Gocycle
®
Owner’s Manual for GX, April 2019
© Karbon Kinetics Limited. All Rights Reserved. 34
Carbon fibre composites are typically a strong, light fibre in a matrix of plastic, moulded to form a
shape. Carbon composites are light relative to metals. Steel weighs 7.8 grams/cm
3
(grams per cubic
centimetre), titanium 4.5 grams/cm
3
, aluminium 2.75 grams/cm
3
, magnesium 1.8 grams/cm
3
. Contrast
these numbers with carbon fibre composite at 1.45 grams/cm
3
.
The composites with the best strength-to-weight ratios are made of carbon fibre in a matrix of epoxy
plastic. The epoxy matrix bonds the carbon fibres together, transfers load to other fibres, and provides
a smooth outer surface. The carbon fibres are the “skeleton” that carries the load.
7.4.12 Why Are Composites Used?
Unlike metals, which have uniform properties in all directions (engineers call this isotropic), carbon
fibres can be placed in specific orientations to optimize the structure for particular loads. The choice of
where to place the carbon fibres gives engineers a powerful tool to create strong, light bicycles.
Engineers may also orient fibres to suit other goals such as comfort and vibration damping.
Carbon fibre composites are very corrosion resistant, much more so than most metals.
Think about carbon fibre or fibreglass boats.
Carbon fibre materials have a very high strength-to-weight ratio.
7.4.13 What Are The Limits Of Composites?
Well designed “composite” or carbon fibre bicycles and components have long fatigue lives, usually
better than their metal equivalents.
While fatigue life is an advantage of carbon fibre, you must still regularly inspect your carbon fibre
frame, fork, or components.
Carbon fibre composites are not ductile. Once a carbon structure is overloaded, it will not bend; it will
break. At and near the break, there will be rough, sharp edges and maybe delamination of carbon
fibre or carbon fibre fabric layers. There will be no bending, buckling, or stretching.
7.4.14 If You Hit Something Or Have A Crash, What Can You Expect From Your Carbon
Fibre Bike?
Let’s say you hit a curb, ditch, rock, car, other cyclist or other object. At any speed above a fast walk,
your body will continue to move forward, the momentum carrying you over the front of the bike. You
cannot and will not stay on the bike and what happens to the frame, fork and other components is
irrelevant to what happens to your body.
What should you expect from your carbon frame? It depends on many complex factors. But we can
tell you that if the impact is hard enough, the carbon fibre component may be completely broken. Note
the significant difference in behaviour between carbon and metal. See Section 2. A, Understanding
metals in this Appendix. Even if the carbon frame was twice as strong as a metal frame, once the
carbon frame is overloaded it will not bend, it will break completely.
WARNING: Be aware that high temperature in a confined environment can affect the
integrity of composite materials, resulting in component failure which could cause you to lose
control and fall.
7.4.15 Inspection of Composite Frame, Fork, and Components
7.4.16 Cracks
Inspect for cracks, broken, or splintered areas. Any crack is serious. Do not ride any Gocycle or
component that has a crack of any size.
Delamination is serious damage. Composites are made from layers of fabric. Delamination means
that the layers of fabric are no longer bonded together. Do not ride any Gocycle or component that
has any delamination. These are some delamination clues:
1. A cloudy or white area. This kind of area looks different from the ordinary undamaged areas.
Undamaged areas will look glassy, shiny, or “deep,” as if one was looking into a clear liquid.
To Next Page
Loading...