Middrive vs. rear hub for my first e-bike

[E-HP]

Clearly, there are good things about any of the options. I just want to mention that I see a fair number of "cargo" bikes around, with 750W direct drive hub motors. We have hills here, 4-5% is more common but there's some 7%. I can't guarantee that everyone with one of those bicycles actually uses it to carry heavy loads. The model I usually see has an advertised weight of 73 lbs, and payload capacity 350 lbs. That payload isn't going up a 7% hill, but your 300lb total weight should be doable under 750W.

I'd guess 750W might be good enough. The street in front of my house is 6%, which is pretty mild for my area (my daughter and I had a tradition of racing up the hill after our bike rides when she was growing up). My regular route from the bottom of the hill to the top, which is about a mile, is 9%, with the steepest sections being 16%, but only for 4 or 5 block stretches. With 230 lbs total weight, the motor probably averages somewhere around 500-600 watts and maybe 800 watts on the steep parts, with me pedaling of course. 750 watts with 300 lbs on a 7% grade sounds about right.

 

[donn]

If choosing a direct drive hub, look for something wired up for slower speed / larger wheel. In any case, whatever type of motor, put a big tire on the rear - you'll be moving faster than you're accustomed, overall, and you may be surprised at what a beating the road can give you, your load, the bicycle, etc.

I installed my hub motor on an old bicycle with ... well, not sure it has sentimental value, but it makes me happy and it's certainly a classic. After a couple months, I bought a different bicycle that would make a better e-bike and swapped the motor to it, and now my old bicycle is back to the way it was designed to work.

 

[minde28383]

hub or middrive for cargo bike.
I see most cargo with these bafang 750w. More expensive with 1000w version.
If you go with it then 1kw for sure. It is upgrade, has better internals, better controller, better long term value. It has better torque.

Go with hub if you don't care about additional weight. You might spend more on battery going with hub as it draws more amps from stand still.

I don't understand why care about flats. Put slime/glue inside tube. You can put it before hand or in emergency but than you need to have on you pump to pump tire.

Go with middrive only if you want possibly light ebike.

Midmotor with gears shines only from stand still. When you role throttle it draws less amps because of gears. But you need to be in right gear before hand.

If you want your bike to be like little moped than powerfull hubmotor, very heavy tail. If you want your ebike to be more electric cargo bicycle than middrive.

If you put 1kw midmotor and put 1kw hub than middrive will be better.
If you put 1kw midmotor and put 2kw/3kw hub than hub wins.

What I want to say that you need to put amps/watts/power to hub motor to make it alive and have advantage.

If you can spend 800eu (200cells 4each cell plus bms) on battery (some get cheap cells from various sources, some used cells, got some local ebike builders, talk with them what they offer) and 300eu to 500eu on hub than go with slow hub as 200cells is kinda on low side anyways but enough for moderat power .
battery at least 60v nominal, better 72v. Don't go with 48v if you have space to store it on the bike. I admit these 48v dolphin style or tube style batteries are ergonomic, but they are small and they are okay for 750w or 1000w middrive.

Find someone localy and raise bicycle with hub by rear wheel. If it does not scare you than hub it is.

If we are talking about components of the shelf, motor, controller, battery. You can't have such performance from 1kw middrive compared with mxus 205 3kw and not even talking about qs205 3kw.
9kv version with 24bicycle wheel
7kv version with 26biccyle wheel


By going with 1kw midrivef and by going with 3kw hub motor we'll get two different transportations. One willbe like moped and antoher more or less like assisted biccyle. Don't get me wrong, 1kw mid drive will go fast ie 60km/h, but hub will be more powerful but heavy.

 

[markz]

https://www.ebikes.ca/tools/trip-simulator.html
Trip Simulator -BETA-
Scroll down, look at left side
Chart Options
Input Type then click on down arrow, choose Google maps.
Scroll out, then scroll in to your area.
Right click your starting point.
Right click your ending point.
Hold down the Left button on the automatic route, and move blue route to desired route. Do that multiple times until you get your desired route.
Click the X to close window and it will give you everything you need to know about your route.

There is also a Motor Simulator, another great tool.
For mid drive simulating, it is possible. Justin_Le mentions you have to convert the gearing, probably by the wheel size I'd assume. Someone can correct me on that, or do a search.

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I am a fan of silence, so I prefer Direct Drive hub motors. MXUS 3000W V2 with a 4T motor (shorter and thicker winding wire, takes more power!) with a generic controller, I am 375lbs, bike weighs gosh I dunno another 50lbs. I am in a 26" wheel, it is good. If I wanted more torque, I'd go 20" or 24" wheel and get less speed, but I'd up the voltage. Upping the voltage means I need a new Low Voltage Cutoff to protect my battery as I use no BMS. Some BMS will cutoff, but the controller does it too.

I'd suggest for you to look at
https://leafbike.com/products/diy-bike-conversion-kit/24-inch-electric-hub-motor-kit/newest-24-inch-48v-1500w-rear-hub-motor-bike-conversion-kit-988.html

or the 20" because they have a display, the Leaf 1500's are great motors, can take lots of power.
Leaf 1500W Direct Drive Rear Hub in a 3T or 4T winding, if Leaf does that, please confirm.
Lace into a 20" or 24" wheel - Either their wheel or your own rim and your own spokes/nipples.
Battery I'd suggest 60V if the Leaf's controllers internals have more then 60V caps. Otherwise 48V battery pack.
OSN Power
Unit Pack Power
www.ebikes.ca
www.em3ev.com

Leafmotor.com
https://www.qsmotor.com/
http://www.qs-motor.com/
https://qsmotor.en.alibaba.com/
https://ebikemotor.en.alibaba.com/?spm=a2700.wholesale.cordpanyb.1.699e718fU5g0nT
https://evfittinggreentime.it.aliexpress.com/store/313864

.

 

[tomtom50]

7% is climbing 7 ft on a 100 ft course. If you find it steep, you must be living on the salted flats. :wink:
7% is 4 degrees of slope.

7% is steeper than it sounds. I live in Seattle. Our hills are steep. Very few exceed 8% for more than 2 or 3 blocks.

I think this is about perception. 8 foot rise in 100 ft doesn’t sound like much, but use google and find a hill (if you can) that rises 425 ft in a mile and try to climb it. Unless you are a strong rider you will get off and push the bike before you get to the top. And even if you are strong you will need a low gear.

Go to bikecalculator.com and see the watts needed to climb a 7% grade at a reasonable clip, and compare against what people can do. Only trained athletes can maintain 400w for any length of time. 200w is a lot of effort, you have to be pretty strong to maintain 200w for 1/2 hour

 

[tomtom50]

I think you'll be a lot happier with a mid drive like BBSHD or BBS02 than you will with a hub motor. Hub motors are easier to install, and they don't punish your bike's pedal gears. But they don't excel at a big range of loads unless you use a really powerful one, which means lots of weight and a costly battery. When your power is modest, you get much better performance at high speeds and on steep climbs by using the mid drive.

Tradeoffs of the mid drive include increased bike maintenance and having to think harder to get the best the motor has to offer. In your case, I think it's worth it.

Agreed. Hub motors are great, but they need to be geared so the motor rpm stays in the efficient zone (at least 2/3 of no load rpm), or they need to be so strong a poor match works anyway.

Mid-drive is a lot more accommodating, your bike gearing will keep the motor in a good zone. And the mid-drive kits are complete and well matched (many hub motor kits are ‘piles of parts’ with too many cables and poor connectors).

But... mid-drive is a literal drag if you don’t want assist all the time. They introduce noticeable friction. It is possible to build up an inconspicuous geared hub system that feels like a bike when you don’t want assist. Powerful direct drive hub motor setups are more foolproof but heavy and expensive and impose more drag.

My first ebike was mid-drive and that was the way to go for a first ebike. Simple, easy to install, decent gearing and motor rpm assured without a lot of calculation and sizing.

Mid-drive tips for a heavily laden climber:

1. Since you lose your front derailleur I’d recommend a 36 tooth or larger rear cog.
2. Chainline (google Sheldon Brown for definition) is important. Mid-drives tend to have the chainwheel further to the right than ideal and this can cause grinding in first gear (chain angles too much from front to rear).
3. Bafang BBS seems to be biggest seller, but TSDZ2 is also a popular and it has a torque sensor built in. Worth reading up on it and considering along with bafang.
4. It sounds like 500w is enough since you aren’t emphasizing speed on the flat. So long as you have a decently low 1st gear 500w is nice to keep battery size down and increase drivetrain durability. Even if the drive you pick can put out more power there is lot to be said for not pushing the drivetrain to the limit. Say you are contributing 150w on your climb, 650w through your drivetrain is more than a pro cyclist, about like a tandem with two strong riders. More than the Shimano engineers would design for. That doesn’t mean you will break a chain or a cog, but wear can be pretty severe.

 

[MadRhino]

...200w is a lot of effort, you have to be pretty strong to maintain 200w for 1/2 hour

Yup, but we were talking about motors. Mine could have maintained 3000 w continuous for a year and a half, since this conversation took place.

 

[tomtom50]

...200w is a lot of effort, you have to be pretty strong to maintain 200w for 1/2 hour

Yup, but we were talking about motors. Mine could have maintained 3000 w continuous for a year and a half, since this conversation took place.

Right. 200w is a benchmark to use in bikecalculator.com to get a feel how steep a % grade is and to get a feel about wattage assist.

3000W is a lot of power on a bicycle. A 3000W mid-drive would not be practical, it would tear up the drivetrain. I think 3000W is power comparable to a Honda 90, motorbike power.

The OP is looking to get started with an ebike, matching a drive to needs. from the post his or her use is not the type where using a battery that can sustain 60A (3000w at 48V) makes sense.

 

[MadRhino]

The OP was looking... in may 2017

Like many newbs enquiring about building their first, we got no feed back about his build.

3kw hub motors are commonly fed 15 to 20kw in acceleration. 4 grade slope is nothing for this kind of power. It is nothing either for a BB drive in low gear. Little power is required to climb it, even with a cargo load. He could have built with just about any kit. We recommended a mid drive kit at that time, because he didn’t plan to ride fast and feed high power.