You're making it more complicated than it is. We've explained this hundreds of times. The motor must be RATED at 250w or less. There is no law that limits charging power, size of battery, power taken from the battery or power produced by the motor.

 

For some inexplicable reason, the UK law does say that the label or plate which MUST be fitted to the e-bike, must give either the maximum speed the motor will assist to, OR THE BATTERY VOLTAGE. I know this is insane, but it does say it. Check here at the Govt web site. Very confusing.

 

https://www.gov.uk/electric-bike-rules

Calibration is not enough. To be a suitable measuring device, they would have to do repeatability and reproduceability test on the meausuring device that showed +/- 4 standard deviations of variation are less than 0.25km/hr. This would only be an argument if the device showed that you were just above the 27.5 km/hr maximum.

 

I'd say anything calibrated by the Swiss calibration agency, METAS, is probably pucker, wouldn't you?

 

https://www.metas.ch/metas/en/home.html

 

Certification Body METAS-Cert

The accredited conformity evaluation body METAS-Cert is a body notified by Switzerland and recognized by the EU for the conformity evaluation of measuring instruments. The conformity evaluation body METAS-Cert provides manufacturers of measuring instruments with the required conformity assessments for the placing of their products on the market.

Was that directed at me or [mention=34503]matthewslack[/mention]?

 

I doubt accurate calculation of speed of a driven wheel rotating in the air was part of Bafang's design brief. What matters is speed in use on the road. Behold in wonder at how fast my bike cuts off at 25kph in use ON THE ROAD (1min 12 seconds onwards) uphill. Works just as fast on flat road.

 

https://www.youtube.com/watch?v=oCBYMm-Vvk8:72

You said his bike was non-compliant because of his solar charging IIUYC.

You said his bike was non-compliant because of his solar charging IIUYC.

What's with the 250W stuff then?

 

Why isn't [mention=34503]matthewslack[/mention]'s charging the ebike battery on his ebike, via solar panels on his trailer while cycling illegal? It's a hybrid of sorts - if he was charging the ebike battery on his bike using a diesel generator situated on his bike trailer, instead of solar panels, why wouldn't [mention=34503]matthewslack[/mention] be clapped in irons and orificed by rozzers? They're two separate vehicles with one electrical system. Charging one ebike battery on the solar trailer, while the other is being used by the bike is legal. Correct me if I'm wrong and please state why.

Edited January 18Jan 18 by guerney

I'd say anything calibrated by the Swiss calibration agency, METAS, is probably pucker, wouldn't you?

 

https://www.metas.ch/metas/en/home.html

 

Certification Body METAS-Cert

The accredited conformity evaluation body METAS-Cert is a body notified by Switzerland and recognized by the EU for the conformity evaluation of measuring instruments. The conformity evaluation body METAS-Cert provides manufacturers of measuring instruments with the required conformity assessments for the placing of their products on the market.

Calibration is not enough, though it depends what's in the calibration procedure. In most cases it doesn't consider the variability of the results. An R&R study is normally a pre-requisite for any device used for measuring anything for legal purposes or any critical features. Once the R&R is proven, you can use a single calibration to prove that the measuring device is set accurately.

 

Take the situation where somebody has been on a long ride and their battery is nearly empty. They do the test and get 20 mph. The owner asks whether they're sure about the results and asks to do the test again. They get 19.8 mph because the voltage is dropping in the battery, so he asks what sort of accuracy it has, when it gives two different results, then asks them to do it again to see which is correct. They get 19.5 mph because his battery has gone down further. Can you imagine taking that to court? The defence would be that it gives a different result every time, always going lower.

 

Another thing. What about the weight on the wheel. The higher the load, the lower the rolling diameter, so the lower the speed. 1/2" compression on a 20" wheel would make a difference of 2.5% to the measured result, so make sure you're sitting on your bike when you do the test.

What's with the 250W stuff then?

 

Why isn't [mention=34503]matthewslack[/mention]'s charging the ebike battery on his ebike, via solar panels on his trailer while cycling illegal? It's a hybrid of sorts - if he was charging the ebike battery on his bike using a diesel generator situated on his bike trailer, instead of solar panels, why wouldn't [mention=34503]matthewslack[/mention] be clapped in irons and orificed by rozzers? They're two separate vehicles with one electrical system. Charging one ebike battery on the solar trailer, while the other is being used by the bike is legal. Correct me if I'm wrong and please state why.

 

Why do you think the charging of an ebike with a solar panel while riding is illegal?

 

The laws on ebikes make no reference to such a thing as far as I know.

 

https://share.google/aimode/LiM40wuEvP5adN9zS

What's with the 250W stuff then?

 

Why isn't [mention=34503]matthewslack[/mention]'s charging the ebike battery on his ebike, via solar panels on his trailer while cycling illegal? It's a hybrid of sorts - if he was charging the ebike battery on his bike using a diesel generator situated on his bike trailer, instead of solar panels, why wouldn't [mention=34503]matthewslack[/mention] be clapped in irons and orificed by rozzers? They're two separate vehicles with one electrical system. Charging one ebike battery on the solar trailer, while the other is being used by the bike is legal. Correct me if I'm wrong and please state why.

The only thing giving power to propel his bike and the trailer is the motor, which is 250w, so legal. That's it.

Calibration is not enough, though it depends what's in the calibration procedure. In most cases it doesn't consider the variability of the results. An R&R study is normally a pre-requisite for any device used for measuring anything for legal purposes or any critical features. Once the R&R is proven, you can use a single calibration to prove that the measuring device is set accurately.

 

Take the situation where somebody has been on a long ride and their battery is nearly empty. They do the test and get 20 mph. The owner asks whether they're sure about the results and asks to do the test again. They get 19.8 mph because the voltage is dropping in the battery, so he asks what sort of accuracy it has, when it gives two different results, then asks them to do it again to see which is correct. They get 19.5 mph because his battery has gone down further. Can you imagine taking that to court? The defence would be that it gives a different result every time, always going lower.

 

Another thing. What about the weight on the wheel. The higher the load, the lower the rolling diameter, so the lower the speed. 1/2" compression on a 20" wheel would make a difference of 2.5% to the measured result, so make sure you're sitting on your bike when you do the test.

 

The device under discussion is a rolling road type of device for measuring maximum speed. It is not measuring motor power which is defined by the manufacturers label anyway.

 

It needs to accurately measure the speed of a tyre running on top of it to see what the maximum assisted speed is.

 

As shown by Notts Police, the device has a label on it, reminding officers that their limit for failing the legal test is 30KPH which is pretty generous - probably applying the usual ACPO recommendation for police reporting speeding offences , an allowance of 10% above the speed limit, plus 1 mph, so no one is being hyper legalistic, or uber vigilant here. 30 kph is 18.64 MPH a full 3mph above the legal limit.

 

The only relevant question is this:

 

Does this device accurately measure speed when a bicycle with a rider on top is operated on it.

 

The device has been certified by the Swiss metrology people.

 

I don't think it is sensible to challenge that the Swiss Institute for metrology, designated as qualified to measure and calibrate devices for EU certification, is not capable of certifying this kind of device.

 

It patently is qualified and if the device made by Wenger is so certified, and it is, the device is obviously capable of accurately measuring the powered speed of any ebike or scooter put on top of it and tested.

Edited January 18Jan 18 by Tony1951

Certification Body METAS-Cert

The accredited conformity evaluation body METAS-Cert is a body notified by Switzerland and recognized by the EU for the conformity evaluation of measuring instruments. The conformity evaluation body METAS-Cert provides manufacturers of measuring instruments with the required conformity assessments for the placing of their products on the market.

You're forgetting that I was a quality manager in automotive sector for 20 years. I know everything about calibration and measuring devices. what's above means very little, except they did a measurement that was in an acceptable range and wrote a certificate for it. METAS just means that they have a lot of accurate equipment and procedures on how to check. They don't know or care what you do with the device.

 

Take a micrometer as an example. You send it to them, they measure 3 or 4 slip blocks of known size in their temperature controlled lab and get suitably accurate results. They give it back wth its METAS certificate. Your inspector takes it out into your freezing stores, winds it up like a G-clamp then tells you the parts are too small.

The device under discussion is a rolling road type of device for measuring maximum speed. It is not measuring motor power which is defined by the manufacturers label anyway.

 

It needs to accurately measure the speed of a tyre running on top of it to see what the maximum assisted speed is.

 

As shown by Notts Police, the device has a label on it, reminding officers that their limit for failing the legal test is 30KPH which is pretty generous - probably applying the usual ACPO recommendation for police speeding offences of a 10% margin plus 1 mph, so no one is being hyper legalistic, or uber vigilant here. 30 kph is 18.64 MPH a full 3mph above the legal limit.

 

The only relevant question is does this device accurately measure speed when a bicycle with a rider on top is operated on it.

 

I don't think it is sensible to challenge that the Swiss Institute for metrology, designated as qualified to measure devices for EU certification is not qualified to certify a rolling road to measure electric bicycle speed limits built into the bikes.

It can't measure the speed of the bike. It simply checks the speed that the rollers are moving. The two aren't necessarily the same, though I can't think of any circumstances where the rollers would be rolling faster than the bike; however, as I mentioned above, there could be a 2.5% difference between a bike on the road with a rider on it compared with the bike on the rollers with nobody sitting on it. Loose spokes could make another 2.5% difference, so 5% in total between the rider on the bike and no rider.

 

None of that matters if the reading is 40 mph, but it could make a difference if the result is close to the decision point.

Why do you think the charging of an ebike with a solar panel while riding is illegal?

 

The laws on ebikes make no reference to such a thing as far as I know.

 

https://share.google/aimode/LiM40wuEvP5adN9zS

 

I don't think charging your ebike's battery, using solar panels situated on your ebike is illegal. For some reason I recall the law prohibits charging the ebike battery via another vehicle while in use, in this case a bicycle trailer. When I recall exactly what and where that's stated, I'll post a link.

Edited January 18Jan 18 by guerney

Why would the rozzers of Nottingham spend so much money on Swiss (anything Swiss is usually expensive) compact dynanometers if the no-load wheel in the air speed limit test was valid? Some sort of health and safety issue? To counter lower back pain of obese rozzers? Because these orificer dudes are anal about exactitude? It's not enough to know vaguely what the illegal speed is, they're compelled to discover exactly how illegal? Cadence sensored KT and Bafang firmware is programmed to calculate speed in use on roads, not hanging around rotating in the air.

Edited January 19Jan 19 by guerney

Why would the rozzers of Nottingham spend so much money on Swiss (anything Swiss is usually expensive) compact dynanometers if the no-load wheel in the air speed limit test was valid? Cadence sensored KT and Bafang firmware is programmed to calculate speed in use on roads, not hanging around rotating in the air.

They could have done it much cheaper with an rpm meter, tape measure and some white spot stickers - less than ten quid for the lot.

https://www.aliexpress.com/item/1005003773418246.html?spm=a2g0o.tesla.0.0.6bd1OhtBOhtBDo&pdp_npi=6%40dis%21GBP%21%EF%BF%A16.84%21%EF%BF%A14.79%21%21%21%21%21%40211b61d017687593958343825eeb93%2112000027116707248%21btfpre%21%21%21%211%210%21&afTraceInfo=1005003773418246__pc__c_ppc_item_bridge_pc_main__c3OzcTb__1768759395956#nav-specification

It looks like they are trying to get things as accurate and clear as possible to prevent any blowback in court.

 

The reporter (as usual) needs to get his facts straight however.

He states:

Riders require a driving licence and insurance if their e-bikes can go more than 15.5mph ( 24.94km/h) without pedalling.

And also:

The equipment was acquired from Switzerland using funds from the office of Nottinghamshire's Police and Crime Commissioner, and allows an accurate testing of a vehicle's top speed when unaided by cyclists "without needing a full test track or laboratory".

Surely, if the bike achieves any electrically motivated movement (above walk assist) without pedaling it's illegal anyway.

 

Also do the BBC not use spell checkers? As in 'licence' and 'pedalling'. Feeling grumpy pedantic this morning.

It can't measure the speed of the bike. It simply checks the speed that the rollers are moving. The two aren't necessarily the same, though I can't think of any circumstances where the rollers would be rolling faster than the bike; however, as I mentioned above, there could be a 2.5% difference between a bike on the road with a rider on it compared with the bike on the rollers with nobody sitting on it. Loose spokes could make another 2.5% difference, so 5% in total between the rider on the bike and no rider.

 

None of that matters if the reading is 40 mph, but it could make a difference if the result is close to the decision point.

 

 

 

Look at the white coloured label in the photograph.

 

The police are operating a very wide margin of a 3 mph allowance above the legal speed limit. It is about 11% allowance.

 

This margin dwarfs any of the issues you have raised (which are nit picking) and in any case, any bike except those with Individual Type Approval can't legally operate with a full speed throttle, and so they would have to be tested with a rider sitting on them and pedalling to make the bike go at speed in the first place. The film I referenced made by Wenger shows people standing on scooters and sitting on bicycles on top of the measuring device. The Notts Police page also shows that, although it also showed an unloaded bike being run with a throttle at speed (illegal except in the case of Individual Type Approval) and a dopey youth, in a police uniform who looked like a teenager dressed up, made a stupid remark in the Notts Police video, talking about battery power because he had no idea what the law says. There is still an issue of inadequate training. It was noticeable that the sergeant knew his stuff.

 

I don't know why you would take such exception to attempts to improve the road side checking procedure. This is a sound device, calibrated and tested and operated with a wide margin of allowance. Your complaints seem vexatious, given what was going on before, with people making ridiculous attempts to test speed which had so many holes in them from a technical point of view that they were positively laughable and would easily have been thrown out by any court.

 

In the end - we all know that e-bikes ( a wonderful and liberating idea for sensible people) have been taken over by lunatics, criminals and law breakers who have made such a nuisance of themselves from one end of this country to the other, that the whole population of e-bike riders, including us, has been tainted with the bad publicity. It has to stop, and the police are right to deal with it. This device, operated with a sensible safety margin (and this one is more than generous) is a perfectly proper response.

 

Here is another, less portable dynamometer type device being used. The Wenger one looks far more convenient and a lot cheaper to make.

 

Edited January 19Jan 19 by Tony1951

Speed allowance to allow for inaccuracies with odometers vary from force to force ,some compensate by speed limit + 1mph + 10% others speed limit + 2mph +10%.

For some inexplicable reason, the UK law does say that the label or plate which MUST be fitted to the e-bike, must give either the maximum speed the motor will assist to, OR THE BATTERY VOLTAGE. I know this is insane, but it does say it. Check here at the Govt web site. Very confusing.

 

https://www.gov.uk/electric-bike-rules

 

That isn't insane, upping the battery voltage from the legal design voltage results in a pro rata increase in speed. Therefore comparing the actual battery voltage with what it's official label says it should be is a check on illicit alteration.

.

 

I don't know why you would take such exception to attempts to improve the road side checking procedure. This is a sound device, calibrated and tested and operated with a wide margin of allowance. Your complaints seem vexatious, given what was going on before, with people making ridiculous attempts to test speed which had so many holes in them from a technical point of view that they were positively laughable and would easily have been thrown out by any court.

I love the way you try to make things personal and invent people's emotions and motivations.

 

All I did was point out that it doesn’t necessarily make a slam-dunk case for prosecution or confiscation, and I specifically mentioned that independent throttles made the whole process moot and that my arguments would only apply to small discrepencies. I like the device and I'm pleased that they're using it, even though it's not a perfect solution.

 

Imagine the situation where your bike is set to 16.5mph because you didn’t verify the 15.5 mph with GPS. The police test your bike with that device, it shows 17.5mph because of the things I mentioned, and the zealous pc decides to confiscate your bike. I was merely pointing out arguments you could use against that. I don’t care about those deliveroo riders with 30 mph bikes. I encourage the police to deal with them. That's different to my feelings 12 years ago, when a few responsible commuters had such bikes, but now it's a problem with them plaguing town centres and pedestrian zones.

That isn't insane, upping the battery voltage from the legal design voltage results in a pro rata increase in speed. Therefore comparing the actual battery voltage with what it's official label says it should be is a check on illicit alteration.

.

Except that the logic in the speed controller ought to cut power st 25 kph.

 

Anyway in the video i referred to, the very young policeman remarked ghst the battery power must be limited to 250 watts, which of course wr sll know to be nonsense.

 

Maybe we are talking about different posts.

Except that the logic in the speed controller ought to cut power st 25 kph.

 

Anyway in the video i referred to, the very young policeman remarked ghst the battery power must be limited to 250 watts, which of course wr sll know to be nonsense.

 

Maybe we are talking about different posts.

 

No, same post. Accepted the young police officer was wrong, but I was replying with this quote from your post:

 

"For some inexplicable reason, the UK law does say that the label or plate which MUST be fitted to the e-bike, must give either the maximum speed the motor will assist to, OR THE BATTERY VOLTAGE. I know this is insane, but it does say it."

 

So as I explained, giving an entirely rational way of checking the battery hasn't been changed to one of higher voltage for increased cut off speed, so neither inexplicable or insane.

 

Also controller logic doesn't necessarily apply. Many pedelecs have been designed with assist speed cut off at the battery's maximum possible voltage, I've owned one myself. They of course have the slight disadvantage of the cut off declining as the battery discharges.

.

I love the way you try to make things personal and invent people's emotions and motivations.

 

All I did was point out that it doesn’t necessarily make a slam-dunk case for prosecution or confiscation, and I specifically mentioned that independent throttles made the whole process moot and that my arguments would only apply to small discrepencies. I like the device and I'm pleased that they're using it, even though it's not a perfect solution.

 

Imagine the situation where your bike is set to 16.5mph because you didn’t verify the 15.5 mph with GPS. The police test your bike with that device, it shows 17.5mph because of the things I mentioned, and the zealous pc decides to confiscate your bike. I was merely pointing out arguments you could use against that. I don’t care about those deliveroo riders with 30 mph bikes. I encourage the police to deal with them. That's different to my feelings 12 years ago, when a few responsible commuters had such bikes, but now it's a problem with them plaguing town centres and pedestrian zones.

 

I had no intention of making it 'personal' here Dave - not in the least. I have absolutely no issue with you as a person and as you know well, I have frequently made appreciative remarks about your contribution here, so if you took the remarks made about 'vexatious' arguments in a personal way this was not intended by me. I was arguing with what I thought you said which seemed to me to be over critical of the device and its use.

 

I have re-read what I said this morning and I have not invented your motivations and emotions, unless you inferred that was what I was doing when I suggested you had taken exception to this attempt to improve the road-side checking procedure. I wasn't being personal, I thought that was clear from what you were saying about the device, which seemed to me, that you thought it wasn't good enough to do the job.

 

I think the device itself was a good way forward from the idiocy of police picking up the back wheel and causing the motor to spin and then announcing on Titter, or whatever that it was capable of 60 miles an hour, which as we all know and agree is totally stupid and indicates that the individuals who posted such announcements were clueless and unfit to be examining e-bikes at all. At least this rolling road device by Wenger can measure the cut off speed. The Wenger site has information about the device explaining that it can not measure maximum speed and from looking yesterday, I think I recall that it pointed out the obvious limitations how it could not assess wind resistance and rolling resistance which are major factors in assessing top speed - things you and I know very well, but many many police posting on the Internet seem blissfully unaware of.

 

Overall - I think it is clear that a massive basic physics and engineering re-education programme is needed for any police doing this kind of assessment. The announcements made frequently show they don't understand basic concepts.

Many pedelecs have been designed with assist speed cut off at the battery's maximum possible voltage, I've owned one myself. They of course have the slight disadvantage of the cut off declining as the battery discharges.

.

Nearly all ebikes I've seen in the last ten years uses a speed sensor signal as a basis to regulate and display the speed. Most older ones with no display or LED display didn't attempt to regulate the speed, and they nearly all went over 20 mph with 36v battery, so already illegal without 48v.

 

Maybe whoever came up with the idea to include battery voltage on the label was living in the past, but, even then, they must have had very limited ebike experience. I suspect, though, that more likely they don't have a clue about ebikes or basic engineering principles, as they still have "continuous rated power", where the "continuous" is superfluous and meaningless in the context it's used, since the rated power can't change anyway.

Maybe whoever came up with the idea to include battery voltage on the label was living in the past,

 

Of course, they were in the past long ago, as I've often posted:

 

"As part of the GB EAPC amending legislation, that will come into force on 6 April 2015, the requirement for the marking identification has been amended. Previously a plate showing the manufacturer, maximum continuous rated power output and voltage was necessary, from April 6 2015 the requirement will be that the manufacturer, maximum continuous rated output and maximum assisted cutoff speed shall be marked on the cycle."

 

It invariably takes the DfT a long time to catch up on changes. It took them 12 years to realise the EU had changed from 200 watts to 250 watts.

.

Edited January 20Jan 20 by flecc

as they still have "continuous rated power", where the "continuous" is superfluous and meaningless in the context it's used, since the rated power can't change anyway.

I agree. Though if they had used "rated continuous power" the "continuous" would not be superfluous, as a manufacturer could choose to rate a motor with more than one rating (eg) "rated continuous power" and "rated peak power"

I agree. Though if they had used "rated continuous power" the "continuous" would not be superfluous, as a manufacturer could choose to rate a motor with more than one rating (eg) "rated continuous power" and "rated peak power"

That's sort of right if you were explaining to a layman, but the standard for rating requires the battery to run continuously at the rated power, so the "continuous" is implied and still unnecessary. In other words, if I tell you that a motor is rated at 250w, it means specifically that it can run continuously at 250w. There is no rated peak power. It's just peak power, so no need to differentiate. This is all intellectual masturbation. The point is that the government website looks amateurish.

Edited January 20Jan 20 by saneagle