Electric Bikes - Crank Motor vs Hub Motor

Hi All,

Help! I am a newbie and I am looking at several ebikes.

One is the R11 model sold by R. Martin in Austin, TX. I emailed Mr martin and he replied that the R11 has a 200 W brushless crank motor instead of a hub motor. He claims the crank motor is better than the hub motor because it allows the bike to get more climbing power with lower battery usage His website also states the crank motor allows the gears to be used with the motor. The bikes look good and I am wondering if anyone with experience/knowledge of this can say if the crank motor on an ebike is really an advantage over the hub motor.

Thanks.

Curt

Just about any motor coupled to the bike's gears will perform better than a hub motor of equal, or perhaps greater, power output. The mechanical advantage offered by gears should not be underestimated.

That said, chain drive systems tend to be more noisy, usually a whining sound. They are generally not very stealthy if you live in a bike-police state.

If I mostly rode where it's flat to moderate hills, I'd go with a hub motor. If there were lots of hills to climb, I'd consider a chain drive. Or do what I'm doing, use both, chain drive on the back, hub on the front :)

I installed the Currie conversion kit on my mountain bike this summer. The Currie kit has a non-hub, chain-drive motor on the rear wheel. One of the big pros of this system for me was the great torque. I'm currently living west of Glacier National Park in an extremely large national forest; there are very few flat areas to ride here. I wasn't riding my bike much at all before I added the kit because most hills here are steep and my knees were killing me. The Currie motor is a trooper and I've been having a ball riding the unimproved, gravel forest roads, many of which have quite steep grades.

There are users who love hub motors who claim great torque, but then they're generally using the high-end, expensive and powerful hub motors that will run you close to $1000. I think many of the hub motors that come standard with most generic Chinese-manufactured bicycles may not have enough torque to perform well in mountainous areas since they tend to be lower-powered motors to comply with e-bike restrictions imposed by the EU.

As for noise on a chain-driven, non-hub motor, I think it's over-exaggerated. I only use my motor for power assist and rarely have the throttle depressed fully. The wildlife out in the forest may look up as I pass, but I don't make enough noise that they bolt. In fact, I still have problems with the wild turkey who tend to cross the roads in number.

Thanks for the reply. Very good information for me to consider. I do not have a lot of steep hills in my area, so i may go with the hub motor.

Curt

Thanks, MTBK. I appreciate the information you provided. I do not have lot of hills to climb in my area and may go with the hub.

Curt

As for noise on a chain-driven, non-hub motor, I think it's over-exaggerated. I only use my motor for power assist and rarely have the throttle depressed fully. The wildlife out in the forest may look up as I pass, but I don't make enough noise that they bolt. In fact, I still have problems with the wild turkey who tend to cross the roads in number.

To each, his or her own of course; the difference between noise and silence in this case is deafening, metaphorically.

LOL, well given the deer and elk in the forest don't bolt when I've gone past them using power assist, I don't think the "noise" of my motor is deafening. They're definitely impartial judges. I have much more noise to deal with once I've reached the peak of a hill and am going down it (clearly with no power assist). Speed-generated wind is definitely noisy.

For hills and hubs you are looking at a 1000w kit at 48v. It has to be gearless and brushless. Anything less for most hills is going to be hard on your AH.

You can't beat a crank motor for going up steep hills. The problem with hub motors is that they develop peak efficiency at around 90% of their maximum speed. When you get to 50% of their maximum speed, the effieciency falls off a cliff so the motor is burning a lot of electricity, but not producing much power at the wheels.



What happens is that if your hub motor is designed for peak effiency at 18 mph so your 500 watt motor produces about 450 watts of real power to the wheel. When you go up a hill at 10 mph the 500 watt motor is only 50% efficient, so you only have 250 watts to get up the hill even though the motor is burning 500 watts of electricity. The steeper the hill gets, the less power you have to get up the hill. It is a vicious circle, you need more power for a steeper hill, but you get less power.



With a crank motor, the motor speed is directly related to your pedaling speed. If your crank motor hits peak efficiency with your pedals spinning at 70 rpm, then you can go up any hill spinning your pedals at 70 rpm by using your gears. The motor will be working at peak efficiency the whole time. This improves your hill climbing and range.



The important thing to remember is that an electric motor's efficiency depends on its speed. Generally speaking, the electric motors used for bicyles are fairly efficient from 70%-95% of their maximum speed. If their speed drops below 75%, then you start burning lots of electricity and losing power at the same time. This kills your hill climbing and range. If the hills in your area are steep enough that the electic motor cannot carry you up it at about 13 mph (assuming peak efficiency at 18mph), then switching to crank based motors would be beneficial.

Right on., crock. Therein lies my one complaint about crank systems which is noise. It's just not easy to keep a high speed motor quiet, plus the chain is always in use under power. Chains make noise as they serpentine sprockets, derailleurs and Teflon chain tunes (recumbents). The eerie silence of a hub motor has it's rightful place, IMO.

Good debate. Lots of good info here. :D

I have put around 10 miles on 4 different hub motors and around 100 miles on a cyclone 500 24 volt recumbent. On one of the hub motors I climbed a little hill. On the cyclone I have gone up hills of all kinds. Even though the hub motors were all 36 volt I know the cyclone 24 volt has much more climbing power. Since my hearing is not that good the noise of the cyclone does not bother me. Also with the cyclone on long rides I turn off the electricity on flats and extend the range many times. Even though my experience is limited with the hub motors I believe the cyclone will be my choice when I build my own ebike.

Where can I find a crank motor?

I'm sold on the advantages. Chief among them being, I can shift gears for the motor as well as for my legs. This can keep the motor turning at fairly high speed when going up some of the hills around here, thus keeping it in its most efficient range. Even when neither the motor nor I have the oomph to go 20 or 30 mph up that long, pretty steep hill.

If I lived in a completely flat area, I'd probably go with a hub motor. Since I'm in a hilly area, though, I'd MUCH rather have one of these "crank motors".

Anyone know where I can find one?

Where can I find a crank motor?

I'm sold on the advantages. Chief among them being, I can shift gears for the motor as well as for my legs. This can keep the motor turning at fairly high speed when going up some of the hills around here, thus keeping it in its most efficient range. Even when neither the motor nor I have the oomph to go 20 or 30 mph up that long, pretty steep hill.

If I lived in a completely flat area, I'd probably go with a hub motor. Since I'm in a hilly area, though, I'd MUCH rather have one of these "crank motors".

Anyone know where I can find one?

If you want a ready-made kit to install on a bicycle you already own, you might look at the one produced by cyclone. Here's a link.

http://www.cyclone-usa.com/store.php?crn=199

nwmtnbkr, great reference! Thank you!

Little-Acorn

Here are some other "crank drives"

I think elation is best, don't have one yet. It has a better mount, freewheel and allows 3 chainrings and a front derailer. It uses the Headline motor like cyclone

http://www.elationebikes.com.au/

epac similar to elation but same motor as eZip.

http://www.epacpower.com.au/Epac_Home.html

cyclone taiwan offers a lot more choice than taiwan-us

http://www.cyclone-tw.com/index.html

The thing about hub motors is there is nothing to fix ever pretty much. No noise, no moving parts and above all things no police bothering you when you ride. I have a friend with a cyclone kit. We hit the open space trails all of the time. He gets bothered by park rangers and police constantly. Most of the time because they hear him coming. I ride all over NYC and most of NJ on and off the road and have never even seen a police officer look at my bike because I have a hub motor and carry my battery in a nice backpack. I have never had to fix my setup. My friends kit requires constant upkeep of his chian and shifter. He goes through rear bearings alot as well. I have over 2k miles on my hub and the only thing I have done is true the wheel 2 times. Think about it before you buy.

One thing I hadn't thought about before: With a crank motor, if you use power, your pedals are ALWAYS turning. You cannot coast and let the motor push the bike for you.

I suppose you could put some foot pegs on the bike somewhere, high on the down tube I guess to keep your legs and feet out of the way of the pedals, but riding that would be a little awkward.

With a hub motor, you can coast with your feet resting on the pedals, and the pedals not turning, and let the motor push the bike for you, on level ground at least.

For those of you who regard e-bikes as pedal-assist power, you won't mind the pedals turning whenever you're using electric power.

But for me, lazy cuss that I am, I've changed my mind. I'm going for a hub motor. I'll pedal to start the bike off, and for going up hills, but for the rest of the time I'm happy to let the motor do the routine work, while I sit there (with feet still) and watch the scenery go by.

Quoting Crock...

You can't beat a crank motor for going up steep hills. The problem with hub motors is that they develop peak efficiency at around 90% of their maximum speed. When you get to 50% of their maximum speed, the effieciency falls off a cliff so the motor is burning a lot of electricity, but not producing much power at the wheels.


Crock, this is generally true as you stated...

I have a brushed geared motor which I have found to be quite efficient at all speeds, with oodles of torque compared to my Crystalyte 406 brushless direct drive. The brushed motor has the disadvantage of having to change the brushes every couple of years, but is effectively "start immediate" without the hassle of hall sensors which I have found to be problematic in wet environments like here on the BC West coast. Using a sensorless controller on those brushless motors to get around the Hall issues, they tend to run rougher with more cogging torque. So at the moment, I prefer the brushed motor to the brushless - not sure why brushed has almost died out - apparently the brushed geared types are about as efficient in general as direct drive non-geared (around 90%) but these efficiencies are obtained at low speeds as well as high speeds. And you get the torque bonus off the line, with good freewheeling. It seems that changing the brushes is the only disadvantage. You also get a considerable saving in weight. Unfortunately, I haven't been able to identify my motor - I aquired 3 of them from a failed business. The controllers are really cheap too, around 24 US plus shipping from ecrazyman on ebay, very easy to set up.
I've got mine on a Giant Revive comfort bike, and totally love the motor overvolted to 48 from the original 24. The gears are holding up well so far after about 300 miles. I generally pedal as well, considerably. I'm pushing close to 900 watts through that little 8 pound motor, top speed around 25 mph at 48 volt Ping 15Ahr battery. It really hauls me up the hills too. So these might be worth checking out if you can find other brushed geared types..


Here is my bike and its motor...

http://endless-sphere.com/forums/viewtopic.php?f=6&t=13255

Just to throw in my 2c...I'm hub motors all the way.

I may be biased by my TidalForce that I bought in 2004. It's gone 7,000 miles without touching it, and in utter, complete silence. It climbs very steep grades even with the heavy grocery and laundry ladened trailer attached.

Just got a new Chrystalite 4840 Racer a while back that I've been pushing me and a heavy custom built trike (550 lbs together) around with. No lack of power but that's close to 2,000 watts. It does make that buzzing "errerrerr" sound though.

"One thing I hadn't thought about before: With a crank motor, if you use power, your pedals are ALWAYS turning. You cannot coast and let the motor push the bike for you."

Not so; my Ecospeed freewheels. I can pedal, use power or both, independently. Can't speak to other crank systems.

Like the one guy said - chains and sprockets are a hassle. When you start delivering considerable power through 'em they wear much faster. Lube, adjustments - messy and noisy!

A lot of the downside about hub motors is because manufacturers have offered too small of motor. If you get into hub motors that can handle 2k watts or more - Crystalyte 5000 series for example - the comparisons change dramatically. Sure, compare cheap Chinese hub motors to geared setups and there's no comparison but those are designed by salesmen - not engineers. Get a hefty BLDC hub motor going and you'll have much less maintenance (other than spokes, lol...) than even the best chain system and a very stealth and simple installation that, in many cases, can be transfered to other bikes rather easily.

They each have their advantages and disadvantages - I have run both for years and I've learned that if I have a big enough hub motor and no extreme grades the hub motor is much less trouble while delivering practical performance for commuting.

while I sit there (with feet still) and watch the scenery go by. :thumb:

BroadwayJoe is right I believe. Where I ride though, I'll stick with my cranker. I tried walking up that hill, once...:)

hub motor all the way. the multi gear setting is overrated. In theory, it makes for a good debate, but in practice, it's a waste of time. Chain drives make a little of noise, but not a lot. hubs are nearly silent. the only time that chains would have an advantage would be with very steep hills, above 15% grade. I have a cheapo wilderness system, and get up hills fairly easily with a little assist.

I come from using multiple chained gas systems, and while all were faster than my current electric, none were as simplistic. I leave my bike in the rain ffs, and it's not an issue. I do keep the controller very well shielded from the elements.

the only time that chains would have an advantage would be with very steep hills, above 15% grade.

If you want speed then chain drives make things even more fun going down a 15% grade, hang on!

Bottom line is chain drives can do it all better, but there's a cost in added complexity, maintenance, noise etc. If chains and gears sucked regular bikes wouldn't have them. You can do more with less with a chain drive, it just costs more, which is a conundrum.

My Kalkhoff Pro Connect uses the Panasonic crank system. There is very little noise and I can't hear it at all if there is any background noise.

http://picasaweb.google.com/BarryHeaven/ProConnectBike1#5399195937345952866

My Kalkhoff Pro Connect uses the Panasonic crank system. There is very little noise and I can't hear it at all if there is any background noise.

http://picasaweb.google.com/BarryHeaven/ProConnectBike1#5399195937345952866


Nice looking bike, may be the Prius of eBikes. If one is willing to accept a 250W motor, a top speed of 15 mph and a price tag of $3000 USD, it may be a good way to go.

Weight is another issue. For the same power, the hub motor weighs a lot more. Would you drive a car that didn't have a transmission? Luckily, bikes are much lighter. If you are just going to let the motor do the work, I am surprised you don't get a moped or motorcycle. I always pedal my ebike, it extends range (a lot) and gives me some exercise for that piece of pie later. If you need the silence so you can break the law, get a hub motor, they are quiet. Ecospeed is my suggestion for an inline motor. A single car going by is louder than the motor, just the noise of the tires on the roadway.

Hub motor systems don't need to be really heavy. A Bionx PL350 is about 18 pounds, but pricey. I wouldn't buy one if I lived in the mountains or if I was an especially heavy rider, but a PL350 handles the worst hills in my suburban Maryland location just fine. For me, just fine is (1) when pedalling normally I can fly up those hills at nearly the same speed I'd handle things on the flats, and (2) if I don't feel like pedalling, the motor still pulls me and my relatively heavy recumbent up the grade at a slower, comfortable speed.

One caveat: I have a continuous uphill grade for about 6 miles or so in the middle of my PM commute -- nothing steep, just long. If I use a lot of assist to keep my speed close to 20 mph the system can get hot and drop out for several seconds at a time to let itself cool down. I haven't figured out yet if it's the motor/controller combo or the battery. If it is the battery, it could be my fault because I have it enclosed in a stealthy cordura cover.

Charlie
http://ElectricCyclist.com

Hub motor systems don't need to be really heavy. A Bionx PL350 is about 18 pounds, but pricey. I wouldn't buy one if I lived in the mountains or if I was an especially heavy rider, but a PL350 handles the worst hills in my suburban Maryland location just fine. For me, just fine is (1) when pedalling normally I can fly up those hills at nearly the same speed I'd handle things on the flats, and (2) if I don't feel like pedalling, the motor still pulls me and my relatively heavy recumbent up the grade at a slower, comfortable speed.

One caveat: I have a continuous uphill grade for about 6 miles or so in the middle of my PM commute -- nothing steep, just long. If I use a lot of assist to keep my speed close to 20 mph the system can get hot and drop out for several seconds at a time to let itself cool down. I haven't figured out yet if it's the motor/controller combo or the battery. If it is the battery, it could be my fault because I have it enclosed in a stealthy cordura cover.

Charlie
http://ElectricCyclist.com

If I didn't go Ecospeed, I'd go BionX. I found it to be a well thought out and executed system, best of breed.

I bought the Ezee kit from ebikes.ca (aka Justin).. I have 400 miles on it now and it is exactly what I hoped it would be. It is not super fast,I get about 19 mph when I crank and pedal, but I now do hills at 16-17 mph that used to slow me down to 8-10 mph. It has really increased my bike usage ,and I have put on about 1100 miles each year for the last 3 years.
The geared hubmotor has one advantage that sold me.. no resistance when I pedal with the motor off. I can regulate my usage that way. For instance ...
In the morning on the way to work its Hammer down, I dont care about how many amp hours I use cause I want to get to work as fast as possible..
In the evening I might not use the motor on flats and downhill because I want to take a much longer ride.
Also Dont rule out Nicad batteries. Thats what I bought. The Li-Ions are great and one day when I build a pleasure bike (super fast of course) I will buy them, But for my everyday get to work and around town I choose Nicad ..Why?
I can work on them. No BMS electronics genius required. If a cell goes bad ,out it goes and solder in another one. From what Ive read on Li-ion one under performing cell can lead to a horror story. I dont have the money,time,or inclination to go there.
One more thing about the Ezee, is it is supposedly pretty waterproof if you need to ride in those kind of conditions. I usually try not to but I live in Central Texas and have a choice...
Also , one thing you need to think about is how much do you want to pedal. I have been pedaling around for 3 years without a motor and I knew I wanted some assistance ,or else I would buy a gasoline motor setup from Staton.If you like to pedal you can regulate the amp hours and get around faster too. It has really improve my life..
I am not affiliated with ebikes .ca except as a satisfied customer.. READ

Nothing wrong with any battery that works! NiCad has it's place and if you treat 'em right they'll love you long time. Just dispose of properly and feel confident that reliable lithium packs are right around the corner if not here.

I think it's best to stay away from cylindrical based lipo packs but some of the latest Prizmatic (sp?) cell packages are looking pretty darn nice. I need to step-up and try one of those soon! But, in the meantime - I mostly use mixture of lead and NiMh and that's fine. Just heavy but I live on 1st floor...

[QUOTE=BroadwayJoe;10079143]Nothing wrong with any battery that works! NiCad has it's place and if you treat 'em right they'll love you long time. Just dispose of properly and feel confident that reliable lithium packs are right around the corner if not here.

Ebikes runs a dispossal program for the nicads , when that time come ( may it be a long time coming)

have you seen this Broadway?
http://www.coloradoadvancedbattery.com/

have you seen this Broadway?
http://www.coloradoadvancedbattery.com/

Yes I have and I'm highly interested. Wouldn't it be nice to have a fat R&D fund - all the stuff that could be tested and tortured?

Oh yeah, check this stackable battery rack solution:

http://www.infineumbike.co.uk/Infineum-Products.asp

The bike is UK limited and the batteries might not be for high power stuff but the physical design is impressive. I often find it would be nice to use just the amount of battery I need for my errands rather than having 20 miles range, size & weight for a 5 mile trip.

I have developed a strategy for my unique situation. I live out in the burbs. I like living out here but it poses challenges to bicycle commuting. It is 7 miles to anywhere,really...I work 7.564 miles from here and have keys to the building and access codes to the alarm system, so when I go for a really long ride, I might bust balls on the way to work, and set up the battery there, and the judicously ride to my next destination ,and may get an hours charge there, and ride back and pick up the battery with some more charg,... you get the picture..

There are no two exact situations but big part of the fun is learning and adapting to the job. 'Sounds like you're living this lifestyle of highly efficient personal transportation.

It's defiinitely not the same as oil power - the other day, about 1 mile out I realized I'd forgot something I wanted to have for work. No way I was gonna turn back and run the risk of flat-lining my fresh lead weights so I managed without. If I had swappable packs, it wouldn't be a big deal but when you only have so much to start with you learn to resepct your limitations and manage with a little less.

I do get the picture - 'have those days where the chargers remain in bulk charge mode all day!