Battle of Seoul
In 2015, while in Seoul, South Korea, Natasha Romanoff deployed her Harley-Davidson LiveWire from the Avengers' Quinjet to pursue Ultron. In route, she picked up Captain America's shield and threw it back to him. Ultimately, Romanoff abandoned the motorcycle after jumping up into Ultron's vehicle. The motorcycle then crashed into oncoming traffic.
In an alternate 2015, Natasha Romanoff rode her motorcycle in Moscow, Russia to maneuver her way past Ultron Sentries. Romanoff used her motorcycle to destroy a few Sentries in order to rescue Clint Barton.
Later, Romanoff rode her motorcycle throughout the post-apocalyptic land. After finding more life, Romanoff rode her motorcycle to investigate, snatching the Soul Stone upon seeing it, and prepared to fight them. However, Romanoff realized that they were all on the same side, before setting her motorcycle aside. During the fight against Ultron, Romanoff rode her motorcycle to get closer to Ultron in order to fire an arrow containing Arnim Zola's analog consciousness into Ultron's eye. The motorcycle was then left behind in Romanoff's universe.
Black Widow's motorcycle was an electric motorcycle that was capable of traveling at high speeds and was highly maneuverable. Like Captain America's motorcycle, it can fix his shield to the front of the bike.