think I pretty much know this motor inside out, though not the sensorless version. I dont have on my website any detailed info on it anymore, I dont sell anymore.
Is a very long story my dealings with tongxin company, to cut a long story short honesty is not a high priority on their behalf (making is money is very high priority) shall we say, and structure of the motor has not been modified to address some problems.
1. two sides axles, high load may cause bending of the internal shaft which holds magnet rotor and is also drive shaft ( outer axles that join to bike frame not one continuous axle, quite low load capability), if that shaft bends even by less than a mm motor wont work properly
2. some magnets known to come unstuck
3. big problem: the larger outer ring has been known to break, design flaw in my view. I visited the company a couple of years ago and pointed out the potential for this to be a problem which turned out indeed to be a big problem. With the motors I sold I think probably a bit under 10% had large ring failure.
4.instart controllers just dont work, they changed design of controller and seem to have lost the plans for the original. Is a very basic thing to have a controller that works with the motor, they just couldn't supply of their own brand that would work. I landed up using another brand controller, company never replaced non working controllers with working ones, just sent same ones again. I lost a large amount of money due to this company, and went through alot of stress in having to replace controllers, and send out new bits/pieces to customers.
5. motor is pressed together, not designed to be repaired, very hard to completely dismantle, extremely difficult to reassemble whole motor if taken apart down to the magnet rotor level. Difficult to put the rollers back together ( gear system no cogged teeth used )
6. basically motor runs very close to design limits, not much safety margin built in, overvolting will burn it out, overamping likely will also burn out windings.
This company is a university based company. A private owned company will continually modify designs to address any problems. Tongxin company has not been able to make design changes to motor, reason unknown. Their attempts to address problems have been to do via the controller, but structural problems just aren't solved by using on pedal first controllers or sensorless controllers. What I think has potential to be a very good motor has turned into a big problem for alot of people.
IF you deal with the company be aware that getting sales is number one priority, how much problem they cause for people along the way is not their concern, I would avoid them like the plague.
They also were involved with a lithium bike, which made the chinese tv news when someone was injured when the battery caught fire, my workman in china saw it on the news. Dont buy lithiums off them!!
Any larger companies thinking of using tongxin in larger scale productions of ebikes is pretty much going to loose out bigtime.
I might put up a page on website showing the problems in detail, I'm amazed this company has stayed in business for so long.
On the positive side!!!! hall sensors have low failure rate
One more negative: if I could have taken the company to court to get back a few thousand dollars I lost due to them I probably would have.