..... I think a lot of the reported problems have more to do with riding style and expectations rather than issues with the motor.
It all depends on how the bike is ridden.......
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If you want a moped that does 25mph+ do not buy a TSDZ2.
+1 for all of that
@vidtek - when you hear of the various TSDZ2 issues, you never know what weight the rider is, the power/volts they are pushing through the motor and the riding conditions the motor is being asked to work with.
I pootle a bit more than you (usually either either side of the 25kph cut-off) but almost all in ECO. I have just passed the 2000Km mark in the 4 months of ownership and I've just had to change the sprag clutch which TBH was a bit disappointing (great vid
HERE on doing this) -but it took me an hour of faffing and cost me £20, so well within the realms of what I'd deem 'bike maintenace' and not too much different in terms of effort/cost in changing a bottom bracket.
EDIT - see note below as it wasn't the sprag clutch!!
At the end of the day, an ebike kit at this price point is going to require some maintenance somewhere along the line. I'm very happy to get my hands dirty rather than being tied to some expensive proprietary brand whose dealership will happily relieve me of my pocket money.
I did take the motor cover off to inspect the 'blue gear' at 1500Km and it looked pristine - I do expect to have to change this at some point (but who knows when?) and I'll stick with the blue one as my motor (with OSF) runs very quiet and I understand that the brass option is noisier.
A bit off topic but for anyone reading this and considering fitting the motor, then when it comes to tightening the cranks, you really do need to tighten them to the 40nm mentioned in the installation guide - I initially did this by hand thinking I'd got it tight enough, but the cranks worked loose and I eventually got a torque wrench and did the job properly.
I also experienced motor power drop-out which caused me a lot of head scratching and I initially suspected the TSDZ2 controller until I swapped out the motor for my wife's TSDZ2 and realised that the battery BMS was the culprit and not the TSDZ2 - a new BMS arrived last week but I'm running in bypass mode on the old one for a while to see how it goes battery balance wise.
EDIT/NOTE - I thought the sprag clutch needed changing as I had the symptom described in the vid I linked to above in that sometimes the chain appeared to 'jump' in a manner similar to what you'd experience with the chain jumping sprocket teeth. On my first test ride today after the sprag clutch change, the problem is still there. Back home I checked for chain wear (I fitted a new chain when the motor was installed) and there was no discerable 'strectch' either as measured by my chain guage or against a 12 inch steel rule - thus I'm now wondering if the free-hub in the rear wheel is the problem (it's my touring bike wheel and has done literaly thousands of miles - 10,000 maybe?) - I need to swap wheels with one of my other bikes to see. Every day's a school day