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RoLLER, DRUM AnD BACK-PEDAL BRAKES
These types of brakes have an enclosed design; brake pads and sur-
faces inside the hub body are largely protected against the influences
of the weather. The braking force is transmitted through cables from
the levers to the brakes. Used as rear brakes they are mostly connected
to a hub gear
With back-pedal brakes maximum braking power is achieved by step-
a
ping on one of the pedals in its rearmost position with the cranks hori-
zontal. With internal gear hubs from SRAM braking power is increased
when having shifted to a lower gear.
The risk of overheating is particularly high with these brake systems.
Brake overheating occurs on prolonged (steep) downhill rides with per-
manent brake dragging. Brake fading is a result thereof which, in ex-
treme cases, can lead to brake failure.
Therefore, if you notice that the braking power deteriorates, stop and let
the brake system cool down. Sometimes, it will be enough to operate
b
the front and rear brake in an alternating pattern. If that will not suffice,
stop for a couple of minutes before you set off again.
G
G
c
G
Checking and Readjusting Back-Pedal Brakes
The chain tension
checked and adjusted, if necessary, after approx. 1,000 km (620 miles)
or 50 hours of use. For more details read the chapter "chain - care
and wear".
G
d
52
(a)
and sometimes they are operated by back pedalling.
Brake cables which are damaged, e.g. frayed, must be re-
placed immediately, as they can otherwise fail in a critical
moment, possibly causing a crash!
If during braking the travel of the brake lever increases, un-
usual noises occur and/or the braking effect is clearly more
or less effective than usual, do not ride your bicycle. In such
a case contact your WHEELER bicycle dealer immediately.
Check regularly whether the torque support
(b)
is firmly at-
tached to the frame or fork. Use a torque wrench and never
exceed the maximum torque values!
(c)
of bicycles with back-pedal brakes has to be
Keep in mind that the back-pedal brake is ineffective if the
chain
(d)
has jumped off. danger of an accident!
gearS
DERAILLEUR GEARS
The gears
(e+f)
of your WHEELER bicycle serve to adjust the gear ratio
to the terrain you are riding on and the desired speed. A low gear (where
in the case of derailleur gears the chain runs on the small chainring
and a large sprocket) allows you to climb steep hills with moderate
pedalling force. You must, however, pedal at a faster pace. High gears
(large chainring, small sprocket) are for riding downhill. Every turn of the
pedals takes you many metres forward at correspondingly high speed.
A
Practise switching gears in a place free of traffic until you
are familiar with the functioning of the levers or twist grips
of your WHEELER bicycle.
I
Read the gear manufacturer's operating instructions, which
you can find on the enclosed CD, and practise shifting gears
until you are familiar with this operation before you set off
for the first time.
operation and control
Derailleur gears always work according to the following principle:
Large front chainring – high/heavy gear
– higher gear ratio
Small chainring front – low/easy gear
– lower gear ratio
Large rear sprocket
– low/easy gear
– lower gear ratio
Small rear sprocket
– high/heavy gear
– higher gear ratio
Normally, the shifters are mounted as follows:
Shift lever right
– rear sprockets
Shift lever left
– front chainrings
Modern city/trekking bicycles can have up to 30 gears. As there are,
however, overlapping ranges, actually 15 to 18 gears are usable. It is
not advisable to use gears which involve an extremely oblique run of
the chain, as this reduces power transmission efficiency and hastens
wear of the chain. An unfavourable run of the chain is when the small-
est chainring is used with one of the two or three outermost (smallest)
(g)
sprockets
or when the largest chainring is used with one of the
inmost (largest) sprockets (h).
e
f
f
g
h
53
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