Tandem bicycle stem that is clamped around the captain's seatpost. The stoker handlebars are typically bullhorns or drop bars with "dummy levers" instead of brake levers for gripping. Because of the extra weight and stresses, tandem wheels may use a higher spoke count, sturdier rims, higher pressure tires, a stronger freewheel, dishless spoke configuration, or asymmetric wheels. Tandems wear out rear wheels faster than front wheels; therefore, they may use non-symmetrical wheel setups, such as more spokes or a sturdier rim on the rear wheel. The dish of a wheel measures the amount of asymmetry between the rim and the hub flanges.
Ship's wheel (though sometimes as few as six or as many as ten) shaped like balusters and all joined at a central wooden hub or "nave" (sometimes covered with a brass "nave plate") which housed the axle. The square hole at the centre of the hub through which the axle ran is called the "drive square" and was often lined with a brass plate (and therefore called a "brass boss", though this term was used more often to refer to a brass hub and nave plate) which was frequently etched with the name of the wheel's manufacturer. The outer rim is composed