If you are looking for something to keep your riding stats in an organized location, any phone app will work. However, you will have to manually add your data from your Fitbit and Cateye into the cycling app you chose since the Cateye does not connect to your phone. If you don't want to do that, I would suggest getting the Wahoo BlueSC speed/cadence sensor which connects to your phone via Bluetooth and will use your phone app to keep track of the cadence and virtual distance. If your Fitbit connects to your phone, you could also use it to keep track of your heart rate on the cycling app. Most cycling apps offer this feature if you get their premium/pro version app. Wahoo makes the Wahoo Fitness app that will do all this and is totally free. However, it may/may not recognize the Fitbit as a heart rate sensor.