Shimano GRX RX 815 Series Dealer's Manual page 14

TO ENSURE SAFETY
• When turning the bicycle upside down or on its side, the brake system may have some air
bubbles inside the reservoir tank which are still there when the bleed screw is closed, or
which accumulate in various parts of the brake system when it is used for long periods.
This disc brake system is not designed to work with the bicycle upside down. If the bicycle
is turned upside down or on its side, any air bubbles inside the reservoir tank may move
in the direction of the calipers and if the bicycle is ridden in this condition, there is a
danger that the brakes may not operate and a serious accident could occur. If the bicycle
has been turned upside down or on its side, be sure to operate the brake lever a few
times to check that the brakes operate normally before riding the bicycle, and if the
brakes do not operate normally, adjust them according to the following procedure.
If brake does not seem to work (feels sluggish) when the brake lever is depressed
Set the bleed section of the brake lever so that it is parallel to the ground, and then
gently depress the brake lever several times and wait for the air bubbles to return to the
reservoir tank.
If the brakes lever still feels sluggish, bleed the air (refer to "Adding mineral oil and
bleeding air").
• If the quick release lever on the hub is on the same side as the disc brake rotor, they may
interfere with each other, which is dangerous, so check that they do not.
• SHIMANO disc brake systems are not compatible with tandem bicycles. Because tandem
bicycles are heavier, the stress on the brake system increases during brake operation. If
hydraulic disc brakes are used with tandem bicycles, the oil temperature will become too
high and vapor locks or ruptures in the brake hoses may occur, causing the brakes to fail.
• When installing the brake caliper using bolt
fixing pins, be sure to use mounting bolts of
the appropriate length.
If not, the bolt fixing pins may not be securely
fastened, and the bolts may fall out.
„ Brake hose
• After installing the brake hose to the brake unit, adding SHIMANO genuine mineral oil
and bleeding air bubbles, depress the brake lever several times to check that the brakes
are operating normally and there are no fluid leaks from the hose or the system.
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Bolt fixing pin