Electric Bikes - Help Please - Trying to decide on what type of motor.

Hi Team,

I am new to the eBike world. I have spent a long time researching to determine what type of motor to select. It appears the more research I do, the more difficult it becomes to choose. I am trying to choose between a hub motor and an external motor that drives through the crank and uses the bikes gears. I have searched many forums and can not seem to find a clear answer. Manufactures both boast their system is more efficient. From what I can understand this appears to be the case:

Hub Motor Pros
1. Easier to install
2. Less maintenance
3. Quiet

Hub Motor Cons
1. Does not have a wide range of gears (usually none) therefore motor can not run at it's most efficient speed all of the time.
2. Once you reach the maximum speed of the motor, you just free spin the pedals.

External Motor Pros
1. Can use the gears of the bike to keep motor running at it's most efficient speed by changing gears on the bike.
2. When cruising and in top gear of the bike, motor does not need to spin as much (but surely this would require more torque). But less turns required to keep the same top end speed.
3. Smaller in size?
4. PWM controller can be internal
5. Tend to be more efficient

External Motor Cons
1. More maintenance due to extra chains etc.
2. Possibly more noise as you have to use the bike chain to drive the bike.

I believe you can rest and not have to pedal with the External Motor, but I have never seen one. So how does this work considering the chain has to move to drive the back wheel. Would'nt this force the pedals to rotate?

There is a reasonable chance that I have some things wrong or missed some points, so please let me know if this is the case so that I can use this information to assist with my decision.

Given the same motor but different voltage, 36 vs 24 means you should get better distance (speed should be the same).

I am looking for something that is 200 - 400 W. I guess 36V (going to 48V means more batteries thus more weight, 24V seems to be a bit small).

Batteries - Will certainly use either NiMH, Li, or LiPO.

I am considering using my existing bike.

My terrain does not have too many steep hills (more gentle gradients).

Any help that anyone can give me here is greatly appreciated.

Thanks in advance.

http://www.texaselectricbikes.com/catalog/electric-bike-motor-p-163.html

Geared hub motor gives you good low speed efficiency, plenty of torque, all in an easy to install package. This motor will freewheel, so that takes care of both of your negatives for hub motors. Battery voltage will determine your maximum speed, and 36v should go 22mph or so.

Some hub motors (BionX) have internal PWM controllers.

Most hub motors without gear are non-freewheeling.

Most hub motors with gear are free-wheeling.

Hub motors with gear are a bit noisier than those without gear, but much quieter than external-chain drive motors.

I would prefer hub motors.

http://www.texaselectricbikes.com/catalog/electric-bike-motor-p-163.html

Geared hub motor gives you good low speed efficiency, plenty of torque, all in an easy to install package. This motor will freewheel, so that takes care of both of your negatives for hub motors. Battery voltage will determine your maximum speed, and 36v should go 22mph or so.Gears in a hub motor are loud and are the weak link along with un suspended weight in the wheel.Cheap controllers made in China are also known for meltdowns.Quality issues must be kept in mind.

Gears in a hub motor are loud and are the weak link along with un suspended weight in the wheel.Cheap controllers made in China are also known for meltdowns.Quality issues must be kept in mind.

The Puma geared hub motor has been tested at 2500W, and considering the original poster is only looking for 400W max it will be fine. As for noise, the Puma sounds quieter than your chain drive. 36v @ 400W isn't going to be melting anything down.

The Puma geared hub motor has been tested at 2500W, and considering the original poster is only looking for 400W max it will be fine. As for noise, the Puma sounds quieter than your chain drive. 36v @ 400W isn't going to be melting anything down. You have never tried kevlar sprockets so how would know about any noise? How would a 20 to 1 gear drive gear motor be more efficient or quieter ? How will the 400 watts be limited to that? How does the hub motor heat escape the hub? How long will it last going 30 mph and how noisy is it at that speed ? How will 400 watts make it to 20 mph without pedaling ?

I believe you can rest and not have to pedal with the External Motor, but I have never seen one. So how does this work considering the chain has to move to drive the back wheel. Would'nt this force the pedals to rotate?

Yes, if you use an external motor that takes advantage of the same gearing that the pedals use, you'll have to set it up so that the motor forces the pedals to rotate, although you may be able to get around this with exotic components-- some tandem bikes are made with parts that allow a set of pedals to sit still while the gear(s) those pedals drive turns.

Yes, if you use an external motor that takes advantage of the same gearing that the pedals use, you'll have to set it up so that the motor forces the pedals to rotate, although you may be able to get around this with exotic components-- some tandem bikes are made with parts that allow a set of pedals to sit still while the gear(s) those pedals drive turns.The only thing exotic is a efficient torque motor that does chain drive the hub with a single chain reduction of 8 to 1.You get the right motor and you do not need the motor to shift through the gears unless you want to go faster than it is safe.

Your help has been fantastic. Much appreciated.

I think I will go with a front hub motor for my first eBike. Seems a bit simpler to start with. Just now trying to fish through the options and select the right motor for me. So, now trying to locate a good value for money hub motor of about 400W. Anyone have any suggestions?

Thanks in advance.

although you may be able to get around this with exotic components-- some tandem bikes are made with parts that allow a set of pedals to sit still while the gear(s) those pedals drive turns.

Yes, you'd have a freewheel in the bottom bracket crank and you'd also have a freewheel on the motor itself. This way, you can run with motor only and not have to pedal or you can pedal without feeling the resistance of the motor. Of course, the best way to extract the most efficiency is to pedal with the motor in the most appropriate pedal-only gear.

I prefer geared external motors as they're far more efficient, but I do understand that hubmotors play an important role with getting people into ebikes, so I support this approach for that reason alone.

Your help has been fantastic. Much appreciated.

I think I will go with a front hub motor for my first eBike. Seems a bit simpler to start with. Just now trying to fish through the options and select the right motor for me. So, now trying to locate a good value for money hub motor of about 400W. Anyone have any suggestions?

Thanks in advance.

http://www.ebikes.ca/store/

A 406 on 36v, or a 408 on 48v will be pretty close to what you're looking for with a 26" wheel.

http://www.ebikes.ca/store/

A 406 on 36v, or a 408 on 48v will be pretty close to what you're looking for with a 26" wheel.

It seems that 406 could be also working on 48V with a higher top speed.

Yes, you'd have a freewheel in the bottom bracket crank and you'd also have a freewheel on the motor itself. This way, you can run with motor only and not have to pedal or you can pedal without feeling the resistance of the motor. Of course, the best way to extract the most efficiency is to pedal with the motor in the most appropriate pedal-only gear.

I prefer geared external motors as they're far more efficient, but I do understand that hubmotors play an important role with getting people into ebikes, so I support this approach for that reason alone.
Currie will figure out hot to make a geard system with their year old company they baught ?
http://www.fallbrooktech.com/05_PressReleases_currie.asp

In somewhat less than one hour of reviewing threads in this forum I am already sick of the bickering between Randy and Lowell. IMO both of you are knowledgeable and have much to offer this community but not if you keep sniping at one another. Furthermore because of the insular nature of being visionary a certain amount of singlemindedness creeps into the information delivered. IMO Randy is the greater offender in this respect. For instance. As regards powering a drivetrain with an external motor an IPS (independent pedaling system) crankset can be used which is a system that can be purchased vs multiple freewheels for crank and motor which will have to be fabricated. And speaking of fabrication, how many of us are gifted with the ability to take salvage automobile alternators and turn them into e-motors by winding custom stators for them?! Few, yet we are hammered on the failures of the marketplace to provide the kinds of motors we really need. Maybe this is the case but... ... it is what we have.

H

In somewhat less than one hour of reviewing threads in this forum I am already sick of the bickering between Randy and Lowell. IMO both of you are knowledgeable and have much to offer this community but not if you keep sniping at one another. Furthermore because of the insular nature of being visionary a certain amount of singlemindedness creeps into the information delivered. IMO Randy is the greater offender in this respect. For instance. As regards powering a drivetrain with an external motor an IPS (independent pedaling system) crankset can be used which is a system that can be purchased vs multiple freewheels for crank and motor which will have to be fabricated. And speaking of fabrication, how many of us are gifted with the ability to take salvage automobile alternators and turn them into e-motors by winding custom stators for them?! Few, yet we are hammered on the failures of the marketplace to provide the kinds of motors we really need. Maybe this is the case but... ... it is what we have.

H What you have on avaliable Crank powered mid drive kits is a freewheel on the motor and the chainring crank drive.The bad part about that is the motor has to be geard down 3 to 1 more to match pedal cadence then geard back 3 to 1 the other way. To have enough torque to do this the high rpm motors need about a power robbing 20 to 1 motor reduction to begin with.The motor freewheels will also get hot from freewheeling at such a high rpm oposed to being on a much slower turning wheel hub without spinning so many gears and weak bicycle chains under both motor and pedal power.Yes what you have may be all you can get but there are options for tinkerers and MANUFACTURES to explore that may some day be available to the general public.
Stock Auto alternators that can be baught for $8. NEW! and do NOT need any rewinding make more efficient motors than you can find anywhere for a ebike.But you need to know how to make motors to use these off the shelf alternator parts.
So is this forum just for OLD technology and Cheaply made expensive chineese kits that can be modified buy adding more batteries ? If so there will be many more disipointed ex ebikers and a lot of ebikes going to the landfills.
Or you could get a high tech axial flux Disc Motor off the shelf with or without gearboxes that are made by the designer Brigs and Straton E-Tek motor.The small geard motor may go for about $100.They are used in efficient battery powered floor scrubers and outboard boat motors..
http://www.marselectricllc.com/

In somewhat less than one hour of reviewing threads in this forum I am already sick of the bickering between Randy and Lowell. IMO both of you are knowledgeable and have much to offer this community but not if you keep sniping at one another. Furthermore because of the insular nature of being visionary a certain amount of singlemindedness creeps into the information delivered. IMO Randy is the greater offender in this respect. For instance. As regards powering a drivetrain with an external motor an IPS (independent pedaling system) crankset can be used which is a system that can be purchased vs multiple freewheels for crank and motor which will have to be fabricated. And speaking of fabrication, how many of us are gifted with the ability to take salvage automobile alternators and turn them into e-motors by winding custom stators for them?! Few, yet we are hammered on the failures of the marketplace to provide the kinds of motors we really need. Maybe this is the case but... ... it is what we have.

H

Agreed, and I tend to respond to often re Randy as well, but unfortunately he tends to play with the truth a bit to much, and I worry that a noob may buy into some of it.
I will try to lay off a bit. :)

The bad part about that is the motor has to be geard down 3 to 1 more to match pedal cadence then geard back 3 to 1 the other way.

To match rear wheell cadence the typical electric motor needs to be geared down 9 or 11 to one. Gearing down in two stages i.e. 3:1 primary 6:1 secondary is done to avoid huge rear chainrings. To match pedal cadence may well require a 20:1 reduction but why would this be power robbing?! It is power robbing NOT to run the motor at its full rated RPM and use a gear reduction to get the proper speed where the power needs to be applied.

The motor freewheels will also get hot from freewheeling at such a high rpm oposed to being on a much slower turning wheel hub.

If the motor is off and the bike being driven under pedal power the motor freewheel will be driven at pedal cadence. This will hardly be enough to get anything hot except the cyclists thigh muscles.

H

To match rear wheell cadence the typical electric motor needs to be geared down 9 or 11 to one. Gearing down in two stages i.e. 3:1 primary 6:1 secondary is done to avoid huge rear chainrings. To match pedal cadence may well require a 20:1 reduction but why would this be power robbing?! It is power robbing NOT to run the motor at its full rated RPM and use a gear reduction to get the proper speed where the power needs to be applied.


If the motor is off and the bike being driven under pedal power the motor freewheel will be driven at pedal cadence. This will hardly be enough to get anything hot except the cyclists thigh muscles.

H At what ever your cadence is your throttle can adjust YOUR pressure it or cadence by a little wist.Running twice the power through a twisting chain derailer through a gearbox s less efficeint than a good chain drive in a streight line to a nice Kevlar sprocket is no comparison in performance and ease of use with less parts..

Unless you are driving hub gears which are less efficient than a well maintained derailleur system, especially the older 3 speed ones, in any gear except the middle one they are very draggy.
Also with the derailleur drive the motor is kept in its efficient rpm range which again gives the advantage to the derailleur drive.
No matter the motor used they have a range of rpm's where their efficiency is very high, anywhere out side of this range the efficiency drops off and often quite dramatically.

Unless you are driving hub gears which are less efficient than a well maintained derailleur system, especially the older 3 speed ones, in any gear except the middle one they are very draggy.
Also with the derailleur drive the motor is kept in its efficient rpm range which again gives the advantage to the derailleur drive.
No matter the motor used they have a range of rpm's where their efficiency is very high, anywhere out side of this range the efficiency drops off and often quite dramatically. So you loose 10% efficiency in multipul gear and chain reductions to drive a twisted bicycle chain through slipping derailer coggs with twice the power they are made for to get efficiency from a gutless motor ?
Its much more efficient to raise the torque of the motor to run efficiently through as little reduction as possiable.A direct drive hub motor is just too big and will loose efficiency every time it starts up.

A few quick corrections, Derailleurs when "in gear' do not slip at all.
A bit of quick research will show that your 3 speed is worse than a Derailleur, Sachs (your geared hub brand?) have even releaed the data in the past confirming this.
You should change gutless to legal in most of the world.
Your drive uses an extra chain so there is no extra loss there and the gear reduction is usually a single stage affair.
But don't let the facts ruin your day

Next to maintenance issues, the main beef I have regarding motors that power through the crank is that electric motor's powerbands are ass backwards with peak power at a lower rpm then max eff.

I've calculated that I could either have good motor assist when I'm dialing it up to 400w if I'm willing for the motor to be gutless (or very wasteful) at the cadence ranges I'd be using the majority of the time, or have good power assist for normal applications but have the motor pretty much revved out leaving me pretty much on my own when I drop the hammer. Can't have my cake and eat it too.

A few quick corrections, Derailleurs when "in gear' do not slip at all.
A bit of quick research will show that your 3 speed is worse than a Derailleur, Sachs (your geared hub brand?) have even releaed the data in the past confirming this.
You should change gutless to legal in most of the world.
Your drive uses an extra chain so there is no extra loss there and the gear reduction is usually a single stage affair.
But don't let the facts ruin your dayThat facts are that you have not tested any of the 3 versions of the hubs I use.