This is great advice from Blackstrida’, I wish I had asked the same question as I recently bought a Strida 3, once I had got it running I quickly realised the limited life it was going to have due to the wear on the gear wheels and the limited amount of spare parts. I have already bought a Strida 5 and all of the shortcomings of the Strida 3 have been addressed and sorted. Disc instead of hub drum brakes are cheap to get replacement pads. Rear gear wheel is aluminium (in my case) and replaceable (not integral to wheel).
The Strida 5 seems to be far more future proof, the bottom bracket is mounted with a solid welded metal case rather than a creaking plastic one.