Brushless motor? Geared Motor? Brushless Geared Motor? DRAG, HUH?

[KBG]

I'm about to purchase an ebike cruiser, and have several options. Like every other new buyer, I'm saturated with too many considerations. Of the four models I test drove, the one that physically fit me best was the e-Joe Gadis. However, periodically on the ride, I felt drag after I turned off the pedal assist. (Actual gear choice and terrain were not the culprit.) At one point it was so bad on FLAT pavement, that I actually had to turn the pedal assist back on. Now, thru research I see mid drive, and brushless motors (so many terms) have a reputation for drag. And I've learned that brushless means gearless, right?

The Gadis on LBS website says Brushless Hub (though the LBS owner looked at me blankly and gave me some rigmarole when I asked why it dragged. . .); The Gadis on the Ejoe website says it is a "Brushless GEARED" motor. How's that if brushless means gearless? So what am I missing about that?

Plus, if I do purchase a Brushless motor and it drags, is there any trick to avoid that? Or to make it stop as I am riding? I want exercise and I do not want to have to use the motor on flat smooth pavement. Advice?

Thanks ALL!

 

[tomjasz]

brushless means gearless

No. "The brushless motors are synchronous units with one or more permanent magnets. Power tools with a brushless motor are now considered high-end products. A DC motor consists of two electrical parts: the stator and the rotor. When powering the motor, it creates a magnetic interaction that sets the motor in motion."

Brushless DC electric motor - Wikipedia

en.m.wikipedia.org

My Bafang mid kits and gear drive MAC motors have less drag than a direct drive.

 

[KBG]

Thanks! But can you see my confusion? Some info out there calls the brushless hub motor, gearless and/or direct drive. And the geared motors explanations are not those. Like search terms "Brushless vs. Geared" or "Geared versus Gearless." My confusion is the info out there implies these are differentiating or opposing terms. . . But then the manufacturer calls their Gadis model's motor "brushless geared." I know the brushless has drag, and the geared is supposed to have less drag. But what happens when those terms collide into "Brushless geared"?

 

[indianajo]

There were brushed DC motors for bikes common up to about 2015. Often they have a sprocket to engage the chain in the straight area, with no pinch roller to keep it in contact. Very cheap & sleazy. Often they are designed for 12 v lead acid batteries. Bing directed me to these when I first started investigating bike electrification. I know from factory work that brushes often lose contact with the commutator after a weekend, and won't start on Monday morning unless the brush is pushed in.
Both Direct Drive and geared hub motors are usually brushless. Don't buy with brushes. The direct drive "DD" motor I bought drug unpowered like being 2 sprockets higher than I was. The geared hub motor I own has an internal one-way clutch that keeps it from dragging when I pedal. As I bought the motor to help me when there is a head wind over 12 mph, not dragging when I pedal is important to me. I pedal for exercise. Most hub motors don't have the "brushless" description anymore. If they do, it is kind of redundant. Bike motors are now 3 phase AC motors with the controller rotating the phases at variable speed. Like $600 industrial motor drives, only now 3 phase 36 to 48 vdc controllers due to IC's are about $30.
Mid drive bikes mostly also drag unpowered. Exceptions are the Yamahas and one model of Shimano, that have a one-way clutch built into them to allow free pedaling. Mid drive motors are now almost exclusively brushless.

 

[rich c]

They are all brushless. Common DC motors have carbon brushes rubbing on a commutator. No eBike motor has brushes. The drag on a direct drive is the armature spinning past the permanent magnets. That can't be over ridden.

 

[Stefan Mikes]

@KBG, some points from my own experience:
The brushless geared motor has a freewheel. Meaning, there's no rolling resistance from the motor itself. You would have noticed that if you got to a decent speed and stop pedalling: e-bike runs, runs and runs. Your feeling of "drag" with no pedalling assistance results from two factors: a. e-bikes are heavy; b. You'd been assisted by the motor before you switched assistance off - that only demonstrated how powerful pedalling assistance is.

My Lovelec e-bike has a brushless rear-hub motor and riding it is a pure pleasure. No drag from the motor. Besides,"geared" only means the fast spinning motor has its RPM reduced by internal gears to the wheel rolling speed; electric motors love spinning fast. However, it is the freewheel that ensures there's no motor drag when not pedalling.

Talking about mid motors I can only say anything about the Brose motor that I have got in my Specialized e-bike. That motor has a clutch so no drag from that motor, either. Again, switch the pedalling assistance off and you are in deep trouble, such powerful the motor is. I had the motor cut off by incident in the Specialized bike. I was pedalling upwind and could only make some 8 mph. With no wind it was up to 11.8 mph. While the same e-bike can ride even 28 mph with the assistance on.

Exceptions are the Yamahas and one model of Shimano, that have a one-way clutch built into them to allow free pedaling.

Bosch mid motors are notorious of their drag. Brose and Specialized motors have no free pedalling drag.

 

[KBG]

Meaning, there's no rolling resistance from the motor itself. You would have noticed that if you got to a decent speed and stop pedalling: e-bike runs, runs and runs. Your feeling of "drag" with no pedalling assistance results from two factors: a. e-bikes are heavy; b. You'd been assisted by the motor before you switched assistance off - that only demonstrated how powerful pedalling assistance is.

Bosch mid motors are notorious of their drag. Brose and Specialized motors have no free pedalling drag.
[/QUOTE]


Thanks, Stefan. What you say here is what the LBS owner tried to tell me; however, there was definitely drag. I could barely pedal the model on flat surface AFTER I used and then turned off motor. I had been pedalingon my own for quite a while before I tried the motor. Used motor uphill, turned it off, then found flat ground almost impossible to do on my own. Plus, it did not happen each time. This cannot be a "cold water feels warm after freezing water" phenom. The folks test driving with me, felt it too. Plus, we had ridden a few others and did not experience this sensation after using motor. Unfortunately those frames didn't work for me.

 

[Stefan Mikes]

Perhaps it was a wrong e-bike, @KBG. It is true it is hard to pedal on an e-bike with assistance off, yet you should be at least pedal slowly back home. At least both e-bikes I own let me do that in emergency.

On a lighter note, that was what happened when a faulty display suddenly cut the power off in my Turbo Vado:
I was just cornering and planning to ride onto an over-pass. Since I'm lazy, I switched the mode to Turbo. The e-bike literally flew uphill and then... it almost stopped. Perhaps not stopped but slowed down dramatically. The gear ratios in the Vado are decidedly not mountain ones; they are for fast riding. So I shifted down and was able to crawl to the top of the over-pass... Nobody claims the Vado is a bad bike per se, yet the change in the resistance was dramatic. As if I hit the wall.

 

[indianajo]

Perhaps it was a wrong e-bike, @KBG. It is true it is hard to pedal on an e-bike with assistance off, yet you should be at least pedal slowly back home.

It is hard to pedal most mid-drive bikes home after electrical failure. It is mildly difficult to pedal a direct drive hub motor bike home after a failure. A geared hub motor or mid drive with a one-way clutch, the only problem pedaling it is the extra weight. I pedaled my geared hub 16 miles home after the first battery failed. I pedaled the direct drive hub 20 miles home after the throttle quit working in a steady rain. I pedal my geared hub 46 of the 60 miles I ride, weekly. The extra 16 lb doesn't bother me. After all, I've lost 50 lb riding a bike since I quit working. Pedaling it keeps the weight that way. The reason for electricity is 25 mph headwinds, which can double my 3.5 hour ride to 6. I don't need that much exercise.

 

[KBG]

It is hard to pedal most mid-drive bikes home after electrical failure. It is mildly difficult to pedal a direct drive hub motor bike home after a failure. A geared hub motor or mid drive with a one-way clutch, the only problem pedaling it is the extra weight. I pedaled my geared hub 16 miles home after the first battery failed. I pedaled the direct drive hub 20 miles home after the throttle quit working in a steady rain. I pedal my geared hub 46 of the 60 miles I ride, weekly. The extra 16 lb doesn't bother me. After all, I've lost 50 lb riding a bike since I quit working. Pedaling it keeps the weight that way. The reason for electricity is 25 mph headwinds, which can double my 3.5 hour ride to 6. I don't need that much exercise.

Oddly, when I started the test drive, I did not use the motor at all and had no problem pedaling. I kicked in the motor after riding a while, on a hill, then after that I felt drag. I went to three other bikes, and came back to the first. Same thing. Did not use motor at first, no problem, then later. . .drag hit me again. I do not think it was the gear I was in either. . .Either way, it seems I'm not going to avoid drag?? But the inconsistency implies it can be controlled??

 

[indianajo]

Was it a mid-drive bike? which brand motor?
My geared hub motor from ebikeling doesn't drag at all unpowered, EVERY TIME. I get more drag if the disk brake pad is out of adjustment. Perhaps the demonstrator bike had a dragging brake pad. People would never notice with the power on. Most purchasers of electric bike intend to never ride without power.

 

[harryS]

Almost all ebikes use brushless motors.

A brushed motor has two wires and runs on DC. It's like the battery operated toys you may have taken apart. A brushless motor ris really an AC motor. Has three wires. You have to spin it with an AC waveform from a controller. Black magic.

All brushed motors will have drag if you spin them without power. It's the magnets dragging across the rotor. A direct drive motor spins the axle directly and is always turning, even if coasting, so you will feel whatever drag it has.

A geared motor only turns when powered. When it's coasting, it stops and a clutch disengages the motor from the axle. You will find geared motors in mid drives and also hub motors. There is still the stiffness of the clutch to provide drag. It's stronger on some motors than others.

Put in perspective, if you lift the rear and spin a regular bike wheel forward, it will go for a minute. A geared motor might spin for 15 seconds. A direct drive motor might move and stop. Depends how powerful it is. Try this next you do a test ride.

 

[KBG]

Was it a mid-drive bike? which brand motor?
My geared hub motor from ebikeling doesn't drag at all unpowered, EVERY TIME. I get more drag if the disk brake pad is out of adjustment. Perhaps the demonstrator bike had a dragging brake pad. People would never notice with the power on. Most purchasers of electric bike intend to never ride without power.

Thanks. It was rear "brushless geared" hub. And it did not drag every time I was without power. So you might be right, there.

 

[AHicks]

I have to wonder, with most bikes able to go a good 20 miles or more under power (some MUCH further), do you see a scenario where you would be riding frequently with the system turned off? MOST riders don't. If the system is turned on, the tiniest amount of power will avoid that drag.

The majority of e-bikes use one of the following drive types -

The direct drive rear hub (no gears) has drag that's unavoidable when there is no power available (system turned off), or PAS level =0.

The geared rear hubs, every one that I'm familiar with, all use a one way clutch internally that lets the motor stop completely, without dragging on anything, when coasting or with the power shut off.

All mid drives, to my understanding, drive through the rear cassette or free-wheel unit (which also have built in one way clutches), making it impossible for them to cause drag.

If you were on a bike that did not behave predictably as above, you may have been on a defective bike.

 

[indianajo]

I have to wonder, with most bikes able to go a good 20 miles or more under power (some MUCH further), do you see a scenario where you would be riding frequently with the system turned off? MOST riders don't.
All mid drives, to my understanding, drive through the rear cassette or free-wheel unit (which also have built in one way clutches), making it impossible for them to cause drag.

Mid drive bikes will all coast, or ride downhill, without drag. What most of them won't do, is be pedaled uphill or on the level without drag. Pedaling rotates the motor, unless a one way clutch is installed in the motor. The confusion about this is compounded by calling the one way clutch in the motor a "freewheel". A freewheel is a bike device with sprockets on it that allows the wheel to turn while the sprockets stay still. Mid drive bikes need a SECOND one way clutch in the motor area to keep the user from spinning the motor when pedaling. Some mid-drives have it, demonstrably yamaha and one shimano. Most mid drives apparently are bosch, and they don't have it. TJ says Bafang mid-drive has it; I can't try one to verify closer than Chicago.
Some of us ride the bike for exercise. The electricity is for the days we don't want to ride for 6 hours; like bad headwinds on a fixed length trip normally 3 hours. Lack of groceries is an inhibitor to delaying the trip for better weather. Or an appointment that must be made. Some commuters will want to arrive at the office clean & dry, then pedal and sweat on the way home.
For those that don't want exercise, live long & prosper. My father tried that in his retirement, had a stroke that ruined his brain 3 years older than I am now, and lived trapped that way for 6 years more. Horrible. Dr. Ken Cooper says 25 minutes of aerobic exercise every other day are required. Many British medical studies have replicated the result.

 

[AHicks]

indianajo, when I was talking about the mid drive cassette and freewheel units in my note. I was referencing the rear sprockets.

I was thinking about coasting without drag. You do make a good point regarding pedaling with no power.

Unless there is a second one way clutch of some sort on the motor of a mid drive, there WILL be drag while pedaling with no power. With no more experience than I have with mid drives, I'm not familiar with them enough to make a statement regarding which mid drive motors have them and which do not - or if any of them do.

 

[Stefan Mikes]

With no more experience than I have with mid drives, I'm not familiar with them enough to make a statement regarding which mid drive motors have them and which do not - or if any of them do.

The Brose or Specialized mid drive motors absolutely have a clutch and coasting with them is a pure pleasure - I should know it better as a Specialized Turbo Vado owner. I hear Yamahas also have the clutch. Bosch motors don't. Not sure about Shimano.

 

[KBG]

I have to wonder, with most bikes able to go a good 20 miles or more under power (some MUCH further), do you see a scenario where you would be riding frequently with the system turned off? MOST riders don't. If the system is turned on, the tiniest amount of power will avoid that drag.



If you were on a bike that did not behave predictably as above, you may have been on a defective bike.

I wondered about this. And yes, I figure that based on what everyone here is telling me, I may have to use the tiniest amount of power. I just wanted exercise; because of a spinal injury, I cannot easily stand up and swerve back and forth as people do to get up hills, so I only wanted hill power. BUT I can work it out. And some of you might be right; If "brushless geared motors" are not supposed to have drag when off, and if the model was only doing it sporadically, maybe the test model had an issue. Thanks!

 

[indianajo]

The Brose or Specialized mid drive motors absolutely have a clutch and coasting with them is a pure pleasure - I should know it better as a Specialized Turbo Vado owner.

Coasting is not the issue. All bikes since 1940 can coast. The question is, what does the bike feel like when you pedal on the flat with the power turned off? Like an unpowered bike of the same weight & tire size?

 

[tomjasz]

Much adieu about nothing.