Hi there,
I'm a mechanical engineer with over 15 years experience in designing, modeling, prototyping and effective manufacturing of different products, ranging from consumer goods to alternative energy systems.
My relevant experience in this field: I designed and built a reverse trike go-cart with the help of one of my friend which is the Romanian Champion for enduro, and several years ago I wanted to launch a new type of bike (made entirely in carbon fiber). During those project I had to do an extensive research on different systems and components for bikes/motos/atv, so I have a large knowledge base about this field. I used a similar system with Bafang to drive a prototype for a kind of mini-lift.
What I learned from this experience: for a good MTB (and this mean comfort, resistence, safety) you'll have to design the frame in such way to be as much as possible lightweight, to have a higher stiffness, and (you'll be surprised) to not use on the front wheel a disk brake. Also you could replace the chain with a sycro belt and instead of derailleur you may use a different system for gearing - for example you could put a CVT on the frame and this way will have a lighter rear wheel.
In order to discuss more, you may open a msg channel here and we'll set the parameters (specs and features) for your bike.
If you'll like my model, on a separate assignment I could even built this bike.
I will deliver 3D model in different CAD formats and the execution drawings + bill of materials.