Planetary gears & pedaling

[eric.dickinson]

I don't currently have an eBike, but I've been reading about them some. And I was hoping that somebody could answer the following questions:

Some hub motors are described as having "planetary" gearing. I understand that planetary gearing can "add" two rotational inputs into a single output. So does this mean that any pedaling performed by the rider is added to the output of the motor? That is, if you're riding along on an eBike at 20 mph solely under power of the motor, and you begin to pedal, then you will begin to ride faster than 20 mph? No matter how slow you're pedaling? Or do you have to pedal "at least as fast as 20 mph" just to keep up with the motor before you see any change in speed?

Is such planetary gearing rare, common, or universal among hub motors?

Many states (I think including mine, AZ) have a 20 mph limit on what they will consider a bicycle. Does this apply to the maximum speed under motor power only? If a rider then pedals faster than 20 mph, is he in violation?

If you have an eBike that goes faster than 20 mph, can you use it at all on the roads? Can you pay registration on it and use it? Are you forbidden from riding in the bike lanes? Can you ride it in normal traffic? (Would you want to?) Or is a > 20 mph eBike completely forbidden on public roads, and serves only as fast toy?

Thanks for any help and insight you can provide.
Eric

 

[fechter]

The planetary gearing on most ebikes serves as a single reduction between the motor and wheel. There is only one input. Human input comes from a completely separate bicycle chain in most cases.

Interesting idea though. The Toyota Prius uses a planetary differential to do something similar.

 

[andys]

"If a rider then pedals faster than 20 mph, is he in violation?" Not in California, but I am not sure about other states. Here they go by 20 MPH max unassisted speed on level ground. You can probably even go a few mPH faster without much chance of a problem, but I have heard of 30 MPH plus hot rod E-bikes getting ticketed, especially in areas of Southern California

 

[Drunkskunk]

Its not dual input, but you can pedal faster than the motor would normaly go, up to a point. the faster you pedal, the less help the motor is going to give. Its very helpfull for getting up steep hills, though.

In Texas, the law is such that your pedaling and motor speed combined can't be more than 20mph. every state has a diffrent law, though.
In most plcaes, as long as the cops don't have a reason to stop you, then they don't care.

 

[dogman dan]

I live in NM and I hope we don't copy your ebike laws. They seem pretty tight to me, given that even very powerful ebikes are still not as fast as a 90 cc gas motorcycle. I think an ebike should be able to go as fast as a moped, since they are essentially the same thing. Here, my bike is basicly a moped legaly, but I want to use the city bike paths so when I ride them I try to keep the speed down close to 20 and don't piss off the other users of the path. On the street, I can reach 30 if I peadle hard enough.

 

[DahonElectric]

I don't currently have an eBike, but I've been reading about them some. And I was hoping that somebody could answer the following questions:

Some hub motors are described as having "planetary" gearing. I understand that planetary gearing can "add" two rotational inputs into a single output. So does this mean that any pedaling performed by the rider is added to the output of the motor? That is, if you're riding along on an eBike at 20 mph solely under power of the motor, and you begin to pedal, then you will begin to ride faster than 20 mph? No matter how slow you're pedaling? Or do you have to pedal "at least as fast as 20 mph" just to keep up with the motor before you see any change in speed?

Is such planetary gearing rare, common, or universal among hub motors?

Many states (I think including mine, AZ) have a 20 mph limit on what they will consider a bicycle. Does this apply to the maximum speed under motor power only? If a rider then pedals faster than 20 mph, is he in violation?

If you have an eBike that goes faster than 20 mph, can you use it at all on the roads? Can you pay registration on it and use it? Are you forbidden from riding in the bike lanes? Can you ride it in normal traffic? (Would you want to?) Or is a > 20 mph eBike completely forbidden on public roads, and serves only as fast toy?

Thanks for any help and insight you can provide.
Eric

You don't need a planetary geared hub motor to have dual power input -- electric motor + human power. Any powered non geared hub, be it Crystallite, Wilderness Energy, Bionx and a host of other cheapee Chinese hubs out there allow you to pedal with the motor on. The advantages of a planetary geared hub are that, you have relative high torque, low weight and a freewheeling hub. The freewheeling hub feature literally mean freewheel, meaning it spins like a free bicycle wheel when no power is applied. This is nice in that, you can treat your converted electric bike as a regular bicycle by taking out the battery pack and leave the motor in place. One advantage comes to my mind is cycling touring, where you would use the electric motor only on hills, while using human power to ride on the flats and coast down a steep downhill!

The planetary geared hub of today is just one speed I believe. Planetary geared hubs are not that uncommon though. Internal geared bicycle non-powered rear hubs of the earlier days also use planetary gears to give you multiple speeds without needing a rear derailleur. I know that this is going to an expensive engineering feat, but if someone could combine the Rohloff Hub 14 speed hub with a built-in motor, then man that thing will be so sweet! The most common and talked about planetary geared motorized hub system is offered by eZee, which comes pre-made with the motor, rim, tube, tire, controller and a Li-Mn 36V battery for like $1250. Good price. Incidentally, their 700c version can exceed the legal speed limit of 32km/h -- about 35km/h. I had tried the eZee kit myself before I got the Bionx and it is one sweet setup. I'm actually contemplating of installing the 700c version to my hybrid ( the Long Hauler) when I raise enough cash.

Speaking of the speed limit. Here's my take on it.. The legal speed limit is setup so that, no licensing, insuring and registration is needed for ebikes. I have seen some cyclists getting hassled by the cops here just simply exceeding the 20mph limit on bike paths. When I ride with my fast ride buddies on my carbon Trek with aerowheels, we can easily exceed the 20mph speed limit if we ride on a pace line, alternating quickly while breaking wind. Problem is, speeds like this are achieved through long and arduous training regimen, meaning you've earned your wings simply by being that fast with experience to boot which comes with the speeds we go for. People who ride ebikes can achieve 20mph without doing any work at all and as such are unaware of the dangers and the consequences of speeds like this can bring harm to yourself or simply to others on the road. As you know, there are slow moving pedestrians, slow moving human powered cyclists. People don't usually think what is the consequences of hitting a pedestrian with a moving ebike going faster than 20mph. If you go 25 to 30mph, what's the difference of the moving pedetrian being hit by a car or a bike? Since you don't have insurance, what are you going to do about this? What if the person sues you? Luckily in Canada, certain home insurance can cover this liability to a certain dollar figure. The riding club I belong to has a rider's insurance covering any sanctioned rides to any rider and 3rd party liable up to 2 million dollars US. We had to actually use our insurance once just because, we were riding on quite road one time and a stupid poddle came running out towards us. At 45km/h, you simply can't stop on a dime. But that doesn't seem to satisfy the woman that owned the dog. The dog's head got severed by the 52tooth chain ring of one of our rider's. And it was in the US and we are Canadians. Which means, lawsuit! And sure enough, she did hire a lawyer and did talk to our retained club lawyer and the last I was told, got a sizeable settlement in her favor. You know what, I wouldn't be able to sleep at night worrying who's going to sue me if I happened to accidentally cause bodily harm to someone on the road because I rode too fast! And if a sizeable settlement is a seven figure amount, I would have to declare myself bankrupt!

Don't forget that you are not insured on the road when you ride a bike. But people think they are because they are so used to driving cars!!

 

[DahonElectric]

I live in NM and I hope we don't copy your ebike laws. They seem pretty tight to me, given that even very powerful ebikes are still not as fast as a 90 cc gas motorcycle. I think an ebike should be able to go as fast as a moped, since they are essentially the same thing. Here, my bike is basicly a moped legaly, but I want to use the city bike paths so when I ride them I try to keep the speed down close to 20 and don't piss off the other users of the path. On the street, I can reach 30 if I peadle hard enough.

I think if ebikes riders are licensed and insured, then I don't see why they should be speed limited. But their appeal is exactly the opposite, which is no licensing, insuring and registration is required for most countries. I think we are seeing people who are looking to save some money by choosing an ebike because of their cost effective appeal and to boost their voltage up so they can be ridden as fast as a motorcycle. Unfortunately, the downside of the equation to this is when the s*it hits the fan, that is when accidents do happen. Who is going to be liable? I mean, the faster you go, the more likely you're going to be involved in some kind of an accident.

I hope that you people don't just walk away from an accident, leaving the injured party unattended and defenseless fearing that you might have to shoulder on the cost of the bike repair and any medical and hospital bills you might have to incur. With a car, I call an ambulance if the person is in serious agony and then when the opportunity avail to myself simply jot down the other person's licensing and insurance information and be on my way. With an ebike, what will you do?

 

[dogman dan]

As usuall my communicating may be inadequate. I meant that in the street, I should be allowed to go 30 mph, and if I read my state law correctly, I belive I can since my ebike is a moped in NM as near as I can interperet it and can legaly go 30mph. I can also ride my non electric bikes 30mph, though not nearly so far, legaly in a 30 mph speed zone. But when I use either type of bike on the bike path, which is used by lots of joggers and other pedestrians, I allways slow down to about 5 mph and warn with a horn, per state law before overtaking, and will pass faster if people are traveling toward me and see me. I try very hard to be courteous and share the path, since I may or may not be allowed on it. At this time, there is no rule allowing or disallowing my use of the path. No speed limits either, but I figure 20mph is as fast as could possibly be safe around the others on the path, and when I need to I will actually stop behind joe oblivious. As i heal up from my own stupid mistake, I am well aware of the consequences of a crash. Thank goodness I have health insurance to cover the $12,000 my over the handlebars boo boo cost. That one was entirely my fault, with nobody else involved fortunately. Never get a water bottle stuck in the front wheel!

 

[dogman dan]

I was just reading again the AZ vehicle codes, and the way I read it, an electric bicycle can never exceed 20mph legaly. So peadling, downhill , whatever, 20 mph is the max in your state. But you can't be kicked off a bike path either, so that is good. If you want to call your bike a moped, then you can go 25 mph max, even downhill or whatever, and have to register and pay a fee. And then no bike paths. So you are just plain stuck with slow in AZ, as I was thinking.

In NM there is no such thing as an ebike in the law, just mopeds. Mopeds can go 30 mph, no registration or fees. But I have to have a valid drivers licence. But since my bike just barely meets the federal consumer products definition of an ebike, I feel ok riding on the bike paths. By that law I'm limited to 20 mph of speed on the motor alone, on flat ground. So if I peadle hard, and go 30 I'm legal, unless the street is limited to 25. Cops here will ticket a speeding bike rider. Under no circumstances is it legal for me to go faster than 30, unless I'm on a regular bike, then the speed limit is the top. But there is no posted speed limit on the bike path. I suppose I go by the adjacent streets speed limit, which is 30.

 

[eric.dickinson]

Thanks a lot for all the info and insight. I guess it's too bad about the single-input planetary gearing and the AZ power-assist bicycle laws.

Any thoughts on which state has the most liberal eBike laws? Obviously with the higher gas prices, now might be a good time to write my local representative, and pointing to another more-permissive state as an example could prove useful.

Eric

 

[pwbset]

Any thoughts on which state has the most liberal eBike laws?

I live in Montana where it's max 50cc (not sure an equivalent sustained wattage of that since cc is volumetric and difficult to directly convert to h.p. etc.) and 30mph for a "bike". My top speed at 84v happens to be about 29-30mph. Convenient. 8) Truth to tell I rarely go over 22-24mph because it starts to feel pretty scary on the old rickety MTB.

Montana Bike Statute - "61-1-123. Bicycle. “Bicycle” means: (1) every vehicle propelled solely by human power upon which any
person may ride, having two tandem wheels and a seat height of more than 25 inches from the ground when
the seat is raised to its highest position, except scooter and similar devices; or
(2) every vehicle equipped with two or three wheels, foot pedals to permit muscular propulsion and an
independent power source providing a maximum piston or rotor displacement may not exceed 3.05 cubic
inches (50 centimeters) regardless of the number of chambers in the power source. The power source must
not be capable of propelling the device, unassisted, at a speed exceeding 30 miles an hour (48.28 kilometers
an hour) on a level surface. The device must be equipped with a power drive system that functions directly
or automatically only and does not require clutching or shifting by the operator after the drive system is
engaged."

 

[dogman dan]

Nice, that means regular mopeds are allowed on bike paths for sure. Here, I think so, but it really doesn't say, so I rely on still being under 20 mph with no peadling, and peadle hard ,or am downhilling to go 30. The heck with faster than 30 on this bike though. Too sketchy.

 

[pwbset]

(2) every vehicle equipped with two or three wheels, foot pedals to permit muscular propulsion

Nice, that means regular mopeds are allowed on bike paths for sure.

Mopeds with foot pedals at least. Most mopeds are step-through/sit-on-top these days aren't they?