Motor swap suggestions/advice for (e)Bullitt Cargo Bike

[DirtSurfer]

Hi there
I recently purchased a LarryvsHarry Bullitt (pictured) which came with a Goldenmotor 1000W conversion kit fitted.
It also has an absolute monster of a battery... with 14 groups of 2.5ah cells to run 48v voltage (52v to be specific). A total of 196 cells). Combined, this makes for a very heavy bike (before loading) and the cracked rim and many broken spokes I've experienced recently suggest the setup is a bit on the porky side especially toward the rear of the bike. When not under power, I also find the current setup feels much like pedalling in quicksand so I'd like to make some changes to make it nicer to pedal and more balanced weight wise. I am considering switching to a 20" front wheel motor and to relocate (perhaps reconfigure) the battery so it can be mounted under the cargo area (pictured), along with the controller. I plan to run a conventional Alfine 8 speed internal hub on a new rear wheel so I can ride it like a normal bike when the mood takes me and thumb in electric power when needed (i.e. hills, when porting slabs of beer home or a load of trail tools to the forest for a trail day). I have to say the 1000w motor there now belts along at a fair clip 45km/hr but it doesn't really need to go quite that fast.
As to options, I have been looking at the Leafbike front 20" wheel motor conversion kit (either 500, 750w or 1000w) and the Goldenmotor front wheel conversion kit which auto switches voltage 500/750/1000 depending on your battery voltage. I dont know which will suit better or be better, similarly I am not averse to looking at other motors as well - including mid-mount. I was hoping the ES hive mind could contribute experience and opinion so I can get a good solution. Thanks...

 

[markz]

Not sure how a front wheel hub motor would suit a cargo bike.

If you were to go that route, look at the Leaf 1500W as its a great choice with great efficiency.

Alfine 8 IGH would be great laced into the rear wheel, I thought a perfect setup for that would be a mid drive motor, like the Cyclone 3000W from http://www.cyclone-tw.com/ however the Bafang BBSHD units are much superior in quality.
https://lunacycle.com/bafang-bbshd-1000w-middrive-kit/
I would highly suggest you look at going the way of the mid drive, and rear hub IGH.
Front wheel hub motors are just not ideal.

edit:
Looking at the bottom bracket crank area, those are very short chain stays, with a very thick bottom bar. Mounting the mid drive motor above that bottom bar just behind that battery would work.

I'd just leave the battery where it is, unless it gets in the way of the motor or pedaling. If so then move the current battery up few inches by getting rid of the black metal vertical divider, and placing the controller vertically on the left or right side of the battery.

 

[amberwolf]

Combined, this makes for a very heavy bike (before loading) and the cracked rim and many broken spokes I've experienced recently suggest the setup is a bit on the porky side especially toward the rear of the bike.

More likely, the problem is too large a gauge of spokes for the rim on the motor wheel back there. The spokes require too much tension for the rim to handle, because they're likely too thick for that rim. May also be too much angle at the nipple, cant' see that part well enough.

Thinner spokes and a better rim would probably work just fine.

I carry very heavy cargo on hubmotor wheels on SB Cruiser (300+ empty, 500+ with me on it, can go over 700 with a couple dogs or cargo) and CrazyBike2 (couple hundred plus, empty), using 13/14g butted spokes radially laced in better-quality wide doublewall eyeletted 20" rims, and I don't have rim or spoke breakage. (would've used 14/15g butted but they werent' available where I was ordering all my stuff from at the time) I've had rim damage on the flanges where the tire mounts, from deep sharp-edged potholes, and even broken motor axles from that, but the spokes don't break and the rim doesn't crack.

But when I have used the thicker 12g OEM spokes and crappy OEM rims on the hubmotors, I had those problems all the time even on "regular" bikes.

So...get a better rim (like Alex DM, etc) and use Sapim (or similar quality brand) 14/15g butted spokes, or 13/14g butted if you have to have thicker ones.

Then what you already have will likely work just fine, as far as that goes.

If you really want a front motor...build the wheel yourself with the above types of spokes/rim, or have it built at a good local bike shop, etc., rather than relying on whatever comes on the motor (regardless of where you buy it, it's highly unlikely to be a good wheel build with good parts, or even the right ones).

CrazyBIke2 is 2WD, but I found that the front motor can't be used in all situations--whenever I make a turn, if there is not a positive traction surface, I have to reduce or cut power to the front or it'll spin out and I'll slide and crash, cuz I won't have steering control anymore either. The rear motor doesn't cause this problem--if I lose traction back there, it's recoverable as soon as I cut power--in the front even if I cut power it's too late, traction is lost and so is control.

A smaller wheel will mean the same motor will run the bike at a slower speed, all else the same.

As far as controllers go, there's a lot of good ones out there, I couldn't say anything about the GM "auto" kit, but it sounds like a gimmick to me. Which would be good for you depends on the specific features you want.

Middrives are difficult to mount on a lot of long cargo bikes like that, becuase of the way they install on the BB. I don't know if any of them would mount to yours without modifying the frame.

You could build a middrive like the stokemonkey type, a hubmotor mounted in the frame that drives the cranks/chain, that would fit in the area in front of the seattube. Would need to be narrow to not interfere with your cranks.



Regarding systems and options, you might go to http://ebikes.ca/simulator and read teh whole page first, then play with various options to see what will perform the way you want it to, first. Might give you a better idea what to get.

 

[DirtSurfer]

Not sure how a front wheel hub motor would suit a cargo bike.

If you were to go that route, look at the Leaf 1500W as its a great choice with great efficiency.

Alfine 8 IGH would be great laced into the rear wheel, I thought a perfect setup for that would be a mid drive motor, like the Cyclone 3000W from http://www.cyclone-tw.com/ however the Bafang BBSHD units are much superior in quality.
https://lunacycle.com/bafang-bbshd-1000w-middrive-kit/
I would highly suggest you look at going the way of the mid drive, and rear hub IGH.
Front wheel hub motors are just not ideal.

edit:
Looking at the bottom bracket crank area, those are very short chain stays, with a very thick bottom bar. Mounting the mid drive motor above that bottom bar just behind that battery would work.

I'd just leave the battery where it is, unless it gets in the way of the motor or pedaling. If so then move the current battery up few inches by getting rid of the black metal vertical divider, and placing the controller vertically on the left or right side of the battery.

Thanks for your comments... I will go the mid-motor Bafang route.
What are your recommendations for choice of model? 500W/750W/1000W?

Thanks

P.S. I will relocate/reconfigure the battery to under the cargo deck as my feet tend to strike it when I pedal (and because it just looks crazy big)

 

[neptronix]

Without a load, i'd imagine that a front wheel motor on a bike that long would be extremely dangerous as where the power would be applied has the least traction. It just takes hitting the throttle on a sandy road while turning to lose traction on the front wheel.

With 35AH of battery on tap. i think a leafmotor 5T winding in the rear would be a lot of fun, and give you a speed boost as well. Especially with a programmable controller instead of the stock POS.

Your magic pie is actually a pretty damn powerful motor...... IF you use an external controller and bump up the amps to push more along the lines of what it's capable of ( >2000w peaks for sure ) Shame about the rim, but golden motor is not exactly known for their rim-manship