Bofeili Crankshaft Drive

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Bofeili Crankshaft Drive

Postby Matthijs » Thu Apr 14, 2011 5:34 pm

When doing a forum search I discovered that only one guy (Nader) on this forum uses this system. He is from Germany. Are there more members that have any experience with this system?

http://www.bofeili.com
http://bofeili.en.alibaba.com/product/3 ... ngine.html

Build thread (Translated)

http://www.nalizadeh.com/ebike/pics/bikes.html



Edit: Here seems to be another one as well from Taiwan: http://www.bicycle-motor.com.tw/b2.html (Already in the forum: viewtopic.php?f=30&t=18255)
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Re: Bofeili Crankshaft Drive

Postby Whiplash » Thu Apr 14, 2011 9:57 pm

Wow! Now that is a clean package! Its a hub motor with the axle being the cranks! Wait a minute, that gives me an idea! 4000 watt crystalyte crank motor anyone?!!! You would just have to replace the axle and move the wiring out of the axle and out the side of the case!
Power is a fascinating thing, the more you have, the more you want, but the real power is having the restraint not to use it all at once...............Um...Yeah..

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Re: Bofeili Crankshaft Drive

Postby Hillhater » Fri Apr 15, 2011 12:10 am

Whiplash..
how are you going to make the electrical connections to the coils which are now rotating with the cranks ?
What you would need is a very low KV in-runner. :wink:
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Re: Bofeili Crankshaft Drive

Postby Miles » Fri Apr 15, 2011 12:46 am

Also, direct drive of the cranks would require a motor around 3 times the size of an equivalent hub motor :P
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Re: Bofeili Crankshaft Drive

Postby Whiplash » Fri Apr 15, 2011 8:14 am

Why 3 times the size? Driving through the gears would make you actually need LESS power? I have looked at my hub at home and I see why this will not work without a LOT of work so it was just an idea..
Power is a fascinating thing, the more you have, the more you want, but the real power is having the restraint not to use it all at once...............Um...Yeah..

The harder you work.....The luckier you get!!

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Re: Bofeili Crankshaft Drive

Postby Miles » Fri Apr 15, 2011 8:20 am

Whiplash wrote:Driving through the gears would make you actually need LESS power?
True, you could manage with less power. For the same power it would need to be bigger, though.
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Re: Bofeili Crankshaft Drive

Postby umejopa » Fri Apr 15, 2011 8:54 am

It seems to be a good drive.
Have any one ask for price of a crankmotor ?
Need some welding to the frame but a steel frame that not so hard.
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Re: Bofeili Crankshaft Drive

Postby Matthijs » Fri Apr 15, 2011 12:01 pm

umejopa wrote:It seems to be a good drive.
Have any one ask for price of a crankmotor ?
Need some welding to the frame but a steel frame that not so hard.


I see they are offered in Europe for € 369 + shipping. But going directly to china would be cheaper but if i saw it correctly minimum order is 100 pieces. :?

Edit: I see here: http://bofeili.en.alibaba.com/product/3 ... 15194.html FOB USD 100~300 / Set

http://translate.googleusercontent.com/ ... pxRG36z4kA
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Re: Bofeili Crankshaft Drive

Postby Whiplash » Fri Apr 15, 2011 2:18 pm

Miles wrote:
Whiplash wrote:Driving through the gears would make you actually need LESS power?
True, you could manage with less power. For the same power it would need to be bigger, though.



ahh I see what you mean...
Power is a fascinating thing, the more you have, the more you want, but the real power is having the restraint not to use it all at once...............Um...Yeah..

The harder you work.....The luckier you get!!

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Re: Bofeili Crankshaft Drive

Postby Miles » Fri Apr 15, 2011 2:37 pm

The Bofeili unit weighs 8.4 lbs for 100-200 Watts and that's a geared motor.....
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Re: Bofeili Crankshaft Drive

Postby boostjuice » Mon Apr 18, 2011 4:03 am

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Re: Bofeili Crankshaft Drive

Postby Miles » Mon Apr 18, 2011 4:09 am

Thanks bj

* No-Load Speed 155Rpm
* No-Load Current 0.8A
* Hall Sensor Yes
* Efficiency 78%
* Normal Voltage 36V
* Phase Angle 120°
* Power 180Watts
* Rated Current 6.4A
* Rated Speed 135Rpm
* Rated Torque 12.7N.m
* Weight 3Kg


So, it can sustain an output of less than 120 Watts, at a cadence of 90 rpm......
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Re: Bofeili Crankshaft Drive

Postby Whiplash » Mon Apr 18, 2011 9:53 am

I just don't get the idea that you need to make a unit only handle stupid low power like that, why not make an off road drive market it as 250 watts @ 24V and make it handle like 48 at least and the ability to take more amps? It seems there would be a fairly large following for something just like this one that could handle higher power levels like this. Hell, even 1000 watts would be enough with the righ gear range!
Power is a fascinating thing, the more you have, the more you want, but the real power is having the restraint not to use it all at once...............Um...Yeah..

The harder you work.....The luckier you get!!

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Re: Bofeili Crankshaft Drive

Postby Miles » Mon Apr 18, 2011 10:59 am

Whiplash wrote:I just don't get the idea that you need to make a unit only handle stupid low power like that.......
Well, as we said, if output speed is constrained to a reasonable cadence, size and weight will be directly proportional to power required, for a given design (internal reduction ratio etc.).
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Re: Bofeili Crankshaft Drive

Postby Whiplash » Mon Apr 18, 2011 11:10 am

Yes, but couldn't these companies that have the resources just build a unit with some headroom?
Power is a fascinating thing, the more you have, the more you want, but the real power is having the restraint not to use it all at once...............Um...Yeah..

The harder you work.....The luckier you get!!

"People who say it can't be done are often interrupted by those that have already figured out how to do it!"

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Re: Bofeili Crankshaft Drive

Postby Miles » Mon Apr 18, 2011 11:11 am

Whiplash wrote:Yes, but couldn't these companies that have the resources just build a unit with some headroom?
What's "headroom"? I need to incorporate that... :)
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Re: Bofeili Crankshaft Drive

Postby Whiplash » Mon Apr 18, 2011 12:35 pm

Its a bit of room to grow by adding amps or volts. Just simply build strong enough to tolerate more than the rated power so individuals can "grow" the output to their liking without total fear of destruction...
Power is a fascinating thing, the more you have, the more you want, but the real power is having the restraint not to use it all at once...............Um...Yeah..

The harder you work.....The luckier you get!!

"People who say it can't be done are often interrupted by those that have already figured out how to do it!"

Email me @ currentcycles@gmail.com
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Re: Bofeili Crankshaft Drive

Postby boostjuice » Mon Apr 18, 2011 10:04 pm

What Miles is eluding too is that a crankdrive offering truly useful power (>~500W IMHO) cannot achieve an acceptable size/weight unless its design separates motor RPM to levels well above Cadence RPM using some form of speed reduction/torque multiplication. The optibike drive system uses a dual stage epicyclic/planetary transmission in order to provide up to 850W in a package of similar size/weight to this POS out of China. Direct Drive crankshaft drive = fail. Not worth the cost and effort of a custom frame, or the weight and complication for a 120W motor IMHO.

Optibike 850W drive system.
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Patent > http://v3.espacenet.com/publicationDetails/originalDocument?CC=US&NR=2002014366A1&KC=B2&FT=D&date=20031007&DB=&locale=
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Re: Bofeili Crankshaft Drive

Postby Hillhater » Mon Apr 18, 2011 11:28 pm

how do we know that the Bofeili unit doesnt have a similar internal gear set ?
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Re: Bofeili Crankshaft Drive

Postby Gregory » Mon Apr 18, 2011 11:45 pm

I like the look of these motors.

The alibaba link seems to indicate it does have planetary gearing.

1. Crank Shaft Electric Motor with Own Exclusive Patent
2. More Beautiful, more logical, more energy-saving
3. Hight Efficlency In power Conversion.(Reduce Mechanical Loss), Highly Efficient In-Line Drive.
4. Model: BFLEM36-001
5. Rated Voltage: DC 36V
6. Rated Power: 150-250W
7. Rated Efficiency: 80%
8. Our motor has a wide range of gear ratio due to using planetary gear and can be adjusted according to your demands.
9. Using Dual-rachet clutch
10. Electric power supply and manual labor are totally separated without interfering with each other, which makes the structure of electric motor more compact
11. High quality and most competitive price, and providing high-quality after services
12. DC Brushless



The OP already linked to Nader's builds and he said

It is a 350-400W very strong bottom brackets engine (Bofeili) and can be operated with both 36 and 48V.
The controller is a 15A.

Thereby is 28 mph loosely possible (with 36V) and 17% hill very easy to drive . :wink:
..and you can read and see the building process in german pedelec-forum (http://www.pedelecforum.de/forum/showth ... -Selbstbau).


1) x5305 Hub Motor in a 24" Sun rim with 10G spokes, Kelly 72601 controller, 74V 10Ah Turnigy LiPo 20C Battery and CycleAnalyst
2) Mac 10T rear hub in a 700C "comfort bike" 15S 5Ah LiPo, stock 28A Xie Cheng controller
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Re: Bofeili Crankshaft Drive

Postby boostjuice » Mon Apr 18, 2011 11:59 pm

Ok, i didn't see that, due in part because i couldn't believe that if it did incorporate a planetary/epicyclic gearbox, that it would be so handicapped in power output.
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Re: Bofeili Crankshaft Drive

Postby Hillhater » Tue Apr 19, 2011 2:32 am

Probably just another case of quoting figures to suit the European laws !
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Re: Bofeili Crankshaft Drive

Postby Miles » Tue Apr 19, 2011 3:17 am

Hillhater wrote:Probably just another case of quoting figures to suit the European laws !
You can check it with the rated torque figure.... If anything, they've inflated the power....
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Re: Bofeili Crankshaft Drive

Postby Matthijs » Wed Apr 27, 2011 7:14 pm

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Re: Bofeili Crankshaft Drive

Postby liveforphysics » Wed Apr 27, 2011 7:21 pm

Whiplash wrote:Yes, but couldn't these companies that have the resources just build a unit with some headroom?



No. The part you're missing is the part Miles said earlier about needing it to be 3x larger than a hub for the same power. He wasn't kidding.

Power is a function of speed and torque. Anytime you drive through the cranks (something that actually spins SLOWER (around 1/2 to 1/3rd) than the wheels even!), you end up in a situation where for a given volume of motor, you're able to give about 2-3times more power output if you just stuck it in the wheel directly.
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