Torque is cheap

[Bigbee]

With the various bike options its confusing to the unwashed like me to really understand the power of each bike.Ive just seen a site that says its bike gives 96 N/M on a 200w motor.I assume thats Newtons and ? Minutes?Monkey?? Any way is that good torque?It would be good if all the manufacturers showed it this way then it would help the would be newbie in undertanding more and make their choice.Does any one know the same calculation for Wisper,Urban Mover,Kalkhoff etc?

 

[tillson]

N/M means Newton metres. As you may know, torque is a measure of the twisting effort produced by a motor for want of a better phrase. Power is a function of the amount of torque and how quickly the wheel is spinning.

Therefore, if the motor is rated at X Watts, as the wheel spins faster, torque will reduce and conversely as the wheel slows, the torque will increase, since Power = T (Torque) X W(how fast the wheel spins). This is quite a simplistic view just to illustrate the relationship of the three parameters. The characteristic of the motor also comes into play which adds another dimension to the real world.

 

[flecc]

It's not really helpful for several reasons.

First is that most manufacturers don't give a figure, so comparison is impossible.

Second is that bikes that drive through the gears like the Kalkhoffs with the centre Panasonic motor unit can apply their torque and power combination at varying speeds to make climbing almost any hill possible.

Third is that on such low powered motors as e-bike ones, the maximum torque is only useful when it coincides with maximum or near maximum power.

To illustrate that last point further, the maximum torque on a typical sample legal hub motor exists from a standstill to about 9 mph, but the maximum power gradually increases from zero at a standstill to it's maximum at about that 9 mph. So you can see that below that 9 mph the power vanishes quickly, and above it the torque diminishes, leaving an optimum of 9 mph to climb a steep hill with the best of torque and power.

The Kalkhoff type mentioned can use the gears to apply that combination of maximum torque and power at a speed to suit the hill to climb, instead of only having it at one speed as in the hub motor.

Finally the added complication is that the 200 Watts or 250 Watts quoted is meaningless, being a notional figure applied for compliance with the law.

The Powacycle Salisbury and eZee Forza are both nominally 200/250 watt motors, but the Powacycle gives a maximum of just over 300 Watts gross power and the Forza one gives a maximum of about 700 Watts, well over double. The best judgement comes from reviews by owners and magazines where an opinion of performance and hill climbing can be gained, and of course the knowledge obtainable in this forum is also a reliable source.
.

 

[john]

96 Nm is a lot of torque if it is at the wheel (e.g. a hub motor) and would easily pull you up a 20% hill. How fast is another matter.

 

[Bigbee]

96 Nm is a lot of torque if it is at the wheel (e.g. a hub motor) and would easily pull you up a 20% hill. How fast is another matter.

It was a centre crank motor,not Panasonic.

 

[flecc]

It was a centre crank motor,not Panasonic.

Probably at low speed in a low gear then.

Which motor was it? Cyclone, Heinzmann?
.

 

[Bigbee]

Probably at low speed in a low gear then.

Which was it? Cyclone?
.

no,I Googled for centre crank motor or some thing and I found an American site.It seemed a good idea how to compare bikes to me,but as usual Ive been proven wrong! I told you I dont understand much!

 

[flecc]

no,I Googled for centre crank motor or some thing and I found an American site.It seemed a good idea how to compare bikes to me,but as usual Ive been proven wrong! I told you I dont understand much!

You haven't really been proven wrong, if all the manufacturers published all their motor data it could be of some use.

There's a quite few oddball centre crank motors around. Swizzbee used to make a bike with a huge circular motor surrounding the pedal crank, in the USA there's the hugely powerful StokeMonkey motor that fit's on Xtracycle long wheelbase conversions, and there's the Cyclone motors that come in a wide range of powers. The best known Swizzbee used a different form of motor mounted at the top of the rear frame triangle using a belt drive to a power combining geared system, but that's now discontinued at present.

Now Yamaha have copied the Panasonic system with their very similar version, so there's lots of them around.
.

 

[Bigbee]

This is it,I think

Hi

I think this is the bike I saw earlier.

 

[flecc]

Hi

I think this is the bike I saw earlier.

I don't know that one, but it's a similar bevel drive arrangement to the original Lafree and Yamaha e-bikes from around the year 2000. Those tended to more like a moped than a good bicycle in the way they performed and most of that type of drive have vanished now. The last to vanish was the only English e-bike, the TGA Electrobike.
.

 

[Bigbee]

so its rubbish?

 

[flecc]

so its rubbish?

No, I wouldn't say that necessarily without knowing more. It's just a configuration that's dropped out of favour, but if it's high powered so more moped than bike in character, it could well be good in that role.
.

 

[Boby]

Catic

It is produced by Chinese gentlemen (Electrical bicycle CATICGZ). I saw it for the first time at Australian eBay – so probably it was equipped with a 200W motor.

The concept is smart – like a Flyer or Panasonic. In my opinion chain drive is most effective. You may climb and ride fast at proper gears. I wonder how it works.