I thought you always had to use "on" after "depend" to mention the complement, as in:
Choosing the right bike depends on what you want to use it for. (example taken from a dictionary)
However, I've come across this:
It depends whether you want to participate or not.
The preposition is omitted.
So, my question is: Is it possible to omit "on" in my first example:
Choosing the right bike depends what you want to use it for.
My guess is that it's not possible, and that you can only omit it in the personal expression "it depends + wh- word", but I want to check.