Hub or Mid Drive? Any views?

[soundwave]

you are missing the point i want control over the motor settings and power levels

and i told you no one would buy those lol.

 

[Wisper Bikes]

you are missing the point i want control over the motor settings and power levels

and i told you no one would buy those lol.

I’d love to give you such control over settings but I’m now not allowed to thanks to EN15194 2017!

You did! We have sold about £350,000 worth of them and are selling off the last dozen or so at almost half price. They are a superb bike at a silly price now.

 

[Nealh]

The hub Wayfarer would/could replace three of my current bikes and in 2 or 3 years, I may be sorely tempted when my batteries I expect will need to be replaced.

 

[soundwave]

yeah well thats not much tbh id want 10m after the first year of production from my bikes id give ppl what they want performance wise and access to change any motor settings.

 

[Deleted member 25121]

Its not scientific ebiker99, although it should be!! The power is the same but because of where the torque is measured 50Nm hub is the same roughly as 100Nm centre. All the best, David

Are you measuring the torque at the driven wheel there?

 

[Wisper Bikes]

yeah well thats not much tbh id want 10m after the first year of production from my bikes id give ppl what they want performance wise and access to change any motor settings.

yeah well thats not much tbh id want 10m after the first year of production from my bikes id give ppl what they want performance wise and access to change any motor settings.

It was a terrible blow Soundwave we had expected to sell at least £10 millions worth in the first few months. But hey ho life goes on!!

All the best, David

 

[Wisper Bikes]

Are you measuring the torque at the driven wheel there?

On the hub yes.

All the best, David

 

[Woosh]

ebiker99 said:
Are you measuring the torque at the driven wheel there?

torque on mid motors is measured at the chainring.
to compare with hub motors, you have to imagine that your rear sprocket has the same number of teeth as the chainring.
On a typical 8-speed set up, you may have 44T chainring, 11T-32T sprockets. If you have a 100NM CD motor (typical of 48V systems), the maximum torque at the wheel will vary from 25NM on 11T to 72NM on 32T sprocket. Gear 4(21T) would have 48NM - roughly equivalent to a 50NM hub motor.

 

[Deleted member 25121]

On the hub yes.

All the best, David

Sorry, I don't understand your answer.

Let me put it another way (and thanks to Woosh for his clarification), what will be the full production model torque from the hub and mid motors?

 

[vfr400]

Sorry, I don't understand your answer.

Let me put it another way (and thanks to Woosh for his clarification), what will be the full production model torque from the hub and mid motors?

With a crank motor, the torque at the back wheel depends on which gear you're in and the actual gearing. You can change it with different sized chain-wheels or bottom gear sprockets. You can get 1000Nm if you want. Also, it depends on your pedal speed. You only get max torque at low pedal speed, where the motor isn't so efficient.

What's more important is real world torque that you feel when riding around, and having enough torque to make your steepest climbs. This is where you see the difference in users friendliness between the two types of motor.

Once you escape from the paradigm of 36v, hub-motors can normally provide all the torque most riders would need. I prefer 48v, which gives 33% more torque than the equivalent 36v system.

 

[Deleted member 25121]

With a crank motor, the torque at the back wheel depends on which gear you're in and the actual gearing. You can change it with different sized chain-wheels or bottom gear sprockets. You can get 1000Nm if you want. Also, it depends on your pedal speed. You only get max torque at low pedal speed, where the motor isn't so efficient.

What's more important is real world torque that you feel when riding around, and having enough torque to make your steepest climbs. This is where you see the difference in users friendliness between the two types of motor.

Once you escape from the paradigm of 36v, hub-motors can normally provide all the torque most riders would need. I prefer 48v, which gives 33% more torque than the equivalent 36v system.

Indeed, Woosh explained the torque specification issue earlier.

This is why I'm asking Wisper for the full production model torque from the mid motors as measured at the chainring. We can then use the number of teeth at the chainring and sprockets to calculate the maximum torque available at the driven wheel. The only reference see is on Wisper's first post: "I should also say that the demo Mid Motor is only producing 75Nm, the same as the Bosch CX or Shimano E8000, so not at the full production model power."

I ask this because I'm interested to see how the maximum torque at the wheel compares between the hub and crank driven Wisper bikes. With cars, diesel engines have far more torque per cc than petrol engines which nicer when pulling away and going up steep hills.

 

[Wisper Bikes]

Hi Ebiker, sorry to have not answered your question as well as Woosh, I misunderstood. (Thanks Woosh)

The production model of the mid drive bike will develop 100Nm, the hub drive will develop 50Nm so the torque on both bikes is about the same.



All the best, David

 

[Wisper Bikes]

A question for you tech gurus.... The Machinery Directive tells us that we cannot use a battery with a maximum Voltage of more than 50V. When our 43V battery is fully charged it reaches a tad over 50V so we are within the rules. When we see systems advertised as 48V are these actually 43V systems or is their maximum Voltage actually much higher and outside the Machinery Directive regs?

 

[Deleted member 25121]

So, unless I'm very much mistaken (please correct me anybody if I am):

The hub driven version will deliver 50NM to the driven wheel.

The crank driven version with a 44T chainring and 11T-32T sprockets will deliver 25NM to 72NM to the driven wheel depending on on the gear selected. Gear 4(21T) would give 48NM, approximately the same as the hub bike. (Thanks for those numbers Woosh).

Conclusion:
In hilly areas the crank driven bike is able to provide almost 50% more torque ie substantially higher assistance.
On flat roads the hub driven bike can provide higher assistance.

 

[vfr400]

Indeed, Woosh explained the torque specification issue earlier.

This is why I'm asking Wisper for the full production model torque from the mid motors as measured at the chainring. We can then use the number of teeth at the chainring and sprockets to calculate the maximum torque available at the driven wheel. The only reference see is on Wisper's first post: "I should also say that the demo Mid Motor is only producing 75Nm, the same as the Bosch CX or Shimano E8000, so not at the full production model power."

I ask this because I'm interested to see how the maximum torque at the wheel compares between the hub and crank driven Wisper bikes. With cars, diesel engines have far more torque per cc than petrol engines which nicer when pulling away and going up steep hills.

You have to specify the conditions. Do you want maximum torque at the back wheel that you can't actually use, stall torque, torque at 8 mph in bottom gear, max torque at normal pedal cadence, torque at 15 mph or what?

A hub-motor gives much more measurable and meaningful torque figure because torque is more or less proportional to current and the controller holds the current more or less constant in the lower half of the speed range. For a crank-drive, everything is changing all the time. If you were only using one gear, say bottom gear, the main variable would be the pedal speed.

The number that Bosch, Shimano, etc give for torque isn't back wheel torque. It's just an arbitrary number for comparison purposes. You can say that a 110 Nm motor gives 10% more torque in some theoretical conditions than a 100Nm one, but you can't really compare with a 50Nm hub motor.

 

[Deleted member 25121]

You have to specify the conditions. Do you want maximum torque at the back wheel that you can't actually use, stall torque, torque at 8 mph in bottom gear, max torque at normal pedal cadence, torque at 15 mph or what?

For cycling in hilly areas I'm referring to the torque available to assist the rider in cycling up hill in a low gear with reasonable speed, comfort and cadence.

 

[vfr400]

A question for you tech gurus.... The Machinery Directive tells us that we cannot use a battery with a maximum Voltage of more than 50V. When our 43V battery is fully charged it reaches a tad over 50V so we are within the rules. When we see systems advertised as 48V are these actually 43V systems or is their maximum Voltage actually much higher and outside the Machinery Directive regs?

The low voltage directive says 50v AC and 75V DC. I can't believe that the machinery directive would do anything other than point to the low voltage directive. My guess is that you've been misinformed. Can you tell us the source of your information?

 

[Wisper Bikes]

I completely agree, vfr400 hence my question in the thread title. We build the bikes and cant quite get a handle on it. We had both bikes here this morning, the mid motor bike has the adjusted software bringing it up to 100Nm according to the motor manufacturers. It does feel more powerful than the previous set up so we are inclined to agree with them. We have ridden both up a 15% incline on the North Downs and they are similar, the centre drive has the edge when both bikes are on the 11 tooth sprocket but certainly nothing like 50% better?

 

[Wisper Bikes]

The low voltage directive says 50v AC and 75V DC. I can't believe that the machinery directive would do anything other than point to the low voltage directive. My guess is that you've been misinformed. Can you tell us the source of your information?

I will dig up the paperwork but my information came from The Light Electrical Vehicle Association Europe. (LEVA EU)

 

[Laser Man]

Going back to Wisper's original question -

The answer is blindingly obvious - especially with their experience of the great looking mountain bikes.

It is all down to branding. Chain drive is pushed by big names that everyone has heard of, whereas hub drives are completely generic with Bafang being the only name that the uninitiated might have heard of.

The generic nature of hub drives isn't helped by the suppliers : I was very pleased with my first MXUS XF08 kit and was happy to order another for my wife's bike. The second kit came with a no-name, no-markings motor in a different casing to the first one. I'm not complaining, since the second motor seems just as good as the first, but any hope of brand loyalty (and recommendation of the motor) is lost.
(I do remain loyal to the suppliers, since they have been brilliant with their support).