How Powerful Should An Electric Bike Be? The UK Is Asking

As electric drives sweep their way to dominance in the automotive world, there’s another transport sector in which their is also continuing apace. Electric-assisted bicycles preserve the feeling of riding a bike as you always have, along with an electric motor to effortlessly power the rider over hill and dale. European electric two-wheelers are limited to a legal top speed of about 15 miles per hour and a 250 watt motor, but in a post-Brexit dash for independence the British government are asking whether that power should be increased to 500 watts.

The Westminster politicians think such a move will make electric bikes more attractive to consumers, and along with a move to motorcycle-style throttles rather than pedal-to-go throttles they want it to accelerate the take-up of greener transport in a country with plenty of hills. Meanwhile cycling groups and safety groups are concerned, the former whether the move is needed at all, and the latter over the fire risk from more powerful battery packs.

The Hackaday electric bike stable gives us a bit of experience on the matter, and our take is that with a 15 mile-per-hour limit there’s little point in upping the motor power. There’s a 350 watt European limit for three-wheelers though, which we could see would really benefit from a raise if applied to cargo bikes. We can however see that a readily-available supply of cheap 500 W motors would be worth having.

119 thoughts on “How Powerful Should An Electric Bike Be? The UK Is Asking

    1. Only maybe. Though if it follows form for most of these yes. As it seems to me most of the time they ask, probably don’t read the responses and then do whatever it was exactly as they planned… Though that is most definitely just my perception based on what I’ve seen without any numbers attached.

    2. If they classified more powerful ones as mopeds/motorbikes and tax/insurance/driving licence was compulsory, and you could only use them legally on roads or dedicated cycle paths, then they can have at it.

      Letting anyone use them on footpaths like they seem to now with those e-scooters is madness.

      1. There are plenty of good reasons to make proper cycle paths rather than the compromised nonsense in most of the UK. If electric bikes are the route to that I’m in favour. It’s a bit costly and doesn’t pander to car drivers though so I can’t see it happening.

      2. It’s against the highway code to ride any bike on the pavement (that’s what we call the sidewalk, for our friends across the Atlantic) if you are over 5 years old. That’s not going to change if they relax the power role for electric bikes.

        1. Nor should it… one should not ride any bike on the sidewalk (pavement) . That’s for pedestrians. Only exception being <6 yr olds and the disabled with mobility devices. Oh, and prams.

          1. In suburban Los Angeles the sidewalks are almost entirely empty and some of the busier streets are quite dangerous for cyclists. Judgement is required.

        2. Tell that to the youths wearing full black gear, with blacked out bikes, and face coverings so you cannot ID them, that flay around on their illegal power level bikes on a scale from being a nuisance to robbing people.

          The problem with the UK is the law does not protect us from criminals.
          But it’s happy to prosecute us for defending ourselves against criminals.

      3. You can already get more powerful ones that are moped/motorbike with all the trimmings of bureaucracy they come with – the question here really is should even a bicycle be more regulated (which will be hell for the parents or and the youngsters themselves that can’t legally get a moped/motorbike yet anyway), and then at what point does having an electrical assist push the danger up too much?

        While the speed limit still in place for the assistance being so very low all the electric motor is going to be doing in most cases is helping you accelerate off the line. Which is a good thing as motor vehicles that may be trapped behind you are not often tolerant of the bicycle, and cycle lanes to separate these road users barely exist in the UK.

        1. 15 mph = 22 fps. For a 20 degree slope, that’s a climb rate of 7.56 fps.

          Take a vehicle + passenger weight of 250 lb.: 1890 ft-lb/sec, = 3.44 hp = 2563 watts.

          Even if hill-climbing speed is limited to a fast walking speed (4 mph), that’s 684 watts. I’d say 500 watts is inadequate, and hill climbing is much more important than acceleration.

          1. It really depends how you 1) measure watts 2) apply the power.

            On the first point it is unclear in the current regulations if the wattage limit applies to peak or continuous power. Most 250w motors can peak significantly higher than the limit.

            On the second point, if the motor is mounted to the pedals (mid-drive) vs either wheel hub you can take advantage of the bikes gears to up the torque for hill climbing.

            It’s totally possible to have a 250w motor get you up a steep hill faster than a brisk walk.

            Just saying theory is great and all but get out there and try it ;-)

  1. “our take is that with a 15 mile-per-hour limit there’s little point in upping the motor power” ….. I have clocked up about 8,000 miles on my Ebike – it’s a proper Cube machine and the battery wont catch fire. I used it for delivering parcels during the pandemic and it would have been well handy to have a 500W motor whilst towing a trailer full of tat up one of the hills on my island. Even without the parcels, 500W would be a nice option to burn up a hill, especially on a busy road where having speed is actually safer. In terms of safety and insurance etc power and speed are completely separate issues. In a nutshell, higher speed = more dangerous and higher power = more safe on busy roads. Very surprised and disappointed that Hackaday advocates keeping Ebikes to 250W :(

    1. I can see their point, 15mph is so slow that entirely without assistance it is very attainable, so more powerful motor doesn’t give you much. I do agree with your points in general, and have very little ebike experince and none towing stuff, so maybe it does work.

      1. 15mph is abysmal. I used to commute by bike and averaged 20mph door-to-door (15 miles in 45mins), including a few sets of traffic lights.

        That said, all this likely does is legalise the bikes that are already on the streets. Because the ones around me are definitely doing well over 15mph.

        1. It’s not max speed of the bike, it’s max speed the motor is allowed to support you. There is nothing stopping you from pedaling to 20 mph or more besides the weight of the bike.

      2. Not here it aint. It’s 70 vertical metres to the top of my road, and I can do it at 8km/h.
        I have a measured** output of 180W, which works up a serous sweat if I keep it up.

        But the real question is: When you can buy a car with 500kW car with >200km/h top speed, and use it on roads with a max of 100km/h, and hundreds of people die, why the hell do they regulate the shit out of ebikes?

        **(this is fun to do – you find the longest constant slope hill you can. You weigh yourself holding your bike, at the gym. Then you time your climb up the constant slope part of the hill, and knowing the height-gain, time, and mass, you calculate your power output. Below 12km/h wind resistance loss is negligible. Allow 15% for drive train and rolling resistance.)

          1. Basically. Backlash or like a satanic panic type reaction too.

            Either way, it doesn’t make a ton of sense. At least make them the equivalent of mopeds which at least where I live can have quite a bit more power than an e-bike and don’t need insurance or registration, just a learners permit and lights. Where a moped is the equivalent of a 2500w e-bike.

      3. Yeah if you have lots of steep hills I can see the appeal, though the UK isn’t all that hilly really. So a ruling for here raising the power limit, but not the speed it can help you at isn’t going to make any difference to most folks.

        Long shallower slopes that are not bad to keep up the pace on are very common, but the steep leg destroying slow you down ones tend to be rather short if there are any near you at all in the UK (though this is of course a generalisation).

    2. As you said yourself, higher speed = more dangerous. And usually mode power also means more speed.
      There is a difference between e-bikes on one side, and mopeds and motorcycles on the other. Anyone can ride a e-bike, you don’t need a license or insurance. On the other side, for mopeds and motorcycles you need to pass a test to get a license, and you need to pay insurance to cover damages when you cause an accident.
      If 250W is not enough, you can get an electric moped.

      1. To ride a moped or low power motorcycle in the UK you do not have to pass a test, and the only licence you need is the “provisional” licence you get simply by applying.

        1. Incorrect. You need to do a days basic training, the CBT (the C stands for compulsory). The instructor running the course can fail you if he deems you unsafe to go public roads.

        1. No, I agree, if there is electronic limiter, more power doesn’t mean more speed, but limiter would be trivial to disable. Kids have been doing it on mopeds for years…
          On cargo bikes more power could be really useful. Maybe the best solution would be to separate rules for regular and cargo bicycles.

          1. It’s not trivial to disable the limiter on a bike with a ‘proper’ motor like Bosch series 4 as there is software that detects tampering and I can confirm through experience that it works rather well !!!

    3. As a motorcycle rider, I love having good power. However, we have restrictions for motorcycles here in California (two classes based on power). M1 and M2 categories for high power and low power respectively. I would categorize anything that has more power as something akin to the M2, requiring licensing, training, full motor vehicle lighting, no riding on bike lanes, etc.

  2. I do love the ‘increased fire risk’ comment… Increasing the power of the motor has no direct correlation to the size of the battery pack or to the battery fire risk while on charge, which seems to be all they focus on… That risk is from the cheap, terribly made often to fundamentally flawed design garbage we keep allowing to be imported… Size of battery makes no real odds there, even a really really tiny capacity entirely too small for a bike lithium battery when mistreated is large and hot enough to ignite something else in the home/garage…

    You want to complain about safety the angle that might make sense is that these things will start getting closer to mopeds in mass as the motors, probably frame and perhaps battery get bigger. Which means its much more dangerous for everyone else in a collision, and collisions are probably going to increase as stopping gets harder. I still don’t think that is a particularly great argument against the power limit change, as that really doesn’t seem unless the assist speed gets raised as well likely to make much odds. But I’ve not really ridden an ebike, maybe that extra power can help you feel safer pulling away with cars behind you etc. Though on a regular bike I know I’d be going faster than 15mph on average for most of my cycling commutes…

    1. I think you’ve hit the nail on the head, the most dangerous part is shoddy battery packs. What we need is a proper set of saftey standards for the pack and charger, and get serious about enforcing that. A bit more power would be welcomed, but only if they tackle the real problem in the process.

      1. FYI Teslas are neck and neck on killing people modes.

        Last year:
        18 from battery packs setting house on fire.
        18 from idiots trusting full self driving to be what is claimed.

        Are those the ‘shoddy battery packs’ you refer to?

    2. Plus the usual bike batteries are nowhere near a high demand application. The usual Bosch power pack is 36 V 400-500 Wh. That means for 250 W it pulls 7 A and empties the pack in ~2h. 0.5 capacities (0.5C) per hour are nothing for modern cells, they could happily deliver 4 times that before you have to think about using high current packs.

      Tool batteries deliver 10-20C no problem, drone batteries go up to over 100C.

  3. Hopefully they will spec what 250w or 500w actually means.
    As i understand, right now it is nameplate capacity: a fairly meaningless number the manufacturer prints on there that relates to maximum continuous electrical power at a particular torque and speed. You can take a 250w watt motor and overspeed it and improve the cooling, and get way more than 250watts out.
    However you can’t use a R/C motor electronically limited to 250w as it doesn’t have a nameplate.
    Wouldn’t just limiting speed make more sense?

    1. >right now it is nameplate capacity:
      Really? Now I want to look up the rules properly at some point – seems like it wouldn’t be hard to make / have manufactured any motor to stick that legal nameplate on it…

      As I understood it to be the only requirement was an actual power limit at the motor so electronic limiters on a more powerful motor would be acceptable.

    2. Its no different than here in the US with the limits on a 50cc scooter. You can put a big block kit on it and no one is going to know. I live in the mountains and I dont need top speed I need climbing power.

  4. Rental scooters are geo-locked, just do the same such that when you’re on the road it’s got a full 2,000 watts of screaming fiery fury, but when you’re on a trail (or, slightly more difficult) a sidewalk it’s only got 250 watts and top speed of 15mph.

    Bonus that google maps already knows where all the trails are. The hard work is done.

    I read that PEVs were making much more effective inroads into saving fuel than EV’s. So this is theirs to screw up.

  5. I’ve ridden an S-pedelec and an ecargo bike. I think 500W 15.5mph only makes sense for ecargo bikes, everyone else is light enough to maintain speed up steep hills with a 250W mid-drive motor. Hub motors I have no experience with. With e-cargo bikes you might as well increase the power further, why is 750W or 1kW any less safe?

    S-pedelecs are really where it’s at, they feel so much safer around cars as you can mostly maintain speed with them. I would support a power increase for those, the one I rode had a 350W Bosch mid-drive motor and it felt happiest at about 20mph. 28mph was pushing the motor a bit too hard continuously. Unfortunately over here they’re considered mopeds so you aren’t even allowed to ride in cycle lanes and that ruins their practicality, they become a worse motorbike. I’d love for the law around them to become more relaxed.

  6. UK eBike user with arthritic knees here. I am severely limited regards where I can eBike to due to to a big hill between my house and the nearest town. A 500W motor would be hugely useful. I don’t want to go any faster, just to be able to get over the hill.

    1. Just get a bigger motor/controller, I’m fortunate to have no health issues and 250w is all I needed to make one hill on my commute go from a slog to pleasant, but if I needed more I wouldn’t hesitate, it just isn’t policed, certainly I’ve never seen it. Or obviously just get a moped/motorbike.

    2. In Sheffield, where I live there are some pretty steep hills (13%+). If I want to do 7mph (3m/s) with the kids on the back of the cargo bike (total weight of bike plus me plus seats plus kids = 160kg). That’s 3*0.13*9.8*160=611W. Let’s pretend it’s completely efficient and let’s say I can produce about 160W myself (cargo bikes usually have a higher lowest gear so I find I can’t pedal so well at low speeds), I’ll need 450W from the motor.

      On the other hand I like that it makes me still do exercise on the school run. With a 500W motor I probably wouldn’t get any exercise! Also only a very few hills are that steep, but my route does avoid one that I know I can’t get up!

    3. I am a ebike rider with arthritic knees, I have a bafang 1000w conversion kit which I have self restricted to 18mph. Also have replaced the original crap firmware with open source version from GitHub which is far superior. I absolutely love riding it. Will risk accept the possibility of having an accident as 250w isn’t enough to get me up the steep hills we have locally.

  7. Reading about these limits, I’m beginning to wonder if I’m living in the Wild West. Here are the requirements from the Ontario Ministry of Transportation:

    E-bike requirements
    To operate an e-bike in Ontario, the e-bike must have:

    – a maximum assisted speed of 32 km/h
    – a maximum weight of 120 kg (includes the weight of the bike and battery)
    – an electric motor not exceeding 500 watts
    – no modifications to the motor to allow it to exceed a power output greater than 500 watts and an assisted speed greater than 32 km/h
    – battery and electric motor securely fastened to the bicycle frame to prevent them from moving while the e-bike is operating
    – all electrical terminals properly insulated
    – minimum wheel width of 35 mm and minimum diameter of 350 mm
    – two independent braking systems that applies force to each wheel and is capable of bringing the e-bike, while being operated at a speed of 30 km/h, to a full stop within 9 metres, on a level asphalt surface, from the point at which the brakes were applied

    Removing the pedals makes the e-bike a motor vehicle, which requires a licence, insurance and registration to operate. It is also illegal to modify your e-bike’s electric motor to make it more powerful or to increase the assisted speed of the bike.

    1. Several years ago, I briefly had an entry-level e-bike, back when the batteries were lead-acid and they had a twist throttle… but it was neither fish nor fowl; too heavy to be an enjoyable bike, but not enough speed and range to be a real transportation asset. I sold it after a year, and I am still enjoying my unpowered bikes. But a decent ebike is in my future.

      What needs to happen here in Ontario is a prohibition on the almost-motorscooter/motorcycle electric things that have some vestigial pedals sticking out the sides, as if anyone would ever want to actually pedal them. These have no business using bike paths or lanes.

      I’m mainly in favour of the pedal-driven ebikes vs throttle-type; I believe they’re the most efficient, and they are ridden more like unpowered bikes, so they seem to coexist better with them on bike lanes and trails. The current Ontario ebike speed limit seems to be sensible for the same reason.

      The current UK limits seem low, by comparison, for sure.

  8. I think the restrictions should be mostly speed-based, not so much power-based. The limit on power should be high enough that one can reach the speed limit even going up hills on a heavy bike. The 500W suggestion sounds reasonable.

    I think a 15 mph limit is plenty fast for bikes that are driven on bike paths and lanes. Bikes that are faster than 20 mph should be on the road, not in a lane with slower human-powered bikes and possibly pedestrians adjacent.

    I commute by bike every day, using a self-powered bike for exercise. I’m frequently passed by delivery riders on e-bikes going 20 mph or more, who often swerve between the road and bike lane as suits their needs.

    I’m not really sure what the best solution is, given that e-bikes can be made that go as fast as cars. Perhaps we need “slow” bike lanes and “fast” bike lanes? Not sure.

    1. ‘heavy bike’ is part of the problem though – heavier it gets the more momentum it has, the harder it is to stop and the more dangerous in a collision. So the limit should probably not be on power at all, but on speed and mass – no motor power over 15mph and bike weight no more than 6? 10? 20kg? is fine. That is pretty darn heavy for a bicycle, but light enough I’d suggest the whole treating it like a motorbike with licensing and tests isn’t required – keeps the two looking visually very different too to make identifying the rouge users easier.

      Limiting the power could be done, but it just isn’t really a useful measure to how dangerous the thing is to those around you, and when you are measuring at the motor hard to pick a good number too – there are too many ways to assemble an e-bike..

    2. We need f’n BIKE LANES and BIKE TRAILS in the US. Especially my city, 30% of households do not have a car. We get the choice between riding in the street (suicide) or riding on the sidewalk (illegal in NY). Most regular people ride on the sidewalk for safety, cyclists in spandex use the road.

      I like this 15mph motor limit. Fast == moped/motorcycle, put it in the street. Slow == bike. Build minimalist walking and cycling infrastructure. Slow humans barely need any flow controls, they just need to be separated from the lethal metal boxes traveling 30mph.

      1. Not cycling on the sidewalk rule is silly. If I followed it to the letter, I couldn’t get anywhere in the city even though we have bike lanes and cycling paths, because in the city center there’s just a handful of routes where you’re explicitly allowed to ride the bike. Even crossing the street at pedestrian crossings, you’re supposed to jump off, push the bike across, then jump back on, every friggin’ block. Nobody actually does that, but the police can cite you for it.

  9. In the EU, bicycles can have far more than 250W power… The 250W is only used in a definition for a 30min thermal test of the Motor (originating from old 2stroke Motors I think). Here is an explanation:
    For example the Bosch CX motor in the link, with max. power of about 600W, completely legal in the EU as long as speed limit of 15mph / 25km/h is not exceeded. Bikes like this would never work woth the 250W Limit, but are legally defined as bicycles:
    I wonder what the increase in power would mean then… does the government not understand the law or do they want to change testing procedures?

  10. I’m confused: are we talking about EU laws being applicable to the UK? I thought the point of Brexit was to separate from EU law… Does the UK have to comply with EU laws regarding electric bicycles? If so, how could they contemplate new, less restrictive laws? If the EU mandates a 250 watt maximum and 15mph (I’d guess it’s in kph), why would that affect the UK? Unless the UK has similar laws, in which case shouldn’t we be referring to current UK law rather than “European” law? Which body has highest jurisdiction over ebikes in the UK, EU or UK? (It seems from the article that if the UK has the authority to change their ebike laws, EU law would be irrelevant).

    1. The UK put all of the EU legislation we had been following into UK law at Brexit – So in effect nothing changed on the day of the switch, all the rules remain consistent to start with. But now the UK can change anything it likes without EU approval.

    1. The UK has about the same income per person as France; it’s better than Spain and Italy, not as good as Germany and Sweden. In short, the UK is doing quite well, thank you, and better off for not being under the thumb of Continental bureaucrats.

  11. I haven’t biked nearly as much since I began my working career. Growing up in a rural / semi-suburban village in the US I used to ride faster than that ALL the time! And the distances I went to get where I wanted to be… 15MPH would have taken too long and not been practical.

    Now when I do bike I don’t usually go faster than that because the roads here in the city I have moved to, and the people driving on them are not very safe. There are bike lanes but I think they are mostly a way to die.

    I bike on trails when I do at all, for exercise and recreation, not to get somewhere. And those trails are narrower plus shared with walkers, skaters and more leisurely bikers. Except maybe on the rare day when fewer people are out, flying down the trail would be kind of a jerk thing to do. There are days though.. when few people are out and I am glad they don’t post a speed limit!

  12. I can say from experience 250w is basically unusable. I had to take a 250w limited bike from Hlafords and hack on a KT36/48v controller upgrade the battery pack to 48v from the original 24v and now it runs well. Can safely run at 1kw with the motor barely warming up. Although cruising is more like 300w. The extra wattage is essential to climb any hills especially for the cheaper assist type bikes that are heavy and come with no gears. A more reasonable limit would be 500w max with short burst up to 1kw for hills. But why even limit them? Screw the government and their shitty laws. It still doesn’t stop teens on 2kw bikes running around with no regards to rules of the road.

    1. The underlying idea with the limit is that most people can’t maintain high output continuously for very long, so the average speeds along bicycle paths are nowhere near the upper limit. With e-bikes you get two classes of people – those who speed around assisted at high speeds, and those who trundle along leisurely to avoid working up a sweat. This creates dangerous situations, especially when bikes aren’t regulated in terms of braking ability, driver skill, and the whole road culture tends to be a bit of a wild west.

      It’s the same as having people going 50 kph on a motorway where other people are driving 100 kph.

  13. Power isn’t the issue, but peak speed. Even 25km/h is worrying amongst pedestrians and cyclists, on footpaths and cycleways. Anything *capable* of beyond that, should be restricted to road use only. Pay your road tax, carry a registration plate, and have-at-it!

    1. Well, momentum is the issue I think, but mass isn’t mentioned much here. A pedestrian has very little momentum in comparison to an ebike or scooter. F = dp/dt, so a metal framed ebike going max speed colliding with slow walking granny is a recipe for broken bones, easy.

    2. Thats essentially how it goes here in Germany, you can have a so called S-Pedilec which essentially is handled like a 50cc scooter, a “Leichtkraftrad”. You need your insurance plate and can’t drive it on a cycle path unless they explicitly say that scooters can drive there too, country roads usually have such a cycle path, look out for the sign “Mofas frei” then.

      And you need a drivers license for it, class AM, around 1000€.
      Unless you already have a license for cars, then that one is included.

  14. Classifications should be inertially based (top speed * (bike weight+average weight of human)) not output power based. That way you have heavy bikes being more speed limited than lightweight ones and people can maintain reasonable speeds going uphill.

  15. For my commute, 50 kW would be nice. Of course that’s a light motorcycle rather than a heavy e-bike. I don’t own an e-bike myself, but it seems that at least in the US , something built to fit moped regulations might be a reasonable compromise between ease of registration and utility.

    1. 50kW is about a 650cc, which I would call middleweight. I have ridden a Zero DS electric motorcycle which has a nominal power of 11kW, making it learner legal in the UK, but it performed more like a 650. You definitely get more bang for your Watt with electric bikes.

  16. I have a 1200W ebike with a throttle (I no longer live in the UK). It tops out at about 30mph on the flat but I find 20 is a more comfortable speed. The power is useful as I live on a steep hill. When I was a lad with a racing bike I reckon I could do 40 with a following wind. So I’d say limit assisted speed to 20mph but don’t limit power. I see no problem with throttles in that case.

  17. Rather than pulling numbers out of their as*, why don’t they look at countries which already implement such regulations on personal electric mobility devices. In Japan for example, there are categories for everything. The classifications are based on multiple criteria: top speed, power output, dimensions of the device, weight. Electric assist bicycles (with pedals) up to 250W and max 20km/h are considered regular bicycles. E-scooters/e-bikes up to 600W and max 20km/h have other requirements (license plates, turn signals, front/rear lights), E-scooters/e-bikes 600W and max 40km/h (mirrors, insurance, drivers license). They lump them into existing motorcycle categories as well, so all the same laws apply as if it were a motorcycle (ex: no riding on sidewalks, mandatory helmets, etc).

    1. “Rather than pulling numbers out of their as*, why don’t they look at countries which already implement such regulations ”

      Because those countries just had some bureaucrats (who don’t ride bikes every day) pull numbers out of their arses. Not a good starting place.

  18. We should see electric bikes another way, most commutes are either under 2km (40%) or 16km (60%), so range and speed should allow to do 16km commute under 30 minutes.

    1. …except that an average speed of 32 km/h is ok on a road, but just too fast on a separate shared path (pedestrians, kids, etc).

      When I worked downtown, my bike commute would be 16 km, mostly on busy bike or multi-use paths. I could do it in 45 min, which was fine.

  19. The question is meaningless and a fools debate. The obvious answer is as much power as necessary to function while obeying traffic regulations, maintaining speed and not impeding the flow of traffic. Licensing is also a meaningless argument, licensed or not the rider is still responsible for obeying the rules of the road.

    How much power that actually means is going to vary based on rider weight, road conditions, grade of hill, cargo load, pulling a trailer, headwind vs tailwind, and are we talking hub motor or mid drive? Because a mid drive brings the gear ratio into play that would drastically alter the speed and performance of a given wattage. Just like a cargo truck has insane horsepower but isnt going to be winning any races, because the practical limit is the drive train.

    I’m over 300 lbs, and my ebike had a 3KW capable motor (Cyclone), limited to effectively 2 KW with my controller and battery setup. Hauling water jugs in my trailer I was able to keep up with traffic and get out of somethings way when needed, but my top speed was around 35 mph. I live in a mostly flat county with some insane winds, and going into a headwind brought me to a complete halt even with all that power. That motor has since burned out and I have been unable to source a replacement.

    Limiting the power to the motor is perfect politics. Completely ineffective at the claimed purpose (controlling speed) and perfect for sabotaging the practical utility of an Ebike. Which is exactly what the oil barons want and exactly the opposite of what we need with WW3 driving oil up in cost and down in availability. But hey, it puts on an entertaining show for the hand wringers who need to think the lawmakers are keeping them safe from “those crazy ebikers who should get a job and drive a proper car like decent folk!”.

    1. > maintaining speed

      Having a smooth flow of traffic generally requires that people drive at similar speeds. Having high power on throttle all the time means you can maintain your top speed, while people on unassisted bikes have much lower average speeds, especially up the grades. When these two flows at different speeds mix, collisions become more likely because one group doesn’t want to slow down, and the other group can’t keep up.

      The same issue applies to the spandex heroes who think they’re training for tour de france on a commuter cycling lane.

      1. The same fallacy applies to unassisted bikes in motor traffic. Or when a farm tractor shares the road with existing cars. Or when your fast and furious fanboys drive alongside soccer moms. Safe overtaking, passing and filtering are practices established long before the rise of assisted bicycles.

        These scenarios are covered by existing regulations and responsible driving, and again, NOT addressed in any practical, meaningful way by regulating the speed of an Ebike, which, again, putting a power cap on the motor fails to do. So the question remains a pointless argument.

      2. Yes, maintaining speed.
        In many states, you can be ticketed for impeding the flow of traffic, and while many cities have installed bike lanes, there are still many roads where cyclists have to share the road with cars.
        A lot of drivers think bikes shouldn’t be on the road. On a busy thoroughfare, I agree, high speed traffic where a cyclist can’t keep up can result in an accident. In another article on here the text is about cars. I commented on how all the newer cars beep, ding, boop, buzz, and chime for every little thing. Now throw that all in with having to watch for cyclists while going 50+ mph. Now I”m not saying a cyclist should have to keep up with 50+ mph traffic but should at least do their best to keep up with the normal flow of traffic. I’m an older cyclist who doesn’t pedal or go as fast as I did in my younger days. A motor to help with the hills, and the occasional burst of speed to avoid a distracted driver is a good thing. I don’t have an electric bike. I don’t need to go fast, I just need to get from point A to point B in one piece. Would I like an electric motor. Sure I would, but I do like to ride and burn some calories. The calorie battery I have around my middle would last for decades. :) I have no problem sharing the road with cars. It can and has been done. Some cyclists have this need to go as fast as possible (your spandex tour de France riders) and some cyclists have e-bikes that can go 100+ miles per hour with a 10,000 watt motor. I think for me, a nice middle ground would be a bike that’s not too heavy, easy to pedal, with a motor with just enough power to help with the hills is a perfect balance.

        1. Bikes shouldn’t be on the road. Period. If you don’t have separate cycling infrastructure, you’re doing it wrong (as a society) in the first place and high-speed bicycles aren’t the solution. It’s just no contest between two-ton cars and people on bicycles.

          Cars generally go at least twice as fast as the average cyclist on a non-assisted bike can hope to maintain, and even that is painfully slow for car drivers, so unless you mandate e-bikes on everyone, the shared road situation is just hopeless.

          1. Whether they should or shouldn’t isn’t the issue. There are roads and streets in America and other countries just don’t have bike lanes so cars and cyclists HAVE to share the road.
            It’s when you get the “the law doesn’t apply to me” types who think they don’t have to share the road or follow the rules be it motorist or cyclist, it doesn’t mix well. I’ve shared the road with drivers who have been courteous, slowed down or moved over, and I’ve shared the road with motorists who have harassed me or otherwise have been a nuisance.
            Yes, in an ideal world cyclists and motorists shouldn’t be on the same road but, it’s not an ideal world is it? Being from NJ, where motorists honk and give the finger, I don’t have a problem sharing the road. Give me the room to operate my bike safely, and I’ll do my best to share the road with you.

          2. >cars and cyclists HAVE to share the road.

            Yes, but that has nothing to do with the question at hand. Having faster e-bikes just doesn’t solve the issue, because a) you don’t want that to be the case to begin with, b) the bike still won’t be fast enough to keep up – unless you make it so fast it becomes hazardous in its own right. Bicycle tires and frames are just too flimsy to handle 40-60 kph speeds and the poor traction, non-existent suspension and weak brakes, means you’d be driving with a death wish.

  20. Finally the UK has freed itself from the shackles of Europe! Now they can focus on the important things, such as how powerful an electric bike could be if anyone could afford one. And had electricity.

  21. A throttle at least for starting at intersections etc from a standstill when feet are split between pedal and ground and you want to get out now, please. Who ever came up with that complicated magic pedal cadence power control junk wanted a “simple” hands off minimalist aproach. Then lawmakers being of the same ilk ate it up and passed it on.

    1. It’s to reduce people zooming unexpectedly in front of traffic. If you have feet on pedals, other drivers can see that you’re going, whereas having your foot on the ground means you’re stopped and not going anywhere in the next couple seconds.

      If you have 1 kW on the throttle, you can suddenly dash across the street in no time – which is what you would like as a rider – but it’s harrowing for car drivers to predict where you will be next.

  22. I’m slightly surprised the nanny-state laws of my home state, NSW (Australia) set the limits at 500W and 25km/h, which is “just a bit” more than the UK rules at the moment…

  23. I bet Colin Furze would like to have a word, two pulse engines (like the ones from the V1 ww2 nazi revenge weapons) strapped on the bike and perhaps two to four rocket engines for assisted take off also attached to the same vehicle, so you won’t have to pedal like a maniac trying to get up the the speed.

  24. “As electric drives sweep their way to dominance in the automotive world”

    About a year behind the news – car manufacturers are dropped ng EVs like hot potatoes now.

    Even the government is backing off EV mandates and ICE bans.

      1. Its because no one wants to buy them.

        Oh, and they catch fire.

        And it costs 20,000 dollars to replace a battery pack after a scratch. Insurers write them off after minor collisions because no one can guarantee they’re still safe.

  25. It’s not the wattage, power or speed that’s the problem, the problem is cyclists who don’t obey the laws.
    Why do you have a 3, 4, or even 10KW motor? I’ve seen youtube videos of some insane ebikes that could give a car a run for its money. Yes, you can have ebikes that go 100 miles an hour with enough power to go up Mount Washington and not strain the motor. I’ve seen cyclists run red lights, nearly hit people , weave in and out of traffic…. It’s insane. So here’s an interesting question, if the speed limit is 70, why do they make cars that can go 80, 90 or 100 mph? Speed limit is 70 right? It boils down to personal responsibility.
    You have a cyclist acting in an unsafe manner and it reflects on all cyclists. Yes I know, different for cars….
    One drunk driver doesn’t mean everyone’s a bad driver, but for some reason bicyclists are all lumped into the same apple barrel. I think it’s because of the unsafe cyclists that the knee-jerk reaction of motor limits etc. are in place. Personally, I’d want as much power as possible if I rode an electric bike. Is 500W too little? 1000W too much? I think if you’re riding in a safe manner, what motor, wattage, battery capacity etc. you have shouldn’t matter. That just my opinion.

    1. We did have cars that had a top speed at 100-120 kph because of the small engine capacities, and they were terrible to drive. Took you a full minute to get up to the speed limit and merging into the highway was a white-knuckle experience – let alone trying to overtake anyone going slower than the limit. You needed miles of open road, because you had to overtake with very small differences in speed, which meant that if you had a truck in front of you, you were stuck going 80 on a 100 limit road.

  26. You don’t need raw power to get up a hill on an e-bike.

    My wife rides to work on an e-bike. There’s a big hill just before the building.

    She at first used the e-bike her father had bought – hub motor with 250 watts. It couldn’t make it up the hill with her pedaling as hard as possible.

    We bought a new mid-motor e-bike, also 250 watts. It zips up the hill no problem. She has to pedal, but it isn’t hard to do.

    The difference is that the mid-motor produces 60Nm of torque from 250 watts while the hub motor produces 25Nm of torque from 250 watts – and the mid-motor drives the rear wheel through the same gear ratio as the pedals. The mid-motor has more torque and makes better use of it.

    You don’t need insane amounts of power. It just needs to be applied properly.

    1. The thing to keep your eye on is that e-bike power is limited based on the electrical power going in, not the mechanical power on the output. Mechanical power is directly proportional to the torque output.

      The relationship between electrical input power and output torque isn’t that simple. It’s a function of the efficiency of the motor and the controller. A good motor and a good controller can produce more torque and therefore more mechanical power for the same input electrical power.

    2. I think the best way to say all that is that the power limit ought to be the mechanical output power, not a limit on the electrical input power.

      250 watts mechanical output power is about 1/3 horsepower or about 1 people power.

    3. Well technically you can keep moving uphill with only a watt or 2 with sufficient gear reduction. But if you want to keep moving at a reasonable speed, and you’re old and can’t put in “hill effort”, then I’d say 250W is marginal. I have a 750W mid motor, and I’d say it’s perfect. It’s not fast up hills but it can keep maybe 6mph up a very steep hill without peddling. I doubt you could do that on 250W.

      1. The idea is not “without peddling.” The idea is to reduce the load on the pedaler to something manageable. With the old e-bike or with a regular bike, my wife has to push the bike up the hill going to work. With the new e-bike, she can pedal right on up without stopping. She has to put in some effort, but it is at least manageable.

        “Without peddling” would be a scooter or motorcycle, not a bicycle.

      2. Your motor is probably not putting out 750 Watts at the speed you’re going. It’s limited by the amount of current it can sustain without overheating the electronics or the motor. The amount of current is directly related to how much torque the motor puts out, while power is related to the product of torque AND speed.

        It’s a curious relationship. Torque is what keeps you going up the hill, but power is what makes you go faster over the same grade. The 750 Watt motor may be limited in torque by being limited in current to the point that it’s not actually putting out any more power than the 250 Watt motor at the speed you’re going up the hill. In essence, the weaker motor could make the same speed in a lower gear.

  27. It seems a little bit like a pointless debate when the existing law isn’t enforced at all. Maybe have a look at the hordes of Deliveroo dudes riding ‘electric bicycles’ with massive motorbike style tyres and multiple kW motors zooming around the city.

  28. I built a 750W mid motor. I think it’s definitely necessary if you want to ride up long, steep hills at a decent speed. Mountain biking uphill would certainly be another use case. On flat ground, yes it could be lower.

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