9point8 Announces New ZS & EC Slack-R Cups

Dec 13, 2023
by 9point8  
Slack-R Head Tube Cups

PRESS RELEASE: 9point8

Following our popular Slack-R IS standard adapters, our Slack-R headtube angle adapters are now available for the EC/ZS standard. Customizable combinations of upper and lower cups will provide up to 2.8 degrees of headtube angle adjustment, and are design for creak free operation

Details:
• Upper headtube bore: EC44, ZS44
• Lower headtube bore: EC49, EC56, ZS56
• Creak-free design.
• Large range of possible headtube angle adjustments (0.8 to 2.8 degrees).
• Mix-and-matchable, pair ZS Upper Cup with an EC Lower Cup or vice versa.
• USD $99 (free shipping in NA) for a kit that includes an Upper and Lower Cup, and everything else that is needed.
• Available NOW!
Exploded view of Slack-R EC Parts and Tools

Slack-R gives you an easy way to tweak the geometry of your bike, exactly as you want.
Slack-R EC Cross Section
Slack-R EC44 upper cup and Slack-R EC56 lower cup section view.

A popular reason is to “modernize” the geometry of any bike by slackening the headtube angle. When put onto bikes with modern geometry, it can change its manners to be biased towards steep and fast terrain.

Slack-R EC installed on bike.

The HTA delta can range from 0.8 to 2.8 degrees depending on the cups selected and the geometry specific to your bike.

There are two upper and lower cup types available: an internal cup, Zero Stack (ZS style) with small offset, or External Cup (EC style) with a larger offset. They can be mixed and matched to achieve the angle delta that you are after.

Slack-R Available head tube standards
Available Slack-R headset cup sizes.

The image below demonstrates how the resulting delta HTA changes depending on the headtube length even when using the same upper and lower cups.

Slack-R Head Tube Cross Sections

The specific geometry changes you will see on your bike will depend on the headtube length. The filters on our product page can guide you through the available options for your bike.

All of our Slack-R kits are all made of 6061 Aluminum and weigh between 57g and 104g depending on the configuration.

Slack-R kits include new headset bearings and seals, star nut, head set cap, and a custom install tool for pressing the Slack-R cups into your bike frame.

Complete photo of all of the components of the Slack-R ZS EC product group.

Our service team will be happy to answer any questions about Slack-R, to help you find the right solution for your bike.

Find more information at 9point9.ca

Posted In:
Reviews and Tech Press Releases


Author Info:
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Member since Apr 29, 2015
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65 Comments
  • 83 0
 Haven't you seen Henry's predictions? Slack-R is so 2023, 2024 is all about Steep-R.
  • 51 0
 Turn it around and it is a Steep-R. Got that covered
  • 2 0
 I’m confused, which is the cool way to install my angle set now? I’ve got a bike picture to post and I need the likes.
  • 21 0
 @thenotoriousmic: install it sideways to put your front wheel off-centre. Concentric-Aligned Steerer Handling-Governed Ratio Bikes - or CASHGRaB for short - gives you more stability in turns to your weaker side and more carving when turning to your strong side. Of course, your current frame, headset, and fork are incompatible with CASHGRaB, but new CASHGRaB-compatible products are coming to market as we speak.
  • 40 0
 I’d lean towards getting one.
  • 36 0
 To what degree do you need one though?
  • 18 0
 @jubs17: 9.8º
  • 15 0
 @kkmb: I wondered what angle the next commentor would take for their joke.
  • 12 1
 I've been meaning to get one for a while, but I've been slacking.
  • 2 0
 @yupstate: my take is that you have lost leverage, you need change position asap.
  • 3 0
 The angle of the dangle is proportional to the throb of the nob..............
  • 18 0
 Put it in the donut
  • 9 0
 I put a Works Components Angle Headset on a 2006 Turner DHR which I got for $500 and it is now a perfect park-sled. Highly reccomended!

www.pinkbike.com/photo/25993337
  • 12 2
 If you have to change headtube angle 2.8 degrees then your bike may need other updates as well.
  • 10 0
 My 2023 Epic Evo can also be my enduro bike now!!!!
  • 2 0
 There are options of nominally 1.0, about 1.6, about 1.9, and nominally 2.5 depending on how you pair the ZS and EC upper and lower cup options, and then the actual head tube length will affect the achieved head angle change, hence the total range quoted. The benefit of the 2 middle options is deciding if you prefer to raise or lower the BB with the head angle change. An EC top and ZS bottom will lower the BB a bit, and a ZS top and EC bottom will lower the BB a bit. Agreed that 2.8 is pretty extreme, but is simply pairing the EC upper and lower option.
  • 2 0
 The big advantage I see, especially with the external load cups are making a full 29er mullet. Bump the forks travel up 10mm + the 10mm of the lower cup and your BB height is close to stock. Have the angle set in the steep position and your head angle is close to stock. I’d run these on the new Jeffsy.
  • 1 0
 I put one on a hardtail. It made the bike better for my riding. Then, I was like, "I got a hardtail"... so it wasn't so much the bike needed updates as much as I just went FS a few months later.
  • 1 0
 @HenkkaK Nah, not that one. With the HA mod combined with the well known and tested link mod, the bike becomes pretty modern and for a Park bike, the rest of the geometry is brilliant. It needs a new chain device, but other than that it's good for park-playing. The resulting lowering of the BB makes it feel like any modern park-sled with 26" wheels. A bit of shimming and tuning of the fork helps as well. Ya just gotta know what you're doing.

Don't knock it until you've tried it! And putting about $700 into a park bike is brilliant as a bike #7.

Mind you, it's not a DH-race bike. For that I have a proper DH bike.

More about the link mod in the comments here: www.pinkbike.com/news/now-that-was-a-bike-john-kircaldies-turner-dhr.html (you can also see it in the photos)
  • 9 0
 Spire owners were able to get out their wallets until they saw no ZS56 upper cup. Back to Works Components!
  • 2 0
 We going Steep-R on the spire?
  • 1 0
 @Ccouch5859: Given that your choices out of the box are 63 or 62.5 - yeah, steeper is usually the choice. Usually when the Spire owner discovers they might want to ride it on a trail that has turns. Smile
  • 1 0
 @Bro-tato: high bb plus and a +1 works is real nice on the Spire.
  • 3 0
 Funny question for the engineers: If I put a Angleset made for a 105mm HT in a 130mm HT doesn’t that cause stickiness because the bearings are not aligned? Works has HT specific Anglesets and I have one from my yeti spare but now that 2024 comes around might steepen the G-Wagon.

Anythoughts?
  • 2 0
 When I think back to geometry lessons, you should be absolutely right.
I'm also curious how prone angle sets are regarding misalignment (radial angular offset upper to lower cup). Can anyone share experiences?
  • 2 0
 @Munne: as for allignment I can tell from experience that they are pretty sensitive — if it’s not on point you’ll be eating through bearings. I had it pretty well aligned but still had more bearing wear then with a conventional headset. But there is also of course strong variance between different headsets itself.
  • 1 0
 @ESKato: A typical angular contact bearing can tolerate up to 1deg of misalignment without a major impact on durability. Keep in mind headsets are a weird use case that actually turns very little and very slowly compared to what these bearings were designed for (continuous rotation), so that may throw off my assumptions.

But if the 1deg tolerance holds, these should be fine - if the angle of the bearing seats is designed for the middle use case of 1.8 deg, then even in the most extreme, short head tube scenario (2.8 deg) it is still only 1 deg out of alignment. It may even be less than that, as the more offset options may skew higher than 1.8 deg at the bearing seat.
  • 1 0
 The cups in the 9point8 Slack-R kits accommodate the full range of head tube lengths while keeping the upper and lower bearings square to the steer tube so the bearings run free. I would suggest cups designed for a specific subset of headtube lengths should not be used on headtubes outside this range.
  • 1 0
 The Slackerizer angleset from Superstarcomponents indeed comes head tube length specific in 15mm increments or so iirc. Depending on the type of bearing, it matters a lot. Not only for durability but also to actually reach the targeted change in head angle. I can imagine there are ways to allow for some wobble room in the bearings if the bearing cups are designed accordingly.
  • 3 0
 I’ve run 2 sets on 9.8 headsets to give some older bikes a longer life. Super happy with the quality and customer service. Stoked to see more options!
  • 1 0
 I bought one for my '17 Trek Fuel EX a year back. Works exactly as intended and not too tricky to install. It does change other elements of the geo so a higher bar or (gasp!) longer stem may be needed for reach/stack adjustment etc.
  • 3 0
 What happens if you install these a bit crooked? Always wondered how to get it straight or just eyeball it?

Also, does this add stack height at all? Thanks
  • 1 0
 It is recommended to mark the frame for center top and bottom, and align the cups to these center lines. A small error shouldn't be a problem, but the handling may get weird if the front wheels is not on the center of the bike. In terms of adding stack, it depends on the options selected. The nominal 1.0 degree kit does not add any stack compared to a standard ZS headset. The nominal 2.5 degree kit adds about 8mm at the crown race and about 6mm at the stem. With the intermediate kits you can mix and match the upper and lower cup options to control where stack is added. With slackening the fork, and if no stack is added at the crown race, the BB will drop a bit. The other options will either keep the BB unchanged or slightly raise it.
  • 1 0
 I assume this doesn't play good with frame warranty... but I am more interested in - does it actually increases the chance of headtube cracking from increased load?

Generally in my experience, some bike manufacturers allow installation longer travel forks, but within 10mm and 0.5 degree change
  • 2 0
 I member that time hardtail party was shaving down the headtube on his buddies carbon chameleon to fit one of these. Id rather over fork and call it a day.
  • 4 1
 Only issue is the higher bb and slacker seat angle.
  • 2 0
 @LukeDeGriselles: Actually if you use the ZS lower and EC upper combo, the BB will lower if installed in the slackening orientation. If you pick the opposite, so EC lower and ZS upper, the BB will come up a bit, and if you opt for the EC upper and lower pair, the BB will stay in about the same spot. Of course how much these slacken the head angle will be different depending on the pairings.
  • 2 0
 As far as I can tell this is a great option. With wolftooth and their ZS, EC combo I could only go 1° slacker. With this headset is possible to go 1,6°.
  • 3 0
 Slack-R is dead, long live the Stack-R!!!
  • 1 0
 2.8 degrees sounds more impressive than .0489 radians.

It’s amazing how much downhill performance you unlock by making your bike .0175 radians slacker!
  • 3 0
 It makes your bike way more rad!
  • 2 0
 @big-red: Rad-R?
  • 1 0
 I put one of these onto my 2019 Norco Sight with a 150mm lyric. Perfected the geometry on that bike I’ve been super happy with it
  • 3 0
 What's the angle here?
  • 2 4
 Press release fails to mention the required 14mm insertion depth. So you have to remove your old headset to check first before you buy one?

I cant think of a single other headset that needs a 14mm insertion for the upper cup, good luck fitting these.
  • 2 1
 Some Nuke Proof EC44 lower headset cups have an insertion of 16mm or so. Not a problem with steel frames that are the most common frame type utilizing the "straight can" 44mm headtube.
  • 5 2
 @jukka4130: None of these headsets are 44mm so none will fit straight can 44mm headtubes.

As I say, how many modern carbon / aluminum frames are prepped to a 14mm insertion depth miminum?
  • 2 0
 Didn’t they say they have a compatibility guide on their website?
  • 2 0
 Add my Intense Tracer 2017 carbon frame. Already converted. Shit load of space for upper and bottom cup.
  • 3 0
 From my experience, most frames are reamed to about 20mm if not more. Never seen one where I'd say this wouldn't fit. Easy way to check tho would be to remove the fork and look how much space there is left above/below your current cups. Then add your insertion depth of the old cups and you'll know for sure.
  • 2 1
 @NickBosshard: Easiest way to be sure is to buy a headset that doesn't have an unnecessarily large insertion depth - they know themselves its a point of issue or why else clearly mention it, no other headset manufacturers do.
  • 1 0
 Curious as to by how much this changes the stress on the front triangle and if it comprises it?
  • 1 0
 ^Compromises
  • 4 0
 I've still never seen anyone break a headtube from over forking, I think its a wives tale. If it was a genuine concern (not just a gmbn talking point) people would have stopped over forking and using angle sets a long time ago.
  • 2 0
 On my old 134 I went from 68 to 65 deg (140->160 fork and -2ang set). Never had any issues and downhill it was noticeably more stable/comfortable.
  • 4 0
 I've ran angle sets in my trail bikes now for several years. I've never had a headtube crack or fail or show any signs of fatigue at all. DH bike HTA on the trail bike is a blast.
  • 2 0
 My frame allows a dual crown so it should be ok and .8 should be enough not 1 degree.
  • 1 0
 Very useful. And good price. Can even save the 65.5 headangled carbon bike featured today.
  • 2 1
 Thank u.. I have been waiting for this for my dreadnought.
  • 8 2
 Been available from Wolf Tooth, SS and Works Components for years, what you been waiting for?

You might want to check your frame is happy with a 14mm insertion headset too.
  • 1 0
 good for my 2016 yeti sb6c, 1 deg to 64.50
  • 1 2
 straight tunes won't work
  • 1 2
 tubed
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