Gas powered electric bike... would it be legal??

Timpo

Well-Known Member
As you know, one of the downside of ebikes is charging time, unlike gas powered scooter or motorcycles, you can't fill up the energy quickly.
I believe all states (if not most) require power assisted bicycle to be electric.

But there's nothing illegal about gas powered electric generator.
I think it's legal to carry it on your bike too.

So, if power assisted bicycles must be driven by electric motor, can you use gas powered electric generator to recharge the battery or to power the electric motor?

Just like Chevrolet Volt? Where gas powered engine is strictly there as a generator? Because Volt's gas engine is NOT attached to drive train.

The gas engine is NOT powering the bike, it is strictly there to generate electricity to recharge the battery.

 

Tars Tarkas

Active Member
I don't know about legal but as a practical matter it doesn't seem like it would be very popular. Who wants to lug around a loud, heavy generator? Maybe if you're on a cross-country trip and you already have a hundred pounds of tools, clothes, camping gear, etc., and you don't want stop to charge, and there are such people, certainly. For most people, if the range of a battery isn't sufficient for their ride, a spare battery is going to make more sense most of the time..

Park Rangers, or other people on the trails aren't likely to be very happy about the noise, so if this were to become popular it would probably very soon become prohibited in some places. Even in a one-off situation, I wouldn't be surprised if a biker in, say, a National Park, with a running gas generator would be stopped and asked to desist.

Someone commuting to and from work could probably get away with it, but why would they want to do it anyway?

I hope battery technology improves faster than any trend that might develop for gas powered ebikes!

TT
 

6zfshdb

Well-Known Member
Another issue with small gas engines is the exhaust can generate sparks. This is not a good thing, especially in dry wilderness areas. Gas engines also require maintenance like tune ups, spark plugs, oil changes etc.

There will always be those who try and skirt the law. I have to admit though, there is the "gadget" factor in carrying a generator to charge a battery. The practicality is another matter.

Diesel / electric locomotives have been using this principle for many years. The reason here is, an electric motor is easier to control than the massive mechanical clutch and transmission that would be required to handle the immense load of a freight train. This problem doesn't exist for smaller, lighter vehicles like cars and ebikes.

As stated earlier in the thread, it's hard to beat the efficiency of simply carrying one or even two spare batteries. A battery would generally cost less than a small generator.

IMO, the only place a generator / battery combo would be practical on an ebike is for an extended multi day off grid trip where charging isn't possible using commercial power.
 
It'd be interesting if someone worked out the math. How much gas would it take to charge a battery? Is that more or less efficient than carrying a spare battery or two? How fast doe sit charge?
 

Citycrosser

Active Member
The gas engine on a Chevrolet Volt is used to mechanically drive the wheels at certain points of operation. The only hybrid on the road currently in the U.S. where the gasoline engine is only used a generator is the BMW i3 REX as the range extender is only used to recharge the battery. All other hybrids, including the Volt, are designed so that the gas engine can drive the wheels. The Volt is unique in that the gas engine is dual mode, it can be used solely as a generator and/or it can drive the wheels.

It could be done and very well might skirt the law in your state. However, it would be difficult to find a lightweight engine/generator combo that would fit on the bicycle. From your picture, it looks like somebody has already built a custom unit that does so. As others have suggested, it seems it would be easier to carry a spare battery.

However, as suggested above, a multi day tour where recharging a set of batteries wasn't feasible but gasoline was somehow available might be the best use of such a hybrid bike.
 

PDXzap

Active Member
It'd be interesting if someone worked out the math. How much gas would it take to charge a battery? Is that more or less efficient than carrying a spare battery or two? How fast doe sit charge?
I didn't do all the math but the Earthquake ig800w in the video has a few Amazon reviews and from one of those reviews:
5 hour run time @ 70% load.
Assuming that figure is accurate:

.6 gallon tank @ $3/gal= $1.80 in fuel cost.
70% load= 560 watts x 5 hours =2800wh = 2.8kwh.
Using this generator and the above figures will produce electricity at a rate of $0.642 per kwh. That generator appeared to be around $250 new around 2014 and I have no idea how long it would last. Not sure if it's more or less efficient and it's not quite as convenient as another battery but it's much cheaper than a spare battery and can be used for other power requirements.
 

6zfshdb

Well-Known Member
I would be concerned about carrying the weight of that generator so high on the rear rack. The high center of gravity would most certainly throw off your balance making the bike difficult to handle. A trailer would be a safer option.

While this principle may technically be legal, explaining it to a law enforcement officer would be difficult. More than likely, you would have to go to court to fight the ticket and argue your case before a judge.
 
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trainman

Member
Most RV'ers don't like RV vehicles next to them with generators, I would feel the same with ebikes riding next to me. If it comes to the time that we have no place to plug-in and recharge our batteries, then we are all in big trouble. I said I would never buy an electric car, now I'm rethinking the idea, just rethinking for the time being.
 

PDXzap

Active Member
I would be concerned about carrying the weight of that generator so high on the rear rack. The high center of gravity would most certainly throw off your balance making the bike difficult to handle. A trailer would be a safer option.
👍
As far as legality in the USA, years ago many states treated any bicycle with a motor under 50cc and under 20 mph, as a bicycle. I'm not sure about now but I would see them quite often in Colorado, I've seen them in Texas, and have seen a few in Oregon. I always appreciated the economy they offered but most were too noisy for me.

The one in the video is listed as 40cc and seems fairly quiet. It would probably garner some attention but I doubt any legal problems would come from having this generator charge a battery as you're riding in the states.
 

Projectm

New Member
That's a pretty good looking mount/lock setup you created, from what the video reveals. Hard to see the details without better static photos.

As to rack strength, I think you are right to be a little concerned, because you have a very high, heavy load. It looks like that generator could put a greater moment (torque) on the rack with bike frame motion & vibration, since it's mass is so high, as compared to intended loading. Generator is cantilevered off the top of the structure, and mounted rigidly, so the mass can put a lot more force into your rack and frame than a rider using panniers could, even with much heavier loads - a bag and panniers would center the mass on the structure better, and be 'softer' for shock loads.

One way to try to assess this, is to manually push the generator around and look for any flexing. Wiggle it. Add straps to pre-load, or braces to reinforce, such as to minimize any flex. Without making anything so stiff that it saves the rack but breaks the bike frame...

Actually I would not be at all surprised to see you post back that it fell off after a bumpy ride. Not saying it will, but it looks a little sketchy and I think you are right to worry. Can you come up with a safety tether that will keep it on the bike if the rack lets go? Not to save your gear, but for the benefit of any bike or car traffic behind you! At least until you feel it's proven durable. Best not to drop flaming hot engine wreckage in the path.

I had a motor fall off a Z50 Honda minibike as a kid, causing both myself and my brother to wreck - he was chasing me on his in bumpy orchards - so I can relate to the potential carnage aspect. Don't ignore it. Drop that generator into traffic, cause accidents, get cops and hazmat called.....you should respect that risk.
 

rich c

Well-Known Member
That's a pretty good looking mount/lock setup you created, from what the video reveals. Hard to see the details without better static photos.

As to rack strength, I think you are right to be a little concerned, because you have a very high, heavy load. It looks like that generator could put a greater moment (torque) on the rack with bike frame motion & vibration, since it's mass is so high, as compared to intended loading. Generator is cantilevered off the top of the structure, and mounted rigidly, so the mass can put a lot more force into your rack and frame than a rider using panniers could, even with much heavier loads - a bag and panniers would center the mass on the structure better, and be 'softer' for shock loads.

One way to try to assess this, is to manually push the generator around and look for any flexing. Wiggle it. Add straps to pre-load, or braces to reinforce, such as to minimize any flex. Without making anything so stiff that it saves the rack but breaks the bike frame...

Actually I would not be at all surprised to see you post back that it fell off after a bumpy ride. Not saying it will, but it looks a little sketchy and I think you are right to worry. Can you come up with a safety tether that will keep it on the bike if the rack lets go? Not to save your gear, but for the benefit of any bike or car traffic behind you! At least until you feel it's proven durable. Best not to drop flaming hot engine wreckage in the path.

I had a motor fall off a Z50 Honda minibike as a kid, causing both myself and my brother to wreck - he was chasing me on his in bumpy orchards - so I can relate to the potential carnage aspect. Don't ignore it. Drop that generator into traffic, cause accidents, get cops and hazmat called.....you should respect that risk.
That’s not my rig, I just grabbed a random video on YouTube Of someone who built a bike with a gas generator on it. You’ll have to contact the guy on YouTube to criticize the design.
 

harryS

Well-Known Member
We ran the little Honda's all day to power timing equipment for our car club. Quiet and reliable. A lot of the volume is gas tank. Ours took about a gallon of fuel.
 

JRA

Well-Known Member
Anything is possible but sometimes not practical.

I am going to go out on a limb to say that the average daily useage of an eBike once they get established in our society will be less than 10 miles (16km). At this time and well into the past history of eBikes here in the US there have been all sorts of contraptions made up to regenerate electricity as a range extender. The only one that has impressed me is the one that Justin LeMere of Grin Technology built and rode last year but it was for a very specific purpose and a proof of concept carried out by some very savvy individuals that looked like a once in a lifetime adventure.

So I wonder to what end the average rider would ever need to add the weight and complexity of any sort of regen system such as a generator or even a solar panel? Access to a plug in receptacle anywhere in the US, outside of the obvious, is pretty easy so there really is no big deal in carrying your charger and taking a long break if necessary to up the Ah's. In fact at the level of prediction a very small battery would be all that is necessary for most applications. Of course there are those that will require more wh's and they seem to be the focus at this time by the manufacturers vis a vis going from 500wh's to 700wh's and offering what it thinks the current bikers want.