Civil Aviation rules in the UK seem to allow a passenger to check luggage with personal electronic items powered by lithium batteries below a certain power limit (high enough not to be an issue for this discussion) provided the battery is integral with the device.
On this basis I have flown recently (with Jet2) with my Di2 and power meter pedals without declaring anything “hazardous” and without any problems though it did occur to me that the Di2 battery is not exactly integral.
Today I was asked to remove my power meter pedals from my bike box and carry them onboard because of their lithium batteries. Jet2 rules will not now allow any lithium powered devices in checked baggage at all - very strict. The Di2 did not occur to me until after my bike had gone through x-ray - which it did without any problem.
For future reference (I fly again in a month) I wonder if anyone knows the definitive position in UK/Europe when it comes to flying with Di2 or power meters (some of which are harder to remove than pedals).