dogman dan wrote:
The best hub motor setup for really heavy weights starts with a very small wheel, like 20", and a direct drive motor that can handle running at less efficient rpms. If the motor is big enough, run lots of power so you stay out of the inefficient rpm ( when heavily loaded) for the motor.
I guess thats why this is the most common setup for most e-scooters / mopeds. I have come to realize slowly that what I am making is no longer a bike but more of an e-moped that can be used as a bike recreationally.
Currently I have a 22" setup which I plan to change to 20inch fat tires like Lithium Super 73, or Moke - ebike. Finally it all comes to how can I manage to give a good reliable product at a decent price. I wonder how did sondors manage to offer his bike for ~$650 with all A-grade components (i saw his campaign and initially the target was 100-200 bikes, which is not a lot for bringing down the costs drastically).
I have come to this same conclusion over the years, I have been building my own Ebikes mainly from DD hub motors, but I have also experimented with a number of different types, friction drive, mid-drive, (recumbent Vision R-40 with Golden Motor in-runner) and I have come to similar conclusions about DD vs geared, but here is what I will add.
If you want to have a product that will just work, and be the "Klashnikov Rifle" of Ebikes, you need a good DD hub, especially as you have described for the delivery companies that will be abused. Where you live, it is VERY hot, so you need to consider several factors:
1) Simplicity - Should be able to be ridden by the average user and take their abuse/use
My father had a nasty bicycle accident in 2007, and we got into Ebikes to help get him back on a bicycle, he is probably the worse case customer for motor abuse. He started with a DD Amped Bikes motor (later sold as 9C, same motor design, different company) and As far as I know, that motor is still being used today, with no issues!
We tried an Amped bikes geared hub motor, for all the advantages we have all seen listed in this thread, however, my father would almost not pedal at all starting the bike (brain injury prevented his really understanding the importance of this) and he killed a 350 Watt geared hub motor about every 1 yr to 6 months, and then we went back to the heavier DD because it just worked. His ride has no real hills, and he would see top speeds of around 28 MPH but this is because he liked the speed and pedaled hard too, but he always stays in top gear, so at the start the motor has to do everything, and he gets going just fine at 36V to boot.
2) Durability - Should not require maintenance more than a bicycle
This is kind of a misnomer, because ALL Ebikes require more than a regular bicycle, (battery, greater speeds/power increase wear etc.) but the goal is to keep it as simple and minimal as possible.
Eventually, all geared motors WILL require replacement or at least maintenance of the gears, a DD doesn't really have these kinds of requirements, other than extreme wet climates (rust builds up inside and can eventually corrode the wiring inside), and normal replacing of worn bearings like anything mechanical.
3) Cost Effective - Should be the best all-round for up-keep and maintenance costs (see reliability)
For your use, both for the delivery businesses and regular customers, I would decide what speed you want to shoot for as the average cruise speed in traffic, get a DD hub motor that has the windings to be most efficient at this speed, match the battery (the main reason that my father got good performance with just 36V was because it was a high out-put Li-Ion battery more than anything else) and use the "industry standard 1000w Motor w/ 20 Amp controller" and limit it to legal power/speed by the battery.
Geared hub motors are a good choice for more experienced Ebike users or just people who are mechanically minded and won't accidentally abuse them, and can be great, but I wouldn't want to be in the business of replacing these gears, on some motors, it is cost prohibitive to do so, and the entire motors are just replaced instead, so if you choose a geared motor, make sure the manufacturer supports replacing gears, not all do.
You really can't beat the simplicity and low nearly maintenance free DD hub motor. I don't personally care for them in the rear wheel, I make custom set-ups with the DD hub as a mid-drive so I have a still gearless Ebike motor, but all the advantages of a geared set-up as now the Ebike motor can use the bicycle transmission.
I have also been impressed by the BBS02 and BBSHD mid-drives from Bafang, these are much higher cost systems, but so much more advantage, that you can get almost twice the distance out of the same capacity of a typical Ebike battery, even with a relatively inefficient 80% motor, compared to the DD motor in the wheel that will at most times be much less than the rated %80 efficiency because you aren't able to ride at full throttle, and much of your power goes to waste heat.
Full disclaimer, I build Ebikes to sell, but I am first an enthusiast and DIY builder at heart!
Good luck in your business in India.