Only the cheap 8.8aH ones seem to be weak. The 10.4 aH ones are better or the 6aH high discharge ones.chas58 wrote: Those bottle batteries look nice, but I hear they don’t have much power (i.e. not much current capacity).
The 201 rpm motor in a 26" wheel will give good power up to about 12mph, and then it starts to reduce. How fast you can go without pedalling depends on your weight, hills and wind. With two 201 rpm motors, your bike will be able to maintain 15mph even up slight hills. I have a 2WD bike with 328 rpm in the back and 201 rpm in the front. It'll hold 15mph in most circumstances, even up a 5% hill, but in favourable conditions, the higher speed motor will take you past 25mph. Once past about 17mph, the slow speed motor is making no contribution, so the overall speed is very dependent on conditions and weight. a 5% hill will have you straight back to 15mph (unless you're light).Beagle123 wrote:Thanks for the great thread.
I'm really interested in seeing the performance you get from these two bikes because I'm planning on making a dual hub motor bike with a low speed (210 rpm) motor on the back and a high speed (328) motor on the front. I want to use cute motors to keep the weight down.
What is the real "no-load" rpm (or speed) of each motor? I'd like to know how the no load speeds compare to the speeds you can actually achieve without pedaling. I'm imagining that your faster (328 rpm) motor will have a very fast top "no-load" speed, but will struggle with wind resistance when trying to go fast in the large (700c) rim. However I should be perfect for your application.
Please report back. I can't wait.
Yep, see my post here:migueralliart wrote:So does this mean one can buy one of these motors for a rear 120mm spacing and it'll fit?
I was thinking lightweight single speed for my next endeavor.
Yep, you are right.Beagle123 wrote:Great report chas. I'm really getting a good understanding of what these motors can do now. I think you found an excellent way to use the 328 RMP cute motor, but it seems to me that most users would do best with the slower RPM version.
For me, I learned that I can't rely on it as a solo high speed motor to achieve 25+ mph alone. I will need a bigger motor with more watts.
I have the Bafang SWXK (front purchased from greenbikekit) and SWXH (rear purchased from elifebikes). So far I have only installed the SWXK (on my wife'ss bike) and ridden the SWXK. They have the same no-load speed and are similarly sized so I assume the will perform similarly. Both weigh 2.9 kg, and both give 27 mph no-load speed in a 700c wheel with 12s lipo near the top of charge, ie 49.5 volts. In actual use the SWXK is quite strong. I'm using it sensorless with the small greenbikekit controller and the shunt soldered to up the amps a bit. With 12s lipo at 20 amps, I can take a 9% grade at 12 mph and I'm over 250 lbs. It gives a bit above 21 mph with no pedaling and about 24 mph with moderate pedaling. Under load it is a bit growly, but at cruising speed it is almost imperceptible. We have seen no signs of overheating, but it has been under 70 f here so far this year.chas58 wrote:Bafang makes 250rpm versions of the SWX series motor. With the ability to do 20mph, that would be a good compromise between the Q100 at 201rpm, and 328rpm. ... Or for both speed and torque, get a bigger heavier higher wattage (higher amp) motor.
Or just build it yourself. Wheel building is pretty easy and only takes a hour or so once you've done one. See Sheldon Browns instructions. I like Edd for figuring the length of spokes to order and Danscomp for ordering spokes.chas58 wrote:For any future wheel builds, I will just order the motor, and use the $$$ saved with shipping to build the wheel locally. That way I can get any wheel I want, and support local businesses.