Shimano Ultegra R8050 Series Dealer's Manual page 96

INSTALLATION OF HYDRAULIC DISC BRAKE SYSTEM
Adding Shimano genuine mineral oil and bleeding air
The level of liquid inside the oil funnel drops at this time, so keep filling the funnel with oil
to maintain the level of liquid so that air is not drawn in.
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To be continued on next page
Once no more air bubbles come from the
bleed nipple, temporarily close the bleed
nipple.
(A)
With the brake lever depressed, open
and close the bleed nipple in rapid
succession (for approximately 0.5 seconds
each time) to release any air bubbles
which may be in the brake calipers.
Repeat this procedure about 2 to 3
times.
96
(A)
Bleed nipple