Time To Discuss Torque Ratings.....Again.

[Ebiker33]

I am looking at electric motor cycles and their foot pound and torque ratings are under the top rated motor Ebike ratings.
For example the Bafang G510/M620 is rated at 160nm, yet these machines can run circles around any bike that has that motor.

An example
This Zero Moto is rated at 78 ft-lb (106 Nm)
ZERO motorcycle

Harley Davidson does one too
They are at 86 foot pounds, they use to have the nm rating as well but took it down, but if you convert it, it sits at about 117nm
Harley Bike
Incidentally they are developing brand new Ebikes....Check This Out

Some other high end mid drive max ratings are:

Bafang M600 120nm
Brose 90nm (Motor is only 250 continuous watts but the battery puts out 630 Wh)
Bosch 75nm
Shimano 70nm

Now we know the power input to these moto's is much higher, but what are we missing on the nm/ft. lbs ratings?
Is there something just throttling down the power draw to cause longevity on the battery like the controller.
It seems the nm ratings might not be a useful statistic, sort of like a Shopvac rated at 6.5 hp when it is only a 14 amp draw at 115V.

It seems you would need a pretty massive infusion of wattage to make full use of Bafang's 160 NM of torque.
Is there a wattage formula for calculating a baseline for basic torque ?

 

[MechaNut]

On a very simplistic level, when it comes to motor systems, horsepower(watts) is what is most important for top speed and torque is what is most important for acceleration and pulling power. Most ebike systems are running at 250 watts to 750 watts (0.25 horsepower to 1 horsepower) which is why a full on motorcycle (80 horsepower and up) will run circles around an ebike. This is a REALLY simplistic answer and it would take somebody much more well versed in physics and engineering than me to give you a more detailed answer. To put it simply, you can't compare motor systems using only torque. Total power output also has to come into the conversation.


Motor System / Peak Power (Watts) / Peak Torque (nm):
Zero Motorcycle / 34000 / 106
Harley LiveWire / 78299 / 117
BBSHD (unlocked) / 1500 / 150
Brose / 250 / 90


So, taken together it is pretty obvious why electric motorcycles run circles around ebikes. Motorcycle motors put out A LOT more power.

 

[Petropoliskhan]

On a very simplistic level, when it comes to motor systems, horsepower(watts) is what is most important for top speed and torque is what is most important for acceleration and pulling power. Most ebike systems are running at 250 watts to 750 watts (0.25 horsepower to 1 horsepower) which is why a full on motorcycle (80 horsepower and up) will run circles around an ebike. This is a REALLY simplistic answer and it would take somebody much more well versed in physics and engineering than me to give you a more detailed answer. To put it simply, you can't compare motor systems using only torque. Total power output also has to come into the conversation.


Motor System / Peak Power (Watts) / Peak Torque (nm):
Zero Motorcycle / 34000 / 106
Harley LiveWire / 78299 / 117
BBSHD (unlocked) / 1500 / 150
Brose / 250 / 90


So, taken together it is pretty obvious why electric motorcycles run circles around ebikes. Motorcycle motors put out A LOT more power.

Thank you for this explanation. I am interested in understanding how the wattage/voltage/torque figures are an indication of realistic city performance of top speed / uphill speed for rear hub drive commuter bikes. These bikes are advertised as 45Km/h, 28mph speedbikes.
However, my research and test rides of several commuter mid drive and read hub drive european speedbikes (Stromer st1x, HNF-Nicolai Urban XD2 ( Bosh gen 4 speed) and Qwic RD11S ) shows that these speeds are rarely attained and only under certain condititons. (BTW I weigh 90kg , approx 180lbs)
What figures would be a good indication that these top speeds can be realistically attained ans sustained going uphill or against the wind.
Do you know of any European road legal alternatives other than a 10000$ Stromer ST5 (850W, 48V, 48nM) that could come close?

I know this topic has been discussed at length in these pages but I have not found any comprehensive answer as relates to rear drive ( i like that propulsion feeling) euro legal commuter bikes.

Thank you

 

[Ebiker33]

On a very simplistic level, when it comes to motor systems, horsepower(watts) is what is most important for top speed and torque is what is most important for acceleration and pulling power. Most ebike systems are running at 250 watts to 750 watts (0.25 horsepower to 1 horsepower) which is why a full on motorcycle (80 horsepower and up) will run circles around an ebike. This is a REALLY simplistic answer and it would take somebody much more well versed in physics and engineering than me to give you a more detailed answer. To put it simply, you can't compare motor systems using only torque. Total power output also has to come into the conversation.


Motor System / Peak Power (Watts) / Peak Torque (nm):
Zero Motorcycle / 34000 / 106
Harley LiveWire / 78299 / 117
BBSHD (unlocked) / 1500 / 150
Brose / 250 / 90


So, taken together it is pretty obvious why electric motorcycles run circles around ebikes. Motorcycle motors put out A LOT more power.

So you have a massive infusion of watts fully utilizing the torque on those motors, it seems if you send 1000 watts of power to a motor rated for 160nm it is being massively under utilized, but on the upside it should never burn out given that it can handle so much more torque.

 

[MechaNut]

So you have a massive infusion of watts fully utilizing the torque on those motors, it seems if you send 1000 watts of power to a motor rated for 160nm it is being massively under utilized, but on the upside it should never burn out given that it can handle so much more torque.

Torque is how much force the motor pushes with. Total output is how FAST it pushes.

A 100nm electric motor is going to push with the same 100nm of rotational force whether or not it is a 250 watt motor or a 2.5 kilowatt motor. The biggest difference is the 250 watt motor might push something at a running pace and the 2.5 kilowatt motor might push something at highway speeds.

Again, this being a gross oversimplification, but I'm hoping you get the gist of what I'm saying.

Thank you for this explanation. I am interested in understanding how the wattage/voltage/torque figures are an indication of realistic city performance of top speed / uphill speed for rear hub drive commuter bikes. These bikes are advertised as 45Km/h, 28mph speedbikes.
However, my research and test rides of several commuter mid drive and read hub drive european speedbikes (Stromer st1x, HNF-Nicolai Urban XD2 ( Bosh gen 4 speed) and Qwic RD11S ) shows that these speeds are rarely attained and only under certain condititons. (BTW I weigh 90kg , approx 180lbs)
What figures would be a good indication that these top speeds can be realistically attained ans sustained going uphill or against the wind.
Do you know of any European road legal alternatives other than a 10000$ Stromer ST5 (850W, 48V, 48nM) that could come close?

I know this topic has been discussed at length in these pages but I have not found any comprehensive answer as relates to rear drive ( i like that propulsion feeling) euro legal commuter bikes.

Thank you

I'm sorry but I'm on the wrong side of The Atlantic Ocean to answer your question with any degree of authority. Also I do not own, nor have I ridden an ebike configured for class 3 (speed pedelec) operation. All I can say is that, in my experience, Mid drives do much better with hills compared to hub drives because a mid-drive can leverage the gears where a hub drive can't. My hub drive bikes have handled up to 40-45mph gusting winds but my speed was much reduced (as expected). I haven't ridden my mid-drive in similar gusty wind conditions so I can't say how well it will do.

 

[Ebiker33]

That makes sense.
But then why does 100nm struggle up on a 15% upgrade at 30Kmh whereas a motor bike goes up no problem ?
Because now it has nothing to do about speed but rather hauling weight upgrade so torque, the moto bike is also much heavier.

 

[rich c]

This might help.

Futility of Motor Power Ratings

"There's no such thing as a rated watt!" Read here for why we don't advertise a simple power rating for the motors we sell. Also, have a look at our Youtube video where Justin talks about the power to propel bicycles in <a href="https://www.youtube.com/watch?v=ALde6zhLPs0">"School of Watts"</a>.

www.ebikes.ca

 

[Petropoliskhan]

Torque is how much force the motor pushes with. Total output is how FAST it pushes.

A 100nm electric motor is going to push with the same 100nm of rotational force whether or not it is a 250 watt motor or a 2.5 kilowatt motor. The biggest difference is the 250 watt motor might push something at a running pace and the 2.5 kilowatt motor might push something at highway speeds.

Again, this being a gross oversimplification, but I'm hoping you get the gist of what I'm saying.



I'm sorry but I'm on the wrong side of The Atlantic Ocean to answer your question with any degree of authority. Also I do not own, nor have I ridden an ebike configured for class 3 (speed pedelec) operation. All I can say is that, in my experience, Mid drives do much better with hills compared to hub drives because a mid-drive can leverage the gears where a hub drive can't. My hub drive bikes have handled up to 40-45mph gusting winds but my speed was much reduced (as expected). I haven't ridden my mid-drive in similar gusty wind conditions so I can't say how well it will do.

Thank you for your response

 

[Ebiker33]

Rich that is really interesting.

 

[HonoraryOrange]

Had a little sit on that Harley motorcycle at CES. Really interesting thing with that electric motor on and humming under you at 60mph!

 

[Stefan Mikes]

I cannot understand the point of the whole discussion. Torque itself means nothing without the second parameter, which is the angular speed, and the latter depends on the rpm. A bicycle rider can pedal at perhaps 80 rpm while electric motorcycle motor can even hit 10000 rpm. Power is torque multiplied by angular speed. The power is transmitted to the driving wheel either by derailleur system (bikes) or by gearbox (motorbikes).

In case of e-bikes, slow rotation of the crank is amplified by the drive-train so the rear wheel can spin faster to achieve decent speed at the cost of reduced power at the rear wheel. Or, in case of the "granny gear", the spin of the rear wheel is reduced to amplify the power delivered, so the rider can climb uphill.

In case of any motorbike, the motor spins very fast. The gearbox and the whole drive-train reduce the rotational speed to figures making the rear wheel rotate to achieve desired motorcycle speed and the power at the rear wheel is greatly amplified.

Again: Power is the product of torque and of angular speed.

• E-bikes: high torque, low angular speed at the crankset = low power = low riding speed
• Any motorbike (electric or not): not so high torque, high angular speed of the motor = high power = high riding speed

Torque itself means nothing.

Did I misunderstand anything?

 

[Ebiker33]

That makes total sense, there are 2 variables, higher inputs of wattage and RPM's causing this.
Makes me wonder what would happen to a G510 if you put 3000 watts into it at 3000 rpm, probably get burnt out from overheating.

 

[ElevenAD]

That makes total sense, there are 2 variables, higher inputs of wattage and RPM's causing this.
Makes me wonder what would happen to a G510 if you put 3000 watts into it at 3000 rpm, probably get burnt out from overheating.

i dont know about 3000rpm but kirby has been pushing his with 4000w for some time with zero issues, no heating problems,sturdy motors for sure.