My understanding of UK law was that ebikes had to only be capable of 250w continuous and the manufacturers get round that by allowing more than that for short periods only.
Dji seem to have done a firmware update that lets you have 1000w all the time. How are they getting round the legalities here?
https://www.emtbforums.com/ams/avinox-motor-update-6-new-features-that-change-the-ride.152/
(Not trying to start an argument, just wondering!)
Presumably they aren’t and if it’s doing 1000w all the time it’s a motorbike?
Need to read it all but it sounds as though it only gives you the maximum power for a max of 30 seconds, but the option is now in more modes instead of just being in boost.
Old rule that made more sense when applied to brushed motors that would overheat, someone who knows more will explain but it's to do with its thermal limit. Fancy brushless motors and speed controllers run lots cooler so output way more power.
Its not just DJI, bosch have been cranking out motors that exceed 500w for 1hr+ for years
Presumably they aren’t and if it’s doing 1000w all the time it’s a motorbike?
In the UK & EU, in other parts of the world, who knows…
Plus enforcement is near enough zero all over the place.
Maximum continuous motor power is a piece of wording that makes absolutely no sense and I have no idea how it made it into EU regulations but here we are.
In the ebike regulations, the only power test that is applied to motors is the normal continuous power test. If the motor is to be rated to 250W then 250W is applied to the motor for 30 minutes while the temperature is monitored. After 30 minutes if the temperature is stable it passes. If the temperature is still rising then it fails.
This is why maximum continuous power makes no sense whatsoever. If you have a motor that can take 1000W for 30 minutes and its temperature is stable at that point then that is a 250W continuous power motor.
However, if your motor was only stable with power up to 200W and at 250W the temperature is still rising, this motor would not be legal to sell as an ebike motor because it fails the continuous power test.
So, Maximum Continuous Power is nonsense. You can have motors that are capable of way more than 250W continuous and they are fine. If you have a motor that is too small to handle 250W then that is not OK and would be illegal to sell. That's the weirdest definition of maximum I have ever seen.
Some people tell me that the continuous power is written into the regulations some other way, often I'm told it's supposed to be written into the firmware somehow. I have not seen these requirements and so far no one has been able to point out the relevant part of the regulations so I suspect they don't exist.
As always, if anyone can point out the specific part of the regulations that deals with power output in the firmware I'm more than happy to be proven wrong.
However, as far as I can tell there is no limit on the power that motors can output and there never has been.
They are legal, they meet the pedal elec rules.
The rule is 250w rated not a peak power limit. You have to go back a long time to find an emtb motor that did not peak above 250w
The rule relates to something on the lines of :an old brushed motor at 250w would product x amount of heat, the amount of heat generated dictated its rating. brushless motors produce the same heat but give way more power, so a 750w bosch motor can get a 250w rated sticker on it.
There may be an Austrian rule that 600w peak was the max, shimano/bosch etc colluded that it would be the limit but DJI came in with huge numbers so everyone is upping their peak now.
Either way the rule is pants and we have been massively over 250w peak for a long time.
Ah ok. So the test is to check it doesn't overheat rather than to limit output. Weird.
Ah ok. So the test is to check it doesn't overheat rather than to limit output. Weird.
More than weird, imo it's deliberately misleading but now everyone is too embarrassed to say, 'Err, actually, we made a wee mistake when we said Continuous power. Soz.' If I had to take a guess, I'd say when the regulations were being written the EU said they needed some kind of power limit and the manufacturers decided to have a go at 'limiting' continuous power and see if the regulators would go for that. Which apparently they did.
I do wonder how much that 500W ebike government consultation last year ended up costing. You could almost see the manufacturers squirming trying to explain why they didn't actually need any more power.
Interesting. I know enough about DC motors to know that I'd don't know enough to properly understand the full engineering complexities.
Also - where I ride Im mostly riding away from others and don't know any ebikers to ride with so this might have past me by but......to non ebike user sharing the same trails has this effective bypassing of the rules made any difference to what you experience? In other words is there a meaningful downside to everyone else?
If an ebike plus bang average fat lad on top of it can put out 1300 watts up hill does that mean features at bike parks will end up being redesigned in time making them impossible to attempt unless you are on such a bike? ie. a arms race. Or are goopy muddy trails that human power alone could not get through now getting ridden through at will with the long term erosion you'd expect?
I'm trying to work out if this is a good thing, a bad thing, or just a thing. Not for the consumer/purchased/rider of that bike but for the rest of the world.
I think last time this came up the point was that Continuous Rated Power had to be 250W and the ISO tests for EPACs check that.
"The maximum continuous rated power shall be measured when the motor reaches its thermal equilibrium as specified by the manufacturer."
What I hadn't fully appreciated before from the EN standard that describes 'continuous duty' (which is what EN standard for EPACs references) is that it doesn't set out to discover the max power the motor can put out at equilibrium, it just verifies the marked rated power, the known and stated stability point. And although a test lab perhaps could fail an EPAC motor that runs continuously at 500W, checking for that isn't what the EPAC EN test demands. The motor rating is tested and marked by the manufacturer under different regs. But it's always been the case that many 250W hub motors in a 36V system will be marked to and run at 350W when used within a 48V system (e.g. for US or Speed Pedelec use). So the fact that a '250W' motor can do more isn't news or anything 'dodgy'.
The risk to others come from a vehicle's mass x speed, an EPAC maxes out at 25kph whatever the power it uses to get there. And keeping the power level open for design of cargo bikes or different types of bike seems reasonable, the standard doesn't limit design in terms of mass or size, and power is related to use, load, etc. Power is speed x torque or work over time and how that happens is variable by product. And whatever a motor alone can do, the overall control system design manages power use and output.
Where I do see an issue is how fast a high watts e-bike can accelerate and how that fails to fit into the infrastructure bikes are allowed in. That's something I understand is being addressed but standards changes take time. Still, you could have a 1500W e-bike that is firmware-managed so it doesn't accelerate too fast, just able to hold a decent speed uphill when loaded.
If this gets us onto whether 1000W or 1500W peak output is ok for an e-MTB .. I'm out. That's an ongoing debate in the e-MTB industry and I CBA with any of it. The box is open and it's too late.
Dji seem to have done a firmware update that lets you have 1000w all the time. How are they getting round the legalities here?
Drift, but when it comes to DJI getting around legalities their e-mtb motors are the least of the concerns. They make drones that are used by Israel and Russia.
If they are legal the motor cuts assistance at 15mph so there is only really a speed differential flat/uphill.
1000w can go 15mph on all but the steepest includes, if there was a 250w peak limit you'd probably see more mixed groups. Full power emtbs are kind of their own category because of the power.
If an ebike plus bang average fat lad on top of it can put out 1300 watts up hill does that mean features at bike parks will end up being redesigned in time making them impossible to attempt unless you are on such a bike? ie. a arms race. Or are goopy muddy trails that human power alone could not get through now getting ridden through at will with the long term erosion you'd expect?I'm trying to work out if this is a good thing, a bad thing, or just a thing. Not for the consumer/purchased/rider of that bike but for the rest of the world.
This has been a problem round here for years now. The trails aren't getting reduced usage in the winter to recover as powerful ebikes are still relatively fun to ride on them. Connecting tracks also used to get left alone now deteriorate even more. It's noticeable at trail centres that you now get braking bumps on uphill corners and power bumps before features. All that is on top of just being able to go further and the increased weight.
Actually limiting emtbs to 250W would destroy the industry. For commuter/road style ebikes the speed limit has more impact than maximum power.
Actually limiting emtbs to 250W would destroy the industry.
Bosch have some support in calling for a max 750W peak output.
It's because of the 15.5mph assist limit I think.
On the flat, at its max 15.5 assist limit, it won't draw more than 250w on average
I looked into it a bit more. The rules are defined in https://eur-lex.europa.eu/eli/reg/2013/168/oj/eng in article 2:
"pedal cycles with pedal assistance which are equipped with an auxiliary electric motor having a maximum continuous rated power of less than or equal to 250 W, where the output of the motor is cut off when the cyclist stops pedalling and is otherwise progressively reduced and finally cut off before the vehicle speed reaches 25 km/h"
This document does not define maximum continuous rated power in instead defers to this document as 30 minute power:
Which says
""Maximum 30 minutes power" means the maximum net power of an
electric drive train at DC voltage as defined in paragraph 5.3.1. of this
Regulation, which a drive train can deliver over a period of 30 minutes as
an average;"
However, the test just tests to check that the motor can do the power it says it can. So a manufacture can say "this is a 250w continuous power motor" - meaning it will not overheat in 30 minutes at 250w. There is nothing to stop them submitting a 1000w motor and saying they only rate it at 250w. Hence the motor can be approved as a 250w continous power motor, but still be capable of doing 1000w until the battery runs out.
Pretty stupid.
Actually limiting emtbs to 250W would destroy the industry.
Bosch have some support in calling for a max 750W peak output.
Conveniently the power their motors do, thus removing any performance advantage from DJI - regulatory capture. If you were to limit max output, there is a stronger argument to limit max power to 200w or something - this seems more representative of what an average cyclist can put out. Even a slow commuter is probably doing 80w comfortably, so total power output of 280w seems fine - quite a bit more than my ftp! Maybe have something different for cargo bikes as I can see a case there, but not seeing why you need an ebike that can do 25kmh up a steep mtb track - it just ruins them.
1000w can go 15mph on all but the steepest includes, if there was a 250w peak limit you'd probably see more mixed groups. Full power emtbs are kind of their own category because of the power.
I think people have a slightly warped view of power as well.
200W, for anything longer than a minute or two, is a LOT.
300W would get you the bragging rights of being able to do a sub 1-hour 25mile TT, maybe even on a road bike. That's not the fittest guy in the group, that's his even fitter mate you met once on a ride, got back to the pub a full hour ahead of the group, drank lime and soda and left early to go to bed.
The "bang average fat lad" convert referenced is not topping up their 1000W motor with another 300, it's more like half that.
300W would get you the bragging rights of being able to do a sub 1-hour 25mile TT, maybe even on a road bike. That's not the fittest guy in the group, that's his even fitter mate you met once on a ride, got back to the pub a full hour ahead of the group, drank lime and soda and left early to go to bed.
Rubbish. I could do 300W no problem, I’m reasonably fit but nothing outstanding, there are several stronger riders in the small local club that I never ride with any more.
I’m also 82kg. Not fat, just fairly big.
(I say could because I haven’t done much proper cycling training for ages and am in my late 50s now. I could definitely do 250 for an hour but 300 I’m less confident about these days).
(I say could because I haven’t done much proper cycling training for ages and am in my late 50s now. I could definitely do 250 for an hour but 300 I’m less confident about these days).
Are you sure? I've never trained until we got a wattbike a couple of years ago (and even then I'm not 'training' but have something that's measuring power). I'm not a racer but am nearly always one of the fittest in any group.
My FTP is 300w. My understanding is that's the constant power I can put out for 20minutes, but I'd be a wreck at the end of it.
150w for your average fat lad - especially in terms of the effort they actually putting in - seems much more realistic. Not least I just don't see people, including myself, getting to the real high exertion efforts on e bikes. The gasping for air and peak heart rate at the end of steep climb on a meat bike just doesn't happen on an e bike.
The last couple of hour long rides I've done on Rouvy I had an average power of c200w. I'd not be riding as hard as that on a normal ride out with mates.
FTP is often measured from a 20 minute effort minus 5%. That’s then meant to be what you can output for an hour.
Interesting thread about the regulations, it’s even worse than i thought. It will be a nightmare to sort out
Actually limiting emtbs to 250W would destroy the industry.
Bosch have some support in calling for a max 750W peak output.
Conveniently the power their motors do, thus removing any performance advantage from DJI - regulatory capture. If you were to limit max output, there is a stronger argument to limit max power to 200w or something - this seems more representative of what an average cyclist can put out. Even a slow commuter is probably doing 80w comfortably, so total power output of 280w seems fine - quite a bit more than my ftp! Maybe have something different for cargo bikes as I can see a case there, but not seeing why you need an ebike that can do 25kmh up a steep mtb track - it just ruins them.
I think Bosch have long had the view that somewhere around 600-750W peak is reasonable and that's why they peak there, Shimano have suggested similar, but whether it's defensive or consistent thinking is open to debate.
Whatever the wattage cap I think having one is needed to prevent e-MTB turning into Max Power Pedal-MX. Or, let them at it and accept that MTB is at a fork in the track.
I did 361W for 20 mins a few years back, my wife and I have two smart trainers that give the same numbers and no reason to think they aren’t legit. It’s not an unreasonable value for a fit fairly large man. I could definitely do more when younger (as measured independently on rowing ergometers). I am quite fit but far from exceptional. These numbers would be quite a bit more impressive for a 60kg midget 🙂
I did a local 10 mile time trial a couple of times and the fast guys beat me by a good distance. I agree that plenty of casual riders are slower of course, just not that doing 300W (ish) is some superpower.
prevent e-MTB turning into Max Power Pedal-MX
The box is open and it's too late
Check the response by some to any new ebike that is appropriately powered for any mountain biking or any commuting that includes infrastructure shared with non-powered bikes and pedestrians… “What is the manufacturer thinking?!? I could buy a bike with 1000w and the battery to use it instead, why would anyone want this low powered thing?”
Check the response by some to any new ebike that is appropriately powered for any mountain biking or any commuting that includes infrastructure shared with non-powered bikes and pedestrians… “What is the manufacturer thinking?!? I could buy a bike with 1000w and the battery to use it instead, why would anyone want this low powered thing?”
Yep, spec numbers win. And like on here, blokes like to talk about watts : )
And there's the 'Sur-rons at QECP' thread - not trolling but for many, e-MTBs bridge the gap between MTB and MX in a convenient way. They think riding e-MXs on MTB trails is ok cos it's all pretty similar - an e-MTB is to an MTB what a Sur-on is to e-MTB. I know, legal status as a bike is the borderline but it doesn't work that way does it. 1000W e-MTBs won't help.
Whatever.. XC will never die (unlike your bike's battery).
(I say could because I haven’t done much proper cycling training for ages and am in my late 50s now. I could definitely do 250 for an hour but 300 I’m less confident about these days).
Are you sure? I've never trained until we got a wattbike a couple of years ago (and even then I'm not 'training' but have something that's measuring power). I'm not a racer but am nearly always one of the fittest in any group.
My FTP is 300w. My understanding is that's the constant power I can put out for 20minutes, but I'd be a wreck at the end of it.
150w for your average fat lad - especially in terms of the effort they actually putting in - seems much more realistic. Not least I just don't see people, including myself, getting to the real high exertion efforts on e bikes. The gasping for air and peak heart rate at the end of steep climb on a meat bike just doesn't happen on an e bike.
The last couple of hour long rides I've done on Rouvy I had an average power of c200w. I'd not be riding as hard as that on a normal ride out with mates.
You're underestimating the amount of effort you have to put in when you're fat. 300W is crawling up a not especially steep hill in granny gear for me. I've hired ebikes before and can generally hit peak motor wattage fairly easily in trail mode (boost provides nothing extra) and drain a 600Wh battery in under 2 hours whilst keeping my average heart rate at a similar rate to a normal ride. Part of the reason I've not bothered with an ebike is that for all day rides they don't provide that much extra help whilst being much worse to ride. I might be unusual though in being both morbidly obese and fairly fit.
My FTP is 300w. My understanding is that's the constant power I can put out for 20minutes, but I'd be a wreck at the end of it.
Nope, your FTP is supposed to be the power output you could sustain for an hour, generally extrapolated from a 20min test.
It’s mostly a bullshit number for those of us not actually training in any meaningful way, but a whole other industry is now based on muggles believing they can churn out 300w+ for an hour.
An FTP around 250w is more or less accepted as about what a reasonably fit/trained individual could manage, so it makes sense to set the average assistance level for normal people to about that, enough to make comfortable progress, not so much that you’d get into lots of trouble.
Peak power is a different matter, it’s less about what is sustainable and more about what you can smash out in 5-10s spurts… 1000w+ is not beyond lots of people for a few seconds, and for cleaning a nadgery climb or obstacle it makes sense offroad. But if you just want it so you can beat an amber light and get to the pub 3mins sooner, meh… Hence the debate from a legislative POV, should e-bikes, which I keep being told are mostly about enabling less physically able people to cycle, also provide more opportunities for them to spanner themselves on public roads?
The rules just can’t keep up with the technology or it’s applications (do they ever?).
My FTP is 300w. My understanding is that's the constant power I can put out for 20minutes, but I'd be a wreck at the end of it.
Nope, your FTP is supposed to be the power output you could sustain for an hour, generally extrapolated from a 20min test.
It’s mostly a bullshit number for those of us not actually training in any meaningful way, but a whole other industry is now based on muggles believing they can churn out 300w+ for an hour.
That makes more sense, as there are regularly FTP efforts of about 20minutes in some of the workouts I do. And of course the more relevant measure for actual performance is watts per Kg...
And of course the more relevant measure for actual performance is watts per Kg...
Kind of. But it very much depends if you are training for a time trail on a pan flat course or a hill climb On the latter, watts per kg is king. On the former, some big units pushing big power numbers have performed brilliantly with quite modest watts per kg.
should e-bikes, which I keep being told are mostly about enabling less physically able people to cycle, also provide more opportunities for them to spanner themselves on public roads?
I don't see why an e-bike can't have 1000W peak to have better loaded climbing ability yet also limited acceleration and anti-roost slip sensors (like there is ABS) so it's not just some over-powered idiotmobile. Power isn't the same as torque and the controller firmware can do whatever a brand wants. The industry has a responsibility to steer what gets made, I think, if it doesn't want to see MTB go further into MX lite. Reviews, advertising, test days, what IBDs sell and service etc. I'm not convinced it will, or maybe we see more of a split.
I thought this was a good article on the point of industry responsibility.
"Currently, some players are playing with fire, exploiting loopholes and unregulated aspects, and thus gambling with the freedom of eMTB riding. Worse yet, industry, influencers, media, retailers, and customers are all playing along. Many ignore – or don’t even realise – that the current arms race to increase performance, torque, and battery capacities has more disadvantages than advantages."
https://ebike-mtb.com/en/e-mountainbike-think-tank-2025-2/
From late March to November this year, I've had a handful or so ebike rides where I've climbed a modest hill (approx 260-560 feet 3%+ average) at an estimated ~4W/Kg (Watts divided by total system weight), while my GT eGrade Bolt has been in turbo mode and I've been putting in a max effort myself where my heart rate has averaged 155-170bpm. With decent weight inputs for the ebike and me while riding, with ebike plus bottles ~16Kg; me plus kit plus bits in pockets ~95Kg.
The estimated Watts from such ebike rides sound reasonable, given they were around the segment ballpark times from my efforts on my 4iiii power meter equipped road bike '18-'22. When I was approx 77-82Kg kitted up and bike was ~10Kg with two bottles.
Given my Bolt only has a 248Wh capacity battery, I cannot use turbo 250W assist very liberally, because although assist tapers off towards the UK road legal 25kph assist limit I don't need to travel 10 miles north east of here to hit the hills and be averaging ~60 feet per mile for the ride overall.
Nope, your FTP is supposed to be the power output you could sustain for an hour, generally extrapolated from a 20min test.
Nope again, it's probably not far off, but in the same way it's assumed to be 95% of your 20min effort, that's just assuming your power Vs duration follows a prescribed curve.
You can measure another metric, which is how long can you hold FTP for. And for some people it might be around an hour, for others it will be 20minutes, for others it might be 2 hours. FTP is better defined as being the knee on the graph, the point at which any higher power becomes rapidly fatiguing and below which the amount you could sustain levels off. How flat the graph is above 20minutes is also a function of how quickly your muscles fatigue, not just how much oxygen you can supply to them.
It's why ramp tests tend to overestimate FTP when untrained, you can hold that power for a minute much easier than you could hold some percentage of it for 20 or 60 minutes.
I could definitely do 250 for an hour but 300 I’m less confident about these days
So actually, you can't do 300W? Which was my point, 300W is a LOT if you have to do it for more than a punchy climb.
People are kidding themselves that 250W is just leveling them upto normal, 250W alone is very fit.
Nope again, it's probably not far off, but in the same way it's assumed to be 95% of your 20min effort, that's just assuming your power Vs duration follows a prescribed curve.
So “extrapolated” like I said, it might be more accurate to say “estimated” using some maths and assumptions to make it appear more scientific, but FTP is still just a mostly imaginary number IMO.
In the context of this conversation however all that really matters it that 250w is taken as a rough estimate for a fit individual’s FTP and thus remains a reasonable basis for setting an average for pedal assistance (is you’re doing it based on power).
I thought this was a good article on the point of industry responsibility.
"Currently, some players are playing with fire, exploiting loopholes and unregulated aspects, and thus gambling with the freedom of eMTB riding. Worse yet, industry, influencers, media, retailers, and customers are all playing along. Many ignore – or don’t even realise – that the current arms race to increase performance, torque, and battery capacities has more disadvantages than advantages."
That is a good read, thanks for the link! 🙂
250W in turbo mode isn't a problem in itself for climbing when the ebike typically weighs 15-30Kg and the rider weighs typically 50-100Kg, but giving ebikes huge battery capacity to use this max assistance on flat and acceleration from a low speed downhill for hours is dangerous.
On the approx 3 hour rides I've done, turbo 250W has been limited to ~20mins of climbing, because I need the rest of the small 248Wh capacity in eco mode around 75W for everywhere else except for most downhills on a ride with 2000-3300 feet of climbing. I then arrive home with ~10% battery left.
So actually, you can't do 300W?
I could definitely do it a few years ago and I was no superstar just a 50-something guy spending some time on Zwift through the pandemic. Just looked it up, 335W up the Alpe about 5y ago, that was 47 mins. Only just over 4W/kg, nothing outrageous. I haven't ridden much recently so can't promise I haven't slowed up a little, my running paces are definitely down from what I was capable of back then. Once you're 80kg, 300W isn't really that big a number.
But like I said I agree with the basic premise that even 250W would be a big big boost to power for basically all riders (other than perhaps a decent sprinter on a short burst).