The Campagnolo Hyperon Ultra Two carbon wheel has 11 spokes evenly distributed around the rim of the wheel. What is the measure, in radians, of the central angle formed by adjacent pairs of spokes?

They are both angle measure units. To visualize a degree, think of a wheel with 360 evenly spaced spokes from the center to the rim. The angle in between each spoke measures one degree. The radian is a more naturally derived angle measure unit. One radian is the central angle cut out of a circle when the arc of that angle (on the circle) measures the same as the measure of the radius of the circle.