Review: Diaz Suspension Designs' RUNT Fork Cartridge

Oct 1, 2020
by Daniel Sapp  

Diaz Suspension Design, or DSD, is a small company based in Durango, Colorado, who offer a variety of suspension tuning services and products. Their fork cartridge, the RUNT, is designed to increase tunability in a fork by replacing the stock volume spacers with an air cartridge that they claim improves the ride quality and adds a coil-like feel, with a wide range of adjustment and a greater amount of suppleness than the stock configuration.

The RUNT is available for a variety of popular forks, including Fox 34 and 36, RockShox Lyrik, Pike, Yari, and Marzocchi Z1 and Z2.
RUNT Details
• Replaces volume spacers on air-sprung forks
• 2-chamber
• Simple installation
• Tunable progression and bottom-out resistance
• Available for Fox 36, 34, Marzocchi Z1, RockShox Lyrik, Yari, Pike, and Revelation
• MSRP: $200 USD
• www.diazsuspensiondesign.com


DSD claim the RUNT combats some issues that air springs have. One of which is achieving a steady linear compression, as air naturally compresses at an exponential rate. A lot of times, compression damping can be used to combat this but, according to them, it's not ideal and compromises small-bump performance. Running less air can help small-bump performance, but that can reduce mid-stroke support, and then things can ramp up harshly at the end of the travel.

By having an air chamber instead of tokens to reduce volume, the RUNT is designed to work around this issue and provide the correct amount of support for riders. When the air pressure in the main chamber is equal to the pressure in the smaller high chamber, there is a floating piston in the high chamber that begins to move up with the piston in the lower chamber. This allows for a more linear pressure curve and, according to DSD, a better ride.

The piston in the RUNT moves when pressure in the main chamber of the fork equalizes.


Setup/Installation

The installation of the RUNT is straightforward. If you've ever changed volume spacers in your fork, it's that easy to drop in the RUNT. If you haven't, you'll need to ensure that you've let all of the air out of the air chamber on your fork (note your current air pressure ahead of time) and then you will remove the air cap and any volume spacers. Drop in the RUNT in place of the top chamber cap, air things up, and you're good to go.

Setting up the air pressure is simple. The team at DSD recommend taking the pressure you're currently running in the air chamber and using that as your starting pressure in the LOW chamber. For the HIGH chamber, you'll double that number to give a 2:1 ratio and a linear spring curve. If you want things more progressive, you can add pressure to the HIGH chamber which will make the curve more progressive in the last third of the mid-stroke. They also suggest that many riders end up using a little less pressure in the LOW chamber than they previously had been running without the RUNT.

Bigger than a stack of tokens but with more tunability.

I set the RUNT up on a 160mm travel Fox Factory 36 with the GRIP 2 damper. I started out with 63psi in the LOW chamber but ended up dropping down to 58psi there with about 110psi in the HIGH chamber. I experimented with running a little more or less in both and the differences that it makes in ride quality are noticeable. DSD recommend making small changes - 2.5psi at a time in the LOW chamber and 5psi at once in the HIGH chamber.

For damper settings, I went with DSD's recommended wide open HSC and LSC while closing the HSR. LSR was a few clicks in from fully open.

It's worth noting that DSD can include shims with the cartridge to revalve your fork to what they feel is a better tune or, you can send your fork in to them for a custom tune along with the cartridge as well to get the best performance. We tested only cartridge itself, without a fork tune or revalve for a true back-to-back in how it works in place of tokens, revalve aside.


Performance

With the cartridge installed in a 2020 160mm Fox 36, the difference in the amount of support throughout the travel of the fork was noticeable. At the suggested 2:1 ratio, with the same PSI I had been running in the factory set up, it was a bit too firm for my liking. There was plenty of support, but that came at the expense of comfort. I then dropped down the air pressures in each chamber while keeping the 2:1 ratio. That made a noticable difference - the increased support was still there, but the slightly harsh feeling was no longer present. This setup felt especially good on bike park style trails, where there were high speed, hardpacked corners to push into.

I experimented with running a little more and a little less air in both chambers on various back to back runs. The cartridge allows a much wider range of adjustment than can be attained with tokens alone. It was easy to make it feel extra plush yet still supported in rough, rocky sections of trail by running a lower pressure in the large chamber and a touch more than 2:1 in the high chamber. This gave lots of active suspension and traction with plenty of ramp up to avoid a harsh slam at the end of travel. On the other end of the spectrum, it was easy to air up closer to the recommended pressures and the 2:1 ratio to ride jump lines and feel like I wasn't plowing through the travel in turns and off of lips. Even when running the fork a bit soft the transition through its travel was smooth and well supported, with a nice ramp up at the end of the stroke.

It's the ease of tunability that sets the RUNT apart more than anything else. Rather than adding or removing a volume spacer trailside, riders can easily add or remove air pressure. It allows for easier fine tuning than what's possible with volume spacers, and could be a good solution for riders who are looking to really dial in their set up.

Pros

+ Well made, easy to install
+ Wide range of adjustability
+ More support
Cons

- May not be a dramatic difference from the stock configuration
- Not a cure-all for poor suspension performance



Pinkbike's Take
bigquotesThe RUNT is an easy way to add a lot of tunability to a fork in a way that is easy to understand. It works great and I wouldn't hesitate to recommend it to a hard charging rider looking for the extra support or the versatility that it offers.—Daniel Sapp





Posted In:
Reviews and Tech Reviews Suspension Fork Diaz Suspension Designs Diaz Runt


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197 Comments

  • 140 6
 Manitou have done this for years.....pity most people don't appreciate their forks.
  • 19 0
 I must ask the experienced here, how's the damping on the manitou forks.
  • 302 5
 @knightmarerider: It has its ups and downs. I'll get my coat.
  • 14 0
 @knightmarerider: all depends on the right setting. if you have the right setup, they work extremly well.
And: a complete service can be done in 30 minutes.
  • 45 0
 Couldn't agree. Owner of 2x Mezzers and Mattocs. They make an exceptional fork out of the box. No aftermarket band aids needed
  • 21 0
 * couldn't agree more
  • 9 0
 @knightmarerider: damping is great. I’d say that they are at the pointy end of the market, and definitely worth considering for an upgrade. A mate just swapped out his vorsprung tuned Factory 36 for a Mezzer.
  • 5 3
 So did they fix the Steeger tube tolerances and the Dorado effect?
  • 10 1
 did they fixed the loose bushing problems ?
  • 1 0
 @woffa04: where'd you get your mezzer? Was looking at buying one a couple of months ago but couldn't find an Australian seller!
  • 4 2
 i have 2018 Fox Factory 36 and a 2019 Lyrik, I also still have a 2015 Magnum thats still going strong on my hardtail, i also had a travis ti years ago. The only thing i can fault Manitou with is the stupid 8mm hex footnut.
  • 2 0
 @SoddenDeath: Shockcraft
  • 9 0
 @Noeserd: according to NSMB they have. They have reported no issues after the first run of mezzers
  • 5 0
 @knightmarerider: very good. The old ABS+ damper on my Minute handily beats the one in my 32 TALAS RL and the MC2 damper in my Mattoc easily beats the GRIP on in my 34 Performance.
For certain types of riding a GRIP2 is very good. I just have a feeling that the damper in the Mezzer has a broader range, catering to both slower riders that want comfort and hard charging riders that would also be very happy with a GRIP2.
But as a short answer, the damper on any Manitou fork will not be the limiting factor compared to other manufacturer's forks of the same price level.
  • 5 0
 @dark-o: I believe they did. The Dorado effect was a thing on the first Mattoc models but fixed with new parts (that can be swapped on old forks as well). The steerer tube tolerances were a QC problem that I don't read about very often lately. I assume they got it under control, but I'm not 100% sure.
  • 3 0
 I'm running a mezzer and dorado. Both are exceptional forks once you set them up.

I can't wait for the proper 29" dorado. I'll be putting it on the front of a mullet supreme when it's available.
  • 3 0
 Having a guy updating the legendary dorado to match the mezzer, I would only think it is amazing!
  • 6 16
flag kubikeman (Oct 1, 2020 at 4:42) (Below Threshold)
 Rock Shox too! I had a Revelation Dual Air years ago. There was a positive valve at the top of crown, and a negative valve at the bottom of the leg. It was a bit fiddly to set up, but the performance was awesome.
  • 12 0
 Manitou also has great customer service.

+1 for Mattoc Pro
  • 5 0
 @knightmarerider: my mattoc expert had pretty flawless damping. One underrated feature of the damper it had was you got only 4 clicks of hsc and lsc, which actually is a huge plus side since you can find a pretty spot on setup without too much faff
  • 8 0
 @kubikeman: that is different to what manitou with IRT or RUNT does though...
  • 9 27
flag Grosey (Oct 1, 2020 at 6:08) (Below Threshold)
 Its 100% the reverse arch that makes me not want a mezzer. Its goofy looking. Im sure plenty of parts on my bike can be made unorthodox and work great - but why??

Short travel Dorado has a better chance of landing on my trail bike than a mezzer.
  • 8 0
 @knightmarerider: Did comparison video between the Mezzer and Zeb Ultimate. Zeb wins for all out stiffness but Mezzer smoothes out braking bumps and feels overall more supple throughout it's travel. The IRT is really effective and you can dial it in to your liking with just a shock pump. Great fork
  • 21 0
 @rpl3000: I have to agree withthe great service. I bought a used Mezzer and broke off the threads on the bottom of the damper. I should have used a torque wrench. I called to see if I could buy the part. I explained to Eric that I bought it used, but he send me a whole new damper for no charge. Installing the damper, I realized I have the older casting and bottom out bushings. That is why I overtightened the footnut initially. I replied to his email that I had the old castings and he is sending out the new updated castings and bottom out bushings for no charge. I cannot believe that they are doing this for a second hand owner.
I have six or seven rides on it and it is the best fork I have ridden. It is also easily serviced and travel change is a breeze.
I am a new Manitou convert and impressed by their customer service. My only complaint is the shipping time.
  • 20 0
 @Grosey: why? Because, as Manitou explains everywhere, the reverse arch increases stiffness:weight ratio. In a perfect world all forks would use this design. Side benefit: keeps mud away from fork seals.
  • 5 0
 @knightmarerider: Once I wear out my Yari I'm moving over to the Mezzer. Spent a month on it through a demo and loved it. The PB review article did cite bushing play but that has been resolved now.
  • 5 0
 @frorider2: I'm not sure how significant the first point is (Minutes didn't seem extremely stiff but the Mezzer is relatively light for its stiffness) but the second point is definitely true.
  • 10 0
 I have a Mezzer at 170mm/29er and a I have a Lyrik at 180mm/650b with the DSD Runt + a Push HC97 (different bikes, so take with a grain of salt):

The Mezzer feels stiffer out of the box, tad bit more precise even with the bigger wheels (both bikes have carbon wheelsets). It's not a huge difference, but it's noticeable.

The Lyrik (RCT3, Charger 2.0, 2019 before mods) has a tad bit easy break-away in parking lot test. I attribute this mostly due to the large negative chamber "suck-down" that rockshox "fixed" in the latest update. On the trail, this really doesn't affect much, except .. maybe.. a bit smoother at low speeds.

To me, the Mezzer wins at real trail speeds - composed, soaks up chunk, & chatter, and has a more linear overall feel at least how I have it setup. It also more easily rides higher in the travel (again, this may be "fixed" in the updated airspring on the Lyrik). The Lyrik with mods is no slouch by any means, but Mezzer is just a bit better all around.

The HBO on the Mezzer is excellent. I can get a gradual ramp up (more linear) and still have bottom out support on the stupid lines or hucks. The Lyrik always felt that it was harder to get full travel, smoothly.

Both setups require more tuning to get "just right" given the extra variables to play with. The adjustability of travel in sub 15 mins internally on the Mezzer is rad too if you want to experiment with travel.

Moral of story - adding the air chamber is a net positive , IMO. I doubt I will ever use volume spacers again if I can avoid it.
  • 2 0
 @Mac1987: I had a real old minute 3:00, and even though I had no clue how to set it up I absolutely loved it. Flexy as hell cuz it was from 2005 but dang, that thing was impressive. Every bit as nice as a top end Fox fork from the same era. I tried out a new Markhor too, as a budget fork it works exceptionally well for the price.
  • 8 0
 @knightmarerider: Have a Mezzer and my brother just got a bike with the new Zeb. Long story short, he's buying a Mezzer.
  • 6 0
 Funny thing here is, every now and then here in the comment section someone claims that Manitou forks are underrated. And you then end up with a long thread full of people raving about Manitou forks. Makes you think they're probably not underrated at all Wink .
  • 13 0
 @vinay: perhaps underexposed is the better word for it. Most everyone seems to love them (the Pinkbike review is the lone negative I have ever seen) but it seems like when it comes time to buy a new fork it isnt at the top of most peoples minds.
  • 7 0
 Came here to see all the Mezzer fanboys, wasn't disappointed.
  • 4 0
 Manitou IRT
  • 4 0
 @Waldon83: someone has to do some marketing for them. They just seem to let the results speak for themselves.
  • 3 0
 @Onetrickpony: Advertising as a manufacturer is so hard, I really feel for them as I'm a manufacturer myself. The cost to saturate the market with enough advertising can be cost-prohibitive for smaller players. Where they really fall down is on inbound marketing. They need to start making content that people want to watch, or find helpful and let the brand awareness grow that way.
  • 2 8
flag toddyfreerider (Oct 1, 2020 at 17:00) (Below Threshold)
 Manitou are two joys, one when you buy and another when you sell
  • 1 0
 @Keepiru: at least, you don’t loose time to service the fork after each descent. Or after you don’t touch your bike during one day.
  • 3 0
 @Waldon83:
They are for a reason ;-)
  • 1 0
 @meSSican: Just subbed. Cool channel!
  • 1 0
 @knightmarerider: best fork.
I have the dorodo and mattocks....super sick
  • 2 0
 @knightmarerider: TPC+ is amazing, even going back as far as the Travis from 2006/7
  • 57 2
 Damn, I need to fix that poor performance of my $1500 fork, it's unacceptable!
  • 38 0
 With all these aftermarket springs and dampers nowadays, it would be interesting to see the modified forks tested against the originals. Can a Yari with Vorsprung/AWK/etc replacement springs and dampers perform better than a top end Lyrik fork? And is it even more expensive?
  • 5 0
 YES that is a great idea.
  • 5 2
 Yari and Lyrik are the same chassis....
  • 10 3
 I have a RUNT in my Lyrik Ultimate. Yes, it performs better
  • 16 0
 @SwampThAAng: that's not quite the point here chief
  • 1 0
 @mollow: Yes, you can maximize the suspension performance of a lower cost fork like the Yari, Revelation or Marzocchi with one of these cartridges via a fairly simple and inexpensive manner. I'd say it's within 85%-90% for most people from what is stock and the adjustments are easier to make. It's that last 10-15% of performance that pushes costs way up (custom tunes, etc.).
  • 17 0
 We often do this with Marzocchi Z1 Bombers and Performance Series Fox 34 / 36. The GRIP damper is really good and very tune-able. If customers buy a fork from us, we include a custom tune ($50 value for Grip 1) and tear it down to check the bushing fitment as well as clean all the excess slick honey out of the air spring. We then replace the TSS seals with SKF seals ($40).

So the pricing breakdown is $700 MSRP for a Performance Series Fox fork or Marzocchi Z1. Plus $200 for the RUNT and $40 for the seals = $940. MSRP on a factory series fork is $1100.

It's tricky with the Yari and Z2 Bombers as the dampers are not very tune-able. Functional, but just not up to par with GRIP.
  • 7 1
 @DiazSuspensionDesign:

I'm glad to hear you giving credit to the Yari damper as functional... I can't count how many times I've read how dangerous or useless it is, what a liability it is, from the dentist crowd.

Motion Control dampers have won plenty of races in their day. It ain't fancy but it works, and a Yari is a great way to get down the trail on a budget. I've had Likes, Lyriks, Fox forks, some shitty old Manitou's, and the Yari is a good, serviceable value option.
  • 2 0
 Yeah, I wasn't even thinking in terms of tuning the stock damper unit. Just replacing it with one of these offerings. It seems a bit of a waste to buy a fancy Lyrik fork and then replace the airspring and stock damper if doing the same with a Yari fork would get you the exact same result. Obviously as both Yari and Lyrik are common OEM units, this option may even influence your choice whether to get the top spec or the bottom spec complete bike. Sure there are other bits but if you're happy with your current brakes, are very picky about your dropper seatpost (and/or very anti-RockShox-dropper) and don't care about a carbon frame then it does get interesting.
  • 3 1
 @vinay: they dont have the same damper and this cartridge does not replace a damper. Am I missing something?
  • 1 0
 @mollow: Yeah sorry, I meant to say that there are both replacement spring and damper units available. I mentioned Vorsprung and AWK in my initial post. I should have said Chickadeehill instead of AWK. AWK is their air spring cartridge, COMO is their damper. But yeah there may be more companies doing spring units than dampers. But for instance PUSH also makes replacement damper cartridges. That said, I suppose you can use the spring unit from one company and the damper from another. I think Formula is quite ahead of the game in that they already have so many tuning options for their forks (neopos in the airspring, different cartridges for the damper) that there is no point for anyone else to make add ons for their forks.
  • 1 1
 @vinay: in that case if you're gonna replace the damper of the lyrik, you're right it would be stupid to buy a lyrik over a Yari.
  • 1 0
 @mollow: Yeah, though I think that Yari forks are mostly found as OEM equipment. That said, this may also imply that you can probably get them lightly/not used for reasonable money. So yeah, someone in the market for that kind of fork could get a new Lyrik or instead get such a Yari and upgrade it, possibly to the point that it is better than a stock Lyrik. So that was my question actually, do these upgrades make it better than a stock Lyrik?
  • 1 0
 @vinay: I often think about this as well. The problem is that so much of suspension testing is subjective and so it's hard to say if the author would admit it's better or not, however hopefully they would at least admit there's a noticeable difference. For instance I got talked out of a Mezzer because of Mike Kazimers review on here however after reading some of the comments above I kinda wish I would've given it a try.

The thing I'm interested in is how compatible some of these things are. I feel like a lot of their testing is with an OEM spring or damper on the other side of the fork. So will some of these design features fight with those from other companies? IDK just thinking out loud.
  • 1 1
 @vinay: the chassis is the same, so if you get a damper you prefer over the charger 2, yes it will be better. But suspension feel is subjective, so better for you is not better for everyone. Kazimer is definitely not a reference for suspensions.
  • 1 0
 @vinay: I decided to see how cheap I could build a min-maxed long-travel mullet bike this summer during covid. I didn't want to invest much without being able to demo and that wasn't on the menu this year. Ended up snagging a brand new '20 160mm Yari 29er for $425 using a Labor Day coupon. That beat used prices by at least a $100 on PB buy/sell. I love the bike, but my hands do take a beating on rides over two hours. Thanks for this eye-opening article, PB - I'll likely be investing in a RUNT at some point in the future.
  • 14 0
 Hi seams very similar to the AWK Tunning Kit ? www.chickadeehill.de/fox-36-awk-lt-ii-installation-instructions
  • 21 2
 The AWK existed earlier. The RUNT is just a good copy...
  • 6 0
 Looks like a refined version of this..
flowmountainbike.com/tests/tested-sd-components-dvc
  • 3 0
 @MantaHai: More of a ok one... The chikadeehill products are based on the tolerances in the product itself of higher quality than most of the time the designated fork
  • 11 1
 @MantaHai: And the AWK is just a good copy of the IRT. :-)
  • 6 0
 @pheise: say what?
  • 12 3
 @MantaHai: That's actually not true, the RUNT was available for sale in 2012. The AWK is a copy.
  • 2 1
 @dlstucki: Don't want to uleash a discussion but that's not true. The first mention of the AWK from chickadeehill on german MTB-News.de forum was on 10th of January 2012: www.mtb-news.de/forum/t/rock-shox-totem-review-teil-2.435024/page-43#post-9094359
  • 3 0
 @timmeygasmus:
between mentioning private fiddling in a forum and „available for sale“ is a slight difference. But who cares? The more competiton, the better.
  • 13 1
 For only $200 you can buy one more Manitou feature for your fork. Or just buy a Mezzer in the first place and get the whole set of features Fox and RS can't match.
  • 7 0
 still seems like a nice option if my bike already has (came with) a fork from Fox/RS
  • 5 0
 @mtmc99: No doubt, if the Runt had come out sooner for my old fork, I may have never bought a Mezzer. But I'm glad I did.
  • 13 0
 Didn't Manitou already acheived that with IRT?
  • 5 0
 And Marzocchi with ATA prior to Manitou IRT! Admitting ATA has a very poor rep, but with some tinkering can be made to work very well. 3 air chambers are amazing! I'm running a Dorado with IRT for dh, and a Marz 55 ATA with NCR damper on my hardtail.
  • 3 0
 @mountainjew: If you could keep the ATA cartridge running, it was an incredible fork. To this day it was one of the best feeling fork I've ever ridden. Got pretty good at replacing o rings weekly to keep it going. Lol
  • 9 1
 I run the German counterpart (AWK) in all my forks. For me it's the only way to get the midstroke support I want in steep terrain with air forks. I tried the new debonair shaft but it's performance is far away from what you get with dual chamber systems like AWK, DSD etc. The AWK system is available for many more forks. I recommend it strongly and yes it makes a huuuuuuuuge difference from what you get from stock configuration. The only downside is that it takes some time to get your perfect setup and you need to understand which effect the different chambers have when you change pressure settings.
  • 2 0
 For me setting it up on fox 36 was easy. HSC to 0, LSC almost to 0, LSR with usual "jump" method. I played with pressure a bit but also was like 15 minutes job. Not far from what they suggest on their site. I wonder when will the 38 version will come out cause a new bike needs it.
  • 1 0
 I want this thing for my boxxer, but it seems like the site is german only, is this thing acquirable outside the europe?
  • 7 0
 I echo this. I have been running DSD for a year and a half now and the midstroke on steep terrain and in corners is confidence inspiring. I didn't realize how much my fork dove in those situations until I had this installed. I'm a firm believer in this system.
  • 1 0
 @goroncy: Its interesting that the damper is just wide open now.
  • 1 0
 @Svinyard: What can I say. Doesn't feel like it is. I'm not exactly a weekend warrior and hit that thing hard. Plenty of mid stroke support and a lot of resistance against big drops.
  • 1 0
 @knightmarerider: you need someone in Europe to send it to you as far as I know. I contacted every dealer who sells them and they refused to shit to the US
  • 1 0
 @Svinyard: "Wide open" is still providing damping, just at the lowest end of whatever adjustment range it has.
  • 1 0
 @goroncy: very cool
  • 1 0
 @goroncy: you are either in the 30kg weight range or your setup choice sucks Wink
  • 1 0
 @Helmchentuned: The only time I haven’t been wide open was at the bike park where I added 2 clicks of high speed. I’m 65kg.l so I echo the compression settings. This was suggested by DSD. I used to be 7-8 clicks in.
  • 10 0
 We need a detailed head to head review of the following:

Mezzer vs Zeb Vs 38
  • 7 2
 200 is a lot for just an air spring tune . If the forks damper is rubbish the fork will still not work properly. Spend a lil more on an avalanche open bath damper , it's a game changer .
  • 3 0
 Amen to that. Additionally get their coil/ air hybrid system and it will fix all the air spring issues as well. I recently put that set up in my Liryk and it's unreal how much better it is. Mid stroke support is dramatically better, I didn't realize how much a stock fork dives until I rode them back to back. And it floats through small bumb chatter like it's not even there.
  • 5 0
 AVA doesn´t fix inherent flaws of 2 chamber air spring, just like 3 air chambers won´t fix bad damper tune.
  • 2 0
 @Mondbiker: it will if you run the hybrid coil set up. I agree that the damper alone will not fix the air spring issues but the addition of the coil on the damper side with the lower air pressure in your air spring really does. The additional benefit is that you also have a spring on both sides so seal friction is reduced.
  • 1 0
 @Mondbiker: Also do you think that a 3 chamber air spring alone can fix all of the air spring issues? Vorsprung and AVA both have bolt on reservoirs to increase volume which makes sense to me, although I haven't tried either, but it does make sense that the lack of enough volume in the air chamber would be an issue. Maybe it's a combination of those things to make an air spring perform perfectly.
  • 2 0
 @shami: Totally agree. Didn't think the Avy hybrid could be better than my fork with a full coil spring and the Avy damper, but it clearly is, and with half the weight penalty. It's hard to imagine a fork feeling better than this.
  • 2 0
 @fpmd: I had the same experience, Avy with full coil in my boxxer and it's amazing, put the hybrid set up in my lyrik and it is even better. Truly the best qualities of both coul and air with none of the shortcomings
  • 8 4
 If the reviewer did not adjust his damper settings, this review is only half complete. Especially on a GRIP2 damper that allows so many adjustments.

With a Runt, you really want to back off HSC and LSC, as the support comes from the air spring. Let that damper move, you don’t need to rely on compression damping anymore.

Also, due to the change in the spring curve (vs stock) more HSR is recommended. DSD sent shims to retune the HSR on my Lyrik and recommended I add HSR on my GRIP2. LSR, tune for desired “pop”.

Ultimately - this is a wonderful product (I’ve bought two), but if the reviewer didn’t adjust his damper settings, then this review is only halfway complete.
  • 5 0
 He did adjust. "For damper settings, I went with DSD's recommended wide open HSC and LSC while closing the HSR. LSR was a few clicks in from fully open."
  • 1 0
 @bicycle019: it’s probably took me about 20 hours to dial in each of my two forks with runts that I’ve owned. Lots of adjusting to find the sweet spot, but’s it’s great once you figure it out
  • 4 0
 @bicycle019: good catch. I missed that. (Guess that's what I get for reading a review on my phone while walking the dogs! lol).

I will say this - the Runt'd Lyrik felt better than the Runt'd 36... but I still prefer both forks with a Runt vs the stock airshaft and tokens. Previously I've tried a Luftkappe and an MRP Ramp adjust... so I've been chasing better control of the air spring for a while. To me, the Runt is the best for an aftermarket airspring option.

For a factory first fit option, my Manitou Mezzer takes the cake. That fork is spectacular.
  • 2 0
 @06hokiemtb: Just wait until you try the Runt with a Vorsprung Secus in a Fox 36!!
  • 1 3
 @Xorrox: lol. No thanks
  • 1 0
 @06hokiemtb: What happens when you pair a 36 with Luftkappe and put in a Runt too?
  • 2 0
 @jacksteel: It might go boom. The Luftkappe sticks up higher than the air piston normally does, and the runt sticks down further than spacers usually do.
  • 1 0
 @velodonata: it will only work at 140mm of travel or less
  • 6 0
 Once again, Manitou forks aren’t supposed to get this... probably cause they don’t need it in the first place! Big Grin
  • 5 0
 Manitou is a cool company doing some interesting things. They even have the IRT for some 20/24in kids forks lol. (which is really smart for the extra tunability.)
  • 6 4
 Basically a volume spacer that compresses under pressure so it reduce the harsh ramp up at the end, also it takes out a lot of space from start so it starts ramp up earlier, but smoother at the end. Yeah I like the idea of this. It's basically an aftermarket ramp up chamber.
  • 9 1
 The MRP ramp up chamber doesn't work like this. It's speed sensitive and doesn't necessarily increase mid-stroke support relative to bottom-out force compared to spacers.
  • 3 0
 @seb-stott: I was referring to ohlins and manitou's dual chamber design.
  • 3 0
 @knightmarerider: Ah, gotcha. It's a much better system.
  • 2 0
 It’s a anti-ramp up chamber to get your fork to feel more linear
  • 2 0
 Seems like a good idea, but I ride mostly in two locations (home & cabin in the mountains). I can currently get away with a slight air pressure adjustment (altitude + trail types and lengths) between riding the two locations. This would mean expanding my OCD somewhat with more options to faff about with.

I probably need a coil.
  • 7 0
 Sounds like you'd need two coils.
  • 3 0
 I’ve got one and it really has improved my fork’s performance, especially on steep terrain. The fork is more supple but will still use all of its travel on a bit hit. Totally worth it.
  • 3 0
 Should have added more supple but much higher in its travel. It stays high until you hit hard.
  • 2 0
 My DSD tuned Lyric equipped with a Runt is the best fork I've ever rode. If you're methodical about setup and recording settings, you can reliably set this up for different trail conditions with just air pressure. Way, way different than the effect of just adding/removing tokens. They're good guys too and I have no problem supporting them and promoting their stuff. They know what they're doing.
  • 3 0
 confused person here; if we're saying that a more linear rate is good for the front why is the a trend for more progression the rear?
  • 2 1
 I believe they're talking about a linear rate of progression, so it gets more progressive in a consistent way through the travel, rather than a sudden ramp
  • 2 1
 because everyone is going coil, which is naturally linear
  • 5 0
 @viatch: so we should be looking to make air more like coil and coil more like air? that might sound a little facetious, I guess its trying to find the happy middle ground between the two systems but in opposite ways.
  • 2 0
 @oatkinso: You are exactly right. The problem is that neither spring nor air is good in fork. Fork operation is linear do the whole suspension characteristics depends on how the spring element works. Metal spring is too linear. Air has a ramp up but it's WAY too sudden in the end. That's why you have those super advanced dampers. 2 air chambers basically eliminate need for ANY compression dumping. Why more companies don't use it is beyond me.

When it comes to frames, usage of air makes sense BUT... you have to know the exact tune of your shock. Frame suspension has it's own characteristics which add to those of the shock. Designing a frame for a metal spring is just much easier and can produce more consistent results with different kinds of shocks.
  • 1 1
 @goroncy: im feeling the urge to dust off my 2007 Pike Dual Air...
  • 2 0
 @goroncy: but you need some control of compression damping - you want the fork to stand up in g-outs, steeps and berms, but be compliant on landings or big hits. This doesn't seem ideal if you have to run everything wide open.
  • 1 1
 @oatkinso: you dont get it at all. bike manufacturers and aftermarket brands, perfect example is Cascade components, are forced to "recalibrate" existing or upcoming designs to accomodate coil shocks since i requires a progressive curve so you dont bottom it out on every single pebble
  • 1 0
 @viatch: im sure you'd be nicer in person
  • 2 0
 @oatkinso: Pike was different. That is Positive & Negative chambers you can adjust. The RUNT is a positive low & positive hi chamber. The negative is still equalized through the positive chamber.
With the RUNT you basically set the low to handle the first 3/4 of travel and the hi to open up at a desired pressure for the last bit.
  • 2 1
 @mountainsofsussex: you need rebound control. Everything else is a bandaid for shitty spring curve.
  • 4 0
 @goroncy: compression damping is useful for dissipating energy and essentially calming your suspension down. No suspension designer relies on solely using the spring to store compression energy and have that dissipated on the rebound stroke.
  • 1 0
 I agree.
"One of which is achieving a steady linear compression, as air naturally compresses at an exponential rate."
Linear and exponential rate...It's either wrong or poorly written..
Air compression is progressive and we can use compression to make it more linear (By having more compression then less)...but it's kinda hacky.. it feels more straight forward to have a linear spring and add progressivity with compression
  • 1 0
 @mountainsofsussex: "wide open" on the adjusters means it is providing damping at the lowest end of whatever adjustment range it has. There is still damping

Also, those situations are exactly what they are intending this second air chamber to help with. Instead of relying on your damper which provides support by slowing down the rate of compression (which is only a temporary help on long steeps), you can rely on increased mid-stroke spring rate to provide more consistent support
  • 1 3
 @oatkinso: i am, i just had to dumb it down to your level
  • 3 0
 @showmethemountains: but that means there's no damping options for lighter or heavier riders, or different styles. The spring provides a different resistance to the damping. A spring (air or coil) provides a resistance based on where in the travel it is. A damper provides resistance based on the velocity of the shaft. Any suspension system needs both. Knowing which to adjust, well, that's where the skill is. How many of us have that skill, that's another question...
  • 3 0
 @goroncy: I'm afraid not. Are you telling me that WRC teams shouldn't be using their fancy compression adjustment, but need a better spring? Or that's PUSH's entire product line is pointless?
  • 1 0
 I like my Runt equipped older Lyrik more then my Acs spring Fox 36 Grip 2. The only downside is the air spring still needs service more often. Next year I may buy a bike that comes with a 38 but they don't make Runts for them yet and that's a drawback.
  • 1 0
 I’ve had my runt for a little over a year and am very happy with it.
Bought it to improve my Rhythm 36 and then swapped it to my performance elite 36.
The short of it is you get to have small bump sensitivity, mid support ( no brake dive), and smooth compression and rebound during big hits. ????
  • 1 0
 Been going back and forth between 1-3 tokens and air pressure for weeks in my Lyrik depending on the terrain. RUNT arrived a little over a week ago and it's been pretty awesome so far. Will be doing the damper tune at my next service, cool that DSD includes the shims and instructions to tune your damper as well.
  • 1 0
 I've had the Runt in my Lyrik since July. I love it, for the first time I'm not constantly messing with the clickers. It just feels "good". I will say, I do like it better with the 2019 Debonair spring vs the new 2021 Debonair spring. I felt like I lost a little front end feel with the 2021, especially when cranked over in rough turns.
  • 1 0
 I had a marzocchi 66 ATA that worked on the exact same principle back in 2008... Shame marzocchi had such horrific reliability with that system they ended up replacing most peoples air cartridges with coil. let's hope these hold up better!!
  • 1 0
 RUNT owner here. Had mine installed into a fox36 grip2 170mm fork ( Scott ransom), for over 2 months now.
Wish I’d brought this mod, before the grip2 dampener upgrade a year ago. As that unit is over valved, and over rated. In comparison to the effects of a RUNT instal, that is. The RUNT lets you run the bike with sooo much mid stroke support, it feels more confident the faster and steeper the terrain gets.
  • 1 0
 Got a Runt on my Revelation 140 with a RC2.1 damper. = the best upgrade! Is practically a Pike ultimate.
Lots of adjustability and the grip is second to none.
Do your homework on tire pressure and service the fork as manufacturer required.
Yes, you will pay the price if you are in Australia, but your ride will improve dramatically.
And the DSD crew is one of the best re help and support.
Coming from a Moto and bicycle nerd l'm.
DSD is a dedicated suspension crew.. not your average milkbar shop.
Buy it and support small business.
  • 1 1
 "One of which is achieving a steady linear compression, as air naturally compresses at an exponential rate."

I get what you're saying, but this wording is quite strange. "air naturally compresses" at whatever rate it is compressed at by external forces. However, the _pressure_ increases exponentially with a given temp and a linear volume reduction (compression).
  • 3 2
 > Cons: May not be a dramatic difference from the stock configuration
You kidding me? HUGE difference and a massive change to the air spring curve. Did you ride the damn thing?
  • 2 0
 Silly question: can this be paired with a @VorsprungSuspension Secus? Would there be any added benefit or would it just muck things up?
  • 4 0
 YES!!! - (at least on the Fox 36 Grip 2). I wondered the same (was thinking the midstroke support would be too great / too harsh) but I pulled the trigger anyway because curiosity got the best of me.

When I got the Secus I tried a bunch of pressure combinations and came back to the original 2:1 pressure ratio in the Runt along with the same pressures I started with. I had been running a little HSC with the Runt but have now backed that off completely with the Secus because it just doesn't need it / it keeps things unnecessarily harsh at higher speeds.

With HSC backed all the way off, 2:1 pressure in the Runt + Secus you get the best of all worlds: softer initial compliance that extends close to mid stroke. A nice firm mid stroke platform to push off / prevent brake dive / eliminate too much dynamic sag on steep technical downhill and finally a nice gentle ramp up to bottoming so that I never feel it bottom although I get really close almost every ride.

The bottom line: significantly more compliance / less harsh ride without loosing mid stroke support. I have a lot of trouble with my hands going numb / loosing grip strength on extend runs and this has made a big difference.
  • 2 0
 @Xorrox: follow up question:
If you could only have 1 of the two, would you go with the Secus or the Runt? And why?
  • 1 0
 @Xorrox: Interesting! My plan is to add a AWK (= RUNT) to a 36 with Luftkappe and I hope I get similar results.
  • 4 0
 @mtmc99: Runt has a more dramatic Positive effect but for me it also made the fork ‘more active’ than stock. This is good for the expert racers out there but not so good if you have problems with your hands going numb. No doubt about it though, for a big guy the Runt is more important. Lighter riders who have trouble using full travel may prefer the Secus by itself more though.
  • 2 0
 @jacksteel: I don’t think the Runt will fit in forks that have a Luftkappe installed, at least that was true on my 170mm Fox 36 (29er). They will physically run into each other at bottom out.
  • 2 0
 In my time we used coil, they are cheap to produce, work well and hardly ever fail.
  • 1 0
 I love the coil on my DH. Would have liked to try the new Z1 coil but I couldn't get a fork demo Frown
  • 1 0
 @Ajorda: is simple: buy one !! love mine
  • 1 0
 @Civicowner: Gonna get the Mezzer instead!
  • 1 0
 @Ajorda: fair enough looks like a good pick mate
  • 3 0
 Would be nice to see DSD get some distribution down under!
  • 1 0
 m.facebook.com/bigmountainMTBservices/posts/pre-orders-for-the-sd-components-dvc-now-being-acceptedshocktherapy-dynamicvolum/3258437647578675
  • 1 0
 I've been using the SD Components DVC for years on a number of forks - matched with Racing Bros seals, it is a winning combination, particularly for a light weight trying to get full travel and mid stroke support. See link from @JBW450 below.
  • 2 0
 Hopefully someday! Right now we are limited being a small US manufacturer. We can and have shipped quite a few to AUS.
  • 3 0
 Now compare and review the Vorsprung Secus!
  • 1 0
 I've always wondered why fox didn't do this from the factory. All of their ATV shocks have this feature built in, they call it the EVOL chamber.
  • 3 0
 Can we drop the word Tuneable and just say Adjustable
  • 2 0
 I have a Z1. Why would I spend $200 to get a "coil like feel" when I can spend $130 and just get the actual coil kit?
  • 2 1
 Two reasons I can think of:
1) This can be adjusted to provide you with the exact "coil" you need for your weight. With actual coil springs there is a good chance you are in between sizes and need to compromise with either too stiff or too soft.
2) This can still provide end of stroke ramp up to avoid harsh bottom outs. So for 2/3s of the travel you get the linear spring rate and then it ramps up.

That being said, your not wrong that you can just go coil and get most of the benefit, especially if you dont love phaffing with your settins.
  • 1 0
 @mtmc99: Coil does and will feel better in the initial and mid stroke compared to this, unless you can get your hands on a secus...
  • 1 1
 Always funny to see all those brands trying to improve air spring with so many tuneable gadget. Finally you spent most of the time trying to have something right... I stay with coil spring and go ride easy.
  • 1 0
 Am I the only one who has no idea what improvement this would make? I have the absolute most basic understanding of suspension and do not understand what this would improve
  • 2 0
 Would love to see one of these for the 40
  • 6 0
 www.chickadeehill.de/neue-seite-3
AWK for various forks including the 40, use(d)/using it on Pike, Yari and 40;
  • 3 0
 @markus-a: tried buying one of these, but could not get through the website puzzle to a webshop. ended up with shippining a Runt overseas.
  • 5 0
 @bikefuturist: you can buy AWK via the online shop of Fahrrad Fahrwerk
  • 1 0
 @markus-a: I don't think it would work with the 2021 Model 40. The negative air can is significantly larger, which minimizes the amount of volume spacers you can use. The Max is 5 spacers now vs the last gen was 6.
  • 1 1
 @jomacba: I agree and chickadeehill has updated their modells for other forks for this reason over time, don´t know if the 40 awk will be updated as well
  • 1 0
 @markus-a: In all fairness, I really haven't found the new Evol air spring to need this. I rode the Ohlins DH38, which essentially has this feature built in. One thing I enjoyed was the massive amount of mid stroke support, without the harshness in the end stroke. I feel that Fox adding the larger negative air can gave an almost identical feel to it. However, id like to try something like this to see if I can squeeze a bit more out of the design.
  • 2 1
 What's the weight pendalty of this more dynamic and configurable ramp control vs static tokens?
  • 2 0
 I have similar thing from AWK. Weights nothing. It's hollow inside. Without any rod. Just a phenolic/plastic piston.
  • 1 1
 @goroncy: I get your point that it's not heavy but I don't think it weighs nothing. Wink I would assume the Runt weighs more than plastic spacers.
  • 5 0
 The RUNT is about 20 grams heavier than the same amount of tokens. Because it's travel specific, the actual cartridge weight varies by travel configuration.
  • 2 0
 @FredrikWestman: It depends on the fork and the design used. AWK as far as I remember may be as light as 55grams. So lighter than tokens. Still. This product is not meant for people counting -+20 grams when increase in performance going down is huge. FOX and rock shox had no problem releasing this year single crown forks that are at least 200 grams heavier than we are used to. In the name of speed. And fun ????.
  • 4 3
 Maybe it's my OCD, but there's no way I could buy a product that's back-to-front once installed.
  • 4 0
 Isn't it random depending on where the thread ends?
  • 5 0
 Just run the fork backwards and then the cartridge will be the right way around
  • 4 0
 Sometimes they line up perfectly, it just depends on how the stanchions are pressed into the crown. Luck of the draw.
  • 1 0
 Also wish the runt would come in Fox blue as opposed to the red offering.
  • 1 0
 Some models of AWK doesn't have this problem, orientation can be adjusted. shop.fahrrad-fahrwerk.de/products/fox-36-2018-awk
  • 1 0
 Would be amazing to see a fork shootout with Lyrik, 36, Mezzer etc to see how it stacks up...@brianpark
  • 1 1
 Im just sitting here in BC looking at those valve recesses and thinking about the dirt and mud build up that would happen. thats a big yikes for me on that design.
  • 1 0
 Late reply but anyone running the RUNT on a Fox 34 Fit4? Mines a new 29 @ 140mm. Thnx!
  • 1 0
 Are there any similar air spring upgrades available for 2020 Boxxers?
  • 2 4
 This just sounds like a terrible advice:

"For damper settings, I went with DSD's recommended wide open HSC and LSC while closing the HSR. LSR was a few clicks in from fully open."
  • 2 0
 Why?
  • 2 0
 this is manitou idea!!!
  • 1 0
 How does this address the CSU creaking issues of FAUX forks?
  • 1 0
 ok, nice but i don't need it .
  • 1 1
 Thought the same...
  • 3 6
 Who still runs a 36mm lol??
  • 7 0
 it pairs well with my 2.2" tires and 21mm rims.
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