The road specialized electric bikes use the aluminum alloy bicycle frame and the suspension, The aluminum alloy frame is strong and durable, and aluminum alloy has a very big advantage in that it will not rust. If you want to choose a frame that will not rust, you can choose this one. And the suspension front fork improves riding comfort. This road e-bike uses the outer battery, so if you want the electric bike conversion road bike, You can remove the battery and battery case, so you also can ride as a road bike. And the other battery box has a lock, don't worry about being stolen.
http://www.supanda-bike.com/electric-bikes/