I've been enjoying my TSDZ2 daily on my classic 90s steel 26" MTB for more than a year now, for daily commuting. It's a great motor. But a problem has slowly arised and now it's becoming frustrating. I hope somebody cand point what the origin could be. It's the 2018 350W 36V model with xh18 controller and no brake sensors. I use it with a 36V 20Ah battery.
The odometer marks 2900km but it started failing perhaps on the 2000s: sometimes, when riding a slope and I shift to a higher gear, or start pedaling (both from stop or in movement with energy), the motor instantly ramps up directly to full speed (high noise), in fact it can't rotate any faster and offers resistance to pedaling. If I stop pedaling until the motor stops rotating, and start pedaling again but more genty or in a lower gear it works ok again. Also switching to no assist then to assist and starting pedaling gently fixes it. At the beginning (months after starting using it) it seldom happened, but gradually it has started to happen more frequently, to the point that now changing gears is a lottery, specially when going uphill, very frustrating.
Sometimes it fixes itself and I can switch gears for 5-10 mins without problem, then it happens again. Others I must swtich gears back and forth several times and pedal very lightly until it works again. Once in correct rotating speed it works ok, but lately even the vibration of going over a pothole (I have no suspension) can also switch to the high whirling speed problem.
My first though was perhaps the torque is being measured incorrectly, but the fact it works once in a stable cadence doesn't make sense. It's like it measures too high torque just moment I apply a big difference on force on the pedal, each day less big.
My other though is mechanical wear: perhaps it needs a re-grease, or the blue gear is worn out, so there is high internal resistance and the motor measures too much resistance when starting to rotate and applies too much power, it only resets the "rpm range" when stopping and starting rotating again with no so much instant resistance to overcome. This could match why it has worked so well for months and has started failing gradually. But I can pedal with the motor off and I don't sense an increase on resistance or noises.
Things I've tried:
- Moving the speed sensor and magnet: when misplaced the motor simply didn't help. My speed readout on the controller is right while it fails. I don't think it's causing the problem.
- Noises: it does the same noise than always (it's pretty quiet) and there're no cracks or jumps when switching gears.
- Derraileur, casette, chain, all were recently changed and are greased and move without friction.
- Battery: problem happens with high or low voltage, no difference.
Any help or suggestion will be very appreciated as I'm not sure what to do, and wouldn't want to open the motor for no reason. I already have a blue gear I bought just in case.