Originally Posted by dsaul

When building a frame for QR axles, one dropout can be filed to correct any alignment issues. It doesn't always happen and its usually only around .5mm that gets filed off, so not a noticeable difference. With thru axle dropouts, you can't file to correct alignment, so the eccentric inserts can save a frame from the scrap pile. I have only built a few thru axle frames that didn't have adjustable rocker dropouts and none of them needed correction after welding, but I'm not building frames in a production setting.