This can be known as cardan transmission, some motorcycles have this system, obviously it loses speed. But very good since it is almost maintenance free. The bearings transfer torque from the front shaft drive shaft to the 13-speed rear gear. This differs from the traditional chain and derailleur and as a result you have to pedal less to get you going. The propeller shaft concept was born from the desire to make a bicycle as efficient as possible. The 21 Ceramic Speed has bearings that produce nearly half the friction of a conventional chain and derailleur while riding. It does this with low friction in rotation. It would be nice to add a 1/4 circle brace around the chainring, so it's not just the left chainring that bears the weight there.