Help me Electrify it!!

Hi Forum I'm kind of a newbie but I feel I,m starting to get up to speed on the ebike world. LOT'S to LEARN!!
My first post was about a 1980's nashbar mountain Bike . This post is about another project. As mentioned before I'm and older big guy 290# I have a 16 year old daughter that has a disability that does'nt allow her to ride a bike. We are blessed here in Columbia Mo with a very good bike trail system which hookes up to the a railes to trailes system that runs across missouri. I'm hoping to do some over night trips on this system whith this bike.
I'm just did the first test ride on this front load cargo trike that I'm building and I'm calling it a success.It cruises nice at slow speeds which is all I need.Top speed wil be 10-15 mph. Safety first!!
This is were you all come in I want to Electrifiy it.
I need to do a couple of short 15 Degree hills to get to the trail. My Daughter weighs about 90#. The cargo bike is all chromoly so not overly heavy.

I'm thinking geared rear hub but will the gears handle this kind of weight!! Grim suggests a gmac. Other vendors say it has to be direct drive because gears can only do 300#.
I want to get a 20+ amphour battery which can be mounted on the front of the bike.48 to 52 volt I think.
Mid drive motor also is a possibility if that is the way to go.
FYI THE S. WHEEL IS JUST FOR SHOW.
Suggestions Are welcome Thanks Chris
https://endless-sphere.com/forums/download/file.php?mode=view&id=280922

GMAC is a good choice. Read more about it here: https://ebikes.ca/product-info/grin-kits/gmac.html

For your application, I think a mid drive like Bafang BBS02 makes more sense than the alternatives. I'm guessing this isn't a critical part of your transportation plan, and mileage accrued won't be all that much.

A mid drive like that allows you to select a gear that gives you as much speed or force as you need, do you don't have to compromise on an approximation that has to work for all circumstances. L

Drawbacks are that your maintenance needs will increase substantially, and running cost, though modest, will be more. More chains, more cassettes and chainrings.

The motor should be place underneath the main weight. Cleanest solution would be a custom middrive powering a differential placed between the two front wheels. But that's going to be a LOT of work and not exactly cheap.
You can also go for 2 small geared hub left and right on your front wheels. There are some - not many - manufacturers out there making single side hubs for cargo use.
And finally comes a rear hub or a bbs. Probably easiest and cheapest solution.

qwerkus said:

The motor should be place underneath the main weight. .

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Cargo bikes sometimes run empty, and sometimes loaded. But there's always a weighted wheel under the driver.

The pictures show it is not single sided in front. But the low speeds and need to pull hills, Sounds like a middrive or a mac in the rear. Git rid of the steering wheel and put some bike handle bars with a bell and flashy lights.

Chris,
You are a great father.
Mike

Depends on what amuses the daughter while riding in the front of the cargo bike.

2 motors means more stuff to install.

BBSHD (Luna Cycle) mid drive or geared rear hub motor (MAC from www.em3ev.com) its a coin toss really.

ZeroEm said:

The pictures show it is not single sided in front. But the low speeds and need to pull hills, Sounds like a middrive or a mac in the rear. Git rid of the steering wheel and put some bike handle bars with a bell and flashy lights.

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16 year old daughter that has a disability that does'nt allow her to ride a bike.

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From grin :
What's Special?
The core motor performance is the same as you would expect from the latest MAC motors. That includes a modern cassette freehub system instead of a screw on freewheel and a powerful 20mm wide stator core made with thin 0.35mm laminations, but the following differences make it really stand out

So the gmac has only a 20mm stator. that's hard to believe I was going to suggest he get a motor that has a 35 mm stator DD.

999zip999 said:

So the gmac has only a 20mm stator. that's hard to believe I was going to suggest he get a motor that has a 35 mm stator DD.

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Direct Drive hub motor would be great for power, for long lasting
Except for the drag when power is not applied. Be a pain to pedal with a load or carrying someone.
User could carry a spare battery, if its just casual riding around neighborhood, campground.

Its not really the gears that need a 300 pound limit, including bike, battery, motor, cargo, and yourself.

Climb a very long, steep enough hill with a motor that can only do 5 mph up that hill, and the motor itself melts. Geared motors tend to melt a bit sooner, since they shed that excess heat poorly.

This calls for a mid drive, big time, and the biggest sprocket you can get on that rear wheel,, meaning a very very low gear. Then the motor can spin at a happy rpm and the whole thing going only 3 mph.

The hub motor approach that would work is a huge one, 2-5000w, and fly up that steep hill. After that, you could happily cruise along the (flat?) trail with 300w and good efficiency.

by dogman dan » Oct 12 2020 6:33am

Its not really the gears that need a 300 pound limit, including bike, battery, motor, cargo, and yourself.

Climb a very long, steep enough hill with a motor that can only do 5 mph up that hill, and the motor itself melts. Geared motors tend to melt a bit sooner, since they shed that excess heat poorly.

This calls for a mid drive, big time, and the biggest sprocket you can get on that rear wheel,, meaning a very very low gear. Then the motor can spin at a happy rpm and the whole thing going only 3 mph.

The hub motor approach that would work is a huge one, 2-5000w, and fly up that steep hill. After that, you could happily cruise along the (flat?) trail with 300w and good efficiency.

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I'm in the habit of riding up hills faster than on the flats. I just speed up before the hill and let off before the top. My hills are small and only talking about speeds of 20-25 mph. If I grind up a hill peddling, I keep the power on the low side.

You can run that geared hub motor in terrible efficiency rpm for short periods. Very short. I've melted motors in less than 20 min. But yeah, charging up the hills helps. Not so sure you will charge them as fast with that much weight though.

On the flat, you can do much lower rpm, but bear in mind, its the load that makes it hot. So 3 mph pulling 100w is fine, 60% of it going into heat is a 60w heater. The motor can wick that much heat away for quite some time before it gets over heated. at 500w, you have a 300w heater. Ever put your hand on a 300w halogen light?

If you must go with a hub motor, get the lowest speed wind you can find, and drill at least one or two small holes in the cover. The hole is not to cool it. its so you can smell it overheating and stop in time. A dd motor can cool itself much better. So time to overheat when running terribly inefficient is longer. You can even hose down the motor to cool it a bit faster.

Ideally, also modify your bike one more time, to have a 20" rear hub motor wheel, and still have brakes.

And again,, if you really must do the hub motor thing,, do it big. 35 mm stator at least, and 2000w, so you can grind up hills at an efficient enough 15 mph. The typical 1000w motor, whether geared or dd, simply slows to too slow a speed up any hill above 5% grade, when it is asked to pull more than 300 pounds total load. Not saying you cannot pull more, just that it becomes a risk of overheating. So you need that hole to smell it overheating in time to stop before you smoke the motor. You cannot put holes in geared hub motors though, because the grease inside gets dirty. I have melted geared motors, that still felt cool on the outside.

Thanks for the replies!! I really think that I’m looking at a mid drive. I love the idea of using the lowest gear and creeping up hills. I’ve done a fair amount of fully loaded touring so I like going slow in those low gears .

overnight trips without a recharge will be an issue with anything electric, unless the rides to and from are short

a 48V 20AH battery is 960 watt hours. if you average 300 watts riding that heavy rig, thats about 3 hours total riding time before needing a serious recharge.

Can always have a second battery or more to swap out. I bought two batteries for distance but have not needed them both yet. So I cycle one then swap them out and cycle the other same number of charges. The one not in use is stored at a mid voltage and climate controlled area and check the voltage weekly.
I have trailers, bringing the other battery is not an issue. Plan to mount the second battery at some point. I like a bigger battery than needed to keep the stress down on it. But it is hot here most of the time and that chips away at battery life.

for really big long range cargo bikes, does anyone use LiFePO4? its not got the same energy/weight density as LiIon such as LiPoly, but they are much safer, and far less inclined to explode at high power levels, and you can get 100AH or larger single cells, so you'd just use 13S1P or whatever for a 48V 100AH (4.8 KWH!). they are brick shaped, so easier to stack than cylindrical 18650/etc cells.

you also can charge a large LiFePO4 at very high current rates, like dumping 40 or 50 amps into a 100AH and fully charge it in just a couple hours.... same deal otherwise, charge at 4.2V per cell, nominal output voltage is 3.6V per cell.

12V LiFePO4 is starting to make inroads in the RV market as they are less than half the weight of an equiv lead battery, and can handle much deeper discharge cycles, while having a life in excess of 1000 charge/discharge cycles.

LeftCoastNurd said:

for really big long range cargo bikes, does anyone use LiFePO4?

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Most e-pedicabs I'm aware of here in Austin use LiFePO4. Those are really big, long endurance cargo bikes. They have an abundance of weight capacity and space they can spend on big heavy batteries.

There was a large destructive fire in a local pedicab barn a million years ago in early 2019, which to the best of the fire investigators' understanding wasn't originally started by lithium batteries. But the many lithium batteries present kept flaring up for many hours, keeping the fire department there all night to quench the outbreaks as they appeared.

I think that, and the suspicion that batteries were the cause of the fire, convinced a lot of otherwise indifferent folks to use LiFePO4 instead of Li-ion.

Not sure if this is helpful but I spent 30 minutes researching it, so here goes. For the middrive motors, they already have an internal gear ratio between what the motor rotates at and what the chain ring rotates at,

https://fasterbikes.eu/en/motors/355/1000w-e-bike-mid-drive-motor-bafang-bbshd-48v

here the reduction ratio is 22:1.

so even before gears of the bike you have a 22:1 gear ratio, giving way more torque on the chain rings for the same torque of the motor.

I know this is quite passè but since you may be loaded down already, for long touring with vast distances between hamlets then a small 400-500W generator would be the ticket, seriously. I wouldnt bother with solar. I'd buy the biggest Ah batteries you can afford.

Hi All I'm moving to the next Phase of my front load cargo bike build .This is what I'm considering for my drivetrain. First my daughter and myself have been tooling around the neighborhood and I'm finding that 35/24 gets me to a very safe feeling 7mph with some bursts to 10 mph on flat and straight is about the limit I want to go at this point.
35/28 I can use to start but feel I need to shift right away. I may have shifted to35/21or18 briefly.
When I look at gearing options it seems that building a a 3-4 cog freewheel makes sense. BUT I hate slipping gears so then I start looking at an IGHs so I can get a heavy chain and a perfect chain line and maybe a chain tensioner if needed.
It seems there is dispute as to whether the IGHs will hold up to the power of the bbshd and the cargo bike weight 400#. I've looked at all the usual suspects . It seems it may come down to durability.
It also seems that even with a 3 speed hub I should be able to get the gearing range I need with the right combination of chainring and cog in the back. What IGHs rate the beefiest for heavy loads?
I think I can baby the drive train during shifting but I guess that is what everyone says Right?
Just to be clear my needed speed range really is just 3 to15 mph and of course I want to keep the rpms high on the bbshd.
Thanks All for all your help my daughter loved the bike but now she wants to go downtown which requires some hills so the motor is the next step.

Sturmey Archer RX-RK5 is supposed to be "pretty" robust.

Nothing will have an issue with human power even uphill from a standing start.

But going to a big fat motor will require a nice controlled gentle ramp-up for the first few mph

If you have the budget, Rohloff Speedhub,

shear pins designed to snap at 130 Nm, so maybe a Cyclone 3Kw motor allowed to lurch

A true FOC controller being the way to go there IMO.

Hmm, slipping gears does suck, but typically it happens with stretched chain, or wore out 14 tooth or smaller rear sprockets.

Pick a front chainring that allows the gearing you want on the middle three gears of the rear freewheel, so you have a nice straight chain line, and don't wear out the sprocket so fast. Then put on a better quality chain that wont stretch as fast as whatever wall mart stocks. If you want to limit the bike to just those three gears, adjust the stops on the derailleur. But I think it will be fine to just use the middle of the freewheel, leaving at least the lowest gears still usable when needed.

Though the load you plan on is high, its not crazy high, and the top speeds you want won't stress the chain as much as trying to make that load go faster. Start in the lowest gear to further reduce strain on the chain.

In any case, its cheap to try that at first, then add an IGH later if you really must.

When I started with the bbshd on our Yuba mundo (often loaded to over 200kg) I also experienced heaps of slipping from the chain when using a derailleur setup. I used a Nuvinci n171 on an earlier bike, people have been running 3-4kw through those. They're literally built like a brick and operate like one as well. My best success has been with the Rohloff, which provides enough gear range that you can even operate on hills without the motor. Initially used a 30t front ring and 16t sprocket, for us that was too slow however it may be ideal for you. Currently on the standard 42t bbshd front and 16t rear, which works perfectly. Hit about 2500km on the Rohloff/bbshd so far without any issues or maintenance other than changing the oil and lubing the chain.

Hi all I’ve decided to get a gmac for my cargo bike build. I’m inclined to just have them lace the wheel using their rim. I need a strong one for this project and I have an experienced wheel builder here in Columbia Missouri so would it be worth just getting the hub motor from grim and getting a rim of my choice and have it built locally?