Yeah, you were the one missing 2" of travel on it if I recall. That's way too much missing travel to be normal, something has to be up with that.
What Fork To Get?
- Thread starter ianjenn
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just curious, what pressures are you running in the two positive air chambers?
the pressures in the ramp chamber are going to be higher than what you'd run if it was a single air chamber (just like the main chamber is going to be lower). one important thing to remember is that you need to have a certain amount of pressure differential between the 2 chambers in order for it to work properly. for your weight it seems to be about 35 PSI; similar weight/travel on the mattoc would be 40psi, so not too far off. the bigger the differential, the later in the travel the air springs will equalize; the smaller the pressure differential the sooner in the travel the air springs will equalize. if you're setting it with too little of a pressure differential then its going to act more like a regular single air spring and be super progressive.
fwiw i had a similar problem when i was setting up my mattoc for the first time, it was too progressive, i shifted the range down (decreased pressure in both chambers to maintain the same pressure differential) and it was a definite improvement.
for reference, the EXT air chart:
the mattoc IRT air chart:
I was (at the time of accident, and through yesterday) running 63+ and 76++ (120%). After yesterday's ride, maximum compression measured by Motion Instruments sensor was 84% / 134mm on a few different step down jumps. Those weren't big in height, but you hit them at full speed, land on a downslope, then it immediately transitions to flat and you're on the brakes, so it should be a pretty solid compression.
I was thinking about it in terms of a differential, but you could be right that it could need to be a certain value. It's good to know that it would behave super progressive if the differential is too little. Maybe I'll try the 154 lb setting (55 / 85), since that ramp value seems a lot closer to what has felt better.
I was thinking about it in terms of a differential, but you could be right that it could need to be a certain value. It's good to know that it would behave super progressive if the differential is too little. Maybe I'll try the 154 lb setting (55 / 85), since that ramp value seems a lot closer to what has felt better.
yea, if you only have a 13 PSI difference, the air springs are gonna equalize super low in the travel, and then ramp up very progressively like a normal single air chamber.
when i first got the IRT i found the same thing when i had too small of a pressure differential, it was very progressive and i didn't get full travel. when i had my mattoc set at 160mm i had like a 40 or 42 psi differential between the two air springs.
if 55/85 feels good, try bumping it to 55/90 to get a 35 psi pressure differential, edit: maybe even try a 40psi differential.
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One thing on the Smashpot and Secus is you can move them between forks. Same with the HC97 across RS forks. Lyrik/HC97/Secus feels awesome. That said, I'm looking forward to trying the ERA eventually.
Thanks. I understood how the chambers interact, but I didn't make the connection that the main chamber is so much larger. So running small delta (high main, relatively low ramp) will act more like a normal fork with a lot of pressure in the single chamber. I'll try to bracket around 55/85, 55/90, and 60/90.
i'd also suggest trying 50/90 or 55/95 to see how a 40psi differential works/feels.
Just checked some setup notes...
Mattoc IRT - 45lb pressure differential.
Lyric RUNT - 63lb pressure differential.
Mattoc IRT - 45lb pressure differential.
Lyric RUNT - 63lb pressure differential.
i remember when the helm launched, someone from CC talked about how they experimented with a dual positive air spring like this, they decided against it because it takes more time to set up. which as you see, can be the case. but once you get it set correctly its definitely a better setup than a single air chamber and token system.
fwiw this is how the DSD runt functions, it adds a second positive air spring. i like the IRT in my mattoc enough i was considering it for my 36, but i have an older version which isn't compatible.
fwiw this is how the DSD runt functions, it adds a second positive air spring. i like the IRT in my mattoc enough i was considering it for my 36, but i have an older version which isn't compatible.
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i think the pressure differential is driven in part by the overall air spring (chamber) volume. the mattoc has 34mm stanchions, while the lyric is 35mm.
You can make it compatible with the MRP Fulfill valve. Three independently adjustable air chambers!
not to shift from the MRP, Manitou focus, but I still cannot be happier with this Lyrik w/ current air spring and HC97 mod. Supportive, smooth, easily fine tuned, and red.
Lyrik/Avy/Smashpot is teh titties for me.
Do you notice a slight platform feel at the top of travel during smooth seated climbing with the HC97? Mine does it even with LSC wide open. Opens right up if you hit a bump, but still kinda weird feeling. That's the only thing I don't like about it. I just did a back and forth swap between the HC97 and RC 2.1 and the difference in support is even larger than it was with the CR2.0.
What year do you need? I think I have a couple of 36 air springs in my parts bin.
Your spring doesn't work because it uses a transfer shaft from the top cap to equalize positive and negative pressure at topout, instead of a dimple in the stanchion. Putting a new spring shaft in there doesn't get you anything because there's no dimple in your stanchion. The Fulfill gets around that by plugging the top of the spring shaft, and adding another valve at the foot nut so you can fill the negative chamber separately.
You physically can't put a newer spring shaft in that generation fork without machining a bit off the negative spring plate so that the snap ring fits.
my 36 is MY2015 with the float NA spring, i think 2018 is when they switched to NA2?
@Andeh
Different fork (Ohlins), but I felt it more helpful to think about % differences.
I ran mine +70% in the second chamber (main chamber x 1.70)
IIRC the DSD Runt recommends approx +100% (main chamber x 2.0) as the starting point (???)
the ohlins fork has the same style air spring? good to know.
also, stop adding unnecessary equations.
The IRT at 45lbs differential was at 1.8
The RUNT at 63lbs differential was at 1.7
yup.the ohlins fork has the same style air spring? good to know.
also, stop adding unnecessary equations.
It’s a closed air cart (different cart for each travel designation) with 2-stage and similar ratios between the chambers.
Yeah, will definitely be watching the ratio. EXT's spec'd ones look to all be right around 1.54.
What I realized though is that they only give one table of suggested pressures for all different fork lengths. But the ramp (++) chamber will be a fixed length, and the main chamber (+) will vary depending on travel configuration. Who knows what length they used as the basis for their table? It could be the base design (170mm), or it could be the shortest (I think 140).
From the Mattoc table that was helpfully posted, you can see that their suggested pressure for a given weight drops by about 28% from 140mm to 170mm, and the chamber ratio increases from 1.5 to 1.69.
Looks like DSD recommends a fixed 2.0 ratio. Ohlins is all over the map, from 2.3 for midgets to 1.64 for clydes.
What I realized though is that they only give one table of suggested pressures for all different fork lengths. But the ramp (++) chamber will be a fixed length, and the main chamber (+) will vary depending on travel configuration. Who knows what length they used as the basis for their table? It could be the base design (170mm), or it could be the shortest (I think 140).
From the Mattoc table that was helpfully posted, you can see that their suggested pressure for a given weight drops by about 28% from 140mm to 170mm, and the chamber ratio increases from 1.5 to 1.69.
Looks like DSD recommends a fixed 2.0 ratio. Ohlins is all over the map, from 2.3 for midgets to 1.64 for clydes.
When I dropped my mattock to 120mm I increased the pressures and I believe the differential decreased. I didn't write down the numbers like a dummy, but I didn't have to mess around with it much.
So...
I dont have one but...
It sounds like you need less shimz in the reboundz
And I bet your dislikes would fade
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Air through an orifice aka ramp control is dumb.
The dsd runt isn't.
And adding one and a fulfill will get you a moar Schraders award, but also will be mega adjustable.
between the two i'd certainly opt for the DSD
My used bike came with MRP ramp control. It sucked. Basically more HSC, but just really inconsistent HSC.
Isn't it basically an orifice damper, but for air? I thought we all agreed orifice dampers were the most basic form of damping. At least I recall those infamous Cloud 9 shocks Cane Creek produced at the dawn of the century, and how bad they sucked.
The only good thing I can say about it is that it made the bike ride so poorly the previous owner sold me the bike so cheap I had to check to make sure it wasn't stolen. It was a bit of a risk but I just had to spend some time undoing all the dumb shit he did to the bike to make it ride well.
Between the MRP and all the spacers he had in the shock it was a wollowy harsh mess.
Need more neg chamber?
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Need more neg chamber?
View attachment 153371
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For when one crown isn't enough but two crowns are obviously too many? Not quite...
It is like a Lefty, with a hook for the other hand.