Originally Posted by
shelbyfv
I'd be surprised if you could tell a difference in the 631 vs 520 frames. In theory it would be lighter but a gravel bike will be heavy regardless.
I agree, it'd be fun to build one, and if a frameset is in stock it could be easier to get than a complete bike, but I think I'd be pretty happy with how the S3 comes stock. I'm not too worried about what brand of tubing it is.