For 26 inch wheel bikes like the DJ Fat Bike, DJ Mountain Bike and DJ City Bike, we would recommend to riders between 5'4" and 6' 4". As for the weight capacity, the manufacturer states the max weight is 275lb. However, we have 300 lb + customers riding the DJ bikes.
For the 20 inch wheel bikes like the DJ Folding Bike, we would recommend to riders between 5'2" and 6'2". The weight capacity is the same.
There is one more thing to mention. The Mountain Bike, City Bike, and Folding Bike equip a shock absorbing seat post. If you replace it with a normal seat post, you can further lower the seat by 2 inches to touch the top of the battery.