How to transform the USA bicycle according to the Honda Super Cub model: eBike as revolutionary USA short distance transportation

Ebiker01

Well-Known Member
interesting to see how the responses go from here.

I feel that popularity here it has to do with the issue of people needing to have lots of great bike riding skills+ mechanic skills+ general “not a lazy coach potato skills” for just tinkering with the ebike/changing tires and so on...

I read an article this evening about GM boss pushing for autonomous EV (Electric cars) legislation. May take few years or 1year , here people will happily get locked inside the car cage , one w/o a steering wheel as that’s how controlled it will be.
But maybe it will be safer for everyone ??

Personally , I’m on a 860watts peak motor BH ebike with a 605wh pack+A spare occasionally, crank changed to a 52t enabling 29-30mph speeds and is almost really good.

There were and still are very few option for a
Reliable speed pedelec. It took me
Two weeks to decide. On >5% hills the ebike can’t do 23-25mph ...but it does 21-22. Is 60lb with the rear heavy duty rack, Granit lock, moto mirrors. 45lb top is the ultimate ebike. I just got a Schawlbe ice spiker front tire ,on a speed pedelec may not last long but is just needed.

This sort of DIY that I did on my ebike the average car customer will never be able to attend to unless a very good bike shop is behind.
But that costs a ton of money and time for working/customizing each ebike.
 

Timpo

Well-Known Member
I am not sure if Honda Super Cub type of ebikes would work in US / Canada.

Although Honda Super Cubs are the most popular vehicle in the world, and there are countries where you can see Super Cubs everywhere, I don't think Super Cubs sold well in North America.

All I see is 1000cc supersport, or big Harley Davidson touring bikes, and some adventure bikes.

In other countries, people may rather have Super Cub for convenience, to save money, or time (avoid traffic jam, etc) but in America? I don't know... big V8 luxury SUVs or Harleys would outsell Super Cubs.
 

Ken M

Well-Known Member
The Bafang M620 U
that's actually a nice combination. i've a software engineering background: one of my first jobs was to write a Vehicle Simulator for Detroit Diesel (hey cool it's being sold online, now, wow! (Link Removed - No Longer Exists)), so i know the math (you can see a recreation of that work, including rolling and wind resistance, below, if you want to try it out)

based on those numbers, let's go through it (ignore efficiency and losses for now), see if the targets are achievable.

120nm is a tall ask for a 1000W motor unless you have a secondary belt-reduction drive similar to the one on the Sur-Ron. if you make sure to use an Axial Flux motor it should be easily doable. https://www.designnews.com/content/new-generation-axial-flux-ev-motors/186519862158706

from figures for the Sur-Ron Motor, 3kW nominal gets you around 25Nm of torque, so let's assume (reasonably) that 1kW would give 8Nm sustained. primary and secondary gearing (belt drive followed by chain drive) would need to be 15:1 to give the 120Nm you're looking for.

now with the gearing known, let's do the motor speed needed to sustain 30mph. 30mph is 12.3 metres per second (i've done vehicle simulations), a 26in diameter wheel is a 33cm radius, multiply by pi and you're looking at around 1 metre of travel per revolution. therefore to get 30mph you have 12 revolutions per second. 12 times 60 is 720 RPM (at the wheel). therefore, multiply that by 15 to get the motor RPM (because the 15:1 gearing is for the torque you wanted): and that's going to be a SCREAMING DEMON at 10,800 RPM to achieve 30mph.

you'll scare kids, go deaf, and unwork the earwax from grannies half a mile away at those RPMs :)

if it was 2kW you could back that down to a more reasonable 5,000 RPM. even 1500W would still be 7200 RPM, which is a little high but doable.

about the hill climbing ability: that's a little more complex as it involves the vehicle weight. rough numbers: the Sur-Ron can do a 45 degree slope at 20mph and the bike itself weighs 50kg. gearing is around a 5:1 reduction and it's 26in diameter MTB wheels. i do have a vehicle simulator online that you can put numbers in to, it has a gradient parameter. i designed it for cars, it *should* cope with ebike numbers as well, feel free to try it out http://lkcl.net/ev/vehicle_simulator/output/Simulator.html

--
(Link Removed - No Longer Exists)
n

The Bafang M620 Ultra is a mid-drive with 160nm with a standard peak rating of 1000W (sounds like some hot rod DIYers are running it higher but not sure how much additional torque / performance they are squeezing from it). Electrek just reviewed the Frey CC commuter ebike with this motor and the rider hit 59kph / 36mph so I think the tech is viable for a 55kph ebike without super high wattage ratings when using a mid-drive motor (not that I don't like DD hub motors for the simplicity).
 

Timpo

Well-Known Member
The Bafang M620 U

n

The Bafang M620 Ultra is a mid-drive with 160nm with a standard peak rating of 1000W (sounds like some hot rod DIYers are running it higher but not sure how much additional torque / performance they are squeezing from it). Electrek just reviewed the Frey CC commuter ebike with this motor and the rider hit 59kph / 36mph so I think the tech is viable for a 55kph ebike without super high wattage ratings when using a mid-drive motor (not that I don't like DD hub motors for the simplicity).
What's the difference between Bafang G510 Ultra and M620 Ultra?

They both have the standard 160nm of torque and 1000W.

Also, I don't think the 1000W is peak rating. I believe it's nominal.
Very rarely ebike companie (or motor companies for that matter) post peak power as standard.
 

Ken M

Well-Known Member
What's the difference between Bafang G510 Ultra and M620 Ultra?

They both have the standard 160nm of torque and 1000W.

Also, I don't think the 1000W is peak rating. I believe it's nominal.
Very rarely ebike companie (or motor companies for that matter) post peak power as standard.

On Bafang's website all the mid drive systems now seem to use a "M" prefix. I've seen the G510 used as well and I'm sure it's the same motor but can cause some confusion.

It's my understanding that the OEM cost difference for M620 160nm motor and the M600 120nm motor is approx. $50. The M600 seems to more optimized for high performance mountain ebikes and the M620 for cargo and urban performance ebikes (where a bit more weight is not an issue and the higher torque will allow for better load capacity or a bit higher sustained speeds).

I still believe there is room for a really good 1000-2000W DD hub motor (~32-35mm magnets & stator width) to be a great urban ebike motor because at high cruise speeds they are very efficient and the regenerative braking can be a great plus to recoup some energy and greatly extended brake pad life cycle. I don't even think a rear brake is necessary if the progressive regen is implemented correctly (Grin shows a their GMAC/Phaserunner kit stopping a bike very effectively without using brakes so a front brake only would be for emergency use0.
 

lkcl

New Member
The Bafang M620 Ultra is a mid-drive with 160nm with a standard peak rating of 1000W

as Timpo mentioned: that's peak rating. as you will no doubt know, the reason why peak rating should not be used is because above nominal rating the motor is unable to cool down. so if you use it at peak rating, sustained, you'll simply burn out the motor.

160nm of torque will be after the gearing. there is not a single 1000W electric motor in the world that will deliver that much torque without gearing. if you do ever find one, they'll be famous for managing to break the laws of physics :) if you can find out what that gearing ratio is.... ah found it: https://www.electricbike.com/bafang-ultra-max/

triple-reduction, 18:1 (which will result in losses at each reduction, let's ignore those for now)

so the actual motor will be 8 Nm of torque (peak) which is pretty close to the estimate i gave above. bear in mind that the Sur-Ron Motor is Axial Flux, which give a far higher power-to-weight ratio and far greater torque delivery than any other motor design with the exception of the LRK Torque Max design.
 

Ken M

Well-Known Member
as Timpo mentioned: that's peak rating. as you will no doubt know, the reason why peak rating should not be used is because above nominal rating the motor is unable to cool down. so if you use it at peak rating, sustained, you'll simply burn out the motor.

160nm of torque will be after the gearing. there is not a single 1000W electric motor in the world that will deliver that much torque without gearing. if you do ever find one, they'll be famous for managing to break the laws of physics :) if you can find out what that gearing ratio is.... ah found it: https://www.electricbike.com/bafang-ultra-max/

triple-reduction, 18:1 (which will result in losses at each reduction, let's ignore those for now)

so the actual motor will be 8 Nm of torque (peak) which is pretty close to the estimate i gave above. bear in mind that the Sur-Ron Motor is Axial Flux, which give a far higher power-to-weight ratio and far greater torque delivery than any other motor design with the exception of the LRK Torque Max design.

With the internal 18:1 gear reduction the torque does seem plausible. There are a few companies using it and claiming realistic top assist speeds as high as 55kph but I'm assuming they have bike drive trains that allow reasonable cadence at those speeds even though a lot of torque will be lost via that gearing. I would think a bike drive train gear ration of about 3:1 could allow comfortable cadence around 40kph and then just allow the motor to dominate at that point without worrying about keeping the rider engaged with realistic cadence.

There is like the advantage the Sur-Ron has...it can have a final drive gear ratio that amplifies the torque even at the faster speeds because it's not an ebike. I remember the Izip Express separated the mid drive system and the human system so both could be optimized but that pretty much means there must two independent drive systems (one on each side of the rear wheel).
 

lkcl

New Member
There is like the advantage the Sur-Ron has...it can have a final drive gear ratio that amplifies the torque even at the faster speeds because it's not an ebike. I remember the Izip Express separated the mid drive system and the human system so both could be optimized but that pretty much means there must two independent drive systems (one on each side of the rear wheel).

interesting to hear about the izip express. separate systems makes a lot more sense, illustrated below.

on the sur-ron, they're basically taking advantage of the e-bike laws to deliver you something via export regulations that are designed for ebikes, which are themselves a part-way-hangover from when scooters didn't have a kickstart or a motor, and you had to pedal the scooter for a few feet in order to get it started :)

so you get a 3kW motor with a cable attached that strangles the power to 500W, a rear sprocket with 25 teeth on it, a set of pedals with another 25-tooth sprocket on it and a one-way ratchet (yes, 1-to-1 pedalling), and a pair of incredibly dangerous e-brake switches, just so the exporters can slap an "e-bike" label on the customs forms.

when it arrives, you cut that cable (which immediately removes the 500W limit), remove the pedals, put a 61-tooth sprocket on the back and you're up to 75km/h with the stock controller (we can do 110 km/h :) ). of course, with the e-brake cut-off switches, you hold the brakes (even just touching them lightly is enough), twist the throttle and nothing happens. you sit there, puzzled, and your hand twitches ever so slightly - enough to "let loose" that ultra-dangerous e-brake switch.

result: the bike launches away from you, pulls your arms out their sockets which of course causes your fingers to twist the throttle even further and from that point you're in real trouble unless you have extremely strong wrist muscles. if not: the front wheel goes straight in the air, your feet slip off the stands, and you smash into the nearest object in front of you. the *very* first thing i did was cut those incredibly stupid e-brake cut-off switches on my e-bike. they're absolutely lethal. i cannot believe the stupidity of the EU regulators who thought they were even remotely a good idea.

anyway, back to the point: if you have powerful drivetrains like this, there's just no way you can integrate pedals into the (exact same) drivetrain in any mechanically-meaningful way.

it therefore just makes a huge amount of sense to me to have two separate drivetrains:

* one with a small sprocket on the motor and a large sprocket on the wheel (like a motorcycle)
* one for pedals with a *large* sprocket then a small sprocket on the wheel (like a bicycle).

i "get" why people like the mid-drive systems, because you can integrate the two into one. it looks... "neater". however... the forces (torque) involved, in such a small space, and to put chains under more force to get those kinds of 50+ km/h speeds? as an engineer i'm actually quite alarmed to hear that's what's being done.

although it sounds weird to have double sprockets on the rear wheel *and* double chains, mechanically it is better matched, and there will, ultimately, be far less wear and tear on the whole e-bike.

so let's take a look at what izip express did:


yep, there you go: you can see a standard derailer on one side, then i *think* it's... a belt drive on the far side, is that right? it almost looks like the drive wheel is touching the back wheel, just like those old french scooters (you've seen "Mr Bean's Holiday"?) but no, it's a separate chain/belt. yeah, that's a really good idea.