A Zip Dash is using Zipline Momentum Conservation and then Dashing or strafe dashing to gain speed and cover distance. The reason that the resulting dash is faster and able to travel longer is because air drag is no longer in effect and the slowdown that typically happens at the end of a dash is removed.

Dropping down from the transit line costs no Stamina, but dashing costs one bar.

Zip Dashes are most effectively utilised with the Vitality item Superior Stamina ( 3,500). With Superior Stamina, you can strafe dash twice in quick succession, which adds speed and distance to your dash. Typical speeds for a Zip Dash with two strafe dashes

Zip Dashes are most often used in pre-game rollouts, to get to the middle of the lane faster than your opponent.

Since Wall Jumps use air drag that is nullified by dropping from the transit line, you can utilise wall jumps after a Zip Dash to go further.

To execute, drop from the transit line, and Strafe Dash.