Slack-R Tensioner 53mm
0000-1346
Regular price $40.00 USDThe 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. ![]() |
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.
Slack-R is now compatible with MOST Tapered IS headsets. There are 3 different styles of upper cups now to go along with the IS52 lowers. IS41, IS42, and IS42S.
IS41/IS52 will fit a number of bikes from manufacturers such as Yeti, Santa Cruz, and Trek (eliminates the need for a Knock Block in most cases). Cube is an exception as they use a deeper upper bearing seat and the Slack-R IS41 will not sit properly in the Cube frames.
IS42/IS52 will fit many bikes from Cannondale, Norco, Marin, Orbea, GT, Revel, Scott and many more including some Specialized with a standard depth IS42/IS52 headset. Standard bearing seat depth is 3mm
IS42S/IS52 will fit Specialized bikes that have the 6.8mm deep upper bearing seat. (some Specialized bearings sit deeper than the standard IS42 geometry so they require their own specific top cup to insure proper fitment)
Headset types do vary across the same manufacturer, make sure you are sure what kind of headset you have. (IS/EC/ZS or hybrids of these)
Some IS bearing seats in the frames have a smaller bearing seat inside diameter than others so in some cases a bit of sanding will be required to fit in the 34.5mm upper sleeve and 44.5mm lower sleeve. In most cases the frame allow the kits to drop right in but in some cases opening up the upper and/or lower bearing seat inside diameter(s) will be required so double check your frame clearance prior to ordering if unsure.
Contact support@9point8.ca if you are unsure about your application prior to ordering.
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 IS Kit Reference Chart
Kit | HTL (Target middle-of-range) | Nominal Angle (Deg.) | Upper Cup | Upper Cup Length (mm) | Lower Cup | Lower Cup Length (mm) | Tensioner | Tensioner Length (mm) | Added Stack (mm) |
---|---|---|---|---|---|---|---|---|---|
Alpha IS41 | 90-98 | 1.5 | 0000-1343 | 22-26 | 0000-1349 | 25-29 | 0000-1345 | 43 | 20 |
Alpha IS42 | 90-98 | 1.5 | 0000-1371 | 22-26 | 0000-1349 | 25-29 | 0000-1345 | 43 | 20 |
Alpha IS42S | 90-98 | 1.5 | 0000-1373 | 22-26 | 0000-1349 | 25-29 | 0000-1345 | 43 | 25 |
Bravo IS41 | 100-108 | 1.4 | 0000-1343 | 22-26 | 0000-1349 | 25-29 | 0000-1346 | 53 | 20 |
Bravo IS42 | 100-108 | 1.4 | 0000-1371 | 22-26 | 0000-1349 | 25-29 | 0000-1346 | 53 | 20 |
Bravo IS42S | 100-108 | 1.4 | 0000-1373 | 22-26 | 0000-1349 | 25-29 | 0000-1346 | 53 | 25 |
Charlie IS41 | 110-118 | 1.3 | 0000-1343 | 22-26 | 0000-1349 | 25-29 | 0000-1347 | 63 | 20 |
Charlie IS42 | 110-118 | 1.3 | 0000-1371 | 22-26 | 0000-1349 | 25-29 | 0000-1347 | 63 | 20 |
Charlie IS42S | 110-118 | 1.3 | 0000-1373 | 22-26 | 0000-1349 | 25-29 | 0000-1347 | 63 | 25 |
Delta IS41 | 120-128 | 1.2 | 0000-1343 | 22-26 | 0000-1349 | 25-29 | 0000-1348 | 73 | 20 |
Delta IS42 | 120-128 | 1.2 | 0000-1371 | 22-26 | 0000-1349 | 25-29 | 0000-1348 | 73 | 20 |
Delta IS42S | 120-128 | 1.2 | 0000-1373 | 22-26 | 0000-1349 | 25-29 | 0000-1348 | 73 | 25 |
Echo IS41 | 97-105 | 1.7 | 0000-1343 | 22-26 | 0000-1350 | 32-36 | 0000-1345 | 43 | 20 |
Echo IS42 | 97-105 | 1.7 | 0000-1371 | 22-26 | 0000-1350 | 32-36 | 0000-1345 | 43 | 20 |
Echo IS42S | 97-105 | 1.7 | 0000-1373 | 22-26 | 0000-1350 | 32-36 | 0000-1345 | 43 | 25 |
Foxtrot IS41 | 107-115 | 1.6 | 0000-1343 | 22-26 | 0000-1350 | 32-36 | 0000-1346 | 53 | 20 |
Foxtrot IS42 | 107-115 | 1.6 | 0000-1371 | 22-26 | 0000-1350 | 32-36 | 0000-1346 | 53 | 20 |
Foxtrot IS42S | 107-115 | 1.6 | 0000-1373 | 22-26 | 0000-1350 | 32-36 | 0000-1346 | 53 | 25 |
Golf IS41 | 117-125 | 1.5 | 0000-1343 | 22-26 | 0000-1350 | 32-36 | 0000-1347 | 63 | 20 |
Golf IS42 | 117-125 | 1.5 | 0000-1371 | 22-26 | 0000-1350 | 32-36 | 0000-1347 | 63 | 20 |
Golf IS42S | 117-125 | 1.5 | 0000-1373 | 22-26 | 0000-1350 | 32-36 | 0000-1347 | 63 | 25 |
Hotel IS41 | 127-135 | 1.4 | 0000-1343 | 22-26 | 0000-1350 | 32-36 | 0000-1348 | 73 | 20 |
Hotel IS42 | 127-135 | 1.4 | 0000-1371 | 22-26 | 0000-1350 | 32-36 | 0000-1348 | 73 | 20 |
Hotel IS42S | 127-135 | 1.4 | 0000-1373 | 22-26 | 0000-1350 | 32-36 | 0000-1348 | 73 | 25 |
India IS41 | 110-118 | 1.5 | 0000-1344 | 42-46 | 0000-1349 | 25-29 | 0000-1345 | 43 | 20 |
India IS42 | 110-118 | 1.5 | 0000-1372 | 42-46 | 0000-1349 | 25-29 | 0000-1345 | 43 | 20 |
India IS42S | 110-118 | 1.5 | 0000-1374 | 42-46 | 0000-1349 | 25-29 | 0000-1345 | 43 | 25 |
Juliet IS41 | 120-128 | 1.4 | 0000-1344 | 42-46 | 0000-1349 | 25-29 | 0000-1346 | 53 | 20 |
Juliet IS42 | 120-128 | 1.4 | 0000-1372 | 42-46 | 0000-1349 | 25-29 | 0000-1346 | 53 | 20 |
Juliet IS42S | 120-128 | 1.4 | 0000-1374 | 42-46 | 0000-1349 | 25-29 | 0000-1346 | 53 | 25 |
Kilo IS41 | 130-138 | 1.4 | 0000-1344 | 42-46 | 0000-1349 | 25-29 | 0000-1347 | 63 | 20 |
Kilo IS42 | 130-138 | 1.4 | 0000-1372 | 42-46 | 0000-1349 | 25-29 | 0000-1347 | 63 | 20 |
Kilo IS42S | 130-138 | 1.4 | 0000-1374 | 42-46 | 0000-1349 | 25-29 | 0000-1347 | 63 | 25 |
Lima IS41 | 140-148 | 1.3 | 0000-1344 | 42-46 | 0000-1349 | 25-29 | 0000-1348 | 73 | 20 |
Lima IS42 | 140-148 | 1.3 | 0000-1372 | 42-46 | 0000-1349 | 25-29 | 0000-1348 | 73 | 20 |
Lima IS42S | 140-148 | 1.3 | 0000-1374 | 42-46 | 0000-1349 | 25-29 | 0000-1348 | 73 | 25 |
Mike IS41 | 117-125 | 1.7 | 0000-1344 | 42-46 | 0000-1350 | 32-36 | 0000-1345 | 43 | 20 |
Mike IS42 | 117-125 | 1.7 | 0000-1372 | 42-46 | 0000-1350 | 32-36 | 0000-1345 | 43 | 20 |
Mike IS42S | 117-125 | 1.7 | 0000-1374 | 42-46 | 0000-1350 | 32-36 | 0000-1345 | 43 | 25 |
November IS41 | 127-135 | 1.6 | 0000-1344 | 42-46 | 0000-1350 | 32-36 | 0000-1346 | 53 | 20 |
November IS42 | 127-135 | 1.6 | 0000-1372 | 42-46 | 0000-1350 | 32-36 | 0000-1346 | 53 | 20 |
November IS42S | 127-135 | 1.6 | 0000-1374 | 42-46 | 0000-1350 | 32-36 | 0000-1346 | 53 | 25 |
Oscar IS41 | 137-145 | 1.5 | 0000-1344 | 42-46 | 0000-1350 | 32-36 | 0000-1347 | 63 | 20 |
Oscar IS42 | 137-145 | 1.5 | 0000-1372 | 42-46 | 0000-1350 | 32-36 | 0000-1347 | 63 | 20 |
Oscar IS42S | 137-145 | 1.5 | 0000-1374 | 42-46 | 0000-1350 | 32-36 | 0000-1347 | 63 | 25 |
Papa IS41 | 147-155 | 1.5 | 0000-1344 | 42-46 | 0000-1350 | 32-36 | 0000-1348 | 73 | 20 |
Papa IS42 | 147-155 | 1.5 | 0000-1372 | 42-46 | 0000-1350 | 32-36 | 0000-1348 | 73 | 20 |
Papa IS42S | 147-155 | 1.5 | 0000-1374 | 42-46 | 0000-1350 | 32-36 | 0000-1348 | 73 | 25 |