I might be stupid (probably just inexperienced) but are they offset toward frame or away from it? Looking at your link they’re all 3mm offset.
Magene chainline for outer ring should be ~47, whereas GRX is 49.7.
So with 3mm offset are we’re talking 44 or 50?
First you mounted the wolf tooth chainring, was it offset too?
And also why different offset based on chainring size? Shouldn’t ideal chainline be the same (whatever that is) independent of chainring size? Or does it have more to do with clearance?
Sorry I’ve never done anything out of standard for any bike really so this is quite new to me.
So the Magene chainline of 47 is measured to the center of the spider, that's because its a 2x crankset, all 2x cranksets chainlines are measured to the midpoint between the 2 chainrings.
1x Cranksets offset is measured to the midpoint of the chainring.
The Wolftooth Chain Ring has no offset so chainline was ~49.5 (same as GRX) and only had less than 2mm space between the frame and the chainring.
3mm Offset bring the chainring closer to the frame. so a 46 with 3mm offset would rub on the chainstay.
The 42T with the 3mm offset brings your chainline to 46.5 (mine measures 46 with the 1 mm spacer) I hardly have enough space between the chainring and the frame to clean with a thin rag.
The chainstay (the part of the frame that runs from the bottom bracket to the rear axle) gets wider as it goes toward the axle end as it has to accommodate the rear hub. Once you go bigger than 42T the chain stay gets too wide so the chainring will start rubbing on the chain stay. to overcome this you have to move the chainring further away from the frame (Bottom Bracket) hence 3mm offset no longer works unless you also add spacers on the crank spindle to move the spider further out. If you add too many spacers on the drive side spindle, your left side will no linger have enough spindle left for the left crank arm to grip safely so you have to consider that too
When you look at the picture, you will see that if I add a bigger chainring it will rub on the chainstay, unless I add a spacer on the spindle
