Sun USX trike build question

[Tryker]

I am considering putting 3 hub drives on a USX trike with the two rears as fat wheels/tires and the standard front wheel with bmx tire for steering mostly. I live in a beach community and want soft sand capability and don't need a lot of speed...35 mph is as fast as I need/want to go but 20-25 is my comfort speed. For sand, I need the grunt for hills and deep stuff. I only have experience installing mid-drives but I want more traction with this trike than my current single wheel drive. Drive wheels are 20 inch as is front.
Questions:
1. Anyone here do something like this?
2. The rear hubs are keyed with a hefty axle...about 3/4 inch or metric equivalent. Can hub motors accept this large of an axle?
3. geared vs direct drive
4. Good source of 20" fat tire rims (I am willing to spoke myself...gotta learn sometime) and a how-to on matching/mating to a hub drive.
5. What else should I ask?
I will build my own battery but want to stay with 48 to 52 volt and go for Ah.
Thanks

 

[amberwolf]

2. The rear hubs are keyed with a hefty axle...about 3/4 inch or metric equivalent. Can hub motors accept this large of an axle?

For almost all hubmotors out there (except for one), you'd have to redesign the rear end, because hubmotors don't fit "on" an axle like the wheels you have, they have it built in, and so you have to have someplace to bolt that new axle into (dropouts).

The only exception I've seen is the Grin All-axle hub, http://ebikes.ca , but you'll have to machine adapters to fit the axle that's in there to the motors.

However, if the trike's existing axle is a "live axle" and not firmly welded in place, then you can't use the Grin All-axle motors either, because they have to "push" on that axle (torque) to rotate the wheel. Hubmotors won't work in that case, and you'd have to use some form of middrive to drive the live axle.

Or modify the trike to remove that and hold the hubmotors as they are designed to be used.