Hi Paul! There are a number of factors to consider here but thanks for sharing your weight and terrain. On a level surface, without wind, for a 200 pound rider given the stock 500 watt gearless motor and 48 volt 8.7 amp hour Lithium battery pack you should be able to go ~10 miles. One of the biggest factors here is acceleration from stop. If you give the bike more time and are gentle with the throttle you will save a lot of energy. Also, if you ride at <= 15 miles per hour the drag from air resistance will be lessened.
I believe the
E3 Dash provides 40 Newton Meters of force but I'm not sure how many amps it draws. The capacity of the battery is 418 watts (48*8.7) so maybe we can use these stats to transform the energy potential into an estimated output?
A basic estimate would be to divide the watt hours by 20 (a rough estimate for what's required to go one mile
according to electricbike.com and
supported by this post using real data from a rider on the forums here). So 418 Wh / 20 (Watts estimated to go 1 mile) = 20.9 (miles) given a top speed of 20mph that means you could ride for >= 1 hour. Unfortunately, this equation doesn't take rider weight, motor size or amps drawn into consideration. I was trying to use
this tool to convert watts to Newton meters but was unable to build an equation that made sense.