The use of "quick" and "quickly" as comparative

[Megyxu]

I am not sure why sometimes you can use "quickest" or "more quickly". What is the reason?

Thank you very much.

[Naamplao]

I am not sure why sometimes you can use "quickest" or "more quickly". What is the reason?

Thank you very much.

Quickest is an adjective.

"This is the quickest way I know of to travel to work"

"Quickly" is an adverb.

"You can travel more quickly to work using this way"