It seems you are trying to prove a theoretical point, but why bother when it will never happen in practice? If you are serious about owning a powered bike, best to stick the real world situation.

 

Here's a real world example giving the combined knowledge of the best European manufacturers and countless buyers:

 

The S class of pedelec was originally only allowed a 250 watt rating for it's permitted 45 kph (28mph). This proved insufficient so the German government where the S class originated upped the allowed power to 500 watts.

 

The makers all promptly launched 500 watt versions, but they've nearly all disappeared since, with most now being 350 watts. That's because both makers and customers found that to be the best compromise to achieve the speed without unnecessarliy losing range due to the higher 500 watt power.

 

That's it in a nutshell, more power means higher consumption in practical situations, as others have said above.

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Doesn't a 350watt motor have to work harder (and generate more heat) to reach 28mph than a 1500watt motor?

 

Isn't a 1500watt motor underperforming at 28mph and therefore is less stressed?

Doesn't a 350watt motor have to work harder (and generate more heat) to reach 28mph than a 1500watt motor?

 

Isn't a 1500watt motor underperforming at 28mph and therefore is less stressed?

 

So the 1500 watt is less efficient, not performing at its optimum, while the best matched-to-the-need 350 watt is performing at its optimum.

 

We are talking electric motors here, and running them below optimum efficiency is very wasteful. The bigger the disparity, the greater the waste. They are very different from ic engines.

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Doesn't a 350watt motor have to work harder (and generate more heat) to reach 28mph than a 1500watt motor?

 

Isn't a 1500watt motor underperforming at 28mph and therefore is less stressed?

For Christ's sake, read what's been written. The motor's designated power has very little bearing on how much power you get from it. That's a nominal rating, i.e. how much power it can handle, not how much power it will give. The power is determined by the controller. Those 1000w and 1500w kits you were looking at have the same motor. It's the controller that's different.

 

In addition to that, power output depends on efficiency , which depends on motor speed vs winding speed. A high speed motor will have low efficiency at low speed, typically as low as 25%, so if you feed it with 1500w at low speed, you get something that gives you more heat than an electric fire.

 

Use the simulator mentioned above to see how motors work and what you need to get what you want.

So the 1500 watt is less efficient, not performing at its optimum, while the best matched-to-the-need 350 watt is performing at its optimum.

 

We are talking electric motors here, and running them below optimum efficiency is very wasteful. The bigger the disparity, the greater the waste. They are very different from ic engines.

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So what motor wattage is more efficient at maintaining 20-25mph unassisted? 500-750watt?

For Christ's sake, read what's been written. The motor's designated power has very little bearing on how much power you get from it. That's a nominal rating, i.e. how much power it can handle, not how much power it will give. The power is determined by the controller. Those 1000w and 1500w kits you were looking at have the same motor. It's the controller that's different.

 

In addition to that, power output depends on efficiency , which depends on motor speed vs winding speed. A high speed motor will have low efficiency at low speed, typically as low as 25%, so if you feed it with 1500w at low speed, you get something that gives you more heat than an electric fire.

 

Use the simulator mentioned above to see how motors work and what you need to get what you want.

I thought that the quoted wattage WAS the motor's designated wattage. Were you able to deduce otherwise by looking at the specs or from your experience?

 

I don't recognize the names of the motors in the simulator. The UK e-bike sellers I've looked at do not mention the motor name either so how do I know which one to use?

So what motor wattage is more efficient at maintaining 20-25mph unassisted? 500-750watt?

 

In ideal conditions 500 watts, but in less than ideal conditions, headwinds etc if you didn't want to assist at all, you'd need the 750.

 

You'll get best efficiency from the lower power combined with adding your own power as required, since you are adjusting the conditions to the optimum that way.

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So what motor wattage is more efficient at maintaining 20-25mph unassisted? 500-750watt?

I can only guess you missed this part of the post you quoted:

...while the best matched-to-the-need 350 watt is performing at its optimum.

I can only guess you missed this part of the post you quoted:

 

I don't think it mattered much though, since my 350 watt answer was in pedelec terms, the rider assumed to be adding their bit.

 

More motor power would be needed if no rider input.

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I have no problems reaching 32 km/h (20 mph) on the flat just twiddling the pedals with a 250 W motor using about 280 W. My ideal motor at the moment is the 250 W 25 A BBS02 - street legal and yet capable of supplying over 1000 W when needed with a 44.4 V 12S Lipo battery.

I don't think it mattered much though, since my 350 watt answer was in pedelec terms, the rider assumed to be adding their bit.

 

More motor power would be needed if no rider input.

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Thanks for the replies flecc.

I have no problems reaching 32 km/h (20 mph) on the flat just twiddling the pedals with a 250 W motor using about 280 W. My ideal motor at the moment is the 250 W 25 A BBS02 - street legal and yet capable of supplying over 1000 W when needed with a 44.4 V 12S Lipo battery.

Your bike is unrestricted, correct? I have a restricted Cyclamatic CX1 with a 36v/8.8Ah battery. Someone suggested I get a new battery (48v/15Ah) and a new controller to do 20-25mph on the flat but I am concerned I might mess up the modifications.

Someone suggested I get a new battery (48v/15Ah) and a new controller to do 20-25mph on the flat but I am concerned I might mess up the modifications.

You are right to be cautious.

Overvolting a small motor will put the motor under excessive stress leading to problems. As you don't know how to fix problems yourself, don't go there.

Thanks for the replies flecc.

 

Your bike is unrestricted, correct? I have a restricted Cyclamatic CX1 with a 36v/8.8Ah battery. Someone suggested I get a new battery (48v/15Ah) and a new controller to do 20-25mph on the flat but I am concerned I might mess up the modifications.

 

That was the speed I was obtaining unrestricted, it is now restricted because the speed sensor works.

Having read through the last two pages of comments I think it may be worth repeating what I said back on page 4, and which has effectively ( and indirectly ) been supported by all the regular contributors to the forum. Upon refection there is one situation in which you would need more power than an S pedelec, which is if you wish to put no effort in yourself, but in that case you might as well get a Honda 50.

 

Getting back to the subject of the opening post of this thread...

As the owner of an S-pedelec I find it hard to understand why you would want a bike with 1500W of power in order to ride it as you say you want to. The S Pedelec would give you all the power you could need to ride like that, and do so in a far more efficient way, giving you a better range for a given battery size.

Germany has the s-Pedelec class and while I think those are fantastic if you want to ride faster demand is quite low.

In 2016 around 600.000 pedelecs have been sold in Germany and only 1% have been s-Pedelecs.

 

My Diamant s-Pedelec from 2013 has a EC CoC and is classifed as a L1e A vehicle with a top speed of 20km/h (because top speed is measured with a rider not moving). Motor assists up to 45km/h legaly if you pedal.

The nice thing about the top speed rating of just 20km/h in the CoC is that you need not wear a helmet riding on them in Germany. If you like you can do so, of course...

 

My BionX motors in that s-Pedelec have 250W stickers on them and the s-pedelec is classified as a vehicle with just 0,25kW. But like other Bionx systems the controller inside is a 48V 30A type.

 

The wattage is just a sticker.

 

Sometimes it's difficult to understand the argument. On the one hand people are claiming that they can easily ride 35 or even 40km/h without motor and therefore they need a fast pedelec, on the other hand they claim to need huge motor power to just get up to 45km/h. I fail to see some of the logic behind this.

 

A BionX d-series motor with its 48V 30A controller for example is very powerful (as long as it does not overheat on very steep mountains) no matter its 250W sticker...

 

This is power consumption (voltage in red and current in blue) of a BionX d-Series Motor (250W) riding uphill at around 5% with around 40km/h and some stops:

 

 

Since 2017 new s-pedelecs in Germany need a brake light and illumination of the registration plate. They already use brakes and lights with E marks and tires with ECE-R75...

 

Insurance of s-Pedelec is around 40 Euro a year just vehicle liability or around 70 Euro a year when also incl. partial coverage insurance for damages, theft, etc...

PS:

 

Have you considered a Grace One as a street legal option for UK?

 

http://www.grace-bikes.com/bikes/one/

 

This one is NOT a s-pedelec in Germany but a moped, because t has an official 1300W motor drive and runs up to 45km/h with throttle only. So it should have a L1E b CoC (just a guess!) and all that moped stuff that is needed. This is a reason for the "stupid" halogen headlight.

 

You still have pedals and a classical bike drive, but you need to wear a helmet.

 

Afaik it is only available used and the company is insolvent.

 

You can find some users in the German epower forum.

PS:

 

Have you considered a Grace One as a street legal option for UK?

 

http://www.grace-bikes.com/bikes/one/

 

This one is NOT a s-pedelec in Germany but a moped, because t has an official 1300W motor drive and runs up to 45km/h with throttle only. So it should have a L1E b CoC (just a guess!) and all that moped stuff that is needed. This is a reason for the "stupid" halogen headlight.

 

You still have pedals and a classical bike drive, but you need to wear a helmet.

 

Afaik it is only available used and the company is insolvent.

 

You can find some users in the German epower forum.

Great looking bike, very elegant but a bit over my budget (even the used ones are close to 3000 euros). Plus, most of the sellers I found on the german Ebay are located in Germany so transportation costs are also an issue.

 

I wouldn't mind going for one of those B-52 stealth bombers but it would attract too much attention, not only from the police but from the local thieving scum.

 

An e-bike that stills resembles a regular bike is less conspicuous and lighter so I can carry it inside buildings.

 

I've even considered getting an 125cc motorcycle, such as the LexMoto Assault that retails around 1300 GBP, but again I am concerned that it'll get stolen within a few weeks.

 

After all, Hull has been voted the worst place to live in England.

I've even considered getting an 125cc motorcycle, such as the LexMoto Assault that retails around 1300 GBP, but again I am concerned that it'll get stolen within a few weeks.

 

But with a 125, you'll be able to carry a really heavy unbustable lock & chain to keep it secure.

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An e-bike that stills resembles a regular bike is less conspicuous and lighter so I can carry it inside buildings.

You can lift a legal electric bike, bearing in mind that most are in the range of 22 to 25 kg, and some are as heavy a 27 kg. The high powered ones with the big DD motors and suitable batteries are often closer to 30kg. Lifting is one thing: carrying is not so easy. Electric bikes are not the same as bicycles.

But with a 125, you'll be able to carry a really heavy unbustable lock & chain to keep it secure.

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But I wouldn't be able to keep the motorcycle indoors.

 

I already have two kryptonite d-locks (one for the frame and one of the front wheel) and two alarms (one underneath the seat and the other on the frame).

You can lift a legal electric bike, bearing in mind that most are in the range of 22 to 25 kg, and some are as heavy a 27 kg. The high powered ones with the big DD motors and suitable batteries are often closer to 30kg. Lifting is one thing: carrying is not so easy. Electric bikes are not the same as bicycles.

The Cyclamatic is 20kg and I can easily carry it around (indoors or up the stairs). 25-30kg is not that bad.

 

What do you think of this kit? (https://www.thesmallgreenroom.com/product-page/1500w-electric-bike-kit-including-52w-21ah-battery-and-our-121-build-assistance)

That's exactly what I am thinking.

 

As for the motor, this 1500w bike is pretty cheap at about 800 pounds. I think most 500w bikes cost thereabout, so why not purchase one with a more powerful motor instead. Does that make sense? Am I missing something?

 

EDIT: It just occurred to me that 48v * 17a = 816watt. Does this mean that I require two of these batteries for a motor which is rated 1500w?

I am thinking of the weight of the very big battery you would need for that 1500W motor to go any distance at 30mph. And your brakes and bike frame would need to be VERY GOOD to handle it all.Believe me, you can have loads of fun and miles with a geared 350W motor going up to 20mph and carry a spare 10A battery in a rucksack for a 60+ mile range. Simples!

The Cyclamatic is 20kg and I can easily carry it around (indoors or up the stairs). 25-30kg is not that bad.

 

What do you think of this kit? (https://www.thesmallgreenroom.com/product-page/1500w-electric-bike-kit-including-52w-21ah-battery-and-our-121-build-assistance)

Get a couple of carrier bags and fill them up with dirt with 5kg in each. Hang them on your Cyclamatic and see how easy it is to pick up.

 

If you want to ride around at 35 mph, that kit will be great, but how are you going to do that without getting caught. There's a couple of comments i'd make about it. 50 mph is very optimistic. I think they mean downhill with the wind behind you. 40 mph would be more like it. Secondly, the motor takes a free-wheel, so you're limited to 7 speed and you'll have to hunt out a DNP one with 11T top gear. Their ad shows a 14T freewheel with a 42T chainwheel. That wouldn't work at all, you wouldn't be able to pedal it. I modified my Cyclamatic to 33 mph, and with the Cyclamatic gearing, it was virtually impossible to pedal. You'd need a 52T chainwheel and 11T top gear to have any chance of keeping up with the motor.

I already have a legal e-bike (Cyclamatic C1, 250watt) and the difference in speed between myself and other cyclists is noticeable.

 

My main reason for getting a new, 1500w, bike is that it'll have better acceleration, in addition to greater top speed. But the main selling point for me is acceleration.

 

[mention=8894]Gubbins[/mention] I live in Hull and there are no bike shops in the area that sell e-bikes.

 

EDIT: Also, it is my understanding that unless you set the bike to the maxium assistance level to, you can't do 30mph. Is that correct?

There is a choice of e-bike shops in York it would be worth the journey.