Here's a "manufacturer" (dealer of Chinese bikes) to avoid: Magnumbikes.com. I bought a Metro step-thru from one of their California dealers last Summer, and had it shipped to me, as there were no bikes in stock in the East. (I'll be doing a one year review of the bike soon.) This was my first geared hubmotor, and while it could be a bit loud at times it was, overall a good, mostly quiet bike - for about nine months. Then the motor started to occasionally get much, much louder, initially for a few seconds at a time. There being no Magnum dealer anywhere near me, I decided to wait until the noises happened more regularly. In the interim the freewheel started to clank, but that's another matter, covered in a topic here.
This wasn't my first interaction with Magnum: When I initially wanted to buy a Metro, there were none to be found - they were apparently in between shipments. So I decided to try their Das Kit on one of my EZIPs, instead. The site listed the kit as " IN STOCK (can be back-ordered)". Assuming that this just meant it was possible to order it even when not in stock, I ordered one, through PayPal. Magnum immediately converted the purchase to a back order. When I saw this I emailed them requesting a refund. No reply. I then initiated a complaint with PayPal, who also did not initially get a reply from Magnum. A week later, as the refund deadline was near, Magnum finally contacted me, claiming that they had been emailing and calling me with no response, and would refund the order. I have both Gmail and voicemail, and there was no way they had been doing this, but I let that slide. (Yes, I checked the spam folder in Gmail. Nothing.)
Anyway, back to the increasingly loud bicycle: as the warranty ended the hubmotor was still functioning fine, but was also getting louder and louder. I emailed Magnum, asking if they would sell me a new rear wheel assembly, at their cost. I never at any point asked for a free replacement. I was then treated to a sort of slow runaround, in which I was asked to take it a Magnum dealer (the nearest is in another state), then I received the following:
First:
"Unfortunately, based on our warranty policy we don't want the end user working on the electrical because something else could fail. We do not provide instruction on taking apart the motor for this reason. Do you have any videos of the noises so that I can hear what is going on with the motor and maybe help you with out having to go to your dealer." (This was after the warranty had ended)
Then:
"Unfortunately, I couldn't sell the anything at our cost. Once I see the video I can show my bosses and see if there is anything they would be will to do. That would be the best that I could do for you."
So I made a "video" that was 90% audio only, because I had to use my smartphone in my seat bag, with the flap mostly closed and just the mic exposed. I posted it to YouTube, and waited. And waited. Then I asked if they had played it. And waited. In fact, I have not received another communication from them, even after being asked to reply twice, over three weeks. Here we have a "manufacturer" who will not sell replacement parts to owners of their products! If there is no Magnum dealer near you (and frankly even if there is, given the company's behavior), I suggest you not buy a bicycle from them. I'll be looked for a direct drive aftermarket hubmotor/wheel/controller to replace the still working but howling one on my POS Magnum Metro.