Originally Posted by
SoSmellyAir
The GRX 810 crank and the GRX 600 crank are both 110/80 BCD, so theoretically should fit. However, the 48T chain ring that comes with the GRX 810 crank is a Hollowgram chain ring and might thus be thicker, as you mentioned. I don't really care about appearance, but of course I do not want to mess up the chain line or the shifting. So perhaps 4 thin spacers would be necessary; that is a worry for the future.
pics of the 810 (top) and 600 (bottom) cranks
can see the difference in the chainring thickness near the mounting area / holes - and how the chainring arm mounts down into the machined recess in the chainring
810 is a much higher quality crank - including the big chainring
600 crank is marketed as 105 level and often described in this manner (possibly also by Shimano?) - but it’s a significant step down from the 810 and is more similar to Tiagra level imo