Geared motors regen ? power to the masses!

still working on my poor man's ebike, I'm wondering why there are not more geared motors with regen function available. wouldn t it be possible to get rid of the ratcheting mechanism inside most geared motors, and use the planetary gears in both ways ? freewheel function could still be added via a classic gearing cassette. and how about mid drives? could some sort of pedals ratcheting be doable in order to have the motor directly connected to the rear wheel? once the motor can be spun in generator mode, all there is left is a rectifier and and tiny buck voltage regulator to produce usable power.
i understand the questionable economics of regen power in everyday commute to work. but i think that we currently severely underuse the potential of ebikes: if every motor can be turned into a decent generator, and thus every ebike into a small power plant (using this), not only would people be able to (partially) reload their batteries, but armies of cyclists could power the equivalent of an entire city. don't know about you, but i would be much more impressed by local contests of cyclists measuring the power they produce knowing that it's beeing fed into the grid (using an inverter) than by wasteful tour-de-france like competitions...

Subtracting the one-way clutch from a geared hub motor would take away its one advantage while leaving it with all its disadvantages.

Most bicyclists have more to gain by being able to coast freely than they do from the negligible energy recovery regenerative braking offers.

I built a stationary generator bike for a larger art project several years ago. It's amazing how much work it is to generate a small amount of electricity. Like if you did it indoors, you'd have to use several times as much electricity just to cool the rider as the rider is able to make with the pedals. An average sized person who is accustomed to riding a bike can make up to 200W of electricity for a while, but it's an ultra-backwards way to make it.

Now, if you were to put pedals and a generator into every car and truck and suv out there, so that all that time wasted sitting in traffic and such could be useful....


FWIW, some companies (like Fusinmotors, no longer around) *have* offered non-freewheeling versions of their small geared motors...and were unsuccessful at getting them to sell.

My Currie folding bike with 16" wheels has a 170W non-freewheeling geared hub. I think they used it to limit top speed, as those bikes aren't stable above 15 MPH.

Geared hubs dissipate heat poorly, so making heat from regen instead of cooling during coasting can push the limits.

There are a few limited uses for a regen enabled geared motor. But since they coast so good with the freewheel, going farther by using regen is not one of them. Better to coast all you can, on the smaller downhills.

On the big mountain, you definitely don't want to lose the cooling time coasting down. Likely you got to the top pretty hot if the climb is over 3 miles long.

But in serious stop and go riding,, manhattan, down town SF, etc, then the better efficiency on the starts combined with regen braking could be a deadly good combo. If nothing else, stopping every block, you could use less wear on brakes.

It should be possible somehow, to break the clutch and have a DD geared motor. Not sure exactly how to lock one up.

I would love to see a huge diameter geared motor, with no clutch, and oil bath cooling. For pedicabs, hot dog vendor trikes, etc. It would be geared even lower than the normal 5-1 in small geared motors. Its speed range would be aimed at 0-10 mph, and it would pull 2000w all day with the oil transferring the heat to the shell, which would also have cooling fins.

qwerkus said:

still working on my poor man's ebike, I'm wondering why there are not more geared motors with regen function available.

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Get a tiny (Crystalyte NSM or something) front wheel DD motor and use it only for regen.

Chalo said:

Subtracting the one-way clutch from a geared hub motor would take away its one advantage while leaving it with all its disadvantages.

Most bicyclists have more to gain by being able to coast freely than they do from the negligible energy recovery regenerative braking offers.

I built a stationary generator bike for a larger art project several years ago. It's amazing how much work it is to generate a small amount of electricity. Like if you did it indoors, you'd have to use several times as much electricity just to cool the rider as the rider is able to make with the pedals. An average sized person who is accustomed to riding a bike can make up to 200W of electricity for a while, but it's an ultra-backwards way to make it.

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you keep disseminating this bull-pucky without any hard numbers to back it up.
wheras the E•S board owner has put in definitive testing that definitively proves you wrong.
can't help but notice you don't have the sack to contradict justin to his face in any of his threads not only on this issue.

i see now where you're thinking is tripping you up.
your stationary bike didn't recuperate any energy from being stationary downhill lol.
ffs is there not a single urban legend that you can accept having had a stake driven thru its heart so we can move forward??
tell you what, as a compromise regen is superior to freewheel coasting only outside of austin city-limits, otherwise stfu.

Justin lives in Vancouver, hilly as frig with lots of stops. It's like an ideal case for regen, and even then his returns were so marginal as to be insignificant.

I'll stand by my assertion that coasting is more valuable than regen for cyclists on average terrain at bicycle speeds.

That's been my experience too, until actually riding mountains, where saving your brakes is very good, coasting gets you higher overall wh/mi results.

Regen gets better though, if you are really stopping every block. If you only stop every 2 miles, not so much return on it. And better still, if your load is 400 pounds on up.

The main thing that can make coasting better, is that under regen you might go 5 mph down a big hill. That does not exactly get you there at e bike cruising speeds. But again, if you and the bike and the cargo weigh 400 pounds on up, 5 mph down a mountain might be perfect for your needs.

As always, it depends.

I get this regen question constantly on the on line chat. My stock answer is to recharge the battery, 500wh, all you have to do is pedal it the equivalent of 300 miles. You pedal 100 watts or so, 100wh per hour, but the battery sees about 15 wh of it for an hour pedaling. (moving, so most of the pedaling goes into motion) stationary would be better results, but still easier to just pedal the bike motor off, than pedal it in regen, even if its a DD motor.

Geared motor that coasts well, for the win on wh/mi, usually.

Chalo said:

Justin lives in Vancouver, hilly as frig with lots of stops. It's like an ideal case for regen, and even then his returns were so marginal as to be insignificant.

I'll stand by my assertion that coasting is more valuable than regen for cyclists on average terrain at bicycle speeds.

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Yes the return in the battery is marginal, but it will lower the wear on the braking system a lot.

Check out the new Heinzman cargopower RN 111 geared hub which has REGEN:

http://ebike.heinzmann.com/systeme/cargopower/motor

- oil cooling
- 100 Nm peak torque
- 1000W
- 4,5kg
- planetary steel gear with 1:10 reduction

For me, regen is used only as braking assistance for emergency braking, mostly on slippery surfaces. I can ride almost all the summer without touching the regen button. I find the brakes are more precise, and I achieve a shorter braking distance with brakes alone in most conditions. Saving the brake pads is not an issue for me, saving my bones is coming first. Regen is not consistent, weak when the battery is fully charged and aggressive enough to make the wheel drift a moment when the battery is low. Also, using regen at every stop can be hard on motor/controller when they are running close to their limits already.

Thank you for your feedback. True that heat might be an issue using break regen on geared hub motors, though can't this be alleviated using a smart wheel design to dissipate the heat there ? Problem with DD motors is always the low efficiency in low power mode and the weight. Oterhwise that idea to use a DD hub front hub motor might be an option. And yes: dynamo pedals should be mandatory in SUVs....

dogman dan said:

But in serious stop and go riding, manhattan, down town SF, etc, then the better efficiency on the starts combined with regen braking could be a deadly good combo. If nothing else, stopping every block, you could use less wear on brakes.

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That would be the general idea.

MadRhino said:

For me, regen is used only as braking assistance for emergency braking, mostly on slippery surfaces. I can ride almost all the summer without touching the regen button. I find the brakes are more precise, and I achieve a shorter braking distance with brakes alone in most conditions. Saving the brake pads is not an issue for me, saving my bones is coming first. Regen is not consistent, weak when the battery is fully charged and aggressive enough to make the wheel drift a moment when the battery is low. Also, using regen at every stop can be hard on motor/controller when they are running close to their limits already.

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I would say it depends a lot on the controller and how the regen works.
With the Adaptto system as example, i have a second throttle for variable regen, and the hydraulics i only use in emergency situations and at very low speeds (where regen don't work anymore). The best thing it can be adjusted so that it also works if the battery is fully charged.
In situations like keeping a constant speed when going down a long hill, it is not unusual that i see 1000W flowing continuously into the battery, and peak above 3000W when braking hard.

Now put 1000W of "stopping power" for a longer time into a 200-300g brake rotor and see what happens.

e-bikes without regen eat through brake pads.

Yeah, different systems and different riders. I am not into holding brakes down a hill, only short braking entering a turn and throttle again. If you had the habit of long braking, it is good that you have got a way to variable regen because you'd be killing brakes at an outstanding rate. :wink:

I just got news from keyde, that they will offer a 2.3 Kg rear hub GEARED motor with regen next month. They say it will be equipped with a temp sensor to avoid overheating in long downhills. Curious to see how that one will work out. I already preordered one, and will keep you updated.

Cool, for the specific use you want to put it to. And if it does get hot, you will either know, or get a shutoff.

Smoothly adjustable electric braking is a controller function, and so very few have it that most ebike riders have never experienced it (and have no basis for comparison). The lesser regen controls are not very good and don't compare at all.

PhaseRuner, Adaptto, Sabvoton have the better controls (and some others).

A geared motor with it's clutch welded will cog and resist motion while not under power like a bastard.
Just keep that in mind.

The only reason you'd want to do it is for low weight.

The leafmotor and other similar 0.35mm lamination DD hub motors however, have very low cogging these days. I was able to pedal along up to 18mph without the power being on on my leaf. a 28 or 30mm 9C/MXUS DD hub would 'freewheel' even better than my 35mm wide motor.

If grin's all axle motor had a rear drive version, i'd say that's the best of both worlds.. light.. most likely extremely low cogging.. and power levels similar to a MAC/BMC/eZee large geared motor.

Regen is 6-9% at most times with general riding.

neptronix said:

A geared motor with it's clutch welded will cog and resist motion while not under power like a bastard.
Just keep that in mind.

The only reason you'd want to do it is for low weight.

The leafmotor and other similar 0.35mm lamination DD hub motors however, have very low cogging these days. I was able to pedal along up to 18mph without the power being on on my leaf. a 28 or 30mm 9C/MXUS DD hub would 'freewheel' even better than my 35mm wide motor.

If grin's all axle motor had a rear drive version, i'd say that's the best of both worlds.. light.. most likely extremely low cogging.. and power levels similar to a MAC/BMC/eZee large geared motor.

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At least on their alibaba store, keyde claims that their geared motors have no clutch at all. Weight is only one factor: from what I understand, DD hub motors are quite inefficient at startup so geared motor is the way to go in stop-start city commute.

qwerkus said:

Weight is only one factor: from what I understand, DD hub motors are quite inefficient at startup so geared motor is the way to go in stop-start city commute.

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In the context of total energy consumption, I wonder how much difference there would be since so little time is spent in actual 'take-off'.

About 20% can be lost by doing enough starts and stops in the city, with a typical normal to fast wind dd, in 26" wheel, and,, not one with enough power to hit 30 mph in 30 feet.

Lots of qualifiers there, but every variable you change, changes everything. That's kind of the worst case scenario, a 9 contintent type dd, 36v 20 amps controller, and city driving with a stop every block or two.

What works under 1000w in that type ride, is a geared motor, or slower speeds travel with a slow wind dd. Up to 20% better as long as you are stopping 5 times a mile. So what he is proposing does make sense.

He will lose something by not coasting, but you can keep the throttle at 50 watts, and a dd will coast. what that costs will be made up by the regen.

So why bother at all? Weight, and brake pad wear. Nothing much else. It won't be dramatically longer range than a geared motor that the rider lets coast a lot. I think its just a lot simper myself, to put some good disc brakes on with long lasting pads, and run a geared motor.

Much thanks to everyone who has posted in this thread. Especially MadRhino, madin88, and Dogman (of course)...real-world results beat theory every time.

Do we have any reasonable maintenance comparisons between Geared motor gears, clutches and brakes, Mid drive gears, clutches, chains, cogs and brakes, and DD with regen brakes and of course tires? For a commuting daily driver these are the issues. My commuting experience was primarily DD motors, with major hills where the brake wear was substantial without regen. When I settled on the Cromotor and Sabvoton (with variable regen on a brake lever) the only noticeable wear I had left was freewheels (only the cheap dicta fits this limited space setup) and moped tires. About 3000 miles for the rear tire, and the freewheel about the same. Lubing the freewheel extended its life. Brakes I have no data on, they never wore out after I got the variable regen working. The front tire was about 10K mile wearout.

Perhaps the biggest issue with non regen brake usage was not just wearout, but brake heating and reserve braking capacity. When descending a long steep 15% gradient the reserve emergency stop capacity was diminished to the point that I wasn't sure there was much left. There was enough braking for the descent, but little more as they were about to fade from the heat. After implementing electric braking on the Sabvoton the dual 203mm front disc brakes are not needed to control speed, so they are 100% ready for the emergency.

So for the several years I ran this system before ending the commute mode (retiring) I basically had to replace a rear tire and cheap freewheel once a year, and repair a rear flat about once a year. Chain and brake maintenance was not really a concern.

If I had been faced with 500 or 1000 mile maintenance intervals with clutches, gears, chains, etc my commuting experience would have been rather different. I did have a couple times in several years where the charging partially failed and that caused me to push a heavy ebike up a couple of hills, but zero rescues were needed, no tire changing on the road either. There were some early controller failures near work where I had to turn around and coast/push back to the office and get a ride home that day, but the Sabvoton ended that issue.

The commuting experience depends on a lot of factors such as distance, speed, road conditions, bike lanes, traffic, gradient, weather, ambient and street lighting levels, availability of emergency ride/rescue, involvement of public transportation, etc. In my case I was able to make a very reliable system where the wife rescue was only needed for a couple controller failures, and there was no availability of public transportation backup (my bike ended up too big/heavy for a cab or bus). These days I have mid drives and even folding bikes with geared hubmotors that would more easily adapt to these backup scenarios but I don't have real world data on their reliability. I'd be a lot less happy with commuting if I had a lot of maintenance to do. I'm accustomed to vehicles with near zero maintenance, at least compared to 3000 or 10K miles. And I want some reserve braking on those big hills. How well do the geared hubmotors and mid drives fit into this use-case compared to a large DD, when taking all this into consideration?

Going up that 15% gradient the big DD makes a 3 times bigger EV grin, too. That's not really a necessity, but it is a fun way to start the end of day commute, and it gets your mind off work issues - right away. On a hill this steep you can pedal hard and make a difference. In this case I can feel the front wheel lifting when I stroke the pedal, as I set the motor current limit just below lifting the wheel. So it takes a bit of extra manual input to get lifting. So during starts and steep climbs you can get some very good sprinting type exercise, even with a big DD, if you set it up right.