The Duo Series. Ebikes for Everyone.The Juggernaut Duo Series is all about flexibility. Hub-drive or mid-drive, step-over or step-thru, single battery or dual battery, entry-level or high-end. No matter your needs, there's probably a Duo for you.Watch this video to see how The 3 Duo models stack up. welcome to the big leagues.The Ultra Duo sits at the top of the Duo range, so naturally, it boasts one of the most powerful motor systems available today. The Bafang Ultra M620 mid-drive motor is loaded with 1500W of peak power and 160Nm of torque. Pair that with the 11-speed drivetrain and you'll be nearly unstoppable.