I'm a Sahel Harmony owner. Once I got the bugs out I've been loving it, except for it being kind of heavy. Right out of the box the configurable setting for wheel size was set wrong, to 2160mm instead of the correct 2030mm, in two places. The size was set wrong both on the display panel settings (which affects the accuracy of the display's speedometer/odometer) and the wheel size setting that's set with an Impulse service unit connected to the engine (which controls when the motor cuts off). So, there's a possibility you really traveled less distance and got cheated out of power because the motor thought you were going faster than you really were. While 50Cycles has the service unit connected, tell them to switch your power mode over to Dynamic too. There are three settings: regular, dynamic, and relax. Maybe yours is on Relax but probably Standard, but once you go Dynamic you don't go back. As they say, nothing is free, and with greater power comes shorter battery life. But really, what happens is that after switching to Dynamic, you find the Eco mode is fine for normal riding, and Sport and Power mode are held in reserve.
The second problem I fixed was the gearing. The Sahel Harmony's Nuvinci is controlled by the Harmony which is a device that can be programed, just like the bike's motor. There's a little rubber flap on the bottom on the device and a USB cable can be connected from there to a any computer which running the Nuvinci Desktop software. This software lets you update the firmware, as well as lets you configure the device. One of the main settings is simply defining the size of the front chain ring and the rear sprocket. Once again I found these settings were set incorrectly on my bike. My brand new Sahel Harmony came with a 38 tooth chain ring and 21 tooth sprocket, and this combination isn't even offered as a choice in the software. With my motor set in Dynamic mode I'e found that replacing the original 21 tooth with an 18 tooth rear sprocket has worked great to bring out the power of the bike. I used to stare at the display panel's power output gauge as I struggled up hills wondering what I needed to do to ever get full power. Now. if I need it, I have it. Maybe somebody else might like a 19 tooth or 20 tooth but 21 tooth is strictly for people who want their motor in relax mode and think 15mph is dangerously fast. Another reason I think they gave it that size rear sprocket is, it rides poorly unpowered because of its weight. I noticed the description of the bike going too fast for your legs and that reminds me of how the bike used to behave with a 21 tooth sprocket. When going down hills the pedals would spin out and I couldn't get any traction to push down.
There have been firmware updates as well that have greatly improved the automatic shifting mode. Last year I was 99% in automatic mode, using Eco mode, and getting 60-70 miles a charge. The latest firnware update was released in December.
http://harmony.fallbrooktech.net/