Slack-R IS42S Upper Cup 42-46mm
0000-1374Regular price $40.00 USD
The 9point8™ Slack-R™ kit changes the head tube angle on bikes with IS headsets. (IS41 and IS42* upper bearing and IS52 lower bearing only.)
Have you found a Kit that fits your bike? There are convenient kits that group the parts you need HERE. But if you want to buy individual Slack-R parts, you are in the right place! You need three individual parts to adapt your bike (Upper Cup, Tensioner, and Lower Cup); use our KIT SELECTOR on the kit page to get the right combo.
Confirm the three checks below and complete the drop down menus to see what Slack-R kits are available for you.
1. Confirm your headset is the IS Standard
If you are not sure, read this article on headset identification by the experts at Park Tools.
| 2. Confirm you have enough steer tube length to install a Slack-R
If measurements A + B are greater than below there is enough steer tube to install a Slack-R
3. Measure or look-up your bike's head tube length (HTL)
Bicycle manufacturers often list your bike's HTL in geometry charts on their websites. You can also measure this yourself as shown below.