I General User Manual 47
21.5.2 Vapour bubble formation
Vapour bubble formation can occur if the brakes
are operated continuously for some time, e. g. dur-
ing a long steep descent.
Instead of applying gentle pressure continuously
with the brakes, operate them for shorter periods,
with more force if necessary, releasing the brake
lever intermittently.
Vapour bubbles form if water in the brake uid
heats up, evaporates and forms bubbles in the
brake system.
As these are easily compressed, the brake lever travel
distance increases.
When transporting or storing the bike upside down,
air bubbles can form in the brake system uid reser-
voir.
If you then use the bike, the brakes could fail and
cause a serious accident.
Once the bike is in the correct riding position, pull the
brake lever several times to check whether the brakes
respond normally.
If not, adjust them as follows:
Adjust the brake lever so it is parallel to the ground
and operate it slowly several times so the bubbles
return to the reservoir.
If the response is still poor, the brake system must
be vented. Have this work carried out by a special-
ist cycle shop.
Brake pads and brake blocks are wear parts. Have the
brake pads of hydraulic disc brakes checked regularly,
and replaced if necessary, by a professional bike
workshop.
21.5.3 Cleaning the brake system
If the brake blocks come into contact with oil or grease,
they must be replaced. If the brake disc comes into con-
tact with oil or grease, it must be cleaned as otherwise its
braking performance will be drastically reduced.
Clean and maintain the brake system using isopro-
pyl alcohol, soapy water or a dry cloth. Do not use
commercially available brake cleaning agents or
agents to prevent braking noises as these can dam-
age components such as the seals.
21.5.4 Fitting/removing the wheel
When removing the wheel, we recommend you
use a brake block spacer. This prevents the piston
om being pushed out if the brake lever is oper-
ated once the wheel has been removed. This also
prevents air bubbles in the expansion vessel om
entering the system.
If the brake lever is operated and the brake block
spacer is not inserted, the pistons may extend r-
ther than normal. Put the bike in an upright posi-
tion to push back the brake blocks. Use a clean,
at screw driver or tyre lever and be carel not to
scratch the brake blocks. If the brake blocks are
not tted, push the piston back carelly without
damaging it. If you have trouble pushing back the
brake blocks or piston, remove the reservoir cap
and try again. Note that some oil may ow out the
reservoir.
Aer tting the wheel, check that the quick-release
lever is on the side opposite the brake disc. If it
is on the same side as the brake disc, there is a
danger of the lever and brake disc obstructing one
another and this could also reduce the clamping
force of the quick-release device.
