We recently received one of the new BionX rack batteries along with a 26" wheel. If there was one thing we learned at Interbike, it's that electric assist is the up and coming thing, and a lot of manufacturers are looking at how they can make batteries less obtrusive. Some have gone the route of putting batteries in the frame (which means the entire assist is integrated and can't be moved to another bike) while others have gone the rack mount direction.

But even those that did a rack mount didn't necessarily think to integrate rear lights into the design, or to make it so easy to slide the battery in and out of the rack.