Now I understand that you are describing your own experiences, but as I've said before mine are different.
The question is why?
Here is my best guess, SB have made lots of different models of motors over the years and some are simply different to others.
I know Flecc has used both the Torque and Quando both of these use the same motor so I would expect them to behave the same.
I have used mainy the old Hill King, BPM and the new QSWS motors.
So how can we test for friction in the motors?
Solution number one is so simple I was stunned to take so long thinking about it.
Lift the drive of the floor run the motor to full speed and measure the current. From this we can calculate the sum of all the losses in the motor, this will include drag/ friction caused by the freewheel and bearings assemblies togeather with the clogging torque of the motor. The clogging torque should be the largest factor here, it is an inescapeable product of electric motors, it is caused by the interaction of the magents and the ferrous core, it should not be present when we are just pedlling along.
At full throttle no load speed of 21mph current through the Hill King motor was 0.8 amps, with the QSWXK 0.65 amps. With o 40V supply this gives 32 and 26 watt consumption for the two motors flat out,
assuming the this is proportional to speed at 10.5 mph this equates to 16/13 watts maximium.
Check out http://http://bikecalculator.com/wattsMetric.html , at 10 mph (16kph), 80kg rider, 20kg bike the power needed to ride on flat groud is 78 watts with mtb tyres and 41 watts with tubular, ( I assume here it's talking of road tyres ).
At 15mph/24kph this increases to 173 watts and 115 watts.
I accept that 15w as proportion of 78w is high at nearly 20%, but at 15mph we get about 22w drag in say 150w a reduction to 14%. All we need to know is the value of the clogging torque.
Well as it happens I have an old motor, I took it apart some years ago to see how it worked, being an untidy git I lost the Woodruff key that holds the freewhell to the axle, so I just hold the motor in the vice run it up and with have the no load current for the motor without, freewheel or hub bearing friction.
It's still not a complete picture because the motor may well run slightly faster with less drag and as the current falls with motor speed the current value will fall very slightly meaning I under value the base clogging power. Right just done the test current for the bare motor at no load speed was 0.7A.
This means that the hub bearings and free wheel combined consumed a total of no more than 40x.1 w,4w at 21mph or 2w at 10.5mph, 3w at 15mph ect.
Thinking laterally for a second, if there is drag in the freewheel on your bike is it possible to demonstrate it?
Again it sounds to simple to work but you may be able to try it out, reverse the motor. The theory is simple if there is drag in the freewheel arrangement it will work both ways, drag when you pedal and drag when you motor. With the back wheel of the ground and full throttle applied the motor should, if there is freewheel drag present, have a tendancy to turn backwards, it may only be slowly but it should be there. I've just tried this whilst writing this neither of the Bafang motors show any signs of running backward even when helped by prespinning them. I've also tried it on my trike with an Ananda motor, ( chain lifted off ), this may have been fractionally slower to stop but it is the only wheel of the three to have a tyre and tube on it, it has a fat Big Apple, so may have had more angular momentum.
So if it all down the the type of motor used all we need is an independant assesment.
So how about my offer to bring a bike down for a test ride. (I think you live somewhere the South Downs area which I can reach within a couple of hours).
The question is why?
Here is my best guess, SB have made lots of different models of motors over the years and some are simply different to others.
I know Flecc has used both the Torque and Quando both of these use the same motor so I would expect them to behave the same.
I have used mainy the old Hill King, BPM and the new QSWS motors.
So how can we test for friction in the motors?
Solution number one is so simple I was stunned to take so long thinking about it.
Lift the drive of the floor run the motor to full speed and measure the current. From this we can calculate the sum of all the losses in the motor, this will include drag/ friction caused by the freewheel and bearings assemblies togeather with the clogging torque of the motor. The clogging torque should be the largest factor here, it is an inescapeable product of electric motors, it is caused by the interaction of the magents and the ferrous core, it should not be present when we are just pedlling along.
At full throttle no load speed of 21mph current through the Hill King motor was 0.8 amps, with the QSWXK 0.65 amps. With o 40V supply this gives 32 and 26 watt consumption for the two motors flat out,
assuming the this is proportional to speed at 10.5 mph this equates to 16/13 watts maximium.
Check out http://http://bikecalculator.com/wattsMetric.html , at 10 mph (16kph), 80kg rider, 20kg bike the power needed to ride on flat groud is 78 watts with mtb tyres and 41 watts with tubular, ( I assume here it's talking of road tyres ).
At 15mph/24kph this increases to 173 watts and 115 watts.
I accept that 15w as proportion of 78w is high at nearly 20%, but at 15mph we get about 22w drag in say 150w a reduction to 14%. All we need to know is the value of the clogging torque.
Well as it happens I have an old motor, I took it apart some years ago to see how it worked, being an untidy git I lost the Woodruff key that holds the freewhell to the axle, so I just hold the motor in the vice run it up and with have the no load current for the motor without, freewheel or hub bearing friction.
It's still not a complete picture because the motor may well run slightly faster with less drag and as the current falls with motor speed the current value will fall very slightly meaning I under value the base clogging power. Right just done the test current for the bare motor at no load speed was 0.7A.
This means that the hub bearings and free wheel combined consumed a total of no more than 40x.1 w,4w at 21mph or 2w at 10.5mph, 3w at 15mph ect.
Thinking laterally for a second, if there is drag in the freewheel on your bike is it possible to demonstrate it?
Again it sounds to simple to work but you may be able to try it out, reverse the motor. The theory is simple if there is drag in the freewheel arrangement it will work both ways, drag when you pedal and drag when you motor. With the back wheel of the ground and full throttle applied the motor should, if there is freewheel drag present, have a tendancy to turn backwards, it may only be slowly but it should be there. I've just tried this whilst writing this neither of the Bafang motors show any signs of running backward even when helped by prespinning them. I've also tried it on my trike with an Ananda motor, ( chain lifted off ), this may have been fractionally slower to stop but it is the only wheel of the three to have a tyre and tube on it, it has a fat Big Apple, so may have had more angular momentum.
So if it all down the the type of motor used all we need is an independant assesment.
So how about my offer to bring a bike down for a test ride. (I think you live somewhere the South Downs area which I can reach within a couple of hours).
