@Szymon
thanks for that info! I didn't know the existence of the Spank Race rims... also I wasn't aware that I could just changing the rim for lighting the bike (I just thinking about buying a whole wheel)
thing is, my rim is about 639g, and Spank Spike Race is about 430g, so, not sure where that -790g came from? 😅 anyway it's good info!!
tubolito thing I knew about that, gonna give it a try!
about the truvativ/Sram GX cranksets I didn't know, I will try to buy them second hand, thanks for the info!!