The choice of nipple material inspires zealotry — some prefer brass, some prefer aluminum, others a mix of materials. Brass nipples are more popular because they’re cheaper, stronger and more corrosion resistant. Aluminum nipples are mostly interchangeable at one third the weight. How to choose? If you’re hard on gear, clean infrequently or ride in adverse conditions, then brass is a sensible choice. For scenarios where weight and performance matter, aluminum is the way to go.
Working with aluminum nipples shouldn’t inspire fear — in fact you may find aluminum nipples turn more smoothly. How do pros work with aluminum? First, use liberal lubrication. When building in the first place, make sure threads are fully covered with oil or other spoke preparation compound. When making adjustments down the road, dribble a thin oil into the nipple and into the rim at the base of the nipple. Second, avoid stressing aluminum nipples by using a 4-sided spoke wrench (e.g. Park Tool SW-40). Compared to a regular 3-sided wrench, a better tool distributes forces more evenly. If your nipple has a secondary hex interface on the rear, that’s a very safe way of applying torque.
Find the right nipples for your wheels in the shop.