DIY Dual Motor EMTB/Cargo Suggestions

[kmccune]

Those Montagues were used in the first Desert Storm. The idea is you can land lightly and move quickly with stealth. No heat signature. The military has one design of a motorcycle that uses almost any fuel. It is diesel and can run on anything peanut oil to aviation fuel.

I do believe the military has basically done away with gasoline-powered stuff, do not know what they run Light ICE-powered equipment on, there sure is an advantage to only having to keep up with one fuel type. Not sure of their default, JP4 or Jet A, I do not have the enthusiasm for weapons of war I once possessed, There is a project that pops up into my mind from time to time the "Moon Buggy" 4 wheels, 3 motors HD bike wheels, articulated want 26 inchers on the back plus size knobbies ,South American trike unit with differential on rear installed on good steel cruiser frame, reasonable cargo platform, articulated front axle, bike steering( only part requiring much welding and fab, fatish 20 inchers on front at least 180 disc on front, single large 203mm 0r bigger disc on rear axle, good seat with suspension seat post 36 volt mid-drive motor 6-7 spd drive, 250 watt( 45 nm torque) on front wheels, dual controller for front motors, torque sensor on mid-drive 25-30 Ah lithium power source should be good up to between 15-20 mph
Of course, it will cost more than I think it would, the front wheels maybe can be acquired for around$400( barring good used assemblies, mid-drive$500, frame less than $100, SA trike rear $400, welding. $100 at least , batteries $400, misc parts( may use a continuous axle on the front or make up a narrower double front wheelset to bolt into the dropout, for around$2500 it could be a reality, still cheaper than a good used golf cart. Just a pipe dream being retired makes money flow much slower( still have to modify the fattire beastie for a little more climbing ability.

 

[kmccune]

Yup. I mentioned above that he should go get a real bike, load it up to the capacity he wants to and then try and ride it like that. Forget about all the build specs. Just ride a bike that is carrying 100 lbs. That learning experience alone will dramatically inform him insofar as a reality check is concerned.

Amen brother, slow and steady will win that race, not forgetting the ability to stop at a reasonable distance

 

[SCIFIcrab]

Amen brother, slow and steady will win that race, not forgetting the ability to stop at a reasonable distance

I can spend a thousand hours looking at spec sheets, but I think I need to get some parts in hand and work out the problems hands on.

In the current market I don't think there are many suppliers ready to ship the parts that I want, but would it be good to start with whatever I can get my hands on and upgrade as I go?

 

[SCIFIcrab]

BTW this idea was tried in 2003, but the technology was not ready yet. It seems like a good solution if using modern battery+motor tech.
https://en.wikipedia.org/wiki/Tidalforce_Electric_Bicycle

 

[SCIFIcrab]

Do you think that dual RH212 Motors each with 72v batteries driven by a phaserunner would be an effective build? Seem to be a good balance, but I'm still not sure that DD will have enough torque required.

OR something like a geared GMAC in the rear plus a DD in front?

 

[m@Robertson]

I was thinking payload as being like a pickup truck. Here is a photo of a screw up. These bikes amplify the sound of motors. I have since learned how to do it right. In this case Great Stuff shot out weep holes and on to the rear disc.

Thats a fascinating idea (filling the frame with expanding foam)

 

[m@Robertson]

I can spend a thousand hours looking at spec sheets, but I think I need to get some parts in hand and work out the problems hands on.

In the current market I don't think there are many suppliers ready to ship the parts that I want, but would it be good to start with whatever I can get my hands on and upgrade as I go?

Absolutely (work out the problems hands-on, using the parts you can get hold of, and evolve the parts list as you learn).

Do you think that dual RH212 Motors each with 72v batteries driven by a phaserunner would be an effective build? Seem to be a good balance, but I'm still not sure that DD will have enough torque required.

OR something like a geared GMAC in the rear plus a DD in front?

I don't think there's any merit to doing dual hub drives of any combination. That was my v1.0/1.5/2.0 combination as 2wd bikes go. I graduated to a mid in the back for a reason, and the reason was power. That hub/hub combination, by the way, is readily available in a 60v-capable system that is known to reach 40 mph even using a single hub. I still would only do one on a street system. Those 80Nm-rated hubs are still not robust enough to tackle serious paved (!) hills. Never mind overland. To be more accurate, they are able to handle it but based on the sounds coming from them and the rate of deceleration suffered thanks to the axle-powered nature of a hub... they won't live long and during that short life they will still degrade output severely as they labor up a hill thanks to their inherent nature.

Put a mid on the back, however, and you are off to the races in even the worst terrain. I have been riding in deep, coarse sloped (and dry) beach sand - that particular environment is impassable to any 1-wheel'd fat bike. Even with the mid powering the back, I am only one zig away from a faceplant thanks to the balance issues that come from riding there, but its an exhilarating experience to master the trip. Best I have found is to stay off the front throttle entirely and let the PAS do just enough to keep the front wheel from submerging. The main power comes from the rear mid drive. AND I learned quickly - and undeniably - the gears are a big deal. I had a perfectly serviceable Shimano drivetrain that had its biggest cog of 32T. I ended up immediately needing that cog as a minimum. I converted to a Box2 Ultra Wide derailleur so I could put on a Box3 cluster that peaks at 46T. Instant improvement now that I could go up another cog to I think 42T. Now I can run PAS only to the front, PAS to the rear but still have good results with rear-only throttle if things get dicey.

As an aside, front throttle is very effective but burns so much power I need to lay off if I expect to make my trip... even though I now have 32ah on that bike). Generally high power in the front wheel is an invitation to a crash even if you have extensive experience riding 2wd.

I also just installed a Microshift Advent 9s on my mid tail that also peaks up at 46T. It has an all-steel, solid (no spiders), fully-pinned cluster that will work great with any other 9s system. Its much stronger given its solid and pinned construction vs. the Box, which is really a Sunrace CS-M983 (also strong ... but nothing like the Microshift).

You can try dual hubs, and then when you try a mid drive+hub in the same terrain you'll get it, immediately. The trick as always with a high powered mid is to build it with the proper chain lines so you don't have wear issues.

That pic above doesn't look so impressive, terrainwise, but I can't stop and stand the bike up on deep sand that I am sinking into. I can only do it on a flat spot that is low/wet/firm.

 

[PedalUma]

The tube to the chain stays from the BB acts like a resonator. It is bad.

 

[JRA]

BTW this idea was tried in 2003, but the technology was not ready yet. It seems like a good solution if using modern battery+motor tech.
https://en.wikipedia.org/wiki/Tidalforce_Electric_Bicycle
View attachment 113006

The Tidal Force bikes weren't two wheel drive though?

"All models of Wavecrest Tidalforce electric bikes have a 36 volt electric hub motor built into the rear wheel hub and a 36 volt battery pack built into the front wheel hub."

IIRC they had NiMh batteries also. They had some fans bitd and there is info on them on the ES forum.

Obviously there are some that have achieved a dual motor bicycle that meets their satisfaction. I don't have any experience with them but do have lots of time on front hub only bikes using the rear drive manually and have felt the advantage of 2 wheel drive in certain situations. But as in most AWD vehicles there is some sort of a mechanized transmission or viscous coupling that senses when and which wheel to distribute the torque too and in the case of the Tesla Model S they have motors at all the wheels that are digitally, independently controlled. Which would be the optimum solution for a dual hub motor bike also? Especially one that is targeted towards mtb use.

The one thing that confuses me is a case like the proposed VanMoof 30+mph bike that has dual 500w motors. I just don't see how they will propel that bike at the speed they are advertising, and certainly not for long as their proposed battery is like 750wh's? While my 1000w+ road bikes will go over 30mph, on level ground, it also is dependent on my being able to pedal effectively at or above the motor torque output. I achieve this using a set of Schlumpf High Speed cranks that have a 2.25:1 overdrive feature effectively giving my bike a 160" high gear or the equivalent of a 60t/11.

I have thought many times of putting a Bafang G31x front hub motor on one of my old mtb's to give it a try as I have ridden my drop bar front hub bikes on some pretty gnarly terrain over the years but it is kind of fiddly because I don't use PAS and m throttle and cruise control set it and forget it feature I use for riding roads doesn't work that well off road. Plus especially now with my FS Ultra bike with plus size wheels I can climb anything I want to it seems. At least as long as I can keep my line. Pretty amazing to me actually how well it does.

 

[PedalUma]

You need to cut rotational weight. You do not want accelerate or decelerate rotational weight. Also cut weight from the ends of the seesaw and put it low and centered like you would when designing a sailboat. That will vastly improve the handling characteristics.
Also I do not know of any geared hub-drives with extra-strong axles.

 

[m@Robertson]

You need to cut rotational weight. You do not want accelerate or decelerate rotational weight. Also cut weight from the ends of the seesaw and put it low and centered like you would when designing a sailboat. That will vastly improve the handling characteristics.

Yeah I gotta believe twin DD hubs has to be a worst-possible-choice kind of setup for the stated use case, even using modern components.

 

[tomjasz]

Yeah I gotta believe twin DD hubs has to be a worst-possible-choice kind of setup for the stated use case, even using modern components.

But it was fun for a week . 2 10t MAC with Grin bits and 2WD harness. 1new and one used but indistinguishable from new. 10% off retail free ship CONUS.

 

[kmccune]

Absolutely (work out the problems hands-on, using the parts you can get hold of, and evolve the parts list as you learn).


I don't think there's any merit to doing dual hub drives of any combination. That was my v1.0/1.5/2.0 combination as 2wd bikes go. I graduated to a mid in the back for a reason, and the reason was power. That hub/hub combination, by the way, is readily available in a 60v-capable system that is known to reach 40 mph even using a single hub. I still would only do one on a street system. Those 80Nm-rated hubs are still not robust enough to tackle serious paved (!) hills. Never mind overland. To be more accurate, they are able to handle it but based on the sounds coming from them and the rate of deceleration suffered thanks to the axle-powered nature of a hub... they won't live long and during that short life they will still degrade output severely as they labor up a hill thanks to their inherent nature.

View attachment 113184

Put a mid on the back, however, and you are off to the races in even the worst terrain. I have been riding in deep, coarse sloped (and dry) beach sand - that particular environment is impassable to any 1-wheel'd fat bike. Even with the mid powering the back, I am only one zig away from a faceplant thanks to the balance issues that come from riding there, but its an exhilarating experience to master the trip. Best I have found is to stay off the front throttle entirely and let the PAS do just enough to keep the front wheel from submerging. The main power comes from the rear mid drive. AND I learned quickly - and undeniably - the gears are a big deal. I had a perfectly serviceable Shimano drivetrain that had its biggest cog of 32T. I ended up immediately needing that cog as a minimum. I converted to a Box2 Ultra Wide derailleur so I could put on a Box3 cluster that peaks at 46T. Instant improvement now that I could go up another cog to I think 42T. Now I can run PAS only to the front, PAS to the rear but still have good results with rear-only throttle if things get dicey.

As an aside, front throttle is very effective but burns so much power I need to lay off if I expect to make my trip... even though I now have 32ah on that bike). Generally high power in the front wheel is an invitation to a crash even if you have extensive experience riding 2wd.

I also just installed a Microshift Advent 9s on my mid tail that also peaks up at 46T. It has an all-steel, solid (no spiders), fully-pinned cluster that will work great with any other 9s system. Its much stronger given its solid and pinned construction vs. the Box, which is really a Sunrace CS-M983 (also strong ... but nothing like the Microshift).

View attachment 113178

You can try dual hubs, and then when you try a mid drive+hub in the same terrain you'll get it, immediately. The trick as always with a high powered mid is to build it with the proper chain lines so you don't have wear issues.

View attachment 113180
That pic above doesn't look so impressive, terrainwise, but I can't stop and stand the bike up on deep sand that I am sinking into. I can only do it on a flat spot that is low/wet/firm.

I did a 2wd steel frame once it was super easy because of the way I did it, stock350 watt rear setup and an "IMortor V2.0" with throttle in the front, the built-in battery(7.2 Ah) 350 watt motor, aside from the weight it worked amazingly well it climbe well and zipped along well on slight grade or the flat had around $1100 total in it with new components, it was a step-through frame, pretty comfortable also. Sold it to a friend at a give away price He took front motor off claimed it was to difficult to load, so it goes.
It didn't occur to Me then( had a 20 Ah battery on it once) I could have deleted front battery and spliced the two motors to the big battery, live and learn I suppose.

 

[PedalUma]

If I were inclined to do a two wheel drive I would use a system like this differential. One central motor would then drive two wheels. It would be even better with limited slip.

 

[tomjasz]

If I were inclined to do a two wheel drive I would use a system like this differential. One central motor would then drive two wheels. It would be even better with limited slip.

Sadly all I found are not setup for platforms or fenders. Front hubs especially heavy DD track really well.
Why not your TSDZ2 Motors?

 

[tomjasz]

So these tested tough universals are parts to convert existing or new rear drive assembly.
the heavy duty seems a real winner. But....

 

[tomjasz]

I’m think a pair of those little gear drive motors from GBK would be stealthy and a cool 2WD.