Next, its' big brother, BPM
(BaFang Permanent Magnet). Ordered from ecity website, $154 that included 7 day shipping from China. Nice looking motor, polished casing with no defects. Motor numbers make sense "BPM48V350W26(14)" ; BaFang Permanent Magnet 48volts 350watts wheel 26" (code?windings 14). I'm suspious that this motor is also know as the "Climber."
Both motors, same 48V Ping batt. Used stock schwinn rims and had the stock spokes cut and roll threaded to 216mm which turned out to be a tad long. Got the 2 cross lacing to work by switching to shorter nipples and grinding the protruding spoke points. Think 213mm for used single wall rim would've been closer. Its' size is about 30% greater than little BaFang and weighs in at 8.75lbs. It's a sensorless motor so don't forget to order the senorless controller. Shenzen & BPM motors are soulmates, the connectors from motor/throttle to controller all match. JRH sells both the sensored and senorless Shenzen controllers, and buying from him is easy/reliable http://holmeshobbies.com/home.php?cat=20
. I fitted a 5speed freewheel yet looked like room for a 6, possibly a squeezed 7speed. 3 simple 16ga wires exit through the axle on the right. Locking spacers came with it, which I believe help a little, but won't replace a torque arm at higher amps. Positively impressive
Negative, the axle nuts fit loose, even when screwed well up on the axle, there's a felt wiggle. So, there's a fine line between getting the nuts tight enough to withstand the motors' load and stripping the threads
I need my e-bike as reliable as my car for transportation, so choose a 20amp controller, but it may hold up and really fly using 25 or 30amps. Can't tell the difference 'tween a sensored or sensorless controller though I do push ahead a few inches before hitting the throttle. It's quiet like its little bro, a reassuring deep whrrr on start up that becomes subdued at cruise speed. Gear engagement and throughout the speed range is very smoooooth. . Top speed is the same for both motors, yet the BPM is much torqueier, one must be seated when you jam the throttle, nor will you get blown below 20mph in a 10-15mph headwind. I headed up our only local hill, 5% grade for .4 mile, meaning to pedal easy, but couldn't stand looking at 19mph on the speedodmeter, so I pedalled a little more moderate and kept it above 19mph all the way to the top! Under same conditions the little BaFang would hold 16mph. Considering only a 20amp controller with 21.5mph being an average cruise speed, not bad
Could barely feel any motor warmth after 3 mile ride in 10-15mph headwind. Controller got hot enough that I could just keep my fingers on it. (update edit) There was some decorative netting on the pocket. So I cut the inside pocket insulation out from around the contoller. Air flows into the pocket now and Shenzen only gets faintly warm.
OK, I saved the best for last:
Top speed motor only:
with moderate pedalling:
cruising speed lite pedalling
5% hill climb lite pedalling;
Still pretty stealthy looking; compare to little BaFang in photo above
Left 'Cute Motor' Right "BPM Motor"