DIY Cargo Bike (Think Kombi E5?)

[Wrightboy]

Looking to build a cargo bike for getting around town. We live in a very hilly area and I have two kids that I'd really love to be able to take with me on errands. The Kombi E5 seems like a near perfect fit, but after coming in at over 4k with accessories I got to thinking if there wouldn't be a way to make my own for cheaper, or at least the same but get the fun of the build.

While I have no doubts in my ability to assemble one, as I've always done the mechanical work on my cars and bikes, I do have doubts in my ability to actually get parts that are compatible with each other.

My main wants are:
Big frame (I'm 6' 2") - While I don't need fat tires, 26" wheels would nice.
High weight capacity - Two kids and groceries.
Decent looks - Petty, but the pride is strong.
Torque sensor - Already have a ninja500, don't need a moped (Ruled out the Kodiak and the Skycap).
Cost - Trying to keep the full build under 3k, if possible.

I've been eyeing the Mongoose Envoy as the base (also the non-electric Kombi could work, but more expensive), it has a great look and seems like it can be picked up fairly cheap. They don't really give a hard weight capacity, but in the video they show it carrying a second adult so it's got to be up there. The downside being having to hunt around for attachments like seats and monkey bars that will be compatible. Totally open for other frame suggestions though.

For the motor, unless I'm mistaken it looks like my only real options are either a TSDZ2 (with OSF?), the X1 Stealth, or some kind of Bafang hub with a Sempu torque sensor? Anyone have strong opinions one way or the other? Was really interested in the BBSHD, but only supports cadence, and would need a custom frame for the "Ultra" that has the sensor. The TSDZ2 seems simpler and cheaper on the whole, but I've come across people saying that torque sensing on a cargo bike doesn't work that great (especially with the TSDZ2 specifically) and that it has a tendency to overheat or explode if you stand on it wrong. The X1 Stealth seems like it wouldn't have any issues (looks compatible, maybe?), potentially overkill but seems more reliable than the TSDZ2 and I can always swap it onto something else down the road (have been curious about an eMTB).

After that lack of knowledge really starts to shine through. What size chain ring would I need with it, the TSDZ2 has a 32T/42T combo, could I still use the stock envoy derailleur for that? With the stealth seems like just the 53T is the only option? What brand of battery should I buy that won't explode in my face? I technically already have a 48V advanced luna charger I got for a crappy mini ebike, but at the same time I was leaning towards taking this one all the way to 52V?

I wonder if anyone is cooking up a pcpartpicker style website for ebikes. Not trying to break new ground or anything here, just want to piece up a fun kit that works.

 

[RunForTheHills]

For long hills with a lot of weight, you probably want a mid-drive. If you need a torque sensor, that narrows the list down to the TSDZ2. For hill climbing, you will want a smaller chainring. A 53T is pretty big and is more about top end speed than climbing with a big load. You have a decent size budget, you may consider getting a Cycle Satiator charger that is programmable for different voltages.

MTA: I love pcpartpicker, but I am not aware of anything like that for ebikes. The Grin motor simulator is great for testing out different combinations of motors and controllers.

 

[Wrightboy]

Actually found another seller with the X1 Stealth but a 32/38T chain ring. I feel this has to be pretty close to what I'm after. Torque sensing with plenty of power for hauling?

--
The more I read the more I feel like this is the way to go. Probably overpowered, but at the very least won't be underpowered or overheat. Planning to order it and the envoy this evening.

 

[indianajo]

There is a thread where another poster converted a Mongoose Envoy with a motor.
I put a $221 ebikeling hubmotor with a $630 luna battery on a $1900 yuba bodaboda and maintained the 24 speed pedal setup. Yuba makes a quality bike; only problem besides normal parts wear is I broke the fender with my foot. Front hub motor works because cargo bike puts my weight on the front wheel.
I cross >80 hills with my bike & 80 lb cargo, over 30 miles. Some hills are 15%, but 100' long. Motor will start without pedal help on that grade with 330 lb gross weight. I can ride it up that grade without electric help due to 32:32 and 32:28 low sprocket ratios. Mid drive messes up the triple front crank. Only Yamaha mid drive even allows two front cranks sprockets.
Ebikeling motor wore out a gear @ 4500 miles. Now I have a $730 Mac12t on the front wheel I bought from lunabikes. It uses less watthours on the commute than the ebikeling motor. The ebikeling motor used to red light & cut out on the last 3 hills on the uphill leg with a 17.5 AH 48 v battery. Now I can do the route between 52 v and 48.5 v with the same battery. Had 20 mph headwind all the way home downhill today, used 52 v to 45.7 v. Usually I pedal unpowered about 80%, but not today. Advantage of hub motor, after wearout I had the new motor installed in 2 afternoons work. Would have been 1 afternoon if the controller mount had not been incompatible for the new motor. I don't keep a car, the bike has to work or I'm pedaling a MTB unpowered. One that threw me on my chin 2 times. Cargo frame has a more stable front wheel with my weight on it.

 

[john peck]

A trailer might better distribute weight for a large amount of cargo. Kiddie bikes are a dime a dozen.
get a couple 16¨ wheels & build sumpin´. Used trail-a- bikes on CL make into a good single whl trailer.

 

[m@Robertson]

I took a Mongoose Envoy and remade it into what I think is a first class cargo bike. I wrote up the whole project and even laid out different kinds of builds with pricing for the DIY builder. As far as I am concerned, the Envoy is maybe the best low cost donor frame for an electrified cargo application

This is Chapter 8 of the series. There's a lot more where that came from

Mongoose Envoy – Chapter 8 (Low Cost Builds)

Introduction: The Mongoose Envoy Project Chapter 1: The Raised Rear Deck Chapter 2: Better Brakes Chapter 3: What Kind of Motor? Chapter 4: Motor Choice Chap…

talesontwowheels.com

I used a BBSHD on this bike and you shouldn't be put off by the cadence sensing. I dig into motor programming for bikes like this (and this one in particular) in other articles on that site.

And... That bike is for sale, complete with indestructo custom wheels I don't think I actually documented. It looks a little different than it did in the articles as I changed to titanium 760mm handlebars and RevGrip Pro grips along with a few other bits. I went bigger and more expensive and now actually have three cargo bikes, so one should go. Comes with the original wheels, too (still perfect).

EDIT: Owning a Cyc X1 myself, I would not consider it for a cargo/utility application. Thats more of a funtime / emtb motor. I'll skip the details as this is already a long post

 

[K PierreR]

Why on earth would you want torque sensing for that application. Torque sensing turns a bicycle into a primary exercise machine. A western world thing about bicycles primarily being for exercise. No way in hell would I want to deal with steep hills, two jumpy kids and groceries on an exercise cargo bike. I would not want to be beat by the time I got home with two fresh kids and groceries to put away. Cadence sensing for me all the way in the utility application.

 

[m@Robertson]

Why on earth would you want torque sensing for that application. Torque sensing turns a bicycle into a primary exercise machine. A western world thing about bicycles primarily being for exercise. No way in hell would I want to deal with steep hills, two jumpy kids and groceries on an exercise cargo bike. I would not want to be beat by the time I got home with two fresh kids and groceries to put away. Cadence sensing for me all the way in the utility application.

I could not *possibly* agree more. You only see torque sensing held up on high in the first world, where bicycles are not depended upon for utility. Look at markets (which are literally an order of magnitude larger in terms of sales) and its 100% cadence sensing.

I wrote an article entitled in part 'I Hate Torque Sensing' and frankly, your argument never occurred to me while I was on my own rant on the subject. I'll revise it as its another very good reason why you don't want it.