The problem with riding a spin bike on Zwift. Is there is no feedback loop. You have inputs like power, speed and heart rate. But there is no feedback from the program telling the bike that a hill is certain percent. A spin bike doesn’t have a resistance loop. It may give you a warm fuzzy feeling that you are riding on Zwift fast. But it is not actually working the way the program was designed. Zwift allows it to happen because it lowers the barrier for those spin bike riders to give Zwift money.