Karen, here’s a PS to my earlier answer. I also noticed that you provide classes at a Christian Center. If this is some sort of non-profit or religious based community center, they often do not charge their members a rate for participation as high as traditional commercial gyms. So you may also want to consider that if they are not charging the participants much, and if their mission is a non-profit one, they may not be in a position to pay exactly what you might expect if teaching classes in a commercial/for-profit gym.
Make sure that you’re comparing “apples-to-apples” when looking at what other cycle instructors in other facilities are being paid.
You are all fortunate in the rates you are getting. I teach a 45 min indoor cycling class and receive $15/class. It is at a large regional chain club in the Western NY region. Instructors are very aware that they are receiving at least $5 less per class than other clubs compensate instructors regionally. I wish we could get more because as we all know, we spend a lot of personal time and money downloading songs and creating and choreographing playlists.