What makes an indoor cycling trainer "smart"? It is the ability to transmit a signal to your device enabling you to use the data for your app or program. Generally smart trainers transmit a bluetooth or Ant+ signal or both. The Bluetooth signal will connect with a tablet, phone or PC that receives Bluetooth whereas the Ant+ signal is for other devices (mainly PC's) and will require the additional purchase of an Ant+ dongle or receiver. Purchasing a smart trainer is no guarantee it will work with your device. You must have the app or program you would like to use installed and updated, and older devices may not be compatible. Some trainers are "smart upgradable" meaning you can purchase a wireless transmitter that transmits speed and cadence and extrapolates power. Less expensive smart trainers, or upgradable trainers do not measure power but estimate it.