9Point8 Slack-R Headset Review

This is where you need a third hand or handy friend

It was a moment of comedy confusion when I cam to the installation of my Slack-R. - How do I hold all this together and the extension and the socket, and the tool... Eventually I purposefully over rotated one cup past the centreline so that on tightening it would come back to central, I had to eye it up and couple of times and it still took a bit of faff-on but (more through luck than judgement I suspect) got it lined up and tight. I also had a bit of binding at full handlebar rotation, but that eased off after a while. I periodically check it, and its remained solid.

Impressed, its a good bit of kit, does what it says, can be installed pretty easily at home, is well finished, and looks the part.

Haven't these been around for years though? I'm sure i considered one of these for my old santa cruz abour 4 years ago.

Scary maaaaan - invented this in my head only last week and it's already manifested in earthly form

^ username checks out 🤣

Agree with many of the points raised and mine currently looks like the one Chips removed with the centre part still fitted to one cup. That frame ended up an unrelated warranty so I haven't found the need to refit but might do so at a later date. I'll likely 3d print something to try stoping the cups rotating during fitting. Wonder if they could extend the tool's length a little and fit an o ring to get around the tool dropping out all the time? That might make fitting easier too.

I've realised that if I'd turned the frame upsidedown, that would have at least stopped the tool falling out. It's something that would be way easier to do from new, with a blank frame, rather than with the forks hanging off the front brake hose, trying to feel or see where the grooves were on the cups with a head torch...

I think I fitted mine using both hands AND my mouth!

THERE'S your extra hand!

DrP

Great review. Thanks for all the installation insights; it's always helpful to know these things up front.

It's not often a bloke my age wants to be a bit slacker up front, but in this case, this is just the kiddy.

@chipps did you ever consider the potential alternative of going up to a 140 or 150mm fork?  Yeti are now saying that (even the older '21) Arcs can run up +20mm forks from the stock 130.

@danieljohnreynolds - I briefly did. However, I only had 130mm forks to hand. Also, while jacking up the front end with an extra 20mm of fork will slacken the head angle by (only) about a degree, it'll do the same to the seat angle, which was already on the edge of a little too slack for modern times..

Am I right in thinking you need to buy a conventional type headset that fits in the Slack-R ?

Am I right in thinking you need to buy a conventional type headset that fits in the Slack-R ?

Good question. My assumption had been that your existing bearings would slot right in to the Slack-R but perhaps the Slack-R needs a specific bearing that may or may not be what you already have?

Am I right in thinking you need to buy a conventional type headset that fits in the Slack-R ?

The bearings I took out of the Yeti headset just dropped into the slack-R cups. This type of design is intended to provide a solution for bikes with integrated headsets, it does that by effectively making it a conventional design, but the cups still use the same bearing sizes.

Oh nice. I thought Chipps had needed to buy a Hope to fit the Slack-R cups, but that must just be the top bearing cover he had on pre-SlackR. cheers!

I fitted one of these kits a few weeks ago and did what nickc did when fitting. Couple of attempts were needed but got it spot in the end. Thing is I’ve not been out on the mtb bike since so I’ve not tried it out yet.

I had one fitted one to my Arc too and am very happy with how it rides, still climbs very well too

No issues at all with it, fitted by my LBS though, no creaks or slipping

Looks super neat, almost looks part of the frame

My frame is an XL and I went for a 1.7° kit (Mike)

Actual measurements were about 2° slacker and about 25mm longer wheelbase

Very cool. Any idea on how it affect other Geo numbers.? Namely BB hight and SA.?

@Sea-Urchin

I took quite a lot of measurements before and after with the bike in exactly the same position.

Seat angle - no measurable difference (within 0.5°)
BB height - 2mm higher

Obviously my measurement methods are not super accurate (e g. lying on the floor squinting with a tape measure) but "not much" is the answer

@Sea-urchin:

it is basically two adjustments:

‘first is that it creates an external cup on the bottom of your head tube/top of fork crown. So, like going to a longer travel fork, this will raise the front, which also slightly raises the BB, and slackens the head angle and the seat tube angle.  The rule of thumb is 0.5 degrees per 10mm, all though his does depend a lot on wheel base.

But, it also changes the angle of the steerer inside the head tube, which will slightly drop the front end again, so the net result will be very little raise to the front end, and even less to the BB. Similarly, the seat tube angle won’t change as much as just adding the externa cup would have.

My wife had an older, but nice, Stumpjumper a few years ago. We passed  it to our 11 year old daughter, knowing she would grow. But, she was already riding some quite challenging trails, and racing local enduros, so the 65 degree head angle was quite steep, especially as it had older forks with 51mm offset (even with a mullet set up).

Adding this gave the bike the extra degree to get it inline with modern geometry. Worked great and she rode, raced (and won!) on it for 2 years. Now she has out grown it, but for 2 years, this buying kit was much better than a whole new bike.

I used one of these on my 2018 hightower lt - now wondering exactly why I decided to take it off again. One reason was the bike really didn’t want a slacker seat tube, even 0.5 deg, I think the other is just that although it felt more stable when fast, the overall balance of the original geo was pretty good for my local twisty trails.

Removal wasn’t entirely straightforward and the slackr cups have some marks left by my stilson wrench