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3.4.2
Chassis
The chassis comprises two components:
•
Frame and
•
steering system
3.4.2.1 Frame
The frame absorbs all forces which act on pedelec
from body weight, pedalling and the ground. The
frame also acts as a carrier for most components.
The frame geometry determines the pedelec's
ride performance. A frame comprises the
following elements:
2
3
4
5
6
Figure 4: Elements of the frame
1
Head tube
2
Top tube
3
Rear frame seat stay
4
Rear frame fork end
5
Chain stay
6
Seat tube
7
Down tube
Suspension frames also feature a rear frame
damper.
MY23Z12 - 12_1.0_26.01.2024
1
7
Carbon frame
Carbon (CFRP) is a carbon-fibre-reinforced
polymer made of high-strength, rigid fibres.
Carbon frames comprise several layers of carbon
with an epoxy resin matrix. The uppermost layer is
known as the visible layer.
Benefits
•
Carbon frames are more rigid than aluminium and
offer greater fatigue strength.
•
Carbon frames do not rust.
•
If carbon frames are fitted correctly and are not
involved in a serous accident, they have a similar
long life cycle to aluminium frames.
•
Fatigue is significantly less common in carbon
frames than in aluminium frames.
Disadvantages
•
Carbon breaks if the maximum load is exceeded.
•
Carbon is highly delicate. Interior damage may
not be visible on the outside after an accident.
Damage can only be detected by pulse
thermography or ultrasonic excitation, for
example, at a specialist retailer's.
•
Carbon frames are sensitive to heat. Several
hours over 65 °C can soften the frame and cause
the individual layers of carbon to separate from
one another. This is called delamination.
•
Fractures which cut through carbon fibres cannot
be repaired. A new frame needs to be acquired in
such a case.
•
Carbon is very difficult to recycle.
Frame size
The size of the frame must be adjusted to the
rider's height.
City and trekking bicycle, folding bicycle and
cargo bike
The tolerance for the frame height and its
associated top tube length is somewhat greater
for city bicycles due to the more upright riding
position. As the handlebars and saddle can be
adjusted to the rider's height, the range of
recommended frame sizes can be somewhat
wider.
Description
27
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