ebike or e-bike? Which one is correct?

Wikipedia uses "e-bike" but quick searching around the internet reveals that "e-bike" and "ebike" and "eBike" are all used interchangeably.

An electric bicycle, also known as an e-bike, is a bicycle with an integrated electric motor which can be used for propulsion.

The "e-" prefix tends to slowly fade into a solitary "e" after the word has become commonplace. During this phase of the word's existence, I recommend "e-bike" but if the term continues to gain acceptance then dropping the hyphen will probably occur more often than not. But this is merely conjecture.

Unfortunately, trying to compare usage rates of these two terms is very difficult since most search engines will treat "e-bike" and "ebike" as identical. At least "e-bike" doesn't get flagged by your local spellchecker.