The easiest way to connect your bike is to enter a ride, and tap on the red bar that says DISCONNECTED at the top of the screen, on the app. MAKE SURE YOUR BLUETOOTH IS TURNED ON.
There will be a pop-up in which your bike will appear. Select your bike, and you are ready to ride. If your bike does not appear on the available devices pop-up window, then look to make sure that the blue light between the handlebars is flashing, If so, then that means the bike is looking to connect. If you're still having trouble, then double-check that your Bluetooth is turned on for your device, and restart the app to refresh. If the blue light is solid, then this means it is connected to something. Check that any other devices you have recently connected to are closed out of the app. If this does not work, then check the Bluetooth settings on the device to which you are trying to connect. Remove or "forget" the connection from the bike, and connect via the app only.