A DIY E-bike Conversion on the Cheap
spectrum.ieee.org
spectrum.ieee.org
I don't know how important some of these improvements are, I just remember reading this advice more than once, and safety is important. So be smart and do your research.
The Grin Technologies motor simulator https://ebikes.ca/tools/simulator.html predicts (the "Load Line") 837 Watts for "MTB upright", 648W for "MTB, Tuck" and 570W for "Road, Tuck".
I do find that in an upright position it takes 100-200W of human power in addition to 750W power measured at the input to the motor controller. The controller's pretty efficient, but the motor (GMAC) is only 85% max, so there's maybe 570W at the axle. The US CPSC and California laws aren't clear whether the 750W/1 horsepower limit is power in or power out, but power in is what shows on the display, so I limit it to that. Also, even a mild grade will cause the motor to approach the 70 deg C limit I chose after 1 minute. I live in the flattish Santa Clara County, but I'd definitely want a mid-drive if I lived in a hilly area. A 250 or 350W Riese & Müller Delite https://www.r-m.de/en-us/bikes/delite/ I test rode needed a lot of human power to hit the 45 kph max, but it climbed hills in Larkspur like a goat.
750W will have no problem getting a recumbent bike to 30MPH, but don't count on it for an upright.
When I think electric motorcycle, I think of something that does not have pedals at all.
The US "class" system seems useful, inasmuch as it more or less specifies the capability of the bike with and without pedaling. I'm all for adding a new transportation / recreation option, and have adopted a wait-and-see attitude for how the technology and its use will evolve. So far, e-bikes have not affected my use of a conventional bike, except for people asking me when I'm going to get an e-bike.
As an example, https://en.wikipedia.org/wiki/Puch_Maxi
The only next thing we saw was the Honda Spree, which as I recall had an electric starter and whatever qualified as an "automatic transmission," and I think that class of scooter is still more or less the standard today. It seemed like a big step forward in terms of ease of use.
And the great bit is that if you are ignorant of these laws and get caught on an electric bike doing higher speeds then you get a penalty as if you are riding a motorbike without insurance or a license - aka penalty points on your regular driving license, plus all the other court shenanigans.
A used bike might fit your bill. Or the DIY route. The friction motor might be a bit iffy, but you might be able to buy an electric front or rear wheel for not too much and use the same electronics.
Most of us really wouldn’t mind if people who needed a little extra help (older people, injured people, people new to the sport) were riding bikes that provided a small assist to help out with the hills. It’s actually great to see older people being able to ride again with some help from a motor, for example.
But instead, we’re seeing a lot of e-bike builders abusing the concept to hack or build bikes that are basically electric motorcycles. It gets old fast when your local mountain bike trail is now crowded with kids motoring up the mountain on their modified e-bikes without even pretending to pedal. It’s even worse when they end up deep into trails they’re not qualified to ride with a dead battery and no natural ability to pedal back out.
The end result has been a blanket ban on e-bikes on most trails and a lot of animosity toward e-bikes. I wish there was a better compromise, but after watching all of the dumb outcomes play out on my local trails from a small handful of people abusing the concept, I understand why it had come to this.
Occasionally there will be someone waiting at the trailhead writing tickets to people who come off the trail with an e-bike or an off-leash dog. This seems to work as word spreads through Facebook groups and people stay away. Also generates some decent revenue when someone can write tickets for an hour and hand out a couple thousand dollars in fines for blatant violations (they stand right next to the very clear signage at the trailhead)
I am pretty sure this is not currently true on almost all US National Forest land. Anything with a motor qualifies as for motor vehicle there and you will only be allowed on trails marked for motorized use on the MVUM maps. This includes mobility devices
For example, a 2021 Chevy Surburban is a HUGE SUV, but does 70mph-0 in 166 feet. Better than a 1999 Camaro Z28 or Mustang GT, at 184 and 182 feet, respectively.
The article with the Suburban data: https://www.caranddriver.com/features/a35048882/tahoe-yukon-...
Mustang and Camaro:
https://www.caranddriver.com/reviews/comparison-test/a151408...
In the 2000s one of the car magazines tested top trim (big engine, race package, etc) classic muscle cars on modern tires and they put down respectable numbers, not better than 00s cars, but respectable.
Suspension and chassis stuff hasn't come all that far since the 90s so high end cars of that era should be able to handle very respectably compared to modern stuff. The differences are more apparent at the low end. Modern crossovers handle very respectably for what they are.
Obviously modern stuff will always win in a straight line because power levels increased massively over the past 20yr.
You have to go back to the days of drum brakes and no power assist for this to even be close to true. Yet it gets tossed around in every comment thread about modifying anything that rolls because it gets easy virtue points from the safety crowd.
OE brakes on damn near every vehicle made in the last 50yr from a Walmart bike up to a semi truck are more than capable of stopping harder than even nice tires can grip the road. Will you go through more consumables if you use the vehicle harder (enabled by having more power on tap) sure? You'll also go through more tires too. That doesn't mean the brakes are insufficient.
You can shift towards the back of the bike with your body for instance.
Like the body of a larger person or a person wearing a backpack?
On the down tube is better. Carrying the batteries in a back pack can be done. I did that for a few months.
It's really life changing. I used to ride a motorcycle, and I still own one, but I seldom use it anymore; the ebike is absolutely perfect for short commutes (under 20 km each way).
That said, complete ebikes are more available now, and at good prices, so conversion kits are becoming less relevant.
You can get cheaper and way more expensive but I think this is the sweet spot. (For comparison My non ebike is a hybrid commuter which was about 600)
Besides people always get suckered into getting way nicer/newer cars than they really need (myself included). Financing is a difficult thing to keep at the low end. So in practice it’s not really comparable. But cars obviously have plenty of other benefits.
So do high-end non-e bikes.
The ones I like are $2000 to $12,000.
I'm waiting for a Henry Ford type of guy to bring those costs down. I guess the lithium batteries are a big factor in costs?
In the mean time, I'm sticking with my old Zapp bikes. I need a battery though.
You can already see a litany of comments expressing support for regulating ebikes so they remain a novelty niche in this very thread.
There is SO LITTLE material overall in a bike, with 99% of the tech having changed little since the '70s, so I guess it's not patents or IP either. It's not the wheels, I can buy replacements for little. It's not the shifting system, a crappy one is 100 EUR and a decent (low-end) Shimano is under 200. It's not the chain, those are 10 bucks, maybe 25 for the higher strength ones appropriate for an e-bike. It's not the motor, as I can get a conversion kit off ebay for 150-200, which includes a wheel and electronics.
Yet, 25kg of ebike costs 12% of 1000kg of a low end city car, while using 40 times less material and not having to undergo all the same rigorous testing, homologation and what else.
What am I missing? Is it all in the frame? Is it all profit? Am I looking at this from a completely wrong perspective ?
Also there's been a lot of consolidation, and there aren't many big bike manufacturing companies, so some illegal collusion is not out of the question.
If you look at bicycle parts then it seems like half the parts get updated once or twice a decade. Yet the old stuff was mostly fine.
Anyway, the cost of ebikes has gone down a lot over the years, especially as more and more competition shows up and production of various parts (batteries, motors, control units) has scaled up. I just had a quick boggle, ebikes start at around €1200 at the moment (cheaper too, but those are folding bikes).
The e-bike has maintenance costs close to 0.
Cars need insurance and fuel at the very minimum.
Not perfectly true. You have to renew brake pads, tires, chain and cassette at regular intervals if you ride a lot. They cost way way less than car maintenance though.
Depending where you live, how much paperwork you can cope with and how much you earn, the government will give you up to 50% of the purchase price back.
Most of the cost of a used car comes after you purchase it, though : )
Very true! French cars are certainly no exception to that rule :-)
This. I gave up after reading the list of documents I would have to produce.
It varies by metropole. Here in Nice it seems straightforward.
He got the better part of that deal. (You have to put a price down on the title when you sell. In this case it was technically $1...)
Downhill mountainbikes are popular conversions. They are designed with high speeds and impacts in mind. The cost may be prohibitive to many DIYers though.
For high speed (50km/h), adequate tires are also necessary. E50 rated tires are now widely available that can handle the speeds and loads.
I wouldn't recommend converting a road bike as they are more fragile.
I’d guess e-scooter/moped is next best thing tho parking is an issue in some places.
A "cheap" bike is just a rigid frame with rigid forks.
A fat tire can stand in for a shock, but "cheap" bikes don't usually fit 3" of rubber either.
[1] https://elettrica-bike.it/en/product/fat-bike-vulcano-s-tipe...
I don’t see any ebikes being sold without at least a 50mm front shock. The added weight of the battery+motor makes it essential
Ahhhh I think I understand - it's a "speedbike" right? So only for driving on roads like a car, so there's no question of forest tracks or gravel walkways.
Yep, they're both commuter/cruiser type bikes, so probably not best offroad.
Both have the top end Bosch Class 3 motor, so they're usually against the rules on trails in my area.
If you ride it like a bicycle and try to avoid potholes and curbs, simpler designs work great.
My assumption is that people buy them since they are a touch more comfortable than a full rigid bike frame.
You're much more likely to target a "trail" full suspension mountain bike or fixed tail bike. You'll have a lot more cost options and they're more suitable for a commuting purpose, they'd still have plenty of travel and braking compared to a standard commuter or utility E-bike. As a note, my mid-level trail bike came with a better set of brakes then my high end cargo hauler e-bike which weighed about 10 times as much.
Long seatposts that bring you up to a typical height are fine. The suspension is doing the work, no need to leave the saddle.
(It's worth mentioning that the other main reason you don't see regen used much on bikes is that freewheel systems allow the use of gearing, which greatly improves starting torque, which really is what matters for ebiking comfort. Direct drive systems are less efficient, so they are already starting from behind the curve with regards to making regen worthwhile.)
Get an electric moped/scooter/motorcycle if you want to ride faster than you can pedal.
I was thinking, the one in the linked article uses friction against the back wheel. What happens the moment you get a good chunk of debris in there? It could get painful very quickly.
There are kits available to convert a low performance e-bike into a high performance one, which runs much faster and needs a registration and a number plate.
But cause an accident, which doesn't even needs to be your own fault with such a revamped bike and your insurance will tell you that you're shit out of luck and you will have to pay for the whole damage. Potentially ruining your life.
As a motorcyclist, electric bicycles make me very nervous.
1. At 60 km/h you are going the speed of a car but car drivers don’t expect you to be going that fast and as a result aren’t wired to look for you. Doesn’t matter how fast you were going when a car going 60-90 km/h didn’t see you and ran you over.
2. Brakes are only half the equation. If your tires start slipping your brakes will lock up and then you go splat.
3. If you do happen to get off at 60 km/h you will have road rash that will take off large chunks of skin even if you wear an armored jacket and armored gloves. In spandex you’ll be looking like Deadpool pretty quickly.
4. Your tires will heat up pretty quickly at these speeds. That will affect how they handle quite a bit.
I certainly wouldn't casually ride the shoulder of a US highway at 35 mph.
Motorbikes are certainly louder which IMO why we should ban motorbikes altogether. I hate visceral hate to them.
Your best bet is to have all your clothing match your bike, Power Rangers style, to increase your chances. And lots and lots of very bright lights. One little handlebar mounted light is going to look like a reflection or a flashlight.
I only road residential roads and bike paths, planned my route carefully to avoid highways. Key things are to take the lane if you can do the speed limit and only give it up if safe to do so. Avoid driving close to parked cars that will open their door and kill you. Watch left turns in front of you.
The thing with riding that on a bike path was that I had no concerns slowing down amongst pedestrians or on blind corners as it was no effort to get back up to speed. I was less inclined on my road bike due to the effort. Road bikes can get up to that speed, had a few that came close to pacing me. I understand the sentiment but I had zero incidents in four years of commuting. I was courteous, used a bell. Half my ride was up hill on the path and it did 30km/hr there. Everyone went pretty fast down of course.
I'll admit, I did enjoy passing spandex on expensive bikes with my beater bike wearing jeans. This was a decade ago when ebikes were not at all a thing.
Many bike paths seem to discourage slowing down for junctions by putting them in dips - the opposite of how some train stations are on a hump as "gravitational regenerative braking".
45-50km/hr idea fairly easy though with a 48 volt system.
>If you do happen to get off at 60 km/h you will have road rash that will take off large chunks of skin even if you wear an armored jacket and armored gloves Wouldn't that happen with a motorcycle too? I don't see your point
didn't a celebrity spin out of control in a backyard and break his back at less than that? https://www.theguardian.com/media/2020/aug/09/simon-cowell-b...
I think part of it may be familiarity perhaps, which I assume is higher in Euroworld.
https://www.youtube.com/watch?v=fvXG4gQ2FWI&ab_channel=Digit...
That would not even remotely be classed as an electronic bike in the EU.
It is far too powerful for that.
His electric motorcycle had a top speed of 60 mph (97 km/h) and a motor power of 15 kW.
The legal limits for a pedelec cycle in the EU are a maximum assisted speed of 15.5 mph (25km/h) and a motor of no more than 250w.
The motor in Simon Cowell's electric motorcycle is 60 times as powerful as the legal limit in the EU
When I first read the story I had assumed the accident occurred at very slow speed or full stop and mashing the throttle - so the 60mph v 25 would not have been something I would consider..
but 15kW vs 250w - now this is something that makes sense in this scenario for sure!
glad to have learned to eye this metric for this.
Riding one yourself, or others riding them? And if you could elaborate, why do they make you nervous?
The difference between the cheap version of a motorcycle and the sport version isn't the engine, it's the brakes and suspension ( and now electronics).
But the main thing is the lack of helmets. One motorcycles, the center of gravity is low. You are more likely to fall and slide than go head over handlebars. At motorcycle speed, you should be wearing a full face helmet. I very rarely see the guys on e-bikes wearing full face helmets.
Then you look at the wheels and tires, higher speeds means more acceleration and faster stops, means more wear- which means much more maintenance. That most people aren't really paying attention to. Maintenance on two wheels is more than just a reliability issue, it's a safety issue.
Finally, people give no respect to bikes on the road. Especially in the US. You could be cruising along at 30 mph at the speed limit and someone will feel the need to pass you because you're on a bicycle.
Some parts/combinations have known issues that you're just better off avoiding.
I haven’t been keeping up with the forums lately. The last I checked, the bottle neck for performance was people’s motors overheating. So there was a general effort to take a stock motor from China and drill coolant channels into it and attach a cooling loop. Dr base had some promising progress but I’m not sure anyone ever finished it.
There used to be this guy who you could send your inverter to in SF who would add extra solder to the power traces and modify it from stock to juiced up and ready for tons of current. The atmosphere in that website was just perfect because it was just a bunch of dudes who were a weird combination of speed freaks and electronics nerds. Amazing times.
That site really defined how good the internet could be. I remember Justin documenting his trip across Canada on one thread. So many cool builds.
I moved eight years ago and turned my ebike into a rope tow for the kids to use on my very small back yard ski hill. So haven't followed it after that sadly.
I would imagine the common issue with integrated systems applies and makes it expensive: the lifetime and quality of the whole wheel is dictated by the lifetime and quality of the worst part. E.g. the brushless motor may run for years, but a battery cell, or crappy ic breaks in months in bad weather.
It seems like they have since pivoted to scooters.
I've seen those used on electric kick scooters that are still supposed to feel like a kick scooter, i.e. no throttle lever or controls on the handlebars.
Kostka, the local kick scooter manufacturer sells those: https://www.kostkakolobezky.cz/hill/920-elektrokolobezka-kos...
IMO the reasons it never took off were:
- Expensive. You can get an electric bike conversion kit for $500 or less, compared to $1000+ for the Copenhagen Wheel. Don't get me wrong, the engineering on the Copenhagen Wheel was amazing, definitely worth the extra money, but it was too expensive for delivery guys to use.
- No replaceable battery: again this rules out delivery guys, as well as all-day rides.
- Requires a smart phone to use it. This was the biggest reason I stopped using my Copenhagen wheel. You needed to use your phone to unlock it or change the speed settings. I don't want to need my phone to ride my bike. What if I lose my phone or the battery dies? What if the server goes down or the company goes under?
Airlines which will happy carry a non-motorized bicycle as a standard checked bag, won't touch a motorized bicycle at all.
So a conversion which can be easily and unambiguously removed, might leave you with a checkable non-motorized bicycle, and unrelated, a small motor, some electronics, and perhaps a TSA-compatible small battery. Then add say a commonplace "portable power station" battery shipped to/bought at your destination.
So no, I am not joking.
Sorry for the tone, I honestly thought you might be joking.
I tried a 72 volt setup for about a week. Too fast lol.
I went through an airport with a home-made LiPo in my backpack. Fortunately one of the TSA recognized it was just a battery but it was a really scary few minutes. Lots of very silent stares
I’ve seen a couple of “spicy pillows” smoke out, never a full thermal runaway fire - thank god
https://www.faa.gov/hazmat/packsafe/resources/media/Airline_...
https://www.tsa.gov/travel/security-screening/whatcanibring/...
A TSA-compatible 99 Wh power brick or two, suitable for checked and carry on, providing limited duration and assistance, but being at hand.
And a COTS "portable power station"[1], which can be ground shipped to meet you at your destination, from home, or from a store.
The ideas are to optimize the bike for shipping by removing any trace of the battery from it. And to optimize the battery for shipping and availability by going generic.
EDIT: Another comment[2] observes the battery in the post is available from Home Depot, so that might suffice for COTS generic availability. So an airline story might reduce to: leave the battery at home; attach the conversion with velcro instead of zip ties (or bring snips and a bag of ties); unbolt and remove the conversion before check in, and bag it separately from the bike; get a new battery at the destination, by visiting or shipping from Home Depot; and put the conversion back together.
[1] eg https://www.amazon.com/s?k=portable+power+station [2] https://news.ycombinator.com/item?id=28270285
This comment[1] reports the article battery as 160 watt hours, so 2x 99 Wh might be an upgrade.
One use case I pictured was last leg after airport arrival when traveling minimalist and budget. As a transportation alternative/supplement to mitigate last-miles time/$/hassle cost.
"While most airlines do not have a firmly defined maximum number of batteries under 100 Wh that can be brought aboard, we'd suggest travelling with no more than 4-5 LiGo's per person in order to avoid extra scrutiny. We have had customers travel by air with as many as 12 LiGo modules on them, but we wouldn't recommend that as a matter of course."
People traveling with folding bikes and LiGos: https://www.bikefriday.com/folding-bikes/the-only-electric-b...
I've got a Tongsheng TSDZ2. You remove the pedals and chainring and slot it in place, and your bike is electric. It's got built in torque sensors so pedalling is amplified - a very natural feeling. There's a range of similar motors made by a company called Bafang (BBS02, BBSHD) which generate more power and are more robust, but don't have torque sensing. For a bike in the EU, where you don't really want more than 250-300W anyway, the TSDZ2 is fine.
There's cheaper kits which use hub motors. Often you get the wheel pre-built so you just remove your existing wheel and insert the one with the motor.
The bike conversion kit is fairly straightforward if you're mechanically minded / have done any bike maintenance before. Sourcing a battery is actually the hard part - good batteries are expensive, and shipping from China is complicated. Once you have the battery it mounts where a water bottle would go. Mounting the kit and wiring everything up took an afternoon.
All in, the equipment cost me around £500. I already had the bike.
I haven't crunched the numbers, but this[0] Low Tech Magazine article from 2011 about the reverse process (generating electricity with stationary bikes) gives me the impression this adds quite a bit of inefficiency to this set-up:
> One reason [for inefficiencies] is the use of a so-called friction drive - the rear bicycle wheel acts upon the small roller of the motor/generator. While chain and belt drives (used in late 19th century pedal powered machines) have an efficiency of up to 98 percent, a friction drive is only 80 to 90 percent efficient (and wears much faster).
Whether or not you think that this is important is a different discussion of course, but I think 10-20% less range is quite significant.
[0] https://www.lowtechmagazine.com/2011/05/bike-powered-electri...
I'd love to see a minimal setup for these requirements :) Does anyone know of something?
Sorry, buddy, but in your dreams only. It is blatantly obvious for anyone if you are riding on your own, or if you have assistance - your body position is different, the power exerted looks different, not even mentioning the battery pack on your back wheel, and the motor behind your bottom bracket. So "OK Boomer" indeed.
On the other hand the real problem is that people who cannot really ride bikes now get easy access to speed. I regularly see them on my daily commute here in Vienna, where - despite the 25kph limit - these boomers ride in a way that scares the hell out of me. They go fast when they shouldn't (combined bike paths with lots of pedestrians), go slow when they don't have to (downhill), and generally are visibly uncomfortable on a bicycle.
I cannot imagine what would happen if you took an elderly person with an old bicycle and converted said bicycle using an unrestricted motor... that's really just asking for trouble.
I mean, people can be generally stupid - just last week a 78 year old driving a moped (!) was caught on the motorway driving in the wrong direction (!!!) in the inside lane (!!!!!) for a few km's before police caught him. And he wasn't even drunk.
Perhaps the solution is to introduce a driving licence category for e-bikes. And if they are unrestricted then they should be banned from cycle paths too.
Let's say there was a speed restriction: if you go above, say, 15km/h, the electric assist turns off and you have to pedal on your own. This would still be iffy in some situations, for example a busy combined cycle/footpath.
Maybe it would work OK if the electric assist was some function of cyclist's own effort. The more power you put out, the more the electric motor adds on top. But you'd need some sort of a power meter and more complex controller, so would not be cheap any more...
I do think the regulations in EU are fine as they are. 25 km/h max speed before it cuts the power etc. It happens that I see someone that should've "earned" their speed by getting used to lower speeds first and then naturally progressing, but I don't think adding a new license for that is worth it.
I think there is a reason, why crank or hub located motors are the norm now.
This article does a much better job of exploring friction drives on bikes. https://www.electricbike.com/friction-drive/
The Kepler drive is the best design I've seen and the build/design thread on that shows you all the issues and challenges. It's quite impressive. https://endless-sphere.com/forums/viewtopic.php?f=28&t=25645
... excluding the cost of the battery. The battery costs $150 in HomeDepot
I suspect one of the links in there would have info on repurposing those as well.
I would also like to make my own battery for the bike. I made a cheap DIY spot-welder from a microwave transformer and spot-welded my first 12V 20 Ah battery last week for a 3d printed robot lawn-mower project.
I've build my first ebike a few months ago. I went for a 1000w Bafang mid drive geared motor with a 48v 20a battery, on an old used Peugeot mountain bike. Adding some new/used bike parts (wheels, tires, chain and rear gear), total project cost arrived at C$1800, less than half the price of a new ebike with similar specs.
Considering my weight, 20 to 23 kph is my speed of choice in pedal assist mode, which is quite safe. It does extends my range a lot compared to other use cases.
edit: I wonder if we're experiencing the difference between 250W continuous rated motors, which is what the legislation covers, and 250W peak rated motors, which is what a lot of people end up incorrectly obtaining.
One's mileage may vary!
I would have rounded off, however the numbers change quite a bit with small changes (according to the random online bicycle wattage calculator I was using).
The biggest issue remaining is the wear of tires, and no good alternatives really exist for bike rims in terms of thicker tires.
A cheap bicycle is extremely dangerous, so a much faster cheap bicycle is crazy.
this is not really true, especially considering the second-hand market.
I think Solex (https://en.wikipedia.org/wiki/VéloSoleX) did that better.
It uses the weight of the engine to press the powered wheel to the bicycle wheel, accounting for variation in wheel diameter due to tire pressure or tire wear. This could use the weight of the battery pack
That's fine for a project, but hub motors and mid drive motors are widely available now.
200 Euros just for the battery pack. And we're not talking some shit 7Ah pack that will last half an hour. An hour at full power is the minimum, anything else is unacceptable.
Whether used for constant speed, acceleration only or pedal assist, what's the point of an E-Bike that's deadweight after less than an hour?
I actually have made a design using a 1KW brushed motor that replaces the pedals and uses the hub gear. It is cheaper, but harder to install (needs at least a custom frame for the motor) and is illegal on bike lanes as the pedals are removed. Could share it if anyone cares.
I'd like to see some data on power usage for different percentages of user-assist for people doing average biking speeds. e.g. 25% of total power being motorised/assisted, the other 75% being human-powered, on average.
After all, using it at full power always isn't a bicycle, it's a motorcycle. The idea of e-bikes is to assist the user, on accelerating from a stoplight, on a hill, after a break, in a particularly strong gust of wind. At these short moments assist can be >90%, but when you're at speed it can be say <10%, averaging to perhaps 25%. The assist can be higher on warm days to prevent them becoming too sweaty days, but it'll still be to assist regular biking.
But yeah less than an hour is not really acceptable, I agree. Unless there's some kind of ubiquitous and convenient charging infrastructure, but I don't see that happening anytime soon.
To me, the idea of vehicles is to get me from point A to B faster and with less effort than it'd take on foot. If muscle power isn't enough, then adding some battery juice seems like a great idea to go further and faster while maintaining the agility, simple construction, and cheap operating costs of a bicycle. Electric assist for hill climbing and acceleration is a thing for some reason, but it's totally fine to want and expect more than that from a machine.
I hope the police catch them and take their bikes away.
They're loud as hell and illegal in some places, though.
That and I'd guess that the engine itself is pretty bulky compared to the electric motor, so the total bulk might even out compared to an electric setup for the same amount of energy, but I'd have to look at the actual numbers.
Ebikes on the other hand are legally bicycles. As long as you have pedals and officially limit yourself to 500W/32km/h, there are no restrictions.
At these low speeds, even a "small" 1kWh battery can run for two hours. That's 60-70km of range. Good for most commutes inside the city. Any further and you can take it with you on public transit that supports bicycles.
Really hard to make a case for two strokes here, maybe you live somewhere more forgiving.
Honestly I'm not sure it was purely better: I had to pedal a bit before engaging the clutch to not stall the motor. It also became hard to breathe when stopped because of the fumes from the engine idling.
Was kinda fun to ride around though, but they outlawed them here. Guess other bike path users don't like smelling burnt oil...
Edit: a quick search shows those still available in 38, 49 and 79 cc models depending on the power needed. 100-150 mpg