MY23P0a -52_1.0_11.10.2022
55
Description
3.3.3.3 Rim
The rim is the metal profile on a wheel which holds
the tyre, tube and rim band together. The rim is
joined to the hub with spokes.
In rim brakes, the outer surface of the rim is used
to brake.
3.3.3.4 Valve
Each tube-type tyre has a valve. Air is pumped
into the tyre via the valve. There is a valve cap on
each valve.
The screw-on valve cap keeps out dust and dirt.
The pedelec has either a:
• Dunlop valve
• Presta valve
• Schrader valve
Dunlop valve
The Dunlop valve, also known as a conventional
valve, is the most widely used valve. The valve
insert can be replaced easily and air can be let out
very quickly.
Figure 35: Dunlop valve
Presta valve
The Presta valve, also known as the Sclaverand
valve or the French valve, is the narrowest variant
of all valves. The Presta valve requires a smaller
hole in the rim, which is why it is especially
suitable for the narrow rims on racing bikes. It is
about 4 to 5 g lighter than a Dunlop or Schrader
valve.
Figure 36: Presta valve
Schrader valve
The Schrader valve can be pumped at filling
stations. Older, simple bicycle air pumps are
unsuitable for Schrader valves.
Figure 37: Schrader valve
3.3.3.5 Spoke
A spoke is a rod that connects the hub to the rim.
The bent end of the spoke which is hooked into
the hub is called the spoke head. A thread
between 10 mm and 15 mm is attached to the
other end of the spoke.
3.3.3.6 Spoke nipples
Spoke nipples are screw elements with an internal
thread which fits onto the spoke thread. Fitted
spokes are tensioned by tightening the spoke
nipples. This straightens the wheel uniformly.
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