The idea is NOT to reinvent the wheel. Use what has been developed. Customize - make it cheaper and affordable.
The project will have 3 main components - a bike frame/wheels; an electric motor and a Lithium-ion (LiFePo4) battery pack with solar panel for charging the battery.
The specs - able to carry a weight of 250 kg (one person between 65 to 100 kg) and balance as a 2nd person/water container/farm produce. The range = 30 miles on full charge. Speed = 25mph max.
Business model - Phoenix based "Local Cars" - use the buyers/users to build cars. The plan - to encourage bike users in villages to help build the bike (they can then support/maintain it later) - lowers the total cost of 'building' the bike - no labor costs.
e-bikes use the hub planetary geared 48V - 500 Watt dc motor that has high torque. Its price is prohibitive ($365 to $600) for poor under-developed countries. Fabricate it much cheaper. Use "TechShops" facilities.