lumenpdx
100 mW
- Joined
- Oct 23, 2015
- Messages
- 35
Been lurking around here forever. Electric vehicles have always interested me, and I've been an avid cyclist since childhood. I just couldn't come up with a way to rationalize building myself an electric bike. Until now. Because screw it, I want one 
Here's the parts I do know:
* I've got a raging crush on the Luna Fat Bike cargo frame. A fat-tired cargo bike would serve my adventure-utility needs perfectly.
* I'm a big guy (210lbs), and need to be able to occasionally haul heavy loads (loaded racks, a trailer up to 200ish lbs) up extended moderate hills.
* Top speed has to be entertainingly high, but not looking to set any speed records. If it can cruise at 30mph I'd be very happy.
* Battery pack most likely in the 48-52v / 20Ah range
Considerations
* Aesthetics are pretty important here. Think cyberpunk-madmax sort of thing. Strapping several big silver controllers wherever they'll fit isn't nearly as appealing as being able to tuck everything in and keep it looking intentional and tidy.
* I'm a strong cyclist and don't intend to stop pedaling. I'm leaning towards using a torque-based pedal assist bottom bracket sensor.
* While I need heavy load hauling ability, and reasonably high speed, it doesn't have to do both at the same time.
* Need to keep the price in check. High value wins out over highest performance.
* Will need to be able to handle rain, snow, mud, playa dust, and everything in between.
* I'd love to be able to implement an on-board charger.
So I'm trying to decided on my drivetrain. Motor, controller, and charger. Lots of options. Here's what I've been considering:
Single large direct drive motor.
Something like a Mxus 3000w rear motor, with an Adaptto (or similar) controller.
PROS: Simple, clean looking, durable, capable of plenty of speed, with CA3 and right controller could handle both torque PAS and variable regen braking, which sounds like a fantastically sporty ride.
CONS: Poor low-end torque could make this less inefficient for hauling heavy loads up long hills. DD hubs are heavy. Would require a battery with a particularly high drain rate.
Pair of geared hub motors
Something like a pair of MAC or BMC 1000W motors. Undecided on controller.
PROS: Fairly simple, fairly durable, should be able to provide the speed I want, with better torque and efficiency for hauling heavy loads and dealing with hills. Redundancy of two complete motor/controller units. Two wheel drive sounds like wicked fun.
CONS: More complexity, and potentially more cost than a single rear motor. No option for regen. May need to use less expensive controllers to rationalize cost.
Mid drive
A BBSHD with a Nuvinci or similar IG rear hub.
PROS: Should have all the torque I could need, along with all the top speed I could want. Probably more efficient than any hub setup. Mid drive would let me use an internally geared rear hub (there's one for fat bike spacing, right?)
CONS: More complexity, more cost then DD setup (especially with IG rear hub), probably not as high powered as my other 2000w to 3000w options, can't use a torque sensing bottom bracket, and likely to need much more drivetrain maintenance then hub motor options.
I'm really undecided. Dual geared hubs or mid drive are the options I'm seriously considering. There must be some magic combination that will deliver on my needs, right? I haven't started calling dealers for recommendations, I wanted to get some less biased input before I start taking up some busy shop guy's time.
So if you were building up a mean fat cargo bike, how would you handle the drivetrain?
Here's the parts I do know:
* I've got a raging crush on the Luna Fat Bike cargo frame. A fat-tired cargo bike would serve my adventure-utility needs perfectly.
* I'm a big guy (210lbs), and need to be able to occasionally haul heavy loads (loaded racks, a trailer up to 200ish lbs) up extended moderate hills.
* Top speed has to be entertainingly high, but not looking to set any speed records. If it can cruise at 30mph I'd be very happy.
* Battery pack most likely in the 48-52v / 20Ah range
Considerations
* Aesthetics are pretty important here. Think cyberpunk-madmax sort of thing. Strapping several big silver controllers wherever they'll fit isn't nearly as appealing as being able to tuck everything in and keep it looking intentional and tidy.
* I'm a strong cyclist and don't intend to stop pedaling. I'm leaning towards using a torque-based pedal assist bottom bracket sensor.
* While I need heavy load hauling ability, and reasonably high speed, it doesn't have to do both at the same time.
* Need to keep the price in check. High value wins out over highest performance.
* Will need to be able to handle rain, snow, mud, playa dust, and everything in between.
* I'd love to be able to implement an on-board charger.
So I'm trying to decided on my drivetrain. Motor, controller, and charger. Lots of options. Here's what I've been considering:
Single large direct drive motor.
Something like a Mxus 3000w rear motor, with an Adaptto (or similar) controller.
PROS: Simple, clean looking, durable, capable of plenty of speed, with CA3 and right controller could handle both torque PAS and variable regen braking, which sounds like a fantastically sporty ride.
CONS: Poor low-end torque could make this less inefficient for hauling heavy loads up long hills. DD hubs are heavy. Would require a battery with a particularly high drain rate.
Pair of geared hub motors
Something like a pair of MAC or BMC 1000W motors. Undecided on controller.
PROS: Fairly simple, fairly durable, should be able to provide the speed I want, with better torque and efficiency for hauling heavy loads and dealing with hills. Redundancy of two complete motor/controller units. Two wheel drive sounds like wicked fun.
CONS: More complexity, and potentially more cost than a single rear motor. No option for regen. May need to use less expensive controllers to rationalize cost.
Mid drive
A BBSHD with a Nuvinci or similar IG rear hub.
PROS: Should have all the torque I could need, along with all the top speed I could want. Probably more efficient than any hub setup. Mid drive would let me use an internally geared rear hub (there's one for fat bike spacing, right?)
CONS: More complexity, more cost then DD setup (especially with IG rear hub), probably not as high powered as my other 2000w to 3000w options, can't use a torque sensing bottom bracket, and likely to need much more drivetrain maintenance then hub motor options.
I'm really undecided. Dual geared hubs or mid drive are the options I'm seriously considering. There must be some magic combination that will deliver on my needs, right? I haven't started calling dealers for recommendations, I wanted to get some less biased input before I start taking up some busy shop guy's time.
So if you were building up a mean fat cargo bike, how would you handle the drivetrain?
