Ok, so I've built up this older I-drive with a SID Dual Air rear shock ..... I have the thing maxed at 250psi, and am measuring about an inch of sag ... the issue is when I actually get the thing on the road, the flex at the pivot is pulling on the front derailure cable(bottom pull) and effectively shifting to the next ring... I've tried a number of tuning tricks, but am not having much luck .... Anyone else had this problem? Any suggestions?