My trainer is the Stages SB20 Smart Bike. It has Erg, Sim and Levels modes that you can control from one of 2 BT connections or any number of Ant+ FE-C connections. Not surprisingly, I chose this bike because I thought its software was good. The lack of resistance mode training option turns out to be due to limitations in workout apps and not the bike. So far no training app adequately exercises (pun intended) its sim and level modes (another hint 
).