Nine Continent Vs. Bafang

[Russell]

I assembled my first ebike this past winter and took my first ride early in February. The bike I converted was a 1992 Raleigh Hybrid I’ve had for a few years and the conversion kit I used was purchased on eBay.The kit was advertised as 250W and included a nice polished Bafang front geared hub motor, a little 36V/15A peak controller (7A continuous, thus the 250W rating), a 36V/9Ah SLA battery pack in a tote bag, charger, rear trunk bag and twist throttle. After 18 rides on the SLA’s I switched to a battery pack made up of three 36V Bosch Fatpack tool batteries in parallel. In total I have ridden the bike 34 times and logged 909 miles.

See more details here: http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=8579


I recently purchased a 9C front motor in a 700C wheel from E-BikeKit for a good price because it was used at a show and because they are closing out the silver models in favor of black. The motor and wheel arrived quickly however it was dirty and there was a chip out of the rim. Cleaning it was no biggie however I have to see whether the gouge affects braking performance.

The new motor is intended for my Kona Smoke however I need some parts yet for that bike (rear bag, torque arms) so in the mean time I decided to run a comparison test with the motor installed on the Raleigh in place of the Bafang. The Bafang, lightweight and freewheeling, is nearly the perfect solution for someone who wants to retain much of the ride qualities of their bike but would like a little assistance but I’ve wanted to know how it compares to a larger direct drive motor such as the Nine Continent motor. Of course the 9C is more powerful and surely faster but I wish to see how the qualities of a direct drive motor compare to the geared motor. I will be checking speed but I’m also interested in how the bike pedals without power, how it sounds and feels and I very much want to see how the overall efficiencies of the two systems compare.


Weight: Advantage Bafang


With the same size and make tire (Kenda Kwest 700x35) and tube (Nashbar self-sealing) installed the Bafang comes in 5 lbs 10 oz lighter.





Appearance/stealth factor: Advantage Bafang


I think the smaller Bafang looks better but there’s no doubt about which one would get noticed, the 9C is a big motor.





No-Load speed: Advantage Nine Continent

Was there any doubt the 9C would be faster? With the same battery charged to 41.2V the no-load speeds are as follows;

Bafang: 21.3 mph (0.80A)
9C: 29.1 mph (1.05A)


I got the 9C installed last night so I haven’t ridden it yet. It’s a beautiful day and that’s coming up…

-R

 

[snowranger]

I'm still waiting for my 26" 9c from that same batch. 29 mph at 36 volts is pretty fast.

How are the torque arms on those?

 

[Christobel931]

Russel,

I'm very interested in your comparison as well... I really like the lighter weight and freewheeling aspects of the geared motor. 8)

 

[johnrobholmes]

The torque arms are longer on the 9c I have from EbikeKit. The bafang just has little washers with tabs on them, while the 9c has about a two inch long arm that needs bolting to something.

 

[johnrobholmes]

Just took apart the 9c as best I could. Could not pull the stator away from the magnets.

Bafang stator measures 93x25mm

9c stator measures 198x30mm, best measurement I could get.

We can say that the 9c has 5.4 times the torque based on stator sizes. Since the Bafang is geared it runs at a much higher rpm to get some torque back at an expense to amp draw. If the 9c was geared down and rewound to compensate it would keep the torque advantage (at expense to amp draw).

Both are made with really thick mild steel lamination, the most inefficient stator material available. Both probably use N36 magnets as they are readily available and cheap. I can't effectively measure the stator gap on them as without the side cover on the stator flops to one side.



MUCH more room in the 9c for rewiring and installing Delta/Wye switches. It is wired Wye from the factory.

 

[Russell]

I'm still waiting for my 26" 9c from that same batch. 29 mph at 36 volts is pretty fast.

How are the torque arms on those?

On the Raleigh the little torque arms provided with the 9C kit nearly line up with the top eyelets on the fork. With a little filing to enlarge the hole they work ok however when I install the motor on my other bike I will probably use torque arms from Ampedbikes.com. BTW, I thought the front version of this motor had a 12mm axle but mine has a 14mm just like the rear motors.




Torque washers are better for rear installations since if they move slightly under acceleration they hit the reinforced side of the dropout however on front if the nuts are loose the tabs on the washers will place pressure on the weak front side of the dropout. They are however nice solid washers and since they fully enclose the axle they are better than nothing if the nuts are kept tight.

-R

 

[Russell]

First ride, first impressions.

Well actually I did two consecutive rides; the first using the 36V/6Ah Bosch Fatpacks, and after draining them and not feeling especially tired I tossed the 36V/9Ah SLA pack on the bike and set out again.

We enjoyed nice weather today in Wisconsin but brisk winds hampered getting good solid speed data so I can only ballpark it for now. Starting out with the lithium pack at 41.2V it appears the top speed of the bike is in the 23-24 mph (37.5kmh) range (w/700x35 tires). On the second ride the SLA pack started out at 39.2V and suffered about twice as much sag as the Fatpacks. I’d estimate the top speed with the SLA’s at just over 22 mph (35.2 km/h).

Noise: Advantage Bafang
Smoothness: Advantage Nine Continent

Now I know folks will tell you that geared motors are noisy but in fact they, or at least the Bafang I have is not. Yes the Bafang makes a whirring sound but I kinda like it and at road speeds it pretty much disappears except during acceleration. The 9C motor is not silent, in fact I find the higher pitch whine emanated from it to be annoying. The Bafang does vibrate under load which is felt and heard while the 9C remains smooth though noise does increase some under high loads.

Acceleration: Low speed; Advantage Bafang, Higher speeds; Advantage Nine Continent

For this test I wanted to compare apples to apples so the ONLY thing changed in the switch from the Bafang to the 9C is the motor/wheel combo; the battery, controller and throttle are all holdovers. I suspect the 15A controller holds back the 9C motor more than the Bafang off the line but for the efficiency rides yet to come I want to use the same controller for both. And it’s slow speed acceleration where the Bafang seems to outshine the much larger 9C. For example on the return leg of the first trip I followed a bike path which crosses many roads necessitating that riders slow down and negotiate the little ramps between sidewalk and roads and in these instances the Bafang seems more “torquey”. In contrast, pull the throttle on the 9C at a crawl and it feels anemic. Once under way however the 9C does pull strongly. For scooting across intersections I do like the Bafang, for satisfying acceleration on the road I do like the more powerful 9C.

Hill Climbing: Advantage Nine Continent

There are plenty of hills around these parts but most are in the 4-6% range. Neither motor is much to write home about in this department; again the 15A controller is one reason, though the 9C holds a small advantage. Each motor prefers that the speed be kept above 12-14 mph when climbing and I needed to pedal less vigorously with the 9C to maintain this speed.

Efficiency: Too soon to tell

Today’s rides were to check the overall performance of the Nine Continent motor install so I didn’t use the throttle as conservatively as I (mostly) do with the Bafang. Still the average speed for the first ride at 16.8 mph (26.9km/h) over 23.1 miles (37.0km) was close to what I normally averaged with the Bafang and overall power consumption at 9.1 Wh/mi (5.7Wh/km) was about a third higher than what I use with the small motor. Some of this was because I simply didn’t pedal as hard as I do with the Bafang and some was because I couldn’t resist doing a few high speed sprints. On the second shorter 12.6 mile (20.1km) ride I used more throttle which was reflected in the average speed of 18.5 mph (29.6km/h) and the elevated energy figure of 12.9 Wh/mi (8.1Wh/km), by far the most I’ve ever used. I’ll need several normal rides to find my average power use for the 9C. Heading into the wind for a couple of miles at 10-15A I did manage to warm up the little contoller.


I can’t comment on the cogging torque vs. freewheeling debate as yet. During today’s rides I used the throttle almost all of the time so it wasn’t an issue, also with the wind as it was pedaling was either difficult or easy depend on which way I was headed. When I do some longer lower speed rides to see how the efficiency of the 9C compares to rides over the same route done with the Bafang it will become more apparent as rider pedaling becomes more important.

-R

 

[kefa]

nice write up russell.

will be interested to hear updates on how you go with the 9c.

voicecoils also did some comparisons with the bafang and 9c in case you missed it.

 

[Russell]

I must say I’m warming up to the Nine Continent motor on this second day of riding, and what a gorgeous day it was; sunny with some big puffy white clouds, warm and moderate winds out of the southwest. Normally on such a day I would head south into the wind so I could return with the wind at my back but north is my favorite route, one that takes me out to the countryside where there are few cars and smoother pavement. It’s also a route which at a tad over 32 miles (51km) requires a conservative throttle in order to make the limited capacity of the 36V/~6Ah LiMn battery pack last the entire ride.

When I started out on today’s ride the wind was actually blowing almost directly from the west with just a small southerly component giving me slightly favorable wind conditions as I headed north. I note this because with a slight tailwind the bike was pretty easy to ride at normal cycling speeds. I think I use my lower gears a bit more with this direct drive motor compared to the previous geared motor but the difference is small. Some of the difference is no doubt due to the somewhat higher weight and even though it’s less than six pounds it is noticeable.

After heading east for a while toward Lake Michigan I encountered one of the common lake effect wind shifts. In this instance the wind direction changed probably 120 degrees to the ESE direction and right in my face and ruined my plans for a coasting test down a 4% grade along this route. My record with the Bafang is 35.1 mph with a significant tailwind though low 30’s are fairly common. Today with the headwind the bike only hit 26.5 mph down this hill. I wanted to see if the 9C would be slower but I’ll have to try another day. Yesterday I did pedal the bike up to 31.1 mph (49.8km/h) down a slight grade with a strong tailwind helping me which isn’t too shabby and is another indication that the 9C motor doesn’t present significantly higher resistance without power compared to the Bafang.

Heading north along a bike trail and with a tailwind I was cruising along nicely at over 20 mph (32km/h) on leg power only. At my turning point 15.5 miles into the ride I had only used 1.8Ah, which is quite low. I have used up to 3.2Ah at this point but again I normally ride this route when the wind is a blowin’ from the north so I can ride with the wind on the way back. Today was just the opposite because as I headed back south it was into a brisk wind which required every little bit of the remaining power to overcome.

These are the stats for the ride;

Distance: 32.09 miles (51.3km)
Average speed: 17.0 mph (27.2kph)

Amp-Hours used: 5.960
Watt-Hours used: 219.3
Peak Watts: 571
Min Volts: 31.50

WH/mile: 6.83
WH/km: 4.27

Of course the whole purpose of this ride was to see how the efficiency of the direct drive Nine Continent motor compares to the geared Bafang hub motor so some comparison data is needed. Last month I rode this exact same route four times and got very consistent results from ride to ride. The temperature range for these rides was 41-50F. Here are the average numbers for those rides;

Distance: 32.13 miles (51.4km)
Average speed: 16.45 mph (26.3kph)

Amp-Hours used: 5.738
Watt-Hours used: 213.75

WH/mile: 6.65
WH/km: 4.16


Today’s ride used slightly more energy but was also faster. Today’s weather was much better than in April, I was wearing just shorts and t-shirt today and I no doubt am marginally stronger at this point in the season. Still what I learned today, and it’s only one ride mind you, is the direct drive Nine Continent motor can be ridden just as efficiently as the geared hub motor.

What I haven’t said up until now is how difficult it was from a control standpoint to keep the big motor reigned in during today’s ride. Like a thoroughbred racehorse being held to a trot the 9C motor was begging to run. It took an extremely light touch on the throttle to keep the current down and the speed at my normal level. I employ a modified trigger throttle on this bike and frankly I doubt I could have kept as fine of control over the motor without it. With my left hand firmly holding the grip and one finger on either side of the lever I was able to modulate the current but it took more effort and concentration than I’d want to do all of the time. The Bafang on the other hand was quite easy to control since the speed range of that motor is right in sync with my abilities. Riding with the Bafang motor I could control the throttle with my left hand with little conscious thought. Basically what I’m saying is that for normal bike speeds the 9C is too much motor.

With that said, if I can come up with a finer low speed control I believe I could like this motor. I’m thinking perhaps wiring up the E-BikeKit controller in place of the 15A controller I’m presently using and trying it with the speed suppression wires (black and white) connected. Another option would be to rewire the potentiometer throttle I’m using to limit it to a lower range.


-R

 

[Christobel931]

Thanks for that great comparison... The little details really help when you can't ride these things yourself.

Its interesting to me that the power consumed is almost the same... even though its the same controller, seems odd given the size difference. I can totally relate to trying to ride conservatively... I only have a couple hundred miles on my kit, but that DD motor just seems to feel super smooth and efficient above 20mph.

You mentioned a 4% grade, is that pretty much the most hill you face normally on your ride? I ask because in my little neck of the woods, I rarely find flat ground, it is almost continuously rolling terrain, so I find I use all the power I can get quite often. But even on the occasional flat straight, I have a hard time staying off the throttle as there is a definite weight and/or motor drag penalty that is not worth trying to pedal through.

Sounds like a nice day for a little research

 

[johnrobholmes]

Think of the power consumption this way- it only takes XX amount of watts to keep up 22mph. Efficiency will make the difference in your watt/hour per mile usage. Now if he didn't hold back on the acceleration it would be a totally different story, as that is where the big amps are burned away. I wouldn't be able to hold the horse back so well With my throttle use, voltage (and controller) I drain about 20 watt/hours per mile on the bafang.

 

[Russell]

You mentioned a 4% grade, is that pretty much the most hill you face normally on your ride? I ask because in my little neck of the woods, I rarely find flat ground, it is almost continuously rolling terrain, so I find I use all the power I can get quite often. But even on the occasional flat straight, I have a hard time staying off the throttle as there is a definite weight and/or motor drag penalty that is not worth trying to pedal through.

Yeah mostly the noteworthy hills that are of any significant length in my vicinity are in the 4-6% range. On the route I followed yesterday the 4% downhill is the steepest down grade I encounter which is then immediately followed by a shorter and steeper 6% uphill. The 9C is marginally stronger going up hill but loads smoother. It feels like the 9C would stall before the Bafang but I don’t have any testing to back that up.

-R

 

[Russell]

34 minute thrill ride at full throttle, yeah baby

What is it they say about Wisconsin weather…if you don’t like it just wait a day! Well today was the antitheses of yesterday; cold, around 50F, and rainy. With the drizzle over but the roads still wet I figured it was as good a time as any for some speed testing of the Nine Continent motor (that’s what the fenders are for, ey).

So it was off to the nearest flat road to find the top speed. The problem is there are no perfectly flat roads around here and precious few windless days but unless I wanted to cart the bike off to some other destination in the dead calm of night this would have to due. I did a two-way run but with the wind and slight up/down grade there was no way to get a definitive result although 23.5 mph (37.6km/h) looks like a good approximation. For the same reasons I simply say the Bafang is capable of moving me and the bike (~255 lbs total) in the low 17 mph range (~27.5km/h) on the flats with the Bosch battery pack charged to just over 41V.

After the full throttle/no pedaling runs up and down the street I was off to see just how quickly I could cover some ground. I used full throttle almost exclusively and pedaled as fast as I could trying to help maintain speed. The ride is anything but flat but there aren’t any killer hills just a lot of 1-2% up and down with some 3 and 4% hills mixed in. The only time I let up was to take corners and on one hill against the wind when I thought the little 15A controller might fry. The small ~6Ah LiMn battery pack was being drained quickly and seeing that my average speed was actually starting to fall I ended the ride sooner than I normally would. Here are the stats;

Distance: 11.79 miles (18.86km)
Average speed: 20.8 mph (27.2kph)
Top speed: 28.5 mph (45.6 kph)

Amp-Hours used: 4.749
Watt-Hours used: 173.0
Peak Watts: 568
Min Volts: 32.91

Wh/mile: 14.67
Wh/km: 9.17

That Wh/mi figure now stands as my personal “best” though I’m sure with the 22A controller provided with the motor the speed and the power consumption figures would have been higher since the little controller was maxed out quite often up any sort of grade. I don’t know how much power my pedaling contributed but from watching the Watts-Up meter it didn’t look like it could have been all that much. By comparison the fastest I ever rode with the Bafang was an average speed of 18.0 mph (28.8km/h) over 25.23 miles (40.37km) using almost exactly the same amount of power (4.81Ah) but at a much greater efficiency of 7.2 Wh/mi (4.5Wh/km). I know I was working hard on that ride and so was the Bafang. The question to ask then is, is 3 mph (5km/h) worth going HALF the distance? I guess if you’re in a hurry but I don’t plan on riding full tilt like this again until I get a bigger battery.

-R

 

[Christobel931]

Think of the power consumption this way- it only takes XX amount of watts to keep up 22mph. Efficiency will make the difference in your watt/hour per mile usage. Now if he didn't hold back on the acceleration it would be a totally different story, as that is where the big amps are burned away. I wouldn't be able to hold the horse back so well With my throttle use, voltage (and controller) I drain about 20 watt/hours per mile on the bafang.

Is your motor the one advertised as 500W? I think I read that Russel's is advertised as the smaller 24v 250 watt, just wondering how they compare at 36volts. I like your idea of higher voltage and lower gearing to get power without drawing a huge amount of Amp Hours.

Going for a ride today and will get my watt hours per mile... My meter is in my trunk bag, but, the light bulb finally clicked on yesterday that I can get my avg. WH/MI with good old fashion MATH...

After the full throttle/no pedaling runs up and down the street I was off to see just how quickly I could cover some ground. I used full throttle almost exclusively and pedaled as fast as I could trying to help maintain speed. The ride is anything but flat but there aren’t any killer hills just a lot of 1-2% up and down with some 3 and 4% hills mixed in. The only time I let up was to take corners and on one hill against the wind when I thought the little 15A controller might fry. The small ~6Ah LiMn battery pack was being drained quickly and seeing that my average speed was actually starting to fall I ended the ride sooner than I normally would. Here are the stats;

Distance: 11.79 miles (18.86km)
Average speed: 20.8 mph (27.2kph)
Top speed: 28.5 mph (45.6 kph)

Amp-Hours used: 4.749
Watt-Hours used: 173.0
Peak Watts: 568
Min Volts: 32.91

Wh/mile: 14.67
Wh/km: 9.17

That Wh/mi figure now stands as my personal “best” though I’m sure with the 22A controller provided with the motor the speed and the power consumption figures would have been higher since the little controller was maxed out quite often up any sort of grade. I don’t know how much power my pedaling contributed but from watching the Watts-Up meter it didn’t look like it could have been all that much. By comparison the fastest I ever rode with the Bafang was an average speed of 18.0 mph (28.8km/h) over 25.23 miles (40.37km) using almost exactly the same amount of power (4.81Ah) but at a much greater efficiency of 7.2 Wh/mi (4.5Wh/km). I know I was working hard on that ride and so was the Bafang. The question to ask then is, is 3 mph (5km/h) worth going HALF the distance? I guess if you’re in a hurry but I don’t plan on riding full tilt like this again until I get a bigger battery.

-R

That is a fast average speed it seems, must have been a lot of pedaling, my avg is mostly right on 18mph, however, I hit a lot of stoplights to go with my hills... Never noticed all the red lights until I went electric.... argh...

 

[Russell]

I think I read that Russel's is advertised as the smaller 24v 250 watt, just wondering how they compare at 36volts. I like your idea of higher voltage and lower gearing to get power without drawing a huge amount of Amp Hours.

My Bafang motor is 36V. I have not found a motor on the manufacturer's website that is rated over 250W.

http://www.szbaf.com/en/product_detail.asp?ProductID=505

You have to be careful when just looking at advertised power figures because quite often it's based on the controller current rather than the motor. With my Bafang I can peak at close to 600W when my LiMn 36V battery is fully charged but the motor should not be pushed that hard on a continuous basis.

-R

 

[Russell]

Another cold day, and a really cold one for May with temps in the 40's...but at least it was sunny.

I installed the 22A controller that came with the 9C motor from E-BikeKit in place of the little 15A controller that came with my Bafang kit. As you might imagine this really woke up the Nine Continent motor which now pulled much stronger off the line and up hills. There is a cost of course for this new found power and that's energy consumption.





I connected the black and white speed suppression wires which made the top speed about 14.0 mph (22.4kmh) with a no-load speed of 17.1 mph (27.4kmh). It also didn't restrict the current, it just limited the speed making it useless to me. It would be a nice feature to use with a 48V pack, you could rig up a handlebar mounted switch and run around 18.5mph (29.6kmh) or hit the switch and enable full speed.



-R

 

[johnrobholmes]

I regularly push 1200 watts though my bafang

 

[Russell]

I regularly push 1200 watts though my bafang

Oh sure I've run close to 1,000W-peak on my Bafang with just 3-12V + 1-6V SLA's and a 22A controller but you need to keep the continuous power down to a reasonble level or risk cooking 'em like Zukster did to one of his while running at up to 1,800W (60V/30A) ( http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=10185 )

-R

 

[tostino]

I want to know how the bafang compares to the 9c while using the 22a controller!

 

[Russell]

I want to know how the bafang compares to the 9c while using the 22a controller!

I did that back in March

http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=9297&start=0

I only used the 22A controller for a few rides with the Bafang back then. What I found was basically the motor was a little more "eager" and power consumption increased a little. I have two of the 9C controllers and eventually one will be used with the Bafang if I get a 48V battery since the small 15A controller can't handle that voltage. I may try to modify that one for a bit lower current limit. For daily use on 36V I find the 15A controller is a good match for the Bafang.

-R

 

[dnmun]

do you really ride with the speed limiter connected through the black/white wires? did you ride the bafang with the speed limiter invoked too? that is sober.

 

[Russell]

do you really ride with the speed limiter connected through the black/white wires? did you ride the bafang with the speed limiter invoked too? that is sober.

I tried it but with those wires connected the top speed with the 9C motor was only 14.0 mph. I didn't use the speed limiter with the Bafang since, well it's got a top speed of low 17's at 36V as it is and the limiter would reduce that to just over 10 mph (about 40% reduction). I am thinking of using the wires connected to a switch if I run the 9C at 48V which would provide for about an 18.5mph limit with it engaged and likely close to 30mph with it off.

-R

 

[Russell]

I only used the 22A controller for a few rides with the Bafang back then. What I found was basically the motor was a little more "eager" and power consumption increased a little. I have two of the 9C controllers and eventually one will be used with the Bafang if I get a 48V battery since the small 15A controller can't handle that voltage. I may try to modify that one for a bit lower current limit. For daily use on 36V I find the 15A controller is a good match for the Bafang.

-R

After writing this I said, "self why not"? I already had the controller opened up before for a look-see so I knew I could access the shunt easily enough by just taking off the blank panel.



The shunt is a single wire and by the looks of it E-BikeKit's supplier has already done the tried and true "solder mod" to increase the current rating of the controller. With soldering iron and solder sucker I removed the blobs on either end of the shunt, closed 'er up and installed it on the bike with the 9C motor. I went for a ride and found the maximum current was now at 15.35A, down from just under 22A. This will be perfect for running the Bafang at 48V.

(EDIT: the controller with the solder mod was from an older E-BikeKit rear kit, the controller I recently purchased has two shunt wires with no solder blobs)

-R

 

[docnjoj]

I've been running 48 volts on a Bafamg since Sep 2008 and it seems to work fine. Once I replaced the gears with one steel and 2 nylon no problem! I'm a big guy on a heavy trike (300 lbs total weight) and it still keeps me going up to about 20 mph. I want another!
otherDoc

 

[Russell]

Docnjoj,

Does your motor vibrate under a heavy load? I like the Bafang but the vibration that I can hear and feel bugs me. I'm wondering if it's just my motor or if it's Bafangs in general that do this. The spokes are all nice and tight and the wheel runs true.

-R