Electrifying Cargo Trike - options

[dilkes]

A friend has a cargo trike - 1 wheel at the back and 2 at the front. The rear wheel has a Nexus 7-speed internal hub, so I don't think they should put a hub motor on the rear. Therefore options seem to be (1) a mid-drive or (2) hub motor(s) on the front wheel(s). Questions:

1. Would a hub motor on just one of the two front wheels work/make sense -- or would it cause the bike to sway to one side?

2. Can a motor be placed in each of the 2 front wheels and both be controlled by the same throttle? Does this make sense?

3. Has anyone done either of the above?

Appreciate any guidance.

The bike is something like this: https://wicycle.com/products/bikes/big-box-trike

 

[Drunkskunk]

Looks like an interesting conversion. a single motor on the front would constantly be torque steering the front, instead of trying to move forward. Twin motors would work, and you can run 2 controllers off 1 throttle. However, the brake placement is on the wrong side for the left hand motor. You can just turn a direct drive motor around backwards and run it in reverse, but DD are heavy. Geared hubs are smaller and lighter, but can't run in reverse. If you have the skills and tools, you could maybe machine one to accept the brake disk on the right side for the left motor.

I don't think a midmount would fit that frame without either hanging too low, or being heavily modified.

A better option might be a rear hub motor that has an IGH built in. They're expensive, but so are are mid drives and the cost of 2 motors for the front.
https://www.ebikes.ca/shop/electric-bicycle-parts/motors/igh-305.html

 

[matmaxgeds]

For two hub motors, Grin now do their all axle hub as a single side axle: https://www.ebikes.ca/shop/electric-bicycle-parts/motors/single-side-all-axle-hub-build.html - see 4:40 in the embedded video for a tadpole trike with this and here is the thread: https://endless-sphere.com/forums/viewtopic.php?t=88266 - not cheap though! Much cheaper and more powerful QS motors also come single sided e.g. meant for small scooters, but a lot of work to integrate one and v. heavy. Then there are fun threads e.g. on two temp sensors and one motor: https://endless-sphere.com/forums/viewtopic.php?f=2&t=95191 and similar for two motors one controller etc.

I have seen delta trikes with just one motorised wheel (e.g. http://www.longabike.com/), they said it works just fine - I guess better on roads where that wheel always has good traction.

Still, I think that a mid-drive (tsdz2 etc) would be much cheaper, easier etc, as long as the frame doesn't interfere with the installation, and may also give better performance at slow speeds due to being able to use the gears in exchange for a bit of noise and a marginally lower reliability. Other options would include a stoke monkey type setup, a friction drive, a mid mount left hand side drive setup.........

 

[dogman dan]

You will quickly learn to steer crooked enough to make up for one front motor. It would only be uncontrollable if the back wheel was a caster.

I'm pretty sure that you could just swap the covers on a front direct drive motor, and have the brake disk on the other side. Or if that won't work, you can rig one motor to turn backwards, and then mount it flipped. One way or another, two motors is technically possible.


I'd try one motor first, and see how it steers. Then add another only if you need the power, or if it really steers that bad. I think it will be ok at lower power levels. Regular trikes drive only one rear wheel from the chain, and at pedal only power, you don't feel it. At 3000w you'd feel it, but if you put a 36v 750w front hub on there, it should do fine.


The other option is also easy, convert to a regular derailleur gear, and then you use a rear hub motor. sell off the valuable IGH wheel. One thing you don't realize yet, is that once you get that hub motor, you won't use those low gears anymore. You won't need them to start, and once rolling, you will just want one or another of the higher gears. Most never shift again, ever.

 

[amberwolf]

1. Would a hub motor on just one of the two front wheels work/make sense -- or would it cause the bike to sway to one side?

It will, but you'd quickly learn to handle it. My old Delta Tripper used the right rear wheel for motor power and the front for pedal power. Was easy enough to deal with; was pretty low power. My SB Cruiser trike is a lot higher power, and while it has motors on both rear wheels, I usually only use one for cruising, the second is to help with startups and hauling a heavy load (especially with the trailer full of hundreds of pounds of whatever).

2. Can a motor be placed in each of the 2 front wheels and both be controlled by the same throttle? Does this make sense?

Yes, there's a lot of 2WD threads, and various ways to do this. Teklektik's Yuba thread probably has the most details on exactly how to wire this.



I'm not sure a middrive thru an 7-speed IGH is a good idea unless it's lower power and soft-start, because it's possible to break the IGH gears; it's happened before here on ES. (more speeds means gears are thinner, and easier to break).

The bike is something like this: https://wicycle.com/products/bikes/big-box-trike

*something* like it isn't enough to give specific recommendations, because the way the wheels mount may be very different, and might be impossible to mount a typical hubmotor to. While there may be other solutions, they can be expensive or complicated (or unreliable).

If the wheel mounts are exactly like the linked trike, then you can probably use almost any common hubmotor that fits the dropout width (probably a front hubmotor), that has disc brake rotor bolt holes. Might need a custom torque plate or torque arm, though.

To find out which one would work best in the wheelsize you need, for the situations, terrain, and loads you have, you can go to the http://ebikes.ca/simulator and read the whole page, then play with different systems of battery, controller, and motor to see what would give you the results you like. Then you can give us detailed info on usage/terrain/range needs/etc and the Wh/mile estimate it gives in the simulator for your chosen system, along with the details of that system, and we can give an estimate on the battery size needed for the application.

If you don't want to go to those lengths, you can probably use any basic kit to make the trike move...but it'll depend on the terrain, situations, loads, range, etc., for the "wattage" you'd need, controller size, and battery size/etc.