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A DIY E-bike Conversion on the Cheap

223 points by PikelEmi 5y ago

thoughtpalette 5y ago
Cool project. Would love a list of part URLs + repos to get set up. Wouldn't mind tinkering with something like this as a getting started guide.
mongol 5y ago
Cool to share battery with a lawnmover. Seems clever to share parts between appliances.
- frabbit 5y ago
  These people use powertool batteries: https://ebiketips.road.cc/content/reviews/electric-city-bikes/arcc-abington-electric-2487 https://ebiketips.road.cc/content/reviews/electric-city-bike...
IgorPartola 5y ago
Before you get on one of these, it’s good to check your perspective on safety: https://youtu.be/wM8Xli2KTzI https://youtu.be/wM8Xli2KTzI As a motorcyclist, electric bicycles make me very nervous.
- 1-more 5y ago
  It’s kind of a thing for me as a cyclist. Like I had to get good at handling a bike every speed slowly because I didn’t get faster overnight, I didn’t just go walking to 40 overnight.
  - IgorPartola 5y ago
    It’s not just about how fast you are going. When you drive a car, do you look out for pedestrians running at 40? Would you be surprised if one showed up in front of you? Now imagine the same thing with a bicycle.
    - 1-more 5y ago
      Wait you lost me. Is the cyclist the pedestrian or the motorist in this scenario?
      - IgorPartola 5y ago
        The cyclist. If anyone on the road does something that the soccer mom or SUV dad texting while driving don’t expect, they are going to be in much greater danger than if they didn’t do the unexpected thing.
- ohmaigad 5y ago
  Somewhat irrelevant in places where motor assist is limited to 25kph (EU for example).
  - NietTim 5y ago
    If the builder of a DIY bike choses to adhere to that....
    - ohmaigad 5y ago
      But that is not an issue with e-bikes as a whole (it is also illegal and fineable in places where restrictions apply).
  - nsxwolf 5y ago
    I wouldn’t want to go faster. 15 mph is probably faster than I’ve ever gone.
    - wikidani 5y ago
      I wouldn't worry too much, I have routinely done about 50-60 km/h on a motorized bike and had 0 issues. Always had the best disk brakes I could buy though.
      - IgorPartola 5y ago
        Anekdata doesn’t prove much here. Some things you might not be considering: 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.
- dharmab 5y ago
  The same channel proposed using a similar kit with a donor motorcycle. You get the advantage of a stronger frame, better brakes and better tires: https://www.youtube.com/watch?v=O2zlYpy6QCM&t=300s https://www.youtube.com/watch?v=O2zlYpy6QCM&t=300s
- corney91 5y ago
  This guy is wrong when he says the UK "has a culture of commuting on two wheels." We have a huge problem with cycle infrastructure, as evidenced by the stats he presents. Ok, London's probably decent but transport everywhere else in the country is built around cars.
  - dharmab 5y ago
    Compared to Canada (where Fortnine mostly films), anywhere in the UK is cycling heaven.
    - corney91 5y ago
      Picking a country like the UK who have stats available would be fine then, but suggesting it's a better case scenario with that comment about culture is just trying to skew the conclusion. It doesn't help that the stats show a massive difference in injuries/deaths as well. By all means, everyone should choose your favoured transport, but the video really seems like FUD.
- c6401 5y ago
  I kind of think that the difference between electric bike and motorcycle is that electric bike ideally should be used on bike lanes within speed limit. So if the intention behind making an e-bike is to use it like a motorcycle then yes, motorcycle will be safer. But if the intention is to use it as a bicycle, using bicycle infrastructure (which arguably is very limited in America unlike how things are in Europe) at bicycle speeds but just without coming to your job covered with sweat then bicycles are safe.
  - SevenSigs 5y ago
    In America, bicycles are allowed to use car lanes ...
    - SevenSigs 5y ago
      I know that this is not popular with car drivers, but it is what it is... I had a few cars that tried to push me offroad...
- loeg 5y ago
  > As a motorcyclist, electric bicycles make me very nervous. Riding one yourself, or others riding them? And if you could elaborate, why do they make you nervous?
  - yonaguska 5y ago
    They make me nervous, bc, as other commenters have pointed out- brakes, suspension, and traction matter a lot. 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.
    - vghjfhg 5y ago
      People feel the need to pass you when you go the speed limit because they are used to driving much faster than the speed limit, not because you're on a bicycle.
      - tshaddox 5y ago
        I assume the commenter was talking about situations where it wouldn’t be possible for a car to pass another 30mph car (or the overtaking car driver wouldn’t be bold enough to try).
        Dylan16807 5y ago
        Feeling the need to pass because of speed plus the ability to pass because it's a bike, is pretty different from feeling the need to pass because it's a bike. At the speed limit both of those things will happen. At 5 over the former will be much less common.
- deleted 5y ago
  [deleted]
shimonabi 5y ago
Very interesting. I would love to see a video where someone does it from start to finish. 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.
- _Microft 5y ago
  Building the battery pack yourself would give flexibility regarding size and shape of the battery pack. Maybe you could put them inside the seat tube?
  - swader999 5y ago
    You can often find faulty drill packs and harvest the good cells from those and cobble together a pack. Charging it safely isn't easy but can be done. There are battery management systems you can integrate. It's difficult to put inside the seat tube but putting it in a custom container on the down tube works well and that's a great place to put the added weight.
  - FPGAhacker 5y ago
    Doesn’t sound like a good idea to me… a malfunctioning battery would turn that into a blowtorch aimed at your nether regions.
nynx 5y ago
Having the motor casing drive the edge of the wheel is clever since it provides the necessary mechanical advantage without gearing.
- Someone 5y ago
  “While it would have been nice to engineer some sort of spring-driven mechanism to control how forcefully the motor pushes against the tire, I kept things simple: I just deflated the tire somewhat, bolted the motor solidly in place, and reinflated the tire.” I think Solex (https://en.wikipedia.org/wiki/VéloSoleX 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
- NathanielK 5y ago
  Assuming his motor is mounted tight enough so that the tire loses traction before his friction drive does, he's likely halving his tire life. That's fine for a project, but hub motors and mid drive motors are widely available now.
wikidani 5y ago
Interesting, but to be completely honest, I think a two stroke motorized bike is better and a lot more fun to build
- eigenspace 5y ago
  I live next to a bike lane, and there's a few assholes with two-stroke motorized bikes who use that bikelane regularly. I absolutely hate it, they make so much noise. I hope the police catch them and take their bikes away.
  - wikidani 5y ago
    I mean, they shouldn't use the bike lane. I agree with you. But, here's the thing. If they are not modified they are very quiet, noise codes should be enforced, but asking for their property to be pretty much stolen isn't a bit much?
- nynx 5y ago
  A motorized “bike” is loud, smelly, expensive, much worse for the environment, and bad for your respiratory system.
  - wikidani 5y ago
    I'm sorry, but I'd rather use a two stroke kit than dealing with all the ethical concerns of (for instance) the lithium batteries on ebikes. Also, when using the stock muffler and a right oil mix they are absolutely not smelly or loud. An argument could be made for the respiratory system, but I don't see how would that be an issue when these are used outdoors
- bserge 5y ago
  Lol at the downvotes, but yeah, nothing beats that for energy density. Could even carry a 1L bottle of petrol with you or something. They're loud as hell and illegal in some places, though.
  - 5y ago
soared 5y ago
I like nerds but man is it out of touch/socially awkward to posture based on how often you use the front brake and link to a decades old blog post doing the same.
- bserge 5y ago
  Could use two of those to turn the wheel by the aluminum rim (same one used by the brakes). More power, more traction, less dirt.
  - unraveller 5y ago
    i've seen someone attach a pulley to the side of a thin rim and use only 1 motor. It looks pretty solid [1]. Only thing stopping direct drive of the rim is probably tooth material strength/weight/cost. [1] https://youtu.be/Vc5kHuZoNoM https://youtu.be/Vc5kHuZoNoM
- isoskeles 5y ago
  Why is it socially awkward to link to an old resource? As far as I can tell, Sheldon Brown's blog is a fairly well-known resource, and it is frequently linked on other biking forums.
- etskinner 5y ago
  Maybe the author was intending it as a PSA. I certainly learned how to brake better by reading what he linked to.
bserge 5y ago
400 Euros is all it takes for a 500W battery, 500W+ direct drive motor E-Bike conversion. 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.
- IkmoIkmo 5y ago
  > 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'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.
  - bserge 5y ago
    Well, yeah, but it's a quiet electric motorcycle. Once you get used to just a hand throttle and zero pedalling (keep that as a backup and for legality on bike lanes), you may not want to go back heh.
  - foxfluff 5y ago
    > 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. 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.
milesvp 5y ago
A word of warning. I started looking a little into motor assist bike mods a few years ago, and very quickly you find that the biggest mistake people make in this area is not altering any of the other systems of the bike. That is, they'll put in the motor, and then just ride. Which works, but then you find that your brakes aren't quite good enough to stop quickly at the new higher speeds. Shocks are no longer good enough to prevent certain issues as well. Maybe the frame needs reinforcing... I don't quite remember the whole laundry list. 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.
- treis 5y ago
  I think ebike is a misnomer. These things are really e-(motor)cycles. This confusion is making it really hard for me to search for what I need. All I want is an assist to take the edge off of hills. Don't need to cruise at 30mph for an hour.
  - germinalphrase 5y ago
    Search for a 750 watt motor. That is the upper limit in many countries for a standard commercial ebike. Bafang and Tongsheng both produce popular motors.
    - treis 5y ago
      Google says those cruise at ~30mph.
      - 1-more 5y ago
        You can get really nerdy and calculate this the way triathletes/time trialists do with a tool like this[0]. I plugged in what I think my numbers are for mass and my relaxed ride CdA and on my road bike and you're on the money. [0] http://www.aeroweenie.com/calc.html http://www.aeroweenie.com/calc.html
8jef 5y ago
That's a great hack. But I'm a big guy, bordering on 285lbs. That kind of low power traction doesn't seem enough to move me. I know European 250w motors are never enough for me. 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.
- kylegordon 5y ago
  250W pushes my 220lbs fat ass along pretty swiftly 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.
  - 8jef 5y ago
    Well, there's probably something magical happening between 220lbs and 285lbs ;) ... and/or new motors perform better.
- derekp7 5y ago
  Your typical high output pedaling will produce about 100 watts of power, which for your weight will get you about 13 miles per hour. Pedaling hard with a 250 watt motor should get you around 23 mph.
  - 8jef 5y ago
    One can't argue with precise calculations. Then the whole point for me is limiting my output and go farther. One's mileage may vary!
    - derekp7 5y ago
      > One can't argue with precise calculations. 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).
axx 5y ago
It would be quite interesting to see how these “tire contact” motors will perform once it starts raining or your tires get really dirty. I think there is a reason, why crank or hub located motors are the norm now.
- swader999 5y ago
  You are right about this. This article does a much better job of exploring friction drives on bikes. https://www.electricbike.com/friction-drive/ 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 https://endless-sphere.com/forums/viewtopic.php?f=28&t=25645
1024core 5y ago
> I was able to come up with an e-bike conversion that cost me less than US $200 and yet functions impressively. ... excluding the cost of the battery. The battery costs $150 in HomeDepot
- fencepost 5y ago
  True, but the core is reusing existing batteries and I suspect IEEE readers are more likely than average to have battery lawn mowers, leaf blowers or (lower voltage @18-20v) battery power tools. I suspect one of the links in there would have info on repurposing those as well.
swader999 5y ago
If you are serious about diy ebike be sure to check out these two links: https://endless-sphere.com/forums/viewforum.php?f=21 https://endless-sphere.com/forums/viewforum.php?f=21 http://ebikes.ca http://ebikes.ca
- matmatmatmat 5y ago
  If buying from ebikes.ca, be sure to write them with your planned purchase and ask them to verify that it makes sense and if they're seeing any issues with it. Some parts/combinations have known issues that you're just better off avoiding.
- supperburg 5y ago
  I can’t believe I’ve seen a link to ES in the wild! I used to love this website. Back in 2010 it was like a second home to me. That was before electric vehicles had undergone the revolution that was brought by Elon musk. If you wanted an electric vehicle that was good you had to literally build it yourself. I think the white zombie will always be the pinnacle of that era. And the countless ebikes that people made. 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.
  - swader999 5y ago
    Yeah I remember that guy and I did do the easier controller mods for better power. 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.
mncharity 5y ago
Perhaps mod this into an airline-compatible e-bike? 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.
- germinalphrase 5y ago
  The problem is probably the battery. They worry about a battery fire int be luggage compartment.
  - mfkp 5y ago
    Exactly, get a removable battery and bring that in your carry-on and it should be fine.
    - swader999 5y ago
      Are you joking? Lipo batteries in a carry on?
      - frankus 5y ago
        The rule is under 100Wh per battery, usually without a clear limit as to how many batteries. https://www.tsa.gov/travel/security-screening/whatcanibring/items/lithium-batteries-100-watt-hours-or-less-device https://www.tsa.gov/travel/security-screening/whatcanibring/...
      - mfkp 5y ago
        If you read the article, it specifies lithium-ion batteries, which just about everyone brings inside the pressurized cabin. So no, I am not joking.
        5y ago
Sebb767 5y ago
Calculating the battery as given feels a bit like cheating for the 200$ number: A cursory search on Amazon puts the cheapest battery at 100€ and most in the 300€ range. Quite unfortunate, as I had hoped the author found a cheap option.
felixfurtak 5y ago
cyclone have been selling cheap conversion kits for around US$300 since at least 2005 https://web.archive.org/web/20061212021226/http://cyclone-tw.com/newkits.htm https://web.archive.org/web/20061212021226/http://cyclone-tw...
eloeffler 5y ago
In Germany you'll need a speed limitation on such a construction (25 or 20 kmh, I think). And it must only assist pedalling, never drive the bike on its own. Otherwise this will count as a motorized vehicle and must be registered accordingly and needs vehicle insuramce. Don't know how hard it is to get it admitted for street use. I'd love to see a minimal setup for these requirements :) Does anyone know of something?
tonyedgecombe 5y ago
It's a shame the Copenhagen Wheel never went anywhere. It looked so promising. https://en.wikipedia.org/wiki/Copenhagen_Wheel https://en.wikipedia.org/wiki/Copenhagen_Wheel
- berkes 5y ago
  Any idea why it was pulled? 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.
  - patchorang 5y ago
    I followed Copenhagen in the early years, it seemed like the product was always in "beta". I was waiting to get one once it went into production, but that never came. My guess is something like what you said. It seems like they have since pivoted to scooters.
- Toutouxc 5y ago
  I believe you can get a system like that (all-in-one motor + battery + controller) 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-kostka-e-hill-max-e2.html https://www.kostkakolobezky.cz/hill/920-elektrokolobezka-kos...
- schwartzworld 5y ago
  I used to work for the company. I came on during the pivot to scooters, so this is just my (probably wrong) opinion. 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?
bullen 5y ago
Here is my tutorial to de-car (unfortunately in Swedish but google translated): https://translate.google.com/translate?sl=auto&tl=en&u=elhjul.se https://translate.google.com/translate?sl=auto&tl=en&u=elhju... The biggest issue remaining is the wear of tires, and no good alternatives really exist for bike rims in terms of thicker tires.
leoedin 5y ago
If you don't want to be permanently tinkering, there's a whole range of e-bike conversion kits which work well. 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. [1]: https://ebikechoices.com/tongsheng-tsdz2-review/ https://ebikechoices.com/tongsheng-tsdz2-review/
Markoff 5y ago
USD200 can buy me new e-bike in China, so I can hardly see how is this cheap
tmccrary55 5y ago
"cheap" and "ebike" don't really belong together. A cheap bicycle is extremely dangerous, so a much faster cheap bicycle is crazy.
- jablan 5y ago
  > A cheap bicycle is extremely dangerous this is not really true, especially considering the second-hand market.
haspok 5y ago
> The lack of noise, combined with the discreet positioning of the motor and other components, makes it hard for anyone to notice that I'm on an e-bike. 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.
- cuu508 5y ago
  > people who cannot really ride bikes now get easy access to speed 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...
- matsemann 5y ago
  Yeah, at least someone not used to using a normal bike is very obvious on an e-bike, as their cadence is often waaaay too slow. That speed with that cadence would basically translate to doing non-stop 100kg squats. Bikes have gears for a reason. 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.
vanderZwan 5y ago
> The approach I adopted is mechanically as simple as you can get. It uses an "outrunner" motor designed for electric skateboards. With such outrunners, the case of the motor rotates. Driving the bike with it merely requires mounting it to the frame in such a way that the case is in contact with the rear wheel. 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-electricity-generators.html https://www.lowtechmagazine.com/2011/05/bike-powered-electri...

223 points by PikelEmi 5y ago

Cool project. Would love a list of part URLs + repos to get set up. Wouldn't mind tinkering with something like this as a getting started guide.

mongol 5y ago

Cool to share battery with a lawnmover. Seems clever to share parts between appliances.

frabbit 5y ago
These people use powertool batteries: https://ebiketips.road.cc/content/reviews/electric-city-bikes/arcc-abington-electric-2487 https://ebiketips.road.cc/content/reviews/electric-city-bike...

IgorPartola 5y ago

Before you get on one of these, it’s good to check your perspective on safety: https://youtu.be/wM8Xli2KTzI https://youtu.be/wM8Xli2KTzI As a motorcyclist, electric bicycles make me very nervous.

1-more 5y ago
It’s kind of a thing for me as a cyclist. Like I had to get good at handling a bike every speed slowly because I didn’t get faster overnight, I didn’t just go walking to 40 overnight.
- IgorPartola 5y ago
  It’s not just about how fast you are going. When you drive a car, do you look out for pedestrians running at 40? Would you be surprised if one showed up in front of you? Now imagine the same thing with a bicycle.
  - 1-more 5y ago
    Wait you lost me. Is the cyclist the pedestrian or the motorist in this scenario?
    - IgorPartola 5y ago
      The cyclist. If anyone on the road does something that the soccer mom or SUV dad texting while driving don’t expect, they are going to be in much greater danger than if they didn’t do the unexpected thing.
ohmaigad 5y ago
Somewhat irrelevant in places where motor assist is limited to 25kph (EU for example).
- NietTim 5y ago
  If the builder of a DIY bike choses to adhere to that....
  - ohmaigad 5y ago
    But that is not an issue with e-bikes as a whole (it is also illegal and fineable in places where restrictions apply).
- nsxwolf 5y ago
  I wouldn’t want to go faster. 15 mph is probably faster than I’ve ever gone.
  - wikidani 5y ago
    I wouldn't worry too much, I have routinely done about 50-60 km/h on a motorized bike and had 0 issues. Always had the best disk brakes I could buy though.
    - IgorPartola 5y ago
      Anekdata doesn’t prove much here. Some things you might not be considering: 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.
dharmab 5y ago
The same channel proposed using a similar kit with a donor motorcycle. You get the advantage of a stronger frame, better brakes and better tires: https://www.youtube.com/watch?v=O2zlYpy6QCM&t=300s https://www.youtube.com/watch?v=O2zlYpy6QCM&t=300s
corney91 5y ago
This guy is wrong when he says the UK "has a culture of commuting on two wheels." We have a huge problem with cycle infrastructure, as evidenced by the stats he presents. Ok, London's probably decent but transport everywhere else in the country is built around cars.
- dharmab 5y ago
  Compared to Canada (where Fortnine mostly films), anywhere in the UK is cycling heaven.
  - corney91 5y ago
    Picking a country like the UK who have stats available would be fine then, but suggesting it's a better case scenario with that comment about culture is just trying to skew the conclusion. It doesn't help that the stats show a massive difference in injuries/deaths as well. By all means, everyone should choose your favoured transport, but the video really seems like FUD.
c6401 5y ago
I kind of think that the difference between electric bike and motorcycle is that electric bike ideally should be used on bike lanes within speed limit. So if the intention behind making an e-bike is to use it like a motorcycle then yes, motorcycle will be safer. But if the intention is to use it as a bicycle, using bicycle infrastructure (which arguably is very limited in America unlike how things are in Europe) at bicycle speeds but just without coming to your job covered with sweat then bicycles are safe.
- SevenSigs 5y ago
  In America, bicycles are allowed to use car lanes ...
  - SevenSigs 5y ago
    I know that this is not popular with car drivers, but it is what it is... I had a few cars that tried to push me offroad...
loeg 5y ago
> As a motorcyclist, electric bicycles make me very nervous. Riding one yourself, or others riding them? And if you could elaborate, why do they make you nervous?
- yonaguska 5y ago
  They make me nervous, bc, as other commenters have pointed out- brakes, suspension, and traction matter a lot. 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.
  - vghjfhg 5y ago
    People feel the need to pass you when you go the speed limit because they are used to driving much faster than the speed limit, not because you're on a bicycle.
    - tshaddox 5y ago
      I assume the commenter was talking about situations where it wouldn’t be possible for a car to pass another 30mph car (or the overtaking car driver wouldn’t be bold enough to try).
      - Dylan16807 5y ago
        Feeling the need to pass because of speed plus the ability to pass because it's a bike, is pretty different from feeling the need to pass because it's a bike. At the speed limit both of those things will happen. At 5 over the former will be much less common.
deleted 5y ago
[deleted]

shimonabi 5y ago

Very interesting. I would love to see a video where someone does it from start to finish. 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.

_Microft 5y ago
Building the battery pack yourself would give flexibility regarding size and shape of the battery pack. Maybe you could put them inside the seat tube?
- swader999 5y ago
  You can often find faulty drill packs and harvest the good cells from those and cobble together a pack. Charging it safely isn't easy but can be done. There are battery management systems you can integrate. It's difficult to put inside the seat tube but putting it in a custom container on the down tube works well and that's a great place to put the added weight.
- FPGAhacker 5y ago
  Doesn’t sound like a good idea to me… a malfunctioning battery would turn that into a blowtorch aimed at your nether regions.

nynx 5y ago

Having the motor casing drive the edge of the wheel is clever since it provides the necessary mechanical advantage without gearing.

Someone 5y ago
“While it would have been nice to engineer some sort of spring-driven mechanism to control how forcefully the motor pushes against the tire, I kept things simple: I just deflated the tire somewhat, bolted the motor solidly in place, and reinflated the tire.” I think Solex (https://en.wikipedia.org/wiki/VéloSoleX 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
NathanielK 5y ago
Assuming his motor is mounted tight enough so that the tire loses traction before his friction drive does, he's likely halving his tire life. That's fine for a project, but hub motors and mid drive motors are widely available now.

wikidani 5y ago

Interesting, but to be completely honest, I think a two stroke motorized bike is better and a lot more fun to build

eigenspace 5y ago
I live next to a bike lane, and there's a few assholes with two-stroke motorized bikes who use that bikelane regularly. I absolutely hate it, they make so much noise. I hope the police catch them and take their bikes away.
- wikidani 5y ago
  I mean, they shouldn't use the bike lane. I agree with you. But, here's the thing. If they are not modified they are very quiet, noise codes should be enforced, but asking for their property to be pretty much stolen isn't a bit much?
nynx 5y ago
A motorized “bike” is loud, smelly, expensive, much worse for the environment, and bad for your respiratory system.
- wikidani 5y ago
  I'm sorry, but I'd rather use a two stroke kit than dealing with all the ethical concerns of (for instance) the lithium batteries on ebikes. Also, when using the stock muffler and a right oil mix they are absolutely not smelly or loud. An argument could be made for the respiratory system, but I don't see how would that be an issue when these are used outdoors
bserge 5y ago
Lol at the downvotes, but yeah, nothing beats that for energy density. Could even carry a 1L bottle of petrol with you or something. They're loud as hell and illegal in some places, though.
- 5y ago

soared 5y ago

I like nerds but man is it out of touch/socially awkward to posture based on how often you use the front brake and link to a decades old blog post doing the same.

bserge 5y ago
Could use two of those to turn the wheel by the aluminum rim (same one used by the brakes). More power, more traction, less dirt.
- unraveller 5y ago
  i've seen someone attach a pulley to the side of a thin rim and use only 1 motor. It looks pretty solid [1]. Only thing stopping direct drive of the rim is probably tooth material strength/weight/cost. [1] https://youtu.be/Vc5kHuZoNoM https://youtu.be/Vc5kHuZoNoM
isoskeles 5y ago
Why is it socially awkward to link to an old resource? As far as I can tell, Sheldon Brown's blog is a fairly well-known resource, and it is frequently linked on other biking forums.
etskinner 5y ago
Maybe the author was intending it as a PSA. I certainly learned how to brake better by reading what he linked to.

bserge 5y ago

400 Euros is all it takes for a 500W battery, 500W+ direct drive motor E-Bike conversion. 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.

IkmoIkmo 5y ago
> 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'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.
- bserge 5y ago
  Well, yeah, but it's a quiet electric motorcycle. Once you get used to just a hand throttle and zero pedalling (keep that as a backup and for legality on bike lanes), you may not want to go back heh.
- foxfluff 5y ago
  > 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. 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.

milesvp 5y ago

A word of warning. I started looking a little into motor assist bike mods a few years ago, and very quickly you find that the biggest mistake people make in this area is not altering any of the other systems of the bike. That is, they'll put in the motor, and then just ride. Which works, but then you find that your brakes aren't quite good enough to stop quickly at the new higher speeds. Shocks are no longer good enough to prevent certain issues as well. Maybe the frame needs reinforcing... I don't quite remember the whole laundry list. 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.

treis 5y ago
I think ebike is a misnomer. These things are really e-(motor)cycles. This confusion is making it really hard for me to search for what I need. All I want is an assist to take the edge off of hills. Don't need to cruise at 30mph for an hour.
- germinalphrase 5y ago
  Search for a 750 watt motor. That is the upper limit in many countries for a standard commercial ebike. Bafang and Tongsheng both produce popular motors.
  - treis 5y ago
    Google says those cruise at ~30mph.
    - 1-more 5y ago
      You can get really nerdy and calculate this the way triathletes/time trialists do with a tool like this[0]. I plugged in what I think my numbers are for mass and my relaxed ride CdA and on my road bike and you're on the money. [0] http://www.aeroweenie.com/calc.html http://www.aeroweenie.com/calc.html

8jef 5y ago

That's a great hack. But I'm a big guy, bordering on 285lbs. That kind of low power traction doesn't seem enough to move me. I know European 250w motors are never enough for me. 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.

kylegordon 5y ago
250W pushes my 220lbs fat ass along pretty swiftly 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.
- 8jef 5y ago
  Well, there's probably something magical happening between 220lbs and 285lbs ;) ... and/or new motors perform better.
derekp7 5y ago
Your typical high output pedaling will produce about 100 watts of power, which for your weight will get you about 13 miles per hour. Pedaling hard with a 250 watt motor should get you around 23 mph.
- 8jef 5y ago
  One can't argue with precise calculations. Then the whole point for me is limiting my output and go farther. One's mileage may vary!
  - derekp7 5y ago
    > One can't argue with precise calculations. 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).

axx 5y ago

It would be quite interesting to see how these “tire contact” motors will perform once it starts raining or your tires get really dirty. I think there is a reason, why crank or hub located motors are the norm now.

swader999 5y ago
You are right about this. This article does a much better job of exploring friction drives on bikes. https://www.electricbike.com/friction-drive/ 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 https://endless-sphere.com/forums/viewtopic.php?f=28&t=25645

1024core 5y ago

> I was able to come up with an e-bike conversion that cost me less than US $200 and yet functions impressively. ... excluding the cost of the battery. The battery costs $150 in HomeDepot

fencepost 5y ago
True, but the core is reusing existing batteries and I suspect IEEE readers are more likely than average to have battery lawn mowers, leaf blowers or (lower voltage @18-20v) battery power tools. I suspect one of the links in there would have info on repurposing those as well.

swader999 5y ago

If you are serious about diy ebike be sure to check out these two links: https://endless-sphere.com/forums/viewforum.php?f=21 https://endless-sphere.com/forums/viewforum.php?f=21 http://ebikes.ca http://ebikes.ca

matmatmatmat 5y ago
If buying from ebikes.ca, be sure to write them with your planned purchase and ask them to verify that it makes sense and if they're seeing any issues with it. Some parts/combinations have known issues that you're just better off avoiding.
supperburg 5y ago
I can’t believe I’ve seen a link to ES in the wild! I used to love this website. Back in 2010 it was like a second home to me. That was before electric vehicles had undergone the revolution that was brought by Elon musk. If you wanted an electric vehicle that was good you had to literally build it yourself. I think the white zombie will always be the pinnacle of that era. And the countless ebikes that people made. 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.
- swader999 5y ago
  Yeah I remember that guy and I did do the easier controller mods for better power. 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.

mncharity 5y ago

Perhaps mod this into an airline-compatible e-bike? 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.

germinalphrase 5y ago
The problem is probably the battery. They worry about a battery fire int be luggage compartment.
- mfkp 5y ago
  Exactly, get a removable battery and bring that in your carry-on and it should be fine.
  - swader999 5y ago
    Are you joking? Lipo batteries in a carry on?
    - frankus 5y ago
      The rule is under 100Wh per battery, usually without a clear limit as to how many batteries. https://www.tsa.gov/travel/security-screening/whatcanibring/items/lithium-batteries-100-watt-hours-or-less-device https://www.tsa.gov/travel/security-screening/whatcanibring/...
    - mfkp 5y ago
      If you read the article, it specifies lithium-ion batteries, which just about everyone brings inside the pressurized cabin. So no, I am not joking.
      - 5y ago

Sebb767 5y ago

Calculating the battery as given feels a bit like cheating for the 200$ number: A cursory search on Amazon puts the cheapest battery at 100€ and most in the 300€ range. Quite unfortunate, as I had hoped the author found a cheap option.

felixfurtak 5y ago

cyclone have been selling cheap conversion kits for around US$300 since at least 2005 https://web.archive.org/web/20061212021226/http://cyclone-tw.com/newkits.htm https://web.archive.org/web/20061212021226/http://cyclone-tw...

eloeffler 5y ago

In Germany you'll need a speed limitation on such a construction (25 or 20 kmh, I think). And it must only assist pedalling, never drive the bike on its own. Otherwise this will count as a motorized vehicle and must be registered accordingly and needs vehicle insuramce. Don't know how hard it is to get it admitted for street use. I'd love to see a minimal setup for these requirements :) Does anyone know of something?

tonyedgecombe 5y ago

It's a shame the Copenhagen Wheel never went anywhere. It looked so promising. https://en.wikipedia.org/wiki/Copenhagen_Wheel https://en.wikipedia.org/wiki/Copenhagen_Wheel

berkes 5y ago
Any idea why it was pulled? 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.
- patchorang 5y ago
  I followed Copenhagen in the early years, it seemed like the product was always in "beta". I was waiting to get one once it went into production, but that never came. My guess is something like what you said. It seems like they have since pivoted to scooters.
Toutouxc 5y ago
I believe you can get a system like that (all-in-one motor + battery + controller) 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-kostka-e-hill-max-e2.html https://www.kostkakolobezky.cz/hill/920-elektrokolobezka-kos...
schwartzworld 5y ago
I used to work for the company. I came on during the pivot to scooters, so this is just my (probably wrong) opinion. 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?

bullen 5y ago

Here is my tutorial to de-car (unfortunately in Swedish but google translated): https://translate.google.com/translate?sl=auto&tl=en&u=elhjul.se https://translate.google.com/translate?sl=auto&tl=en&u=elhju... The biggest issue remaining is the wear of tires, and no good alternatives really exist for bike rims in terms of thicker tires.

leoedin 5y ago

If you don't want to be permanently tinkering, there's a whole range of e-bike conversion kits which work well. 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. [1]: https://ebikechoices.com/tongsheng-tsdz2-review/ https://ebikechoices.com/tongsheng-tsdz2-review/

Markoff 5y ago

USD200 can buy me new e-bike in China, so I can hardly see how is this cheap

tmccrary55 5y ago

"cheap" and "ebike" don't really belong together. A cheap bicycle is extremely dangerous, so a much faster cheap bicycle is crazy.

jablan 5y ago
> A cheap bicycle is extremely dangerous this is not really true, especially considering the second-hand market.

haspok 5y ago

> The lack of noise, combined with the discreet positioning of the motor and other components, makes it hard for anyone to notice that I'm on an e-bike. 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.

cuu508 5y ago
> people who cannot really ride bikes now get easy access to speed 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...
matsemann 5y ago
Yeah, at least someone not used to using a normal bike is very obvious on an e-bike, as their cadence is often waaaay too slow. That speed with that cadence would basically translate to doing non-stop 100kg squats. Bikes have gears for a reason. 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.

vanderZwan 5y ago

> The approach I adopted is mechanically as simple as you can get. It uses an "outrunner" motor designed for electric skateboards. With such outrunners, the case of the motor rotates. Driving the bike with it merely requires mounting it to the frame in such a way that the case is in contact with the rear wheel. 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-electricity-generators.html https://www.lowtechmagazine.com/2011/05/bike-powered-electri...