Tandems are bicycles built for two or more riders. The range included track bikes, road bikes, touring bikes, tandems and off-road bikes. Tandems come with both upright and recumbent seating. Ibis tandem, utilizing the "Uptube" design borrowed from Rick Jorgensen's Tango Tandems. Besides safety bicycles, models included tandems and a Pedersen. These have front mounted carriers and in tandems the two axle housings are different. Derny also built a touring adaptation called the 'Solo' and tandems and mopeds. Until then, riders had been sheltered by tandems of two and three riders. Derny also built a street adaptation called the Solo as well as tandems and mopeds. Tandems can be used by two or even three paddlers. Occasionally eights are rigged with one or more tandems&colon; several rigs are possible. The exception was early model tandems, which shared their separate wheelbases. Some modern tandems use disc brakes, with all the advantages and disadvantages that entails. Speeds rose when engines were added to pacing tandems. Taylor and Adrian Peterson were considered one of the NFL's top running back tandems.