Motorcycle chassis
A motorcycle frame includes the head tube that holds the front fork and allows it to pivot. Some motorcycles include the engine as a load-bearing (or stressed) member; this has been used all through motorcycle history but is now becoming more common. The rear suspension being an integral component in the design. Frames have been made from titanium, aluminium, magnesium, steel and carbon-fiber along with a combination of these materials.
Frame Materials
Steel
- Examples
Norton Featherbed frame Early Honda CBR600F
Aluminium
- Examples
Aluminium and carbon-fibre
- Examples
Bimota SB8K (composed of two aluminium alloy beams and carbon fibre plates)
Carbon Fibre
Bimota TESI 3D
Titanium
- Examples
1971 Titanium Husqvarna
Magnesium
- Examples
Magnesium and Aluminium
- Examples
Aprilia ETV 1000 Caponord (aluminium alloy welded on to aluminium-magnesium alloy castings)
Frame Types
Pressed frame
The frame is mass-produced by sheet metal pressed or stamped into shape. Typically a single-cradle structure is used.
- Examples
Single cradle
The motorcycle engine is held in a single cradle with a single spine.
Half-duplex cradle frame
The motorcycle engine is held in a double cradle with a single spine and single downtube.
- Examples
(Full) duplex cradle frame
The motorcycle engine is held in a full by two separate cradles, normally with a single spine.
- Examples
Double cradle or perimeter frame
Two cradles follow the perimeter
- Examples
Spine or backbone frame
The motorcycle engine is suspended from a single spine.
- Examples
- Honda CD200-T Benly
- Lots of (new) Triumphs.
Beam
Twin beams join headstock to swingarm pivot in as straight and short a line as possible.
- Examples
Monocoque
Supports structural load using the external skin of the frame.
- Examples
Trellis
Similar to the beam frame, connecting the steering head and swingarm pivot point directly as possible. The frame is made up of a large number of short steel (or aluminium) tubes welded together to form a trellis.
- Examples
- Most modern Ducatis
- Suzuki SV650
- Kawasaki Versys
- Honda VTR250