For the first version of the Bike, which does not have an LED, verify that once it is plugged in, you can hear the magnets moving slightly.
Second, make sure that the device you want to connect your Bike to meets the following specifications.
It has Bluetooth Smart 4.0
For PCs, make sure that the Bluetooth 4.0 drivers are updated to the latest version.
If the operating system is Windows, remember that you need Windows 8.1 or higher.
Finally, remember that Bluetooth pairing is 1-to-1, meaning that the Bike can only connect to one device at a time.