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.
Flip-flop hub Flip-flop hub Flip-flop hubs, also called double-sided hubs, are rear bicycle hubs that are threaded to accept fixed cogs and/or freewheels on both sides. There are several different types of flip flop hubs available for different applications. Their main purpose is to allow changing between two different size gear ratios on one rear wheel without the added complications of a derailleur or internal hub gear, or between a fixed and freewheeling option. By removing the rear wheel and flipping it around, the rider can switch between the two options. They are traditionally found on track bicycles, but can also be