Cargo trike build

[richjmaynard]

Hi all,

I'm in the process of building a Christiana-style trike for a friend of mine. She has an autistic son who can't ride a bike and neither she nor her husband drive, so the idea is to give them a bit more mobility.

I'm thinking about adding some electric assist to the setup and would be grateful for any advice.

Primarily this needs to be a cheap solution. We can't tell if the young man in question will take to the idea of riding in a box so the whole thing could be a complete waste of time and money. I'm building as cheaply as I can with an eye to upgrading bits as they fail or break, but an ebike kit is a lot of money to get wrong!

Do I go rear hub for cheapness and reliability, or mid drive because it can use the rear gears to run more efficiently at lower speeds?

Can I get away with a cheap Voilamart style DD hub?

Can I use a generic battery pack like this:
#Aliexpress ￡45.40 28%OFF | Panasonic 36V Battery 10S4P 42V22Ah Battery 500W High Power 22000mAh Battery 36V Ebike Electric Bike Charger BMS + 42V2A Charge

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I don't need to worry about mounting as it will be fitted permanently under the front seat in the cargo box.

 

[richjmaynard]

 

[sjpt]

Can I get away with a cheap Voilamart style DD hub?

NO. NO. NO. Good for high speed on the flat and nothing else, and need a really powerful battery so end up expensive. (see lots of other posts here). And illegal without all the tax, etc etc overheads.

You want something with good power at low speeds to help with the extra load and any hills. I think the way the bottom support is welded will rule out most crank drives, and I expect driving just one wheel at the front will have handling issues, so rear hub kit looks best as you say. I'm sure Woosh could suggest best kit. You could probably get something suitable a bit cheaper from Yosepower.

If you are confident to source a compatible bits separately and have them shipped from China you could save quite a bit more. If you go that route ask here before you order any bits, there are lots of incompatibilities. from inconveniences such as mismatched connector types (it looks as if you could handle those), and bits that just won't work together.

 

[WheezyRider]

View attachment 36054

Interesting project. I assume you are going to put in some more bracing and support on that BB to box section weld? You may need some reinforcement on the main front steering bar too.

Check your distance between rear drop outs, that will affect your motor choice to a certain extent.

Go for a 250W geared hub, not the direct drive, as has already been said.

Keep us updated

 

[richjmaynard]

Thanks for the replies so far!

I haven't actually welded the BB yet, so it could be done (I hope) in such a way as to allow a mid drive.

Yes, there will be some more diagonals added around the BB as well as some bracing to the bottom of the pivot on the cargo platform.

 

[richjmaynard]

Yose Power sold out of antything suitable.

Woosh have no kits until July.

What about this one?

Voilamart 36V 26 inch Rear Wheel Electric Bicycle Conversion Kit for sale online | eBay UK

Find many great new & used options and get the best deals for Voilamart 36V 26 inch Rear Wheel Electric Bicycle Conversion Kit at the best online prices at eBay UK! Free delivery for many products!

www.ebay.co.uk

 

[WheezyRider]

Yose Power sold out of antything suitable.

Woosh have no kits until July.

What about this one?

Voilamart 36V 26 inch Rear Wheel Electric Bicycle Conversion Kit for sale online | eBay UK

Find many great new & used options and get the best deals for Voilamart 36V 26 inch Rear Wheel Electric Bicycle Conversion Kit at the best online prices at eBay UK! Free delivery for many products!

www.ebay.co.uk

Yes, they are ok, I have bought one, but a couple of points. 1) it is 155 mm OLD, so much larger than standard drop out width. This was perfect for my old Powabyke, as it had a humungus original motor in it with a large OLD. 2)The price has rocketed recently. I paid £117 for mine, just a couple of months ago. Go direct to Voilamart UK, they are usually cheaper there than on eBay. 3) It is basic in terms of control, twist and go throttle or PAS is basically fully on or fully off. On the Voilamart website you can order controllers with LCD capability, but it's an added extra, plus you then need an LCD.

 

[richjmaynard]

Looks like I might have picked the wrong time to do this project.

Lots of people out of stock, prices going up all over the place.

Boo to lockdown!

 

[peter.c]

The idea is great but before you commit, several things to over come, the hardest problem to solve is not getting rolling but stopping and steering around corners .
Disc brakes and a low centre of gravity will help.
As for the drive system a cheap rear hub will not be good for hill climbs, and what you save on the hub will be lost as it will require an extra spend on a larger battery

 

[richjmaynard]

The idea is great but before you commit, several things to over come, the hardest problem to solve is not getting rolling but stopping and steering around corners .
Disc brakes and a low centre of gravity will help.
As for the drive system a cheap rear hub will not be good for hill climbs, and what you save on the hub will be lost as it will require an extra spend on a larger battery

Good points all...

I'm hoping that by using all new brake components I can go some way towards stopping efficiently. An upgrade to discs will be hard, won't it? Something to go away and research.

Trying to keep wheels small and weight low down to minimise the centre of gravity as far as I can.

I'm attracted back to the tengshong mid drive option again due to simplicity of use for my friend. As I understand it you just get on and pedal...and it's not much more expensive than the rear hub with a decent LCD control system. Plus if our little friend doesn't like the vehicle I can transfer the motor to my bike...

 

[sjpt]

As for the drive system a cheap rear hub will not be good for hill climbs, and what you save on the hub will be lost as it will require an extra spend on a larger battery

That is true of many cheap hubs, especially the heavy direct drive ones. Even though this one is Voilamart it is geared; not one of their evil DDs, so may not be too bad.

 

[peter.c]

Check out cheap 2nd hand kids bikes fitted with disk brakes 20-24 inch wheels often had very little use too
Rim brakes will not cope with the extra weight and if applied uneven will it cause steering problems.

The tsdz2 is my current go to mid drive motor, a quick easy build the bike in my profile picture only took a couple of hours from bare frame to finished bike .[but my fat bike took weeks and the fat trike months ]

The torque sensor makes sense and a more natural ride more like a human powered bike with a helping hand in eco mode or an abrupt shove in turbo mode

But a hub kit is still a good option if speed is not required, a small front chainwheel will solve gearing problems

 

[WheezyRider]

That is true of many cheap hubs, especially the heavy direct drive ones. Even though this one is Voilamart it is geared; not one of their evil DDs, so may not be too bad.

The 250W Voilamart geared hub motor is ok, but it doesn't have as much torque as a Bafang. On a heavy bike, probably a good idea to run such a motor on 48V rather than 36V.

 

[Nealh]

No reason why a mid drive can't sit above the bottom rail once it is welded to the BB, one might need to think about the motor cable outlet as the rear bottom (five o'clock) position.

 

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should be good for about 250mph and under 20kg

 

[richjmaynard]

No reason why a mid drive can't sit above the bottom rail once it is welded to the BB, one might need to think about the motor cable outlet as the rear bottom (five o'clock) position.

I'd probably need to buy one before welding anything up

 

[Nealh]

I'd probably need to buy one before welding anything up

Yes no reason why you can't fit it I to the BB shell, offer the the chassis bar up to position to just tack weld then remove the drive to finish the job proper.
The Woosh TSdz at 48v 250w is meant to be very good though stocks may be very low.
Most bikes don't allow anything other then an underside mount because of the acute triangle angle, by mounting above the pull down torque of the motor is instantly resolved.

PeterC or Woosh might be able to add some more insight for top side mounting.

 

[richjmaynard]

Now, what about the battery? Is there any reason why I can't use a generic li-ion battery pack like this?

US $58.5 25% OFF|Panasonic 36V Battery 10S4P 42V22Ah Battery 500W High Power 22000mAh Battery 36V Ebike Electric Bike Charger BMS + 42V2A Charge|Battery Packs| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

 

[vfr400]

Now, what about the battery? Is there any reason why I can't use a generic li-ion battery pack like this?

US $58.5 25% OFF|Panasonic 36V Battery 10S4P 42V22Ah Battery 500W High Power 22000mAh Battery 36V Ebike Electric Bike Charger BMS + 42V2A Charge|Battery Packs| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

You can't charge a 22AH battery with a 2 amp charger in 4 hrs, like it says in the advert, neither can you make a 22AH battery out of 40 18650 cells.

To build that battery yourself, after deducting the cost of the charger, connectors and other materials, you'd be paying about 75p per cell. The manufacturer would have to pay a maximum of 40p per cell to make a profit. The cheapest usable cells that you can buy are about £2, and even those are hardly suitable. Hello!

My guess is that it has been built from recycled cells, like these for $0.17 each. It's an 8.8Ah battery capable of sustaining about 5 amps, which is totally useless for an ebike:

Panasonic CGR18650CE Cell Specifications

Warning: The information in this thread was obtained from various sources on the Internet, including any datasheets linked below, and is provided for reference only. It is not guaranteed to be accurate. To prevent fire or personal injury, never charge or discharge a cell before verifying the...

secondlifestorage.com

Any battery that costs under £150 will almost certainly be unsuitable for your project.

 

[richjmaynard]

You can't charge a 22AH battery with a 2 amp charger in 4 hrs, like it says in the advert, neither can you make a 22AH battery out of 40 18650 cells.

To build that battery yourself, after deducting the cost of the charger, connectors and other materials, you'd be paying about 75p per cell. The manufacturer would have to pay a maximum of 40p per cell to make a profit. The cheapest usable cells that you can buy are about £2, and even those are hardly suitable. Hello!

My guess is that it has been built from recycled cells, like these for $0.17 each. It's an 8.8Ah battery capable of sustaining about 5 amps, which is totally useless for an ebike:

Panasonic CGR18650CE Cell Specifications

Warning: The information in this thread was obtained from various sources on the Internet, including any datasheets linked below, and is provided for reference only. It is not guaranteed to be accurate. To prevent fire or personal injury, never charge or discharge a cell before verifying the...

secondlifestorage.com

Any battery that costs under £150 will almost certainly be unsuitable for your project.

Wow. I'm used to AliExpress vendors inflating their specs but that's in a different league!