The 9point8™ Slack-R™ headset angle kit changes the head tube angle on bikes with IS headsets. (IS41 and IS42* upper bearing and IS52 lower bearing only.) CLICK HERE FOR MORE INFO ON IS41 vs IS42 vs IS42S Confirm the three checks below and complete the drop down menus to see what Slack-R kits are available for you. 1. Confirm your he