never heard of putting battery in downtube.. not really the best way. I've always had it in the seatpost itself or seattube. Canyon really put it there from factory.
Brain fart on my part, I meant to say seat tube. Then again, I can't say for sure where they put it, b/c I haven't removed the BB to get in and have a look.
To answer a question from another poster - I've seen a number of mentions on airlines' policies that Lithium Ion batteries cannot be put in checked baggage and must be carried on:
From American Airlines: "Please remove batteries from devices in your checked bags and put them in your carry-on in separate plastic bags."