Drive Through Gears on E-bikes
- Thread starter flecc
- Start date
Do I understand correctly your thesis? You say that driving through gears on e-bikes does not give extra efficiency in standard British (EU) conditions. You must obey a 250W power limit and a 15mph speed limit. A standard motor hub is sufficient and is simpler to built and easier to ride.
I think that – as to the rule - chain drive systems (or generally – gears using systems) offer more efficiency.
Flyer owners report rider assisted speed ~25mph (Flyer max power 200W). Various tests of bikes equipped with Cyclone or eLation kits show that these bikes can go really fast (let’s ignore now whether it is rational to have a bike going 30-40mph): Cyclone, eLation.
Motor hubs are more popular worldwide. US cyclists like e-bikes going ~30mph and more. Usually they use direct drive motor hubs (700-1500W continuous power). Such bikes are fast but they need strong and heavy motors (usually direct drive hubs) and heavy batteries. Similar max speed can probably be attained with a chain drive motor twice smaller.
I must obey only max power limit (250W). Sometimes I may need to go ~25mph on a public road. Will a 250W motor hub allow me to attain such pedaling assisted speed? I doubt it. A properly geared chain drive system probably will go so fast (YouTube - Cyclone Kit Australian Test).
In my opinion Americans like motor hubs since they like heavy and energy inefficient bikes (just like cars). Europeans like motor hubs since they cannot use extra efficiency offered by chain drive systems (speed limit on power assistance).
Moreover, hub motors are simpler to build/install in bikes (cheaper!) and simpler to use. But if you need a climb-able and fast lightweight e-bike – the best choice is a chain drive system.
I think that – as to the rule - chain drive systems (or generally – gears using systems) offer more efficiency.
Flyer owners report rider assisted speed ~25mph (Flyer max power 200W). Various tests of bikes equipped with Cyclone or eLation kits show that these bikes can go really fast (let’s ignore now whether it is rational to have a bike going 30-40mph): Cyclone, eLation.
Motor hubs are more popular worldwide. US cyclists like e-bikes going ~30mph and more. Usually they use direct drive motor hubs (700-1500W continuous power). Such bikes are fast but they need strong and heavy motors (usually direct drive hubs) and heavy batteries. Similar max speed can probably be attained with a chain drive motor twice smaller.
I must obey only max power limit (250W). Sometimes I may need to go ~25mph on a public road. Will a 250W motor hub allow me to attain such pedaling assisted speed? I doubt it. A properly geared chain drive system probably will go so fast (YouTube - Cyclone Kit Australian Test).
In my opinion Americans like motor hubs since they like heavy and energy inefficient bikes (just like cars). Europeans like motor hubs since they cannot use extra efficiency offered by chain drive systems (speed limit on power assistance).
Moreover, hub motors are simpler to build/install in bikes (cheaper!) and simpler to use. But if you need a climb-able and fast lightweight e-bike – the best choice is a chain drive system.
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for the efficience....
its not the fast speeds were the chain-drive-systems make there points but the slow speeds...
a good hubmotor can have a higher efficience than a chain-drive motor which most likely needs gears and than also has to use the gears of the bike as well
lets say the direct-drive hubmotor has a peak efficience of 80%
the chaindrive-motor has a peak efficience of 82% BUT: has to use a planetary gear for gearreduktion (95% efficience) AND the gears of the bike (98% efficience)
the the maximum over-all efficience of that chaindrive-system would be: 0.82*0.95*0.98 = 76%
so we see here 80% vs. 76%
at maximum speed the hub-motor would here most probably show higher efficience than the chain-drive-sytems
BUT: when we come to a hill...
the hub-motor will maybe fall down to 40% or even less
the chaindrive-motor can stay close to his peak-efficience-point
and will be still near 76%
so: on the hill this chain-drive-system will have maybe close to double the power of the hub-motor (or need only halve the current for same power) than the hub-motor which was supperior on flat terrain at his sweet efficience-spot
you said:
on a flyer you can not drive without pedaling
you have to pedal (and not only pseudo-pedal for the frequenz but real pedaling for the torque)
so: when you want 250Watt from the motor you have to pedal most propably with at least 150Watt (depending on the factor for assistance set on the controller)
so: even when the motor puts out only 250Watt, you see there 400Watt to the wheel because it does only put that out when you also pedal...
this can also be done with an hub-motor, maybe even better because of probably higher possible efficience at higher speeds
comparing becomes interesting up steep hills with less than 10km/h, were from the 400Watt Hub-Motor maybe 100Watt go to the wheel,
wereas the 250Watt chaindrive can still put out 250Watt to the wheel
chain-drive is good for steep hills..
if you live in an area with no hills -> benefits of chaindrive get smaller and smaller, the cons are maybe bigger than (con: shifting, con: higher wear of chain,...)
its not the fast speeds were the chain-drive-systems make there points but the slow speeds...
a good hubmotor can have a higher efficience than a chain-drive motor which most likely needs gears and than also has to use the gears of the bike as well
lets say the direct-drive hubmotor has a peak efficience of 80%
the chaindrive-motor has a peak efficience of 82% BUT: has to use a planetary gear for gearreduktion (95% efficience) AND the gears of the bike (98% efficience)
the the maximum over-all efficience of that chaindrive-system would be: 0.82*0.95*0.98 = 76%
so we see here 80% vs. 76%
at maximum speed the hub-motor would here most probably show higher efficience than the chain-drive-sytems
BUT: when we come to a hill...
the hub-motor will maybe fall down to 40% or even less
the chaindrive-motor can stay close to his peak-efficience-point
and will be still near 76%
so: on the hill this chain-drive-system will have maybe close to double the power of the hub-motor (or need only halve the current for same power) than the hub-motor which was supperior on flat terrain at his sweet efficience-spot
you said:
i think there are other reasons..
on a flyer you can not drive without pedaling
you have to pedal (and not only pseudo-pedal for the frequenz but real pedaling for the torque)
so: when you want 250Watt from the motor you have to pedal most propably with at least 150Watt (depending on the factor for assistance set on the controller)
so: even when the motor puts out only 250Watt, you see there 400Watt to the wheel because it does only put that out when you also pedal...
this can also be done with an hub-motor, maybe even better because of probably higher possible efficience at higher speeds
comparing becomes interesting up steep hills with less than 10km/h, were from the 400Watt Hub-Motor maybe 100Watt go to the wheel,
wereas the 250Watt chaindrive can still put out 250Watt to the wheel
chain-drive is good for steep hills..
if you live in an area with no hills -> benefits of chaindrive get smaller and smaller, the cons are maybe bigger than (con: shifting, con: higher wear of chain,...)
thats maybe the part of reason, why the swiss Flyer is so popular in switzerland and most driven electric bike there
defakto the switzerland-people do not say electric bike but they say "flyer" (sometimes even when they mean other bikes)
the flyer is there for over 10 years and for that hilly area it was and is more suitable than hub-driven bikes (even when you considere the weak hill-performance of hubmotors from 10years ago)
defakto the switzerland-people do not say electric bike but they say "flyer" (sometimes even when they mean other bikes)
the flyer is there for over 10 years and for that hilly area it was and is more suitable than hub-driven bikes (even when you considere the weak hill-performance of hubmotors from 10years ago)
Thanks kraeuterbutter. 
Boby, I was referring to mechanical efficiency which is a different thing from whether any particular setup suits a rider and their circumstances. Drive through the gears does indeed make less power capable of climbing hills, but that means the motor is subject to the transmission losses which on hub gears can be quite high.
A hub motor by comparison drives the wheel more directly and is not subject to those losses. The top speed it's geared for doesn't affect that.
As my conclusion says, use a drive through gear system for steep hills if those have to be climbed, but for people who are in flat areas or only have moderate hills, the hub motor is more efficient since it avoids those transmission losses.
This of course is the same as kraeuterbutter is saying.
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Boby, I was referring to mechanical efficiency which is a different thing from whether any particular setup suits a rider and their circumstances. Drive through the gears does indeed make less power capable of climbing hills, but that means the motor is subject to the transmission losses which on hub gears can be quite high.
A hub motor by comparison drives the wheel more directly and is not subject to those losses. The top speed it's geared for doesn't affect that.
As my conclusion says, use a drive through gear system for steep hills if those have to be climbed, but for people who are in flat areas or only have moderate hills, the hub motor is more efficient since it avoids those transmission losses.
This of course is the same as kraeuterbutter is saying.
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Gentlemen – thank you for your explanations. It sounds very reasonable.
You confirmed that motors using gears may be more effective in untypical conditions – eg. at low speeds without pedaling assistance (climbing ability). I still focus on maximum speed. One reason is that I am more interested in max speed at this moment and the second is that I find it easier to make calculations using max speed argument (lack of technical education).
You said that one great advantage of the motor hub is that it does not use chain and it saves on standard bike transmission loses. I think that we may ignore transmission loses since any simple well maintained derailleur system offers 98-99% efficiency. Even 95% efficiency should allow us to ignore this element.
Let me come back to the car gearbox analogy. A motor hub (esp. direct drive, but also geared hub) is like a car using one gear. Usually the 3rd one. The engine can move the car and you can drive pretty fast as well.
If you have an opportunity to use 5 gears, you can start easier (1st and 2nd) and you can drive faster (4th and 5th) – with the same engine.
This analogy is imperfect at least for two basic reasons:
1. the electric motor useful RPM range is far more wider than useful RPM range in any internal combustion engine.
AND
2. as flecc pointed out – the electric bike has two power sources: the motor and the rider. The rider can support the motor when it is inefficient (low speeds). The idea of power assisted bike is based on the assumption that the biker keeps on pedaling even when motor works.
But maybe this analogy is still reasonable (to certain extent). Let me give you an example, let figures talk (German speaking people would probably say: Zahlen erzählen)
I take a reputable motor, Suzhou Bafang SVXK (Suzhou Bafang Electric Motor Science-Technology Co.,Ltd.). 250W, max load 195RPM. I am trying to check what would be the maximum speed of the bike. To make matters simpler I assume that we have no pedaling assistance.
In the calculations below I use two bike simulators: Human Powered Vehicle Speed Simulator and Cycling: Steady State Power Equation. The bike's weight = 30kg, the biker's weight = 80kg, high rider, relaxed position, wide slicks.
Let’s assemble the motor in a 26” wheel, semi-slick wide tires 26x1,95.
Max load 195RPM produces the speed of 22,5kph (14mph).
Theoretical calculations for 250W continuous power (ignoring RPM aspect) show that the bike should reach the speed of 36,5kph (22,7mph). This speed represents 298RPM. The rider may start pedaling at 22,5kph and try to attain 36,5kph, but the motor works just as a freewheel at any speed above 195RPM (22,5kph).
What power does the bike require to maintain the speed of 22,5kph (14mph)? The simulator shows that this speed requires just ~80W. Other simulator confirms this calculation (85W).
What does it mean? I understand that the bike is undergeared (in car terminology). It delivers 250W at 195RPM. At this wheel size 195RPM = 22,5kph (14mph). On the other hand 22,5kph (195RPM) requires only 80W.
Maximum motor power (250W) in good conditions (quality flat road, no face wind, etc) would effectively be used at 300RPM. As we have no gears and we loose the opportunity to use this motor power effectively.
Are these calculations correct? Any mistake in reasoning?
If the above is correct – I believe it confirms the thesis that electric ride in order to be energy effcient requires gears. One gear (eg. motor hub) means that the motor drives the bike using the gear designed for average conditions – no extra climbing ability and no extra speed (like the 3rd gear in the car).
You confirmed that motors using gears may be more effective in untypical conditions – eg. at low speeds without pedaling assistance (climbing ability). I still focus on maximum speed. One reason is that I am more interested in max speed at this moment and the second is that I find it easier to make calculations using max speed argument (lack of technical education).
You said that one great advantage of the motor hub is that it does not use chain and it saves on standard bike transmission loses. I think that we may ignore transmission loses since any simple well maintained derailleur system offers 98-99% efficiency. Even 95% efficiency should allow us to ignore this element.
Let me come back to the car gearbox analogy. A motor hub (esp. direct drive, but also geared hub) is like a car using one gear. Usually the 3rd one. The engine can move the car and you can drive pretty fast as well.
If you have an opportunity to use 5 gears, you can start easier (1st and 2nd) and you can drive faster (4th and 5th) – with the same engine.
This analogy is imperfect at least for two basic reasons:
1. the electric motor useful RPM range is far more wider than useful RPM range in any internal combustion engine.
AND
2. as flecc pointed out – the electric bike has two power sources: the motor and the rider. The rider can support the motor when it is inefficient (low speeds). The idea of power assisted bike is based on the assumption that the biker keeps on pedaling even when motor works.
But maybe this analogy is still reasonable (to certain extent). Let me give you an example, let figures talk (German speaking people would probably say: Zahlen erzählen)
I take a reputable motor, Suzhou Bafang SVXK (Suzhou Bafang Electric Motor Science-Technology Co.,Ltd.). 250W, max load 195RPM. I am trying to check what would be the maximum speed of the bike. To make matters simpler I assume that we have no pedaling assistance.
In the calculations below I use two bike simulators: Human Powered Vehicle Speed Simulator and Cycling: Steady State Power Equation. The bike's weight = 30kg, the biker's weight = 80kg, high rider, relaxed position, wide slicks.
Let’s assemble the motor in a 26” wheel, semi-slick wide tires 26x1,95.
Max load 195RPM produces the speed of 22,5kph (14mph).
Theoretical calculations for 250W continuous power (ignoring RPM aspect) show that the bike should reach the speed of 36,5kph (22,7mph). This speed represents 298RPM. The rider may start pedaling at 22,5kph and try to attain 36,5kph, but the motor works just as a freewheel at any speed above 195RPM (22,5kph).
What power does the bike require to maintain the speed of 22,5kph (14mph)? The simulator shows that this speed requires just ~80W. Other simulator confirms this calculation (85W).
What does it mean? I understand that the bike is undergeared (in car terminology). It delivers 250W at 195RPM. At this wheel size 195RPM = 22,5kph (14mph). On the other hand 22,5kph (195RPM) requires only 80W.
Maximum motor power (250W) in good conditions (quality flat road, no face wind, etc) would effectively be used at 300RPM. As we have no gears and we loose the opportunity to use this motor power effectively.
Are these calculations correct? Any mistake in reasoning?
If the above is correct – I believe it confirms the thesis that electric ride in order to be energy effcient requires gears. One gear (eg. motor hub) means that the motor drives the bike using the gear designed for average conditions – no extra climbing ability and no extra speed (like the 3rd gear in the car).
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Yes, I agree with this Boby.
There are two reservations though. One is that as you've acknowledged, the hybrid element of the human power cannot be ignored since it an important part of the e-bike in law as well as in practice.
The other reservation is that in most implementations of the Panosonic system, hub gears are used and they are much less efficient than derailleur gears. Also most of an e-bike's life is spent in top gear which in a hub gear is at the extreme of inefficiency, having the largest degree of gearing up.
I think it's partly for those two reasons that most Panasonic motor bikes on test return lower average speeds than most hub motor bikes, these tested by the same people on the same routes. (A to B magazine). Typically the Panasonic motored bikes return averages of 12 to 13 mph and the hub motor bikes 13 to 16 mph. This is also my own experience, even in my very hilly area, where my Lafree returned a 12.4 mph average over it's life and my two hub motor bikes return 16 and 19 mph averages.
The latter one has a very high geared hub motor to give 22 (illegal) mph maximum and therefore demands more of me on hills. That points to another reason for the difference, the Panasonic unit being not well matched to riders for best performance due to the low cadence allowed for maximum assistance, below 40 rpm. By contrast my hub motor bikes allow me to perform at my optimum.
However, this doesn't alter what you've said, and a bike and motor unit with software designed for best performance using drive through derailleur gears can indeed be very efficient. Of course my article was written for the UK law and what we have available to buy, hence the discrepancy.
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There are two reservations though. One is that as you've acknowledged, the hybrid element of the human power cannot be ignored since it an important part of the e-bike in law as well as in practice.
The other reservation is that in most implementations of the Panosonic system, hub gears are used and they are much less efficient than derailleur gears. Also most of an e-bike's life is spent in top gear which in a hub gear is at the extreme of inefficiency, having the largest degree of gearing up.
I think it's partly for those two reasons that most Panasonic motor bikes on test return lower average speeds than most hub motor bikes, these tested by the same people on the same routes. (A to B magazine). Typically the Panasonic motored bikes return averages of 12 to 13 mph and the hub motor bikes 13 to 16 mph. This is also my own experience, even in my very hilly area, where my Lafree returned a 12.4 mph average over it's life and my two hub motor bikes return 16 and 19 mph averages.
The latter one has a very high geared hub motor to give 22 (illegal) mph maximum and therefore demands more of me on hills. That points to another reason for the difference, the Panasonic unit being not well matched to riders for best performance due to the low cadence allowed for maximum assistance, below 40 rpm. By contrast my hub motor bikes allow me to perform at my optimum.
However, this doesn't alter what you've said, and a bike and motor unit with software designed for best performance using drive through derailleur gears can indeed be very efficient. Of course my article was written for the UK law and what we have available to buy, hence the discrepancy.
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Additional chain drive resistance: I had never tested the Panasonic system. The idea looks similar to a basic Cyclone kit (picture 1) – one chain shared by the rider and the motor. The Cyclone kit motor mechanism creates a significant chain rolling resistance. It was irritating when riding without the electric assistance. Does Panasonic drive produce the same drag without electricity?
Geared hubs efficiency: I saw a draft showing efficiency of various hubs with 7-9 gears compared to Rohloff speedhub. Rohloff declared a flat 98% efficiency and competitors ~96% at a direct gear and minimum ~92% at lowest gears. Unfortunately I cannot find this website now.
I think that the chain drive e-bike system should meet two conditions:
1. The design – the motor useful RPM range should be equal to the rider’s most efficient cadence range. Probably the motor max RPM should be equal to the highest attainable cadence (eg. 90, but adjustable to individual preferences).
AND
2. The ride – the motor should always work at the efficient RPM range equivalent to the optimal cadence range, eg. 50-90. The optimal motor RPM should be maintained regardless of the rider’s pedaling input. Even if the rider is not pedaling (assuming that the motor can work independently), the cadence should be 50-90 in order to keep the motor in the efficient RPM range.
The second condition requires rider’s input. Maintaining the motor RPM (and the cadence) in the most efficient range requires some training. Probably a cadence sensor should help (just like a car tachometer). A cadence information will be of crucial importance if the rider stops pedaling for any reason. No pedaling means no cadence (and RPM) control. This may lead to a wrong (inefficient) gear choice and may result in a shorter range.
The system which may meet both conditions may look as showed in the second/third/fourth picture. Two separate chains and two freewheels allow for a pedaling-only ride, for a motor-driven ride and for a hybrid ride. Various crankset and motor chainrings sizes can help to obtain the optimal gearing.
It means that the first condition is not met. If you start pedaling fast the motor becomes a freewheel – am I right?
Your article also describes a mass market product. I think that the condition (2) requires a lot of training and discipline from the rider. Glaring at the tachometer and changing gears is not what you expect to do when riding the e-bike. Therefore a product meeting conditions (1) and (2) would be properly used only by enthusiasts in no-speed-limit countries (ie. very rare).
Attachments
The Panasonic chain drive path is far better than the inefficient Cyclone one, the drag being not much different from a deraileur rear mechanism. The motor does freewheel above 15 mph/25kph with the standard legal rear sprocket. There's more on the action of it's software here.
The efficiency claims of Rohloff are silly and they've been frequently questioned. In a variety of tests over the years, the best claim has been for the SRAM (Sachs) 3 speed hub with 92%, but that has been challenged by other testers. In general the best is about 89% for 3 speed hubs, diminishing as the gears numbers increase. The SRAM 5 speed is nearly up to 3 speed standards since it avoids compound epicyclic use, but the hubs with 7 gears upwards only return about 85%, diminishing with time and neglect. The tests are normally carried out with oiled hubs, but as supplied they are greased so the efficiencies for consumers are lower. Lowest of all is the Nexus Inter-7 which has no direct gear and uses compound epicyclics. No hub gear approaches the efficiency of derailleur gears. With the Rohloff it's worth noting that it is exceptionally noisy, and you will appreciate that this noise arises from mechanical losses.
I fully agree with your two conditions for chain drive e-bike efficiency, and as you've illustrated, there have been designs that can meet the conditions, though two chains mean efficiency losses.. For some reason however they don't seem to have succeeded over the years, and even the Panasonic system almost disappeared from the market when Giant discontinued it's use. It's only the increased interest in e-bikes leading bike manufacturers who needed a motor to enter the market that's enabled Panasonic to re-enter, but even Panasonic have now introduced a hub motor which they are further developing and seem to be staking their future on.
Although I mentioned a mass market product, I say again that the article was written for the UK market on what was available here. At the time of writing the article this pedelecs site was only a few months old with almost exclusively UK members at that time.
I agree that a product meeting your two conditions would only be suitable for countries with no e-bike speed limits and few riders would use the system well anyway. Certainly the majority of bike owners are very poor at using multi chainwheel derailleurs efficiently, so riding for motor efficiency as well is even more unlikely. Maybe a case for sophisticated software control with automated gear changing and adjustable presets for rider preferences!
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The efficiency claims of Rohloff are silly and they've been frequently questioned. In a variety of tests over the years, the best claim has been for the SRAM (Sachs) 3 speed hub with 92%, but that has been challenged by other testers. In general the best is about 89% for 3 speed hubs, diminishing as the gears numbers increase. The SRAM 5 speed is nearly up to 3 speed standards since it avoids compound epicyclic use, but the hubs with 7 gears upwards only return about 85%, diminishing with time and neglect. The tests are normally carried out with oiled hubs, but as supplied they are greased so the efficiencies for consumers are lower. Lowest of all is the Nexus Inter-7 which has no direct gear and uses compound epicyclics. No hub gear approaches the efficiency of derailleur gears. With the Rohloff it's worth noting that it is exceptionally noisy, and you will appreciate that this noise arises from mechanical losses.
I fully agree with your two conditions for chain drive e-bike efficiency, and as you've illustrated, there have been designs that can meet the conditions, though two chains mean efficiency losses.. For some reason however they don't seem to have succeeded over the years, and even the Panasonic system almost disappeared from the market when Giant discontinued it's use. It's only the increased interest in e-bikes leading bike manufacturers who needed a motor to enter the market that's enabled Panasonic to re-enter, but even Panasonic have now introduced a hub motor which they are further developing and seem to be staking their future on.
Although I mentioned a mass market product, I say again that the article was written for the UK market on what was available here. At the time of writing the article this pedelecs site was only a few months old with almost exclusively UK members at that time.
I agree that a product meeting your two conditions would only be suitable for countries with no e-bike speed limits and few riders would use the system well anyway. Certainly the majority of bike owners are very poor at using multi chainwheel derailleurs efficiently, so riding for motor efficiency as well is even more unlikely. Maybe a case for sophisticated software control with automated gear changing and adjustable presets for rider preferences!
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Your conclusions are correct but not because of your calculations. A bike using gears should be able to use the motor more efficiently because motors run most efficiently at around 80% of their maximum rpm. Gears would help to maintain the motor at close to this speed in varying conditions.
john – I understand that 80% of RPM is the optimum level. What would be the useful RPM range of a brushless electric motor installed in an e-bike (we talk about high/normal speed motors, not direct drive hubs)?
Let’s take into consideration the standard motor with the max load RPM – 300. The max motor power is irrelevant for the purpose of this calculation.
• Optimal RPM level is 240 (80% of max load RPM).
• Typical (optimal) cadence – 60.
• Good drive system should allow the rider and the motor to work together at their optimal cadence/RPM.
• The motor 240RPM = the rider cadence 60 (4 : 1).
• Chainring – 52 teeth (20” bike).
• The motor gear 13 teeth = 52 teeth chainring (1 : 4).
Is that correct?
Please look at Cyclone motors technical data: Cyclone motors. They declare motors efficiency 97,5 – 93%. Is it possible?
I understand they report only the motors efficiency without mentioning about the RPM reduction (smaller engines are equipped with planetary gears 9,5 : 1). Anyway – it looks impressive. Assuming this data is reliable – is such a high efficiency typical for fast rotating motors?
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Flecc, I wonder what your opinion of this kit would be. Assume 300w and no speed limit.
eLation eBikes
It seems to be a good system to me. I've heard of speeds in excess of 40km/h on it (which surely must be pumping out a lot more than 300w for that) and range of 12kms at full throttle.
The motor is geared down with the sprocket outputting roughly at 300rpm. This is then reduced on to the 42 front chainring. I'm not sure how much though 65-85 rpm seems a reasonable range.
If I was to get this kind of kit, I'd be interested in range as well as speed. The re are precious few options in NZ without importing, and this is one of the few with a local agent. (Coincidentally the same as the agent for Wispers. electricbikes.co.nz - Electric Bikes, Kits, Ebikes and More ! - Home)
eLation eBikes
It seems to be a good system to me. I've heard of speeds in excess of 40km/h on it (which surely must be pumping out a lot more than 300w for that) and range of 12kms at full throttle.
The motor is geared down with the sprocket outputting roughly at 300rpm. This is then reduced on to the 42 front chainring. I'm not sure how much though 65-85 rpm seems a reasonable range.
If I was to get this kind of kit, I'd be interested in range as well as speed. The re are precious few options in NZ without importing, and this is one of the few with a local agent. (Coincidentally the same as the agent for Wispers. electricbikes.co.nz - Electric Bikes, Kits, Ebikes and More ! - Home)
I've seen this mentioned before and it has much in common with the Cyclone kits, though it's motor position is very much better and the freewheeling chainwheel looks better. Like all these motors, the power rating will be an averaged assessment and the actual peak power will be quite lot higher. There's no doubt a bike using it could reach 40 kph, we had a similar arrangement in the UK on our now defunct TGA-Electrobike using a smaller motor and that could make that speed. Other examples are the high speed class bikes using the Panasonic unit. They sit in the 40 kph class in Germany and use a 250 watt rated motor, and owners of the BikeTech Flyer bikes using that S system report up to 43 kph assisted.
I can't really judge the range, so much depends on the usage conditions, hill length and steepness, rider weight, degree of throttle usage and pedal assistance given. The chosen battery type also affects things. In general, this type of motor system isn't very sophisticated and relies on the rider behaviour to provide its "software", so it can be anything from a greedy short range system to a frugal long range one, that entirely in the hands of the rider and their fitness.
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I can't really judge the range, so much depends on the usage conditions, hill length and steepness, rider weight, degree of throttle usage and pedal assistance given. The chosen battery type also affects things. In general, this type of motor system isn't very sophisticated and relies on the rider behaviour to provide its "software", so it can be anything from a greedy short range system to a frugal long range one, that entirely in the hands of the rider and their fitness.
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Hi all,
I am new here but have been playing with e-bikes for close to a decade on and off.
Personal experience leads me to question some of the information presented regarding through gear systems especially with the low power limits legally usable in Australia and the UK etc.
Chain strength is not a factor with the outputs that are legal, I have previously covered a lot of Km with a motor over double the legal limit running through the BB with the cheapest chain I could buy and it never looked like failing and its use included 20% grade hills every ride.
I currently have a recumbent trike setup with a Stokemonkey style BB drive using a Tongxin hub motor driving the left crank thus allowing the use of all 27 gears, it allows the tiny hub to give great assist even on a 25% hill and will climb 20% hills for prolonged periods with close to no heat build up, at the other end of the scale it can still give a decent boost at 60 kph.
One of the great benefits of the drive though is that if you set it up to suit your cadence it will boost you up to a more powerful cadence and then basically drop out.
I have also done some initial dyno style testing (high end trainer with a wattage output at the rear wheel function) with and analog Amp meter and input to output is about the same percentage as the efficiency of the hub suggesting that through gear losses are close to irrelevant with a well maintained derailleur system.
With Winter coming I will have more time for more testing and have just received my Turnigy watts up meter so will be able to get more exact data down the track.
If you have steep hills this style of drive is ideal IMHO.
Just as backround I also have or had direct drive hubs, geared hubs and single speed chain driven rear drives varying from 160w to over 1kw.
I find I enjoy electric assist more than pedal assist on the higher powered bikes.
Cheers
I am new here but have been playing with e-bikes for close to a decade on and off.
Personal experience leads me to question some of the information presented regarding through gear systems especially with the low power limits legally usable in Australia and the UK etc.
Chain strength is not a factor with the outputs that are legal, I have previously covered a lot of Km with a motor over double the legal limit running through the BB with the cheapest chain I could buy and it never looked like failing and its use included 20% grade hills every ride.
I currently have a recumbent trike setup with a Stokemonkey style BB drive using a Tongxin hub motor driving the left crank thus allowing the use of all 27 gears, it allows the tiny hub to give great assist even on a 25% hill and will climb 20% hills for prolonged periods with close to no heat build up, at the other end of the scale it can still give a decent boost at 60 kph.
One of the great benefits of the drive though is that if you set it up to suit your cadence it will boost you up to a more powerful cadence and then basically drop out.
I have also done some initial dyno style testing (high end trainer with a wattage output at the rear wheel function) with and analog Amp meter and input to output is about the same percentage as the efficiency of the hub suggesting that through gear losses are close to irrelevant with a well maintained derailleur system.
With Winter coming I will have more time for more testing and have just received my Turnigy watts up meter so will be able to get more exact data down the track.
If you have steep hills this style of drive is ideal IMHO.
Just as backround I also have or had direct drive hubs, geared hubs and single speed chain driven rear drives varying from 160w to over 1kw.
I find I enjoy electric assist more than pedal assist on the higher powered bikes.
Cheers
Hi Geebee
I agree that derailleur gear transmissions can stand up to motor and rider power combined reasonably well, but much depends on conditions of use. For example, you won't have to look far in the forum for those whose chains fail at as little as 1000 miles with the Panasonic systems when used in poor conditions, for example with quantities of road salt corrosion in winter. This emphasises the effect of double loading through transmission of rider and motor power.
However, there are two things you possibly haven't picked up on with the Panasonic system which make a crucial difference. The first is that the motor power is concentrated entirely on the pedal thrust stroke only, so doubling up variably during the downthrusts and then unloading the chain rhythmically. This constant snatch and ease-off produces more transmission stress than the constant smooth drive load of the types of motors that you are using.
The second difference concerns the hub gears so often used with the Panasonic system. To avoid excessive torque load damage in the lower gears, the makers of these gears like Shimano, SRAM and Sunrace-Sturmey generally advise the chainwheel should be at least twice the size of the rear sprocket, and that's for a rider's power only.
However, that rule tends to be slightly broken with the Panasonic systems which use 37 or 41 tooth non-changeable chainrings, commonly with 22 or 23 tooth rear sprockets to comply with assist speed limit regulations. Since these carry both the motor power and rider power, the excess torque in the lower gears is far above the hub gear manufacturers recommendations. Indeed, it was the high failure rate of the Nexus Inter-4 speed hub on the Panasonic equipped Lafree that caused Shimano to abandon it, leaving a large gap in their hub gear range.
As for the hill climb ability, I agree that with the steepest hills like 20% or more, drive through the gears is usually better as I've said in the second part of my article. And of course, if you want the motor to do most of the work, that becomes essential with limited motor power.
By the way, we have long ignored the 200 watt limit in the UK since the EU 250 watt law was also written into our legislation in 2003. Plans are currently in hand to make the EU 250 watt law absolute in the UK, and I think 250 watts is under consideration in Australia too now.
We also have some legal 250 watt models on the market that have very high peak powers, to over 700 watts in some cases with the odd ones hitting 1000 watts. That makes quite a difference on the hills.
.
I agree that derailleur gear transmissions can stand up to motor and rider power combined reasonably well, but much depends on conditions of use. For example, you won't have to look far in the forum for those whose chains fail at as little as 1000 miles with the Panasonic systems when used in poor conditions, for example with quantities of road salt corrosion in winter. This emphasises the effect of double loading through transmission of rider and motor power.
However, there are two things you possibly haven't picked up on with the Panasonic system which make a crucial difference. The first is that the motor power is concentrated entirely on the pedal thrust stroke only, so doubling up variably during the downthrusts and then unloading the chain rhythmically. This constant snatch and ease-off produces more transmission stress than the constant smooth drive load of the types of motors that you are using.
The second difference concerns the hub gears so often used with the Panasonic system. To avoid excessive torque load damage in the lower gears, the makers of these gears like Shimano, SRAM and Sunrace-Sturmey generally advise the chainwheel should be at least twice the size of the rear sprocket, and that's for a rider's power only.
However, that rule tends to be slightly broken with the Panasonic systems which use 37 or 41 tooth non-changeable chainrings, commonly with 22 or 23 tooth rear sprockets to comply with assist speed limit regulations. Since these carry both the motor power and rider power, the excess torque in the lower gears is far above the hub gear manufacturers recommendations. Indeed, it was the high failure rate of the Nexus Inter-4 speed hub on the Panasonic equipped Lafree that caused Shimano to abandon it, leaving a large gap in their hub gear range.
As for the hill climb ability, I agree that with the steepest hills like 20% or more, drive through the gears is usually better as I've said in the second part of my article. And of course, if you want the motor to do most of the work, that becomes essential with limited motor power.
By the way, we have long ignored the 200 watt limit in the UK since the EU 250 watt law was also written into our legislation in 2003. Plans are currently in hand to make the EU 250 watt law absolute in the UK, and I think 250 watts is under consideration in Australia too now.
We also have some legal 250 watt models on the market that have very high peak powers, to over 700 watts in some cases with the odd ones hitting 1000 watts. That makes quite a difference on the hills.
.
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hey...
in German forum in the moment lot of people are building there own "drive through gears"-bikes
most common is the little Tongxin, i think in the U.K. more famouse under the name "Nano".
we bought that motor in a centralized buying for 90 Euro each motor
the most advanced bike was build by vautech with that motor so far...
outstanding imho.
its a fully, weights only 14,4kg including the 37V 10Ah Battery (!!!)
he also build the bike by himself..
14,4kg for a Fully is realy a very good value (considering that it is electric)
the motor is only rated for 160-180Watt
for short periods (up a hill) it can be used with up to 10Amps, puting out around 230Watt
the crank has a freewheel
battery is in the frame, can be inserted from behind
in German forum in the moment lot of people are building there own "drive through gears"-bikes
most common is the little Tongxin, i think in the U.K. more famouse under the name "Nano".
we bought that motor in a centralized buying for 90 Euro each motor
the most advanced bike was build by vautech with that motor so far...
outstanding imho.
its a fully, weights only 14,4kg including the 37V 10Ah Battery (!!!)
he also build the bike by himself..
14,4kg for a Fully is realy a very good value (considering that it is electric)
the motor is only rated for 160-180Watt
for short periods (up a hill) it can be used with up to 10Amps, puting out around 230Watt
the crank has a freewheel
battery is in the frame, can be inserted from behind
Attachments
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only 4 pics alowed:
here from the other side:
i like this bike for it is not "amy-Style"
Amy-Style = 5000Watt RC-model-Motor, resulting in a bike with 10times motorpower compared to legpower..
in my eyes there should be a balance between motorpower and legpower..
for that ~200Watt Power from the motor is a good value
(in my Eyes)
even considering that it can use the gears
here another variant from vautech, with Bafang-Motor:
more power than the little 80mm tongxin (nano)
but also not as quiet
weight of this bike: 13kg without battery
here from the other side:
i like this bike for it is not "amy-Style"
Amy-Style = 5000Watt RC-model-Motor, resulting in a bike with 10times motorpower compared to legpower..
in my eyes there should be a balance between motorpower and legpower..
for that ~200Watt Power from the motor is a good value
(in my Eyes)
even considering that it can use the gears
here another variant from vautech, with Bafang-Motor:
more power than the little 80mm tongxin (nano)
but also not as quiet
weight of this bike: 13kg without battery
Attachments
Last edited: