It's been a long while that I am eyeing FM599 frame on AliExpress, but I am not able to find any feedback on the frame online. Looks like no one build a bike with it, or if they did they did not post about it.
Does anyone have experience with this frame ?
Also the seller seems very unresponsive on AliExpress so that is kinda off putting.
https://a.aliexpress.com/_soArv9

I dont have any feedback on the frame, however due to the lunar new year holiday and the corona virus scare going on in China, many factories are closed or running at reduced capacity.  I'd give them a little extra time to get back to you, at least until things settle down.