Bafang CST Motor - No load test

[jmwhite151]

I just received a Bafang CST motor from BMS Battery. I bought the 500W, 270 RPM motor: https://bmsbattery.com/ebike-kit/589-bafang-36v-cst-rear-driving-e-bike-motor-wheel-ebike-kit.html

On the motor, it says:
CST 36V500W 26
1506 7052-6

Is there any way to confirm that this is the 270 RPM motor? I've seen a list of motor codes (https://endless-sphere.com/forums/viewtopic.php?f=2&t=43106 and other places). But I haven't been able to find where the code is listed in the above numbers.

UPDATE: I just did a quick test. I was getting a no load speed of 38.3 MPH (using a wheel circumference of 2300 mm programmed into the cycle computer) at a battery voltage of 53.5 V. If I did everything correctly, that corresponds to 446.65 RPM @ 53.5 V or 8.35 RPM/V or 300.5 RPM @ 36 V. That seems to check out. It's a little higher than 270 RPM, but I think I read that the 270 RPM is actually a little faster than 270 RPM. Looking forward to getting it on the road to see how it performs...

Jeff

 

[motomech]

That motor only comes in one speed.
It's a mid/fast motor and at that Voltage it should top out around 28 mph(26"wheel).

 

[d8veh]

The 500W Bafang CST from BMSB is normally exactly 270 rpm at 36v. With a fully charged 36v battery (42v), it goes about 10% faster.

38.3 mph is going to be too fast for its power. I can't see it being very efficient unless you run it at high speed in a low resistance bike like a road bike or hybrid with thin wheels and forks.

Please let us know how you get on and whether you get any heat problems.

 

[jmwhite151]

Thanks for the input. I have it on a 26" rim, so it will actually run around 33 MPH with no load. (I used a bike computer from a different bike that is set up as a 29er. That's why the linear speed was reported as higher.) I will let you know how it works out. But it might be a couple of weeks before I get it on the road.

d8veh, I believe you have a bike with the CST motor. Is it the 500W? What do you use for a torque arm? This is going an aluminum Trek 4500 frame.

 

[d8veh]

Yes, I stil have my Bike with the CST motor. I also have one with the Xofo clone, which is more free-running, though a bit slower.

I use one BMSBattery.com torque arm on the disk side, fixed to the disk mount. I've built many bikes with 500w geared motors like that.

You have to drill a new hole in the tie-bar and cut off the end. You need a 5% cobalt drill to drill it.

Alternatively, and probably better/easier, make your own tie-bar out of a strip of mild steel, which is easy to drill. The tie-bar doesn't need to be hard steel.