Once again, that depends on the bike's settings. The full input on the three centre drives bikes I tested, didn't need much pedal effort in their high power settings. And that is logical programming. Lightening the pedal effort to no apparent input, they did let the power stop. So there is a difference. But since I come from a push bike, the centre drive felt much smoother and more natural. And on the steep hill test, there was no need to hit the bottom of the hill with speed ... my test was to enter the hill (it not being very long) and then move up the hill.you were given a bad cadence sensored hub bike to test.
A modern controller reduces its power to keep you pedalling at all times if you slow down your pedalling when you go round a corner for example.
That is an important point to keep in mind. If your test bike does not do this, ask for another one.
Controllers respond more quickly to a torque sensor than a cadence sensor because cadence sensor requires more intensive computing but the difference in response time is not very big, we are talking about may be a few tenths of a second here. You soon won't take much notice. The advantage of cadence sensor over torque sensor is that cadence sensor lets you ride up a hill with much more ease.
I think you have misunderstood a lot there. A mid drive motor uses a very high rpm low torque motor through internal gears to generate a high torque at low speed. You can create more torque with the gearing and this is still true of the external gears in a bicycle drivetrain. The torque doesn't remain the same. If one gear is 1:1 so the torque at the crank is 90Nm and therefore the torque at the rear wheel is 90Nm minus losses in the chain then you have to understand when the front crank is 90Nm and the gearing is high and the rear wheel rotates 3x as much for one crank rotation 3:1 then that power is now 30Nm minus the losses through the chain. This is very simple and undisputable data which is completely accepted everywhere. If you have a cassette that is 11-52T that is getting close to 5x so you roughly get a fifth of the torque in the highest gear compared to the lowest.Bonzo, thanks for the statistics. Thanks for the info on the dominance of hub motors in China, and around the world.
Just a few points. You said the following:
" However on a mid-drive motor with lets say 85Nm it may be you get 90Nm for its lowest gear but its very slow with a high cadence and then as you go higher you get 70Nm, 50Nm, 40Nm, 30Nm, 20Nm, 10Nm etc so the faster you go the less assistance you get. "
That's not true. I would refer you to Newton's second and third laws. The first law is that force = mass times acceleration. And his third law says that for every action (force) there is an equal and opposite reaction.
Gears don't extinguish that force.
The hub motor does have more of its energy available, because there are less friction losses. But a gear box is able to utilise its energy better in varying loads. And its energy losses are slight. In low power elect motors, the gears - for my usage - are well worth the slight energy loss due to friction.
The basic issue is that a hub motor is stuck inside a single gear. Namely the wheel. If you put a hub motor from a 28" wheel into a 20" wheel, its performance is going to behave very differently. That's because of the design of the motor and primarily because the wheel is the single gear the electric force is restricted to.
There is no magic loss of energy due to gears, except for a tiny bit in friction, and also, there is typically more mass in a mid drive setup. The idea you are propagating, is that gears can loose in your example, 90% of their energy. They don't.
I'm not unfamiliar with electric motors, energy, and gearboxes. I ran a factory with 45 large electric motors, and most of them drove gearboxes, and many had variable speeds. I've burnt out and re-wind a lot of electric motors. Recycling plastics from film into film, about 1000 Olympic football stadiums of heavy plastic film every year.
The big issue IMO for bikes, is that most of them are artificially restricted. We would not be having this discussion, if there were no power limits on bikes. I reckon if there weren't such limits, the logical solution would be a hub drive. Afterall Dr Porsche used that concept in the first world war, to power Germany's rail system, so that less or even no locos were required. Ironically now, Porsche is one of the few electric car makers that actually incorporates a gear box. You can research why elsewhere!
For myself, I've done enough testing now, and I am opting for a central gearbox solution. This is because I want a light bike that is easy to ride, and is compact, well priced, rides well, is fun, and can handle both my pier and marina access (I have a yacht and ride an old bike to the marina and it has some tight turns) and I also want my bike to be able to handle non mown grass and be able to attempt to get from a river bank up the typical steep inclines that I reckon are common when we go camping in the Australian bush. My wife also has ridden a fair bit, and she did not like the instant reponse feel of the hub drives - the obviously not well setup ones for us "newby" ebike riders.
I'm intrigued. What e-bikes have you ordered?...in a mid drive setup, in my case in the bikes I have just now ordered, one kilogram more compared to the same bike with a rear hub drive setup.
Today I payed a deposit, for two Dahon K-One bikes. The shop is putting racks, are carry bag, mud guards on them, and changing the tyres from 1.75 wide tyres to Schwable 2.15 Fat somethings. I wanted more aired tyres, for ride and also to handle grass better. The rear motor version was 1 kg lighter at 19kg. Otherwise the bikes were similar. The cost of each bike without the options was in British Pounds after tax, 1,115. The rear wheel hub motor version would have cost $1,000 pounds. I don't know if the bike is sold in the UK. Its available in the USA, and its on special in the USA at the moment. There's a lighter bike available now with a different motor gearbox, and a nicer frame, the whole combo is only 17kg for the mid motor bike. The motor used in that bike is only 200 watts. I don't think there is a hub motor available in that bike. I presume one will come out later. My wife and I both loved the bike.I'm intrigued. What e-bikes have you ordered?
Some mid motor bikes don't have gears at all. They can still go up hills. If the gearing is similar, they'd go up marginally worse (due to weight and friction effects - Newton's second law - than a single geared hub motor bike.The whole point of gears is to amplify our torque for hills at the expense of speed. You must understand that you need to go to a low gear on your bike to tackle steep hills?
It's not clear (Dahon don't say) which of Bafang's extensive mid-drive motors is actually fitted, or if it's CanBus or UART... the later most desirable if you want to be able to tweak the bikes performance.Today I payed a deposit, for two Dahon K-One bikes. The shop is putting racks, are carry bag, mud guards on them, and changing the tyres from 1.75 wide tyres to Schwable 2.15 Fat somethings. I wanted more aired tyres, for ride and also to handle grass better. The rear motor version was 1 kg lighter at 19kg. Otherwise the bikes were similar. The cost of each bike without the options was in British Pounds after tax, 1,115. The rear wheel hub motor version would have cost $1,000 pounds. I don't know if the bike is sold in the UK. Its available in the USA, and its on special in the USA at the moment. There's a lighter bike available now with a different motor gearbox, and a nicer frame, the whole combo is only 17kg for the mid motor bike. The motor used in that bike is only 200 watts. I don't think there is a hub motor available in that bike. I presume one will come out later. My wife and I both loved the bike.
It's not that I don't understand Newton's third law I honestly don't understand why you are quoting it here its not applicable surely to how gearing works and the whole point of gearing to increase torque at the expense of speed or vice versa.Some mid motor bikes don't have gears at all. They can still go up hills. If the gearing is similar, they'd go up marginally worse (due to weight and friction effects - Newton's second law - than a single geared hub motor bike.
As far as bikes with gears, I guess you don't understand Newton's third law. Shame.
Leave out the ChatGPT son.Well, actually, its the first time I've used ChatGTP.
So be honest.Well, actually, its the first time I've used ChatGTP.
ChatGPT still has some training to go through before it understands properly Newton's laws.And I sort of wrote this:
Newton's second law of motion states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Mathematically, it can be expressed as F = m * a, where F represents the net force applied to the object, m is its mass, and a is the resulting acceleration.
When it comes to mid motor bicycles, where the motor is positioned near the bike's bottom bracket (center motor), Newton's second law is applicable. The motor in a mid motor bicycle provides additional force or power to assist the rider's pedaling. As a result, the net force acting on the bicycle is increased, leading to enhanced acceleration. This is particularly advantageous when climbing hills or riding on challenging terrains since the combined power of the rider and the motor helps overcome resistance.
In contrast, a front hub motor bicycle, where the motor is integrated into the front wheel hub, doesn't directly impact Newton's second law. The motor in this configuration provides assistance by driving the front wheel, but it doesn't affect the net force applied to the entire bicycle. Instead, the force generated by the motor is transmitted through the wheel to propel the bike forward. The rider's pedaling, in combination with the motor's power, helps achieve the desired acceleration.
Newton's third law of motion states that for every action, there is an equal and opposite reaction. This law is relevant to both mid motor and front hub motor bicycles. When the motor applies a force to propel the bike forward, an equal and opposite reaction force is exerted on the motor itself. In a mid motor bicycle, this reaction force is primarily absorbed by the bike's frame and structure, which are designed to handle the additional stress. In a front hub motor bicycle, the reaction force is transmitted through the fork and other components connecting the front wheel to the frame.
Overall, while both mid motor and front hub motor bicycles involve the application of Newton's second and third laws, the specific mechanical configurations and positioning of the motor affect how these laws come into play. The mid motor design has the advantage of utilizing the bike's gears and achieving a balanced weight distribution, which can result in improved acceleration and climbing ability.
Well, actually, its the first time I've used ChatGTP. That took ... a couple of seconds. Interestingly, maybe its not all that smart, as it forgot to mention tyres!
I doubt I will. I did research them some time ago though, and established which one it was. But that maybe 7 weeks ago. On the control setup - the hub motor version had a large display, while the mid motor version had a small and mean looking display. Although the small display was easy to use, it was small screen but with big buttons. Both of the e-bikes (hub and mid) have an area for I presume electronic controls. The performance was fantastic actually, and besides increasing the top speed, I didn't feel a need to fiddle with the controls. I had thought that changing to 48 volts would not assist warranty and doubted it would be easy to do on those bikes, and also, would decrease the small battery range. The bikes felt very sprightly though, even on setting one the bike felt quick, and two quite powerful.It's not clear (Dahon don't say) which of Bafang's extensive mid-drive motors is actually fitted, or if it's CanBus or UART... the later most desirable if you want to be able to tweak the bikes performance.
it's ChatGPT, Generative Pre-trained Transformer. it's not GTP.I didn't know about chat GTP until last night!!!
There are a lot of problems in your understanding of mid and hub motors, torque, force and power. There are quite a few aspects to consider that you should really discard the pre-conceived idea that mid motors are more efficient than hub motors. Both systems have equally strong proponents.The facts are that the loss from a mid motor is minimal. There is extra lost power from the mid motor when one looses a tiny bit of power from the friction of the gears.
If one really considers the issues, a mid motor will accelerate better than hub motor by using gears. And if the gears benefit the power usage - such as on heavy grass which slows the bike down, or thick sand, or up hills - then the mid motor's ability to use gears increases efficiency. That means a mid motor is more efficient, if the gears are a benefit to the bike.
And for the sake of completenessThere are a lot of problems in your understanding of mid and hub motors, torque, force and power.
Its wet and for us, pretty cool at 12.7 degrees Centigrade (that's only 34 degrees fahrenheit) and its raining.
I look forward to ignoring ChatGPT's review, son.I didn't know about chat GTP until last night!!!
Yes, its scary stuff. My son told me about it. He is in building automation. He said its scary. He used it to make a draft for a building process - and it was very close to what he wanted. In about 10 seconds.I look forward to ignoring ChatGPT's review, son.