A sticky, or fixed position navigation bar is a must these days, especially for mobile devices. If your users are having to scroll back to the top of the (possibly very long) page each and every time they need to explore your site, they may become frustrated. If you're frustrating your users, then you sure as hell aren't converting them.
In this video below see how I take the website of art gallery Friedman Benda, currently without a sticky nav, and with a minimal amount of CSS, effectively enhance the user experience.
See some of our projects that use a sticky nav.