Hub or Mid Drive? Any views?

[sjpt]

You input your speed, weight etc from which it can compute the power needed; and from the settings it knows how much of that power is yours and how much comes from the motor.

I'm a great believer in simplifications where appropriate; but in this case speed is not beside the point so simplifying it out is not appropriate.

 

[Audio2]

The hub gear bike tested by dealers was this torque or cadence sensing?
What pedal revs is the hub motor with torque sensing optimised for?

 

[Deleted member 25121]

The hub gear bike tested by dealers was this torque or cadence sensing?
What pedal revs is the hub motor with torque sensing optimised for?

Hub driven bikes typically use cadence sensing, presumably because torque sensing would be more expensive to implement.
With crank driven bikes the torque sensor can conveniently be mounted in the same box, as can a cadence sensor. Some, like Bosch, use both types of sensor which has several benefits.
I've been unable to find any more techical info on the Wisper bikes shown in the first post and unfortunately Wisper seems to have stopped responding to our questions on this thread.

 

[Audio2]

The Wisper hub gear is available as either torque or cadence sensor.

 

[Deleted member 25121]

The Wisper hub gear is available as either torque or cadence sensor.

Pity it doesn't utilise both, Bosch's dual sensor system works very well.

Were did you see that info about the Wisper bikes?

 

[vfr400]

Hub driven bikes typically use cadence sensing, presumably because torque sensing would be more expensive to implement.

The type of sensing has no relation to the type of motor. Cadence sensing is probably used in preference to torque sensing because it's cheaper, more reliable and easier to maintain.

 

[Amoto65]

Wisper hubs have been either cadence or torque for a long time it is on their website.

 

[Deleted member 25121]

The type of sensing has no relation to the type of motor.

But there IS a relation when torque sensing costs more to implement than cadence sensing on hub driven bikes.

Admittedly it's an indirect relationship and doesn't directly effect the maximum torque available from the motors.

 

[KirstinS]

The type of sensing has no relation to the type of motor.

You are right there of course

But i know where he is coming from. Most cheapo hub kits do seem to use cadence over torque?

Certainly historically true but maybe it is less so as time progresses

 

[Deleted member 25121]

Wisper hubs have been either cadence or torque for a long time it is on their website.

I see that now on their website:

Wisper 905 Crossbar Touring E-Bike

Discover the Wisper 905 e-Bike - a blend of performance, comfort, and style. Checkout the features, battery life, and suitability for daily commutes.

wisperbikes.com

It's interesting that the torque sensor option costs £300 more than the cadence sensor on the Wisper 905 Crossbar, which demonstrates my point very well.

Even then I don't think it would match the Bosch system which uses both types of sensor.

 

[Amoto65]

Not sure on that having only ridden the cadence motored 905 against the Bosch Activeline plus.

 

[flecc]

depending on the motor but typically, you have to pedal at well over 100 - 120rpm to start losing power on a crank drive.

Not always though. On the original Panasonic crank drive Giant Lafree, power dropped progressively above a cadence of 40 due to it having power phase down from 9.4 mph and halving by 12 mph!

But I think more important is how much effort someone can put into a torque sensor at given cadence. Many struggle to input enough force to get full power above a cadence of 60.
.

 

[Woosh]

But there IS a relation when torque sensing costs more to implement than cadence sensing on hub driven bikes.

Admittedly it's an indirect relationship and doesn't directly effect the maximum torque available from the motors.

the material cost differential is very little.
Most of the difference comes from the effect of production volume. Cadence sensors are much easier to integrate compared to torque sensors, then there's cost to develop the software to suit the torque sensor's behavior, again volume is king.
The cost differential of crank drive motors vs hub motors come from gearboxes.

 

[Deleted member 25121]

the material cost differential is very little.
Most of the difference comes from the effect of production volume. Cadence sensors are much easier to integrate compared to torque sensors, then there's cost to develop the software to suit the torque sensor's behavior, again volume is king.

Not just production volume but also complexity of assembling the component parts (eg torque sensor and housing onto crank) and assembling the part into the bike (crank and sensor onto bike).

But whatever the reason, there is a significant cost difference, £300 in the case of the Wisper 905. It would be a brave supplier who fitted torque sensors as standard onto their hub driven bikes.

 

[Deus]

With regard to it been a fallacy that hub motors are not as good on hills as mid drives that is only true when it comes to roads but when it comes to hills offroad the mid drives rule my friends Mac motor 12T @ 2000w will not climb hardly any of the hills my Bafang midrive @ 1500w gets up with ease.

 

[Woosh]

your Bafang has a 20:1 gear reduction ratio, the torque of the motor is multiplied by 20 when transmitted to the chainring. Your friend's motor is a direct drive, it's made for speed, not hill climbing. Horses for courses.
Crank drives can extend the range of usability on torque as well as speed by there is no free lunch, you pay more for the bigger gearbox and higher maintenance of the drivetrain.

 

[vfr400]

. It would be a brave supplier who fitted torque sensors as standard onto their hub driven bikes.

There have been a few that have done it quite successfully, Bionx for example. There have even been some cheap Chinese ones.

 

[Deus]

your Bafang has a 20:1 gear reduction ratio, the torque of the motor is multiplied by 20 when transmitted to the chainring. Your friend's motor is a direct drive, it's made for speed, not hill climbing. Horses for courses.
Crank drives can extend the range of usability on torque as well as speed by there is no free lunch, you pay more for the bigger gearbox and higher maintenance of the drivetrain.

I know that i was just making the point that what vfr400 said about it been a fallacy that hubs are not as good on hills as mid drives is not strictly true, my m8s Mac motor was bought with a winding for torque not speed.

 

[Nealh]

The 905T utilises a daul PAS set up and can use cadence as well, primary is Torque sensing and the rider a can change to cadence using the 'F' setting.

 

[Deleted member 25121]

The 905T utilises a daul PAS set up and can use cadence as well, primary is Torque sensing and the rider a can change to cadence using the 'F' setting.

But not both sensors at the same time.