Spin sessions differ from instructor to instructor , my GF is a spin inst'r , and its quite a hard sesssion , 45 mins long and you know youve done it , ive attended others who are lets say less dynamic , it suits some people , so they can say they go to spin class but as they say , no pain no gain ,quads burning ! ive left her classes and my legs are feel like jelly , but , thats me pushing myself , if at first you find it hard , wind back the resistance , and just keep up the cadence, after a few weeks , it gets easier , if you live in or near West London she will get you some free passes, see how you take to it