For hubs, again minimising frontal area exposure is the key for lowering aerodynamic drag. The front hub is around 15% of the total drag of the front wheel, so minimising its size is the most important factor for front hub design. For this reason, you see a very small hub on the Swiss Side front wheels. A small hub does not impact the rim stiffness or bearing life if it’s engineered correctly. For the rear hub, aerodynamics doesn’t matter. Here stiffness, weight and most importantly, reliability, are the key factors.