9point8 Intl
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Kit HT Length Upper Cup Min L Max L Lower Cup Min L Max L Tensioner L
Alpha 90-98 0000-1343 22 26 0000-1349 25 29 0000-1345 43
Bravo 100-108 0000-1343 22 26 0000-1349 25 29 0000-1346 53
Charlie 110-118 0000-1343 22 26 0000-1349 25 29 0000-1347 63
Delta 120-128 0000-1343 22 26 0000-1349 25 29 0000-1348 73
Echo 97-105 0000-1343 22 26 0000-1350 32 36 0000-1345 43
Foxtrot 107-115 0000-1343 22 26 0000-1350 32 36 0000-1346 53
Golf 117-125 0000-1343 22 26 0000-1350 32 36 0000-1347 63
Hotel 127-135 0000-1343 22 26 0000-1350 32 36 0000-1348 73
India 110-118 0000-1344 42 46 0000-1349 25 29 0000-1345 43
Juliet 120-128 0000-1344 42 46 0000-1349 25 29 0000-1346 53
Kilo 130-138 0000-1344 42 46 0000-1349 25 29 0000-1347 63
Lima 140-148 0000-1344 42 46 0000-1349 25 29 0000-1348 73
Mike 117-125 0000-1344 42 46 0000-1350 32 36 0000-1345 43
November 127-135 0000-1344 42 46 0000-1350 32 36 0000-1346 53
Oscar 137-145 0000-1344 42 46 0000-1350 32 36 0000-1347 63
Papa 147-155 0000-1344 42 46 0000-1350 32 36 0000-1348 73



The 9point8™ Slack-R™ kit changes the head tube angle on bikes with IS headsets. (IS41/28.6 upper bearing and IS52/40 lower bearing only.)



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 20mm 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.


What does installing a Slack-R do to your bikes geometry?

Click HERE to take a deeper look.


Want more customization? Add additional parts to your Slack-R Kit to fine tune your HTA and test the extremes. Individual parts located here.


CompatibilityThe Slack-R is compatible ONLY with bikes using the IS41/28.6 upper headset bearing.  Some frame specs are listed as IS 1 1/8" 1 1/2" but this is NOT enough information to determine compatibility, since IS 1 1/8"  1 1/2" covers bikes with an IS41 and bikes with an IS42 upper bearing.  IS42 upper bearings have an outside diameter of 41.8mm and ARE NOT COMPATIBLE with Slack-R.  Only bikes with an IS41 upper bearing, which has an outside diameter measurement of 41mm are compatible.  For example most Specialized mountain bikes use an IS42 upper bearing and are NOT compatible.  Sorry Stumpy owners...  Contact [email protected] if you are unsure.


Does your bike have a Trek Knock Block headset? The Stop Chip must be removed from all Trek Knock Block headsets before installing a Slack-R. Read more here.

Slack-R Kits

  • Product Code: Slack-R
  • Availability: In Stock
USD$99.00

Available Options




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