Yes, I agree.  If these frames are actually 21" then they will work for me.  But if they are actually 480mm, then a 400mm seatpost will not even be enough.  I need about 84cm from middle of BB to top of saddle.

I am interested in the FM-M009 and ST-M006 that have been showing up on Aliexpress and eBay lately, but their frame sizing is confusing me.  I am 197cm tall, so I was looking at the 21" frame.  Based on the geometry chart, the 21" frame is only 480 mm (~18.9") from middle of bottom bracket to top of seat-tube.  Likewise, the 19" frame is 450 mm (~17.7"), the 17" frame is 429.5 mm (~16.9"), and the 15" frame is 400mm (~15.7").

I thought the entire basis of stating a frame size was the measurement from middle of bottom bracket to the top of the seat-tube.  From my limited experience, most other manufacturers (Chinese and domestic) seem to use this measurement without modification when stating their frame sizes.  Do some manufacturer's state an 'effective' frame size based on other aspects? (stack and reach?)  Based on the geometry chart, only the size 17" FM-M009 / ST-M006 frame matches up with the seat-tube measurement.

I asked someone from Tideace about this and they said "The size chart is real as frame, our frame size measure maybe not same as others."     If someone has purchased the 21" FM-M009 or ST-M006, could you please confirm whether it is 480 mm or 21" (530 mm) from middle of bottom bracket to top of seat-tube.

Cheers,

Kristian