Apologies to those who may have read this survey on the Cycling UK forum but as there's no response so far (03May22), I'm posting here as I'm sure there will be greater interest.
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I love this little Tongsheng motor and much prefer it to the Bafang BBS02 I had previously. The Bafang felt very unresponsive being cadence only and I had to keep upping and downing the power level all the time or use the throttle.
I've now done about 3000km on my Tongsheng running the Mbrusa OSF for original displays. I have the 48V 750W version with the VLCD6 mini display and no throttle or brake sensors.
I have twice re-greased the main gears with general multi-purpose grease. This stops a whirring sound when it becomes a bit dry. Once the torque sensor connector plug came loose and I got a sensor error. It was a simple repair by tweaking the pins a bit and re-connecting. Very occasionally the motor continues to run by itself (ghost pedaling). Apparently this can also happen with the stock firmware, so it's not the OSF. When this first happened I panicked and forced it to stop with the brakes. This blew the controller! A new replacement was about £40. Brake sensors would have stopped it and saved the controller. Switching off the display works but takes a few seconds. Restarting, and the motor runs fine again. I've had this happen three times, it's not good, but not such a big deal. They now offer the 8 pin connector with the small VLCD6 display so I'd highly recommend this and fit the brake sensors!
My motor is mounted on a full-suss Yeti ASR frame with a small 48V 12Ah battery giving about 60km range. I ride almost exclusively off-road. My 11/40T cassette with the standard 42T chainring gives excellent gearing for fast and slow riding.
The TSDZ2 worked well straight out of the box but I loaded the OSF as the stock firmware limits the power to 90rpm cadence. This is ok but sometimes it's good to spin a bit faster, to power up ramps for instance.
I'm quite light (about 65kg) and usually ride in tour mode (level 2, approx 6 amps) using the gears. I occasionally use more power for steep hills at speed and rarely use full power.
I have my OSF set default to eMTB mode which is perfect for me. I've tried the other modes but none have the same excellent feel I get with the eMTB mode. My controller is labelled 15A max but the motor only demands 12A at full power in this mode. Doing the maths this is just under 600W. This is plenty enough for me! I prefer the feel on the pedals at level 2 (out of 4) and use the gears. I can climb almost any gradient that's not so steep to make the front wheel rise up. I rarely use the biggest cog (40T) unless I want to go very slow.
My motor never gets hot, only warm to touch after a high power climb. I guess people who have problems with overheating must be thrashing the life out of this little motor or they are much heavier than me and use full power all the time.
I find the motor easy to dismantle and all parts are available and cheap. Bearings are standard and easily replaced. That said I haven't needed any yet.
I guess most people publish problems on these forums and rarely post with a good report. But for me the Tongsheng TSDZ2 really is a brilliant little motor and worth every penny of it's purchase price.
Finally I must say thanks to all those who worked on the OS firmware, it's very clever and has some great features.