Air resistance increases exponentially the faster you go. 30mph is practically a wall. But what about gravel speed? Here savings are claimed at 20mph on bars 4cm smaller (21:00). Should you ride tiny bars? This rider may not want to (22:45).
(A simple extrapolation would yield 36 watt savings with our Svelte series -9cm at 20mph (9/4 * 16).)