For e-bike geeks only: Here I show how I successfully installed two Zippy 10S 5800mah long lipos inside my A2B Metro frame. I bought three foot long aluminum bar stock two inches wide and an eighth of an inch thick from Home Depot along with a $25 big industrial pack of 2″ wide Velcro. I put a bend in the end of the aluminum bar to keep the batteries from slipping downward and then velcro’d the heck out of the aluminum bar and batteries to keep them in place and protected from chafing. I finished with two 6mm stop screws to keep the “trolley” in place once inserted into the down tube. I also had to extend the power and balance wires from the battery pack highest up inside the down tube.