planetary geared mid-drive verses geared hubmotor?

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Jun 20, 2015
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I am almost finished building my Mt.Goat Cycletruck / with Cyclone mid-drive. I am thinking about using a different motor on another bike that would also carry cargo. So I need some ideas. Can every one just tell me the pros and cons of using a 5 to 1 [or lower if possible] geared hub motor compared to something like the Bafang BSHD 1000w geared mid-drive?

With only one gear ratio. The hub motor would be more simple, but the mid-drive could be a more efficient hill climber?? but it seems to me as if the mid-drive could have much lower gear.

And can the BSHD have two chainring gears? This is what I want to do with my Cyclone, and only one gear in the rear, simply because I cannot hear or feel the gear my rear sprockets are in, then I some times get a jolt when I start the motor again. So I have taken to changing the rear gears while I am pedaling with the motor off. Not easy in high gear.

There may not be much argument for using any hub motor, like how is it possible to compare a mid drive with a gear as low as 20:1 or 17.7:1? [6:1 x 3.34:1=20.04 to 1 ratio]…. This is a lower gear than I had thought it would be. Maybe it would be better to compare it to using two geared hub motors?

How would they compare if they could?

1. In steep hill climbing with a large total combined weight?
2. Battery size needed?
3. Wasted energy as heat?
 
Mid Drive's are good for hill climbing because you can choose the gearing with your bikes shifters. The downside to a Mid Drive is that it sticks out to anyone viewing from the side angle. Brits/Aussies/NewYorkers/Some Europeans seem to care about obeying the law for wattage.

Both are noisy due to the gears. I rode the Cyclone 3kw and people could hear me coming from behind, I also rode a 300W geared brushed motor, same thing. The rear geared hub can be hidden easier then the mid drive, front hubs would need a funny looking front pannier system. No one thinks twice at a rear pannier system, hiding a rear hub.

I am not up to date on gearing of geared motor, just know there is a (or some) with the ability of 2 speeds inside the hub itself.

Here is a good article to read. Has a list of 2 speed hub motors.
https://www.electricbike.com/2-speed-e-matic-xiongda/
 
As I understand it (no actual experience here) geared hub motors have to have their gears rebuilt periodically. Whereas a gearless hub motor is probably going to be quieter and not need gear rebuilding. With a gearless hub motor you can still use the derailleur system you have, but not an IGH.
 
If you pull more than 300 pounds total weight up long steep hills with a typical 500w rated geared hub motor, you are risking melting it. at 400 pounds total weight, you pretty much guarantee a meltdown on a hill longer than 3 miles. They come in 5 to 1. I'd love to see a giant size motor with 500w rating and a lower ratio. Would be great for pedicabs and such. Basically the same core, but big ass, lower ratio gears on it.


These motors are not designed for cargo, or 250+ pound riders. A large DD motor will be the better choice if you want a hub, but the best choice may still be a mid drive. Because it can run in as low gears as you have. Most mid drives though, only give you one, not that small front ring.


Really big cargo, and or really big hills, a really big dd hubmotor works fine, with at least 2000w feeding it. I would maintain 15 mph up 8% grades weighing 450 pounds total. Me 200, bike including big ass battery 150, and 100 of cargo. These hills were the rocky mountains, so up to 10 miles of continuous grade on some of them.


This all pertains to one 500w rated geared hubmotor, the big ones. TWO geared hubmotors would be able to stand 600 pounds total weight with few to no problems.


FWIW, I only explored the limitations of this type motor by testing to destruction on a mountain. They pulled fine with big weights on flat ground. Lots of stops would heat them up, but if not stopping every block, they got hot but not melting at 400 pounds. I never found the destructive weight limit for that motor on the flat. Something over 400 pounds is all I know.


As for wasted heat, only the big DD hubmotor is capable of pulling 400+ pounds up steep hills fast enough to stay in a relatively efficient rpm. smaller 500w rated dd motors would slow and get inefficient, but not melt by top of the mountain, but theyd waste energy into heat. The big ass 25 pound dd motor would just cruise up it at 15 mph, and stay barely warm all the way, in summer heat. Pulling 2000w up a long ass hill does take watts, but they were not wasted watts. If you want to be heavy up hills with a hubbie, make it big. ( or two motors)


Mid drive, low low gear, and 7 mph up that same grade would take less power, and more time. Mid drive for the win on total energy cost.


No energy penalty for the big ass dd motor once over the hill though, both types, at 15 mph on the flat, will pull very efficiently. 15 mph or less of course, you start to pedal a lot of your total watts, really increasing efficiency. Nothing efficient about 30 mph on the flat, either type motor.
 
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The planetary gears in the cyclone are nylon and do not make enough noise to hear, and they last for many years. Maybe I should open it up and gerease it every summer? There is no rebuilding, just pop out the old ones and pop in the new ones. I also do not hear my chain, do large chains make noise?. The only noise I hear is the motor, and on the walking trail I ususaly slow down to pass people so they don't even hear that over the rattling of my trailer.

The myth that gears waste energy is simply not trrue, they use energy to convert kinetic energy into torque thrust. That is not a waste. Without gears we would be a world of wasted energy.

Hub motors on the other hand waste so much energy as heat that they have a hard time getting rid of it; If you want to see a thread about how to vintelate them better. This one uses fans: https://endless-sphere.com/forums/viewtopic.php?f=28&t=64098

Too bad they don't make a stronger hub motor that has two gears. There is the that 250 watt two speed hub motor but that is not enough power to climb steep hills with cargo [I wonder what the weight limit on that would be]. They need to make one that can put out at least 1300watts. I suspect that most hubmotor users zoom up hills so fast that they do not understand the need for gears, also having a large battery pack can keep you going fast enough to not have a problem with hills.

I really need to build a 36Ah pack. Then I would have more than enough power to climb our steep hills with a load of bricks, or children [500 to 600lbs total combined weight]. But I would still need a super low gear, unless I could use the full 3000w my cyclone can put out at 72volts. But I suspect that it would still overheat the motor and/or battery.

My planetary geared cyclone has a 6:1 reduction and I use 20:1 for the steep hills and 16:1 for most other hills with a 11:1 for crusing. I don't bother to pedal because my knees are wipped out with arthritis.

I am averaging about 40watt hours hours per-mile without pedaling at an average of 10.5mph and crusing about 16mph. With a total combined weight of about 400lbs.

The only time my cyclone got hot was when I was climbing a mild hill with too much fire wood in a high gear at 1400 watts. After shifting down to my lowest gear the motor used only 650watts.

No one told me that li-ion batteries need to use only half of capacity [80% charge] to last longer than a few years.

The first steep 16% hill I climbed I was accelerating when I saw a car coming up behind me. But then I realized that I did not have a meter on the bike yet and had no idea how much power I had left. So later on the same trip, when I droped the voltage below the cut off point I did not know that all I had to do was to reboot the controller.
 
Hugh-Jassman said:
The myth that gears waste energy is simply not trrue, they use energy to convert kinetic energy into torque thrust. That is not a waste. Without gears we would be a world of wasted energy.

That torque conversion happens at less than 100% efficiency-- sometimes a lot less. Gear teeth slide against each other's faces under heavy pressure; there's also lots of load on the pins that they revolve on, which more often than not have plain bearings. The fact that when you put 1kW into a gear reduction, you get less than 1kW out is what people are talking about when they say gears waste energy.

Gears are slightly less efficient than clean chains and sprockets, per stage.
 
Planetary systems have extremely low forces on the bearings except what the chain imparts on the output. The simple nylon gears in cyclones have soaked up many miles at +4kw.
Compare that to the BBSHD eating gears at half the wattage.
 
Grantmac said:
Planetary systems have extremely low forces on the bearings except what the chain imparts on the output. The simple nylon gears in cyclones have soaked up many miles at +4kw.
Compare that to the BBSHD eating gears at half the wattage.

Yes the Cyclone 3kw is a great motor, it could haul my phat 380lb ass, up a 15-20% grade with ease. Victoria is a very nice city, been there a few times myself. I rode a CCM down the Galloping Goose Trail from Swartz Bay Ferry Terminal to downtown victoria, what a nice ride. I was doing it old school no electrification. I can't remember many hills even in Victoria, but its nice warm weather. I laughed when it was -10C and they gave out a cold weather warning and them cold weather shelters opened up for the homeless. But to my suprise that -10C was bitter cold, maybe that humidity gives it that extra bite.
 
I believe that would be the Lochside trail, a lovely one that I've ridden before ebikes were around.
My riding is in the Highlands area which is aptly named, lots of steep areas especially off road.
 
what would be the waste fator compaiered to just using a high gear?
my battery is too small to test it out.


Chalo said:
Hugh-Jassman said:
The myth that gears waste energy is simply not trrue, they use energy to convert kinetic energy into torque thrust. That is not a waste. Without gears we would be a world of wasted energy.

That torque conversion happens at less than 100% efficiency-- sometimes a lot less. Gear teeth slide against each other's faces under heavy pressure; there's also lots of load on the pins that they revolve on, which more often than not have plain bearings. The fact that when you put 1kW into a gear reduction, you get less than 1kW out is what people are talking about when they say gears waste energy.

Gears are slightly less efficient than clean chains and sprockets, per stage.
 
Hugh-Jassman said:
what would be the waste fator compaiered to just using a high gear?
my battery is too small to test it out.

There are too many variables. Precision of the gears, type of bearings in the gearbox, type of lubrication, number of reduction stages-- gears can range from about as efficient as a clean new chain drive to, well... however inefficient you can imagine. Consider really cheap wind-up toys.

The gears that e-bikers are willing to pay for aren't about to win any prizes for efficiency. I'd put them on par with dry, worn, and dirty chains, per stage.
 
well I supose I will need to consider that energy loss as "used" energy.

the planetary gears on this cyclone are almost silent....





Chalo said:
Hugh-Jassman said:
what would be the waste fator compaiered to just using a high gear?
my battery is too small to test it out.

There are too many variables. Precision of the gears, type of bearings in the gearbox, type of lubrication, number of reduction stages-- gears can range from about as efficient as a clean new chain drive to, well... however inefficient you can imagine. Consider really cheap wind-up toys.

The gears that e-bikers are willing to pay for aren't about to win any prizes for efficiency. I'd put them on par with dry, worn, and dirty chains, per stage.
 
Hugh-Jassman said:
well I supose I will need to consider that energy loss as "used" energy.

the planetary gears on this cyclone are almost silent....

Cyclone and Bafang gears are both surprisingly good given the price point. I expect they use as much energy as a secondary chain reduction, give or take a little. The small reduction loss is definitely worth how clean and low-maintenance they are.
 
LeftieBiker said:
With a gearless hub motor you can still use the derailleur system you have, but not an IGH.

I'm still trying to figure this one out. Why not...?

Internal gear hubs don't use derailleurs (except those with cassettes like SRAM Dual Drive and Sturmey Archer CS-RF3).

A derailleur can still be used as a chain tensioner for a bike frame that has vertical dropouts.
 
Chalo said:
LeftieBiker said:
With a gearless hub motor you can still use the derailleur system you have, but not an IGH.

I'm still trying to figure this one out. Why not...?

Internal gear hubs don't use derailleurs (except those with cassettes like SRAM Dual Drive and Sturmey Archer CS-RF3).

A derailleur can still be used as a chain tensioner for a bike frame that has vertical dropouts.


<Slaps head> Damn, I knew that! For some reason I was reading "IGH" as just "geared hub(motor)" (the gears are internal in those, too). Ooops!
 
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