I wish they were! We used to have plenty of fun in this forum and were very lighthearted in our posting practice, but in recent months it's becoming ever more po faced.

I blame the ageing membership myself, lets take away the over generous pensions so they can't afford these toys any more.

Oh dear Mr Mussels, Baby-boomer envy perhaps!!

Anyway, this chap has gone the twin motor route by having two currie 24V electrodrives at the back so he can overvolt to 48v and split the amps between the two motors to prevent overheating. Good for near 30mph, but I'm not sure I like the battery in the trailer.

 

Still should be fun though!

 

On the flat, you could ride with normal pedelec controlled assist from the existing rear motor. When approaching a cliff face, you would then whack the thumb throttle supplied with the front motor wide open, and storm the hill with two motors pulling. Don't expect to go scortching up the hill like a half arsed astronaut, more likely the machine will slow to around 10 MPH which is the roadspeed at which these motors achieve maximum torque. The realm of fantasy maybe, but food for thought none the less.

 

Hi Guys,

 

I've seen this idea of a maximum torque speed on the forum a couple of times, and its not quite correct. Maximum torque from an electric motor is at zero speed. Its not quite an inverse linear relationship with speed because in most cases the controller intervenes to limit the battery current.

 

What does vary with speed, and in different ways, is the efficiency and the power. The power (input or output) depends on the supply voltage as well as the motor, and for a given system there is a speed at which it peaks. On a well designed system that peak power will also deliver good efficiency. At lower speeds the efficiency can drop off sharply.

 

In summary then, there is a speed to aim for, or a speed to keep above. But it is all to do with efficiency and not about torque. As you go slower the torque will rise and you may be able to climb the hill.

 

In fact, when analysing hill climbing capability, the crucial question is not can you get up a particular hill, but at what speed can you get up the hill.

 

Nick

 

To get back to the question about two motors, the plan to use the second motor as a manually activated one that is used only on hills seems perfectly legal, particularly if the first motor is pedelec controlled, the second motor is manually controlled and the assist speed is less than 15mph. If the second motor isn't used all the time, but just on hills, then its power contribution cannot reasonably be said to be "continuous" using any normal definition of the word. It's a particular case where compliance with the law seems quite straightforward to prove.

 

Jeremy

 

I still disagree with this interpretation Jeremy. The law states maximum continuous rated power, not what flecc uses on his way to the shops. Note the word maximum, not what's used but what can be used. Any two legal e-bike motors exceed the legal limit and if the rider can use them both at the same time, the bike fitted with them is an unregistered, unlicenced and uninsured motor vehicle, lacking type approval. The consequences are expensive and are very likely to include loss of driving licence.

 

Some motors carry their rated continuous power on them, Heinzmann for example, and If I ride down the road with two basic Heinzmanns, each declaring it's 200 watts, I'm riding equipped with 400 watts of rated power whether I'm using it or not. The evidence of those plates is more than enough for the bike to be seized and crushed.

 

Whilst I agree that the likelyhood of detection is low, and have posted as much above, it's not non-existent. I know of one serving and one retired police officer in this forum where this law has been extensively discussed, and with 1 in 300 of the population serving police officers, on the basis of the law of averages there may be 4 serving officer members. Many Met Police officers are cycling club and CTC members and I'm sure this is true nationally, so the number of CTC police members will be at least in the hundreds, the relevance being that e-bike law has been discussed in the CTC forum as well.

 

Many areas including my own have had programs of seizures and crushing of illegal two wheelers, one seized in my area being an electric one, again showing the risk is far from non-existent.

 

Therefore the advice I gave to wibble was sound and safe, your contradictory advice at the very least being risky. However, I do derive some amusement from the vision of you arguing aircraft engine practice in the defence of an e-bike case in a magistrates court.

.

Edited October 21, 200817 yr by flecc

Flecc, Jeremy,

 

If we may, for a moment, concentrate on the crucial phrase "maximum continuous rated power", or MCRP for short

 

Do you think that means the MCRP of the motor itself, or of the motor/controller/battery combination?

 

That would make a very important difference. For instance, a powerful motor that was limited either by controller electronics or battery voltage would be illegal under one interpretation and legal under another.

 

Nick

Flecc, Jeremy,

 

If we may, for a moment, concentrate on the crucial phrase "maximum continuous rated power", or MCRP for short

Where would that power be measured - electrical input to the motor or kinetic output after conversion losses?

 

Edit:

Thinking about it how would the output power be calculated as it power = torque x angular speed. Legally on a pedelec power should decrease as the bike speed increases so using a high RPM is no good and torque drops of massively at low RMP in hub motors, so by my calculations whilst MCRP may be stamped on the side of the motor it would be largely irrelevant and unmeasurable in practice.

In the spirit of things I think power should be measured at the DC power supply as that can be easily tested and encourages efficiency, but who wants to make life easy for the authorities?

Edited October 21, 200817 yr by Mussels

Flecc, Jeremy,

 

If we may, for a moment, concentrate on the crucial phrase "maximum continuous rated power", or MCRP for short

 

Do you think that means the MCRP of the motor itself, or of the motor/controller/battery combination?

 

That would make a very important difference. For instance, a powerful motor that was limited either by controller electronics or battery voltage would be illegal under one interpretation and legal under another.

 

Nick

 

In this context Nick, I don't think it matters, since most would use the appropriate controllers for the motors. There would be no point in fitting two motors which run at the same time and then limiting them to legality

 

As Jeremy has posted, it's up to the manufacturer to state their motor maximum rated power and that would be likely to hold sway at law. If, as in my example, my hypothetical two Heinzmanns stated themselves to total 400 watts, the law has been broken and it's demonstrable that I as the person creating that bike has knowingly broken it, leaving me without a viable defence.

.

Tiberius

 

I'm quite sure your right about the realities of two motors. To be honest, I'm more at home with lathe 'n' mill than anything electronic!. On the occasions when I have worked with electronics the results have been "interesting", (hence the forum "nick"). In defence, I should point out this was in the field of high powered RF amplifiers, I've yet to succeed in blowing anything on an Ebike....there's a first time for everything!.

 

Now, I'm sure this will upset a few apple carts, but the simple fact is, skinny over-pensioned retiree's such as Flecc, myself and others, will always enjoy better performance from a legal Ebike than those who admit to being "a bit overweight".

 

Perhaps that's the answer....shed the pounds guys and watch that bike fly!!.

 

INCOMING: rocket propelled skinny-envy!!!.

 

Ah, a big orange truck has just delivered a prezzy, Good old Bob in sunny Scotland has sent me a battery and charger without buying a kit, cheers Bob!.

 

Best wishes to all (honest)

 

Bob

In this context Nick, I don't think it matters, since most would use the appropriate controllers for the motors.

 

Flecc, I beg to disagree. It makes a huge difference. Motors and controllers generally come from different manufacturers. There is generally a choice of combinations and more than one appropriate controller.

 

What, for instance of the case of a motor, which the motor manufacturer declares is 300 W MCRP, and the bike manufacturer mates with a controller/battery that will only take it to 200 W MCRP?

 

Nick

Of course I agree with that Nick, but my point was as said, in the context that no-one is likely to controller equip a motor for less than 200 watts when they seek more performance by fitting two motors. Therefore they are certain to breach the 200 and 250 watt legal limits, since no controller combination they choose is likely to drop the motors to 100 or 125 watts each continuous rating.

 

In many and probably most cases as with Danny and his Powacycle proposal in another thread, an additional motor would be added to a bike that is already rated at the legal limit, so illegality would be assured with any added combination.

.

Edited October 21, 200817 yr by flecc

This dilemma of how "continuous power" should be defined and demonstrated to a curious police officer is the root cause of the "two motor problem".

 

In essence, the onus is on the bike manufacturer to define a continuous power rating and appropriately placard this on the bike. There is a well-proven precedent in law for this being the case - motorcycles are required to have a data plate that states the power, and, in the case of mopeds, the design speed. If you modify a motorcycle (as I have just done) then you are required to amend the data plate accordingly.

 

There is also a precedent for determining who the vehicle manufacturer is in law. In the case of a home constructed, or significantly modified, vehicle, the "manufacturer" is the person who creates the finished vehicle. Again, I've direct evidence to support this, as I have had to take responsibility for being the new "manufacturer" for my modified motorcycle.

 

This leads inevitably to the conclusion that someone who converts a pedal cycle to an electric bike is almost certainly the individual who has to set the maximum continuous power rating. There is a clear logic to this; continuous power is a system rating, not a motor rating, nor a battery or controller rating. One reason for setting a lower continuous power rating for a system than any of the individual components can tolerate might be heat dissipation. Whilst a complete system (motor, controller, battery, cables and bike) might be able to deliver high power levels for short periods, a builder/manufacturer might, quite reasonably, wish to set a lower "continuous power" rating to avoid damaging heat build up in some of the components.

 

This is obviously what most (perhaps all?) commercial electric bike manufacturers do, as most (all?) of those available in the UK have a real maximum power that is greater than 250W. The many tales of battery cut-outs, blown controllers etc indicate that peak power levels are fairly high for many ebikes.

 

Jeremy

There is a clear logic to this; continuous power is a system rating, not a motor rating, nor a battery or controller rating.

 

Hi Jeremy,

 

This is the question I was driving at, but it got sidetracked by the two vs one motor point.

 

If you follow the logic through of basing the continuous power rating on the motor alone, then almost every e-bike could be shown to be illegal. From the engineering point of view it only makes sense as a system parameter.

 

I don't know how one would deal with the curious police officer who kept pointing to the label on the motor and saying "but that's a 500 W motor" or "but those are two 250 W motors".

 

Nick

 

PS. I think I ought to take the 406 sticker off my Crystalyte in case someone thinks its the power and not the model number.

 

PPS. We seem to have got off the two motor question, so apologies to the original poster, but it is an important discussion and not entirely irrelevant.

Edited October 21, 200817 yr by Tiberius

I think a better option would be a Tongxin Nano in the front wheel for four reasons...

 

Thanks for your suggestion Flecc. I agree with you on the Tongxin Nano - but they're practically unavailable to the end-user direct from the Chinese manufacturer of Tongxin. Tony Castles is the only easily orderable source in the UK of the Nano motor that I know of.

About £300 without the battery.

 

Whilst the Alien kit, not only has a potentiometer with which the owner can choose to derestrict, if they so desire, the 15 mph max cut-off point all the way up to 20 mph,

- BUT also comes with a 36volt 10 amp battery, (plus rear rack for the nicely designed battery), and comes in at £439 or thereabouts. In effect the Alien motor, on it's own is seriously cheaper than the Nano.

 

I also like the care that the Scottish AlienOcean retailer has gone to on his eBay site numbering all the wires to make things as simple as possible etc., However, if the Nano is the best choice, then eventually it would tell after the initial cost of the Alien had fallen from memory, and freewheeling motor capabilities became bothersome. My thinking is, with the initial cost of my e-bike plus the additional motor kit, I would have a bike to suit me for a final spend of £800- £900 all-in, whichever motor I chose.

 

Also, if ever I decided to sell the Salisbury, I would refit the original wheel and use the motor kit on one of my other pushbikes, (or what about this - fitted to a Kalkhoff, if a Kalkhoff was my choice in 2009 that is, whatever, my next e-bike MUST be from a manufacturer that offers a range of frame sizes).

 

Was talking it over with a friend at lunchtime today, raised eyebrows were the order of the day with the advice I should get my fitness level back to its previous level before making any further purchase decisions. Tend to agree with that - but that's what an e-bike is for, those occasions where your fitness is well below par, many have posted on here to going back to enjoying there pushbikes once again now that their e-bike has tuned up their fitness levels. So the two-motor option is on the back-burner for the moment; but what an opportunity - If I pay around or well over the £1k mark next year for THE bike of my final choice, a second motor fitted will be out of the question, it's now or never, what with my current cheapo second-hand e-bike, obtained for barely more than the price of a new battery.

 

Yes Danny, you could fit the front motor Alien kit to the Salisbury, but, you might have to replace the front forks with a pair designed to accept a motor hub. these are currently available from Wheelcare.co.uk on Ebay at around £24. I'm almost certain they have the 110 m/m clearance needed on the drop-outs...

 

Thanks for that advice Bob; I have seen that eBay listing previously. Measured the forks on the Salisbury at the time and I think they'd j-u-s-t lose out a smidgen, but not for the Nano motor.

 

Don't try running both motors off one battery, the combined demand would almost certainly result in enough voltage sag to trigger a low volt shut down. Anyway, the flat shaped Phylion 36 volt 10ah battery supplied with the Alien kit will easily fit on the Salisbury's rear rack...

 

And here you get right to the nub of the matter. I'm not enamoured of pre-calculating every journey to the last mile to see if I can make it back home with enough battery power still available to do so. I want to go off and clock up 40, 50, 60 miles and not give it a second's thought; just like on my 'tourer'. So the obvious solution, like so many others would be to purchase a second battery - £209 at present for the Salisbury, (24v/10.5amp). So... if I fitted a second motor, then that second battery, (about the same price as the Salisbury battery), would always be there and available for back-up duties to the salisbury's motor where the worst of the hills have it whimpering and running for cover. Wouldn't that be great? I reckon if either the Alien or Nano could give similar to the Salisbury's battery which currently allows me 27 miles per charge, I could expect 50 mile outings with power to achieve that minimo, AND 'cliff-face' climbing ability on tap, to boot! Yes?

 

...Obviously, there will be a little additional drag from the extra motor, but there simply has to be a net gain when both motors are pulling. If this extra drag became a problem on the flat, you could always give the "resting" motor a whiff of gas on the thumb throttle to even things up.

 

This how I think it would work.

 

On the flat, you could ride with normal pedelec controlled assist from the existing rear motor. When approaching a cliff face, you would then whack the thumb throttle supplied with the front motor wide open, and storm the hill with two motors pulling. Don't expect to go scortching up the hill like a half arsed astronaut, more likely the machine will slow to around 10 MPH which is the roadspeed at which these motors achieve maximum torque. The realm of fantasy maybe, but food for thought none the less...

 

Yes, that's how I envisaged it, otherwise the two batteries would effectively only last the lifespan of one battery. Expensive, if both used uneccesarily at the same time. (Well 25% of the front motor's battery would be used at the same time as the rear motor's battery when called upon for 'hill duty').

 

As to motor drag; that's a point that made Flecc choose the Nano motor, it's ability to freewheel better than most. Would the drag from both the Alien and the Salisbury motors hinder badly if/when I had to pedal home with two exhausted batteries I wonder?

Edited October 21, 200817 yr by Danny-K

 

This leads inevitably to the conclusion that someone who converts a pedal cycle to an electric bike is almost certainly the individual who has to set the maximum continuous power rating. There is a clear logic to this; continuous power is a system rating, not a motor rating, nor a battery or controller rating. One reason for setting a lower continuous power rating for a system than any of the individual components can tolerate might be heat dissipation. Whilst a complete system (motor, controller, battery, cables and bike) might be able to deliver high power levels for short periods, a builder/manufacturer might, quite reasonably, wish to set a lower "continuous power" rating to avoid damaging heat build up in some of the components.

 

Jeremy

 

But as I've observed Jeremy, many if not most would be adding a kit motor to an electric bike which already had a stated continuous rating at or about the limit. With the kit also having a defined manufacturer limit, I can't see this "vehicle creator" argument standing up in any court. It would merely be adding additional power to an existing e-bike rather than creating an entirely new vehicle from a bicycle. It would be a pairing of two of the complete systems you mention. Your heat build up mention seems to me to be just clutching at straws, since we are speaking of previously defined maximum continuous ratings of known systems, by definition not subject to damaging heat build up.

 

I don't think most people would want to place themselves in the position of having to argue the tortuous and unproven case that you make for legality, based as it is on motor vehicle legislation which e-bikes are outside of. My advice therefore remains that two legal e-bike motors on one bike are illegal, this being the safe position, and I believe the correct one.

.

Edited October 21, 200817 yr by flecc

We're both entitled to our view, flecc, so perhaps we should agree to differ.

 

My view is based on my own experience, plus, as many will have guessed, a certain detailed familiarity with the intricacies of the application of law and the workings of our judiciary. Yours is based on your own years of experience, of course.

 

One telling point is that I am unaware of any successful prosecutions, nor am I aware of any ebikes being confiscated and crushed by any UK authority. Being British, we just love to make up rules, beseech others to abide by things which are clearly daft and best of all, we have, as a national trait, the rather unpleasant habit of trying act as policemen to each other if we even get a sniff of some arcane and technical legal infringement by another.

 

Some also hate to be contradicted or even have their wisdom questioned, but perhaps it's best if I don't go there.

 

Jeremy

We're both entitled to our view, flecc, so perhaps we should agree to differ.

 

Agreed.

 

My view is based on my own experience, plus, as many will have guessed, a certain detailed familiarity with the intricacies of the application of law and the workings of our judiciary. Yours is based on your own years of experience, of course.

 

An unwise assumption Jeremy, since this "certain detailed familiarity" I share, having been involved in numerous defence cases, both in case preparation and research, and as a witness in most levels of court in this country, including the Old Bailey, the Chancery Division at the Law Courts in the Strand and appearances before Judges in Chambers.

 

One telling point is that I am unaware of any successful prosecutions, nor am I aware of any ebikes being confiscated and crushed by any UK authority.

 

With respect I can't see that as "telling", since it in no way demonstrates that it will not happen. Our prisons are full of people assuming they would never be caught.

 

Some also hate to be contradicted or even have their wisdom questioned, but perhaps it's best if I don't go there.

 

I mentioned clutching at straws, and this strikes me as desperation! As a scientist you are clearly used to determinedly arguing your position, so I think the boot may well be on the other foot on this occasion.

 

As someone familiar with the law and it's administration Jeremy, you know as I do that when a court has to interpret the effect of a law, it endeavours to determine the intention of the legislators, this referred to as the spirit of the law.

 

The spirit of the law on powered bicycles is so clear that I'm confident that your defence would fail if faced with a competent prosecution. That's why I'm arguing the point, it having nothing to do with having my wisdom questioned or being contradicted.

 

P.S. As an afterthought, I'd add that acting as an "unpleasant policeman" is entirely alien to me, all of my criminal court involvements being in largely successful defences against the police in cases and appeals. My concern here is the severity of the possible consequences to anyone advised that two motor use is legal, and I'm not prepared to take that risk with another.

.

Edited October 21, 200817 yr by flecc

I just knew you'd "bite" at that last point, Flecc! Sorry, I was simply doing a small experiment and you honoured me by responding entirely as predicted...........

 

I am confident that the judiciary, in the form of the local bench, would not behave in quite the draconian manner that many seem to think. The law is applied remarkably reasonably at it's lowest level, although to read some rather one-sided reports in the media one could be forgiven for thinking otherwise.

 

As for the rest, I'm not entering into a "I have more knowledge/experience etc etc" contest with selective quotes, as it's both futile and a faintly juvenile exercise. As I said before, we'd best agree to differ.

 

I have no doubt that you will have the last word on this, Flecc............

 

Jeremy

Only to agree with you Jeremy, both about local benches and the pointlessness of having an experience contest.

.

Flecc, Jeremy,

 

I really don't wish to question your legal experience, but it seems to have happened in a parallel universe, staffed in the main with good and honest people doing their jobs.

 

My own experience (both civil and criminal) is a sorry tale of venal solicitors, laughably incompetent barristers, downright dishonesty on all sides, judges who work on prejudice rather than the facts before them and magistrates who rubber stamp what the police tell them.

 

The only part of it that "does what it says on the tin" is the Legal Complaints Service.

 

You will forgive me if I doubt that a test case would result in anything that someone who understood electric motors would consider correct.

 

Nick

Flecc, Jeremy,

 

I really don't wish to question your legal experience, but it seems to have happened in a parallel universe, staffed in the main with good and honest people doing their jobs.

 

My own experience (both civil and criminal) is a sorry tale of venal solicitors, laughably incompetent barristers, downright dishonesty on all sides, judges who work on prejudice rather than the facts before them and magistrates who rubber stamp what the police tell them.

 

Nick

 

Only a very small parallel universe Nick.

 

I share your above experiences in various areas of the law and have many horror stories, but it doesn't have to be entirely that way. In my own case I teamed up with a dedicated and highly skilled Inner London solicitor specialising in criminal law, working with him over a number of years with very considerable success.

 

The whole story of why I did this is a long one, but suffice it to say that my engineering life, while always interesting, lacked the "buzz" that makes life exciting, and taking on the Metropolitan Police service head on provided that.

 

Chris the solicitor had the legal knowledge and connections that ensured we always enjoyed the best of suitable barristers working for us, while I had the contacts with those on the wrong side of the law, the resources and the inquiring mind to unearth the potentially effective defence areas and bring in the cases.

 

After years of doing this I ended on a triumphant note. Having won four cases against two Met divisions in a row, I was spotted at court on the fifth and last and respectfully approached by a police sergeant asking if I was involved in the defence. On my confirmation he returned to a police inspector for a conversation and a following phone call, after which the sergeant advised my defendant that the case was being dropped. It doesn't get much better than that, and my experience shows that good experiences at law are possible.

 

However, for most people without the right dedicated support, the experience all too often matches what you've expressed.

.

Edited October 22, 200817 yr by flecc

now that was a great thread

However, for most people without the right dedicated support, the experience all too often matches what you've expressed.

.

 

Hi flecc,

 

I rather fear that is the reality for most customers of the British legal system. You seem to have found someone to team up with who is interested in a little investigation - normally only seen in TV lawyers - and have the advantage of repeatedly tackling similar aspects.

 

My own contacts with the system have all been at different levels and on different topics so I was a beginner each time. I also found it extremely capricious. The first time I acted for myself the opposition tried to take advantage of it and the recorder slapped them down; the second time the district judge was so outraged at the impertinence that I was sunk before entering the room.

 

Being an expert witness is so much better than being a customer, and not only because you get paid instead of paying. They actually listen to what you say.

 

We've strayed off the original topic, but I hope forum readers are getting the message that its a potential minefield. Being technically correct is not all that matters.

 

Nick

Yes, I think that's a good example of just some of the problems with the system Nick. Of all the professions/trades/occupations, the law does seem to have a surprisingly high proportion of individuals who are incompetent, arrogant, selfseeking, and sometimes downright dishonest.

 

Unfortunately, even if that were not so, the system would still not work well. Few defendants would understand the system, many are inarticulate, and simple interviews are normally insufficient to mount effective defences. On occasions I would spend weeks and even months as a friend of a defendant, family and friends, even to the extent of employing one defendant, before uncovering some evidence absolutely crucial to the case.

 

Since the police and legal system have so much stacked in their favour, having all those involved therein at a high level of competence could actually stack things further against defendants, since the long term support that Chris and I gave to the few could never be given to the many. In fact police and previous defence incompetence was often our greatest ally in achieving acquittals.

.

Edited October 23, 200817 yr by flecc

Out of interest - What's the regulations about off-road use. All of the steep uphills I have to tackle have bridleway routes. Would it be legal to use a second motor on them, or would the extra power mean that it was no longer classed as a bicycle and therefore not allowed on the bridleways at all ?

 

Maybe I should look at a 9-speed hub (no way I'm paying for a Rohloff at those prices) for the back wheel to get a bit of extra range out of the gears?