW and Zündapp at the K models from 1933 onwards, they were also referred to as box frame. The torsional rigidity of such frame was always problematic.

Double loop tubular frame

1950 as " spring bed frame " called double-loop tubular frame was presented at Norton racing motorcycles. The typical feature of the spring bed frame are the steering head intersecting pipes as well as the soft elbows. The time excellent properties of these out in a double loop tube construction convinced other manufacturers. From 1969 to 1996, the double-loop tubular frame with a frame reinforcement on the steering head ( gusset plate ) and a strong oval tube, BMW was installed. The weight of this facility amounted, including the swingarm, with the BMW R 100 S 17.6 kg. Meanwhile, was the double-loop tubular frame, displaced with respect to market shares, by the bridge tubular frame, in which the motor-gear unit is incorporated as load-bearing assembly.

Bridge tubular frame

The bridge tubular frame or bridge framework was developed by the double joists removed and the motor gear unit is incorporated as a supporting assembly from the double-loop tubular frame. The bridge tubular frame and bridge frame ( this very often made ​​of aluminum ) is now installed in nearly all manufacturers of high-performance motorcycles. BMW sat for the first time with the BMW K 100 has a tubular composite bridge as a framework in which the engine-gearbox unit was used as a supporting element; frame weight amounted to 11.3 kg.

Spaceframe

A further reinforcement of the steel tube frame is given by the creation of additional frame triangles. The resulting patterns led to the naming. The stability, but also the manufacturing cost is high due to the many joints. The Trellis frame, developed in 1952 by Moto Guzzi, is used on modern motorcycles with high performances. In manual production it is made for special individual or with automatic multi-point welding equipment in volume. Users are BMW, Ducati, KTM, MV Agusta, Italjet, and in which the unclad frame parts are used visually stylistic influence. The weight of the space frame of MKM 1000 was 11.6 kg.

Monocoque

Through the use of box sections of the motorcycle frame was used more and more over the years around the engine. First newer monocoque frame were identified as " Delta -Box" designated under Yamaha and called as monocoque frame of the Kawasaki ZX -12R ( 2002). Currently use the Ducati 1199 Panigale and the Kawasaki ZZR 1400 has a monocoque frame made ​​of aluminum.

Double tubular frame with Geradwegfederung (BMW)

Double-loop tubular frame (Norton Manx )

Double tubular frame from square tube ( Suzuki GS500 )

Aluminium bridge frame (Yamaha R6)

Backbone tube frame (Yamaha )

Spaceframe (Ducati S2R Monster)

Monocoque ( Kawasaki ZZR 1400)

Breakdown by engine and transmission mounting

Closed Frame

Based on the bike was at the beginning of motorcycle development uses only the closed tube frame. The engine sits in the lower triangle and is well protected against mechanical damage. A disadvantage of the closed tube frame for one of the high center of gravity because the frame tube is carried out under the engine and transmission, on the other hand, the less lateral stability. These disadvantages of the Einrohrrahmens were bandaged with the closed, by cross tubes, reducing double pipe frame, which is still installed. Simple Run are provided with only one top tube.

Open frame

As a variant of the open frame where the engine and transmission were also used as load-bearing components originated. Rösler & Jauernig developed in 1903 for the first time a motorcycle with an open bottom frame. The frame is in the lower part, are placed in the engine and transmission, open. Wherein the overall weight and center of gravity is lowered. But with fixed screw are also transmitted vibration to the frame. In elastic suspension the motor gear unit may only partially contribute to the stabilization. Thus, these frames when conceived as a single-tube, little rigid. This also as center tube bridge frame designated open frame has been used, for example, from the MZ TS 250.

Today, the open tube frame is only used for light mopeds and motorcycles with low power. In contrast, the open frame has established itself as a double tube frame, bridge tubular frame and space frame. To increase the rigidity, various tube cross-sections are combined.

Breakdown of the rear suspension

Rigid

When Rigid rear axle is firmly bolted to the frame. This design dates back to the early days of motorcycle development. The lack of rear suspension road bumps just by the tire or the entire bike can be added, resulting in an uneasy ride with little comfort. By the development of the oscillating saddle riding comfort is improved. However, the unsprung masses remained high. This until the 1930s, widespread construction is now only used in choppers for optical reasons.

Geradewegfederung

With the Geradewegfederung you tried to improve performance and comfort of the rigid frame. The axis can move independently of the frame vertically to compensate for any unevenness by attached to the rear frame end spring elements. The increased comfort is matched by a significant increase in weight with low travel. The sliding guides wear out and deteriorate the driving safety. Furthermore, constantly changing during compression, the distance of the rear wheel for fixed under mounted engine / transmission, what additional effort for the power transmission means (thrust piece shaft drive or tensioner with chains or belt drive ). This construction method is now obsolete.

Swing frame

When you swing the rear frame is performed in a rocker arm which is mounted close to the transmission output. The rear wheel during compression describes a circular path about the pivot point, the distance changes the springs are low. Also possible to achieve significantly greater suspension travel. Therefore, these frames shape ( with two lateral or central spring element ) today state of the art. If both front and rear, a swing arm used for suspension, one speaks of the full swing arm suspension.