Help! 40k flat commute @ 40k/hr, Direct Drive or Geared?

[HRC]

Hi all, after a great first mid drive tsdz2 build I need to start my second ebike project. (Yes, I'm definitely infected by the diy ebike virus)
I need to build an ebike to commute 40k a day and I want to able to do it at not less than 40k/hr on very flat terrain (Belgium). I could do that speed on the 750w tsdz2, but it's not the optimal tool for the job (I now installed that motor it on my wife's bike).
Due the terrain is really flat so high torque situations will not happen often
With above goal in mind, I plan to buy a 500-750ish Watt rear hub drive motor, but I'm not sure about what type of motor and brand to buy.
- Would a direct drive be the best choice and make less long term problems? Or nowadays the geared hub motors work well enough?
- Seems a sinewave controller should be a must?
- I guess I should aim not less than 48v/20Ah controller?.
- How many Wh/km should I consider when choosing the battery? Around 15?
What would the experts recommend? Any proven brand recommendations?
Important too: I don't want to break the bank
Thanks!

 

[Woosh]

- Would a direct drive be the best choice and make less long term problems?

at higher than 40kph, I would say direct drive hub, but 40kph is reachable by both crank drives and geared hubs. You pay the penalty of heavier weight if you go for a direct drive kit.

- Seems a sinewave controller should be a must?

no. The difference is minimal. Sinewave gives slightly lower noise.

- How many Wh/km should I consider when choosing the battery? Around 15?

for your distance, 48V 12AH would suffice at 40kph but I think 48V 15AH is definitely better, less stress on the battery.

Important too: I don't want to break the bank

The BBS02B is perfect for the job.