Chain Wheelies

A chain wheelie is when a wheelie is started immediately after another wheelie ends. These require very good timing - poor timing can result in the front wheel of the bike touching the floor (called a drop down), which results in a large loss of speed. Drop downs on the Bowser Bike are especially detrimental to the run, as Bowser Bike has a poor acceleration stat. A chain wheelie which is timed to perfection will result in only a very minor speed loss. These take a lot of mastering at first, as they are fairly difficult to perform.

Luck wheelies
Perfect chain wheelies are often called "luck wheelies." The wheelie time is mainly 4 seconds, this means a total of 6 "wheelie sounds" in each wheelie. When the wheelie ends, you have a frame (0.016x second window) that allows you to get the wheelie without losing much speed.

Spamming
GCN and Classic Controller users often spam the "up" button on the d-pad rather than rely on pure timing. This results in more random results, hence where the term "luck wheelies" came from.

Uses
Good chain wheelies are crucial to getting good times on tracks with long straights, especially on tracks like LC or MC, where luck wheelies are a must to get a strong time.