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Anyone running an MRP Ramp Control Cartridge?

mdc

Monkey
Jul 8, 2006
243
15
Uxbridge
I have it in my MRP Stage fork and really like it. It makes a noticeable difference in how progressive the forks feels without having to take the fork apart and add or subtract volume spacers.
 

StiHacka

Compensating for something
Jan 4, 2013
21,560
12,508
In hell. Welcome!
I think it's totally different in the coil, I'm guessing adjusting something in the damper, vs the cartridge for air forks which changes volume.
It is the same thing - it limits speed with which air gets displaced to the lowers during high speed compression.
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
2,066
1,437
SWE
Does it help with small bump sensitivity in the very beginning of the shock stroke?
Having a piston and seal with the right dimensions is more likely to help for small bump compliance. I don't know which generation is your 36 but the 2015 to 17 ones were randomly bad... I don't know if the newer generations are better.
 

StiHacka

Compensating for something
Jan 4, 2013
21,560
12,508
In hell. Welcome!
Does it help with small bump sensitivity in the very beginning of the shock stroke?
Kinda - indirectly. It prevents bottoming out in a reasonably setup fork so you don't have to dial as much HSC as you'd have to without the cartridge. In other words, if you compared two forks with the same resistance to bottoming out - one with the ramp up cartridge, one without, the one with will have less compression damping and therefore better small bump sensitivity.
 

Sorgie

Monkey
May 20, 2005
265
80
Rochester
I put one in my '16 36. I bought it specifically for the claims of better small bump performance rather than bottom out. I'm pretty happy with it. It was easy to install and it does feel smoother in the initial stroke. I feel like I also notice better traction in loose corners. I'm 180 in riding gear and I run mine with about 50 psi in the positive chamber and 55 psi in the negative chamber. I don't regret the purchase at all.
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
2,066
1,437
SWE
I bought it specifically for the claims of better small bump performance rather than bottom out
From MRP's website:
  • Isolate and tune bottom-out with minimal changes to initial and mid-stroke.
https://www.mrpbike.com/rampcart/

I'm 180 in riding gear and I run mine with about 50 psi in the positive chamber and 55 psi in the negative chamber.
50 psi for your weight seems way too low. I had around 70psi for 160lbs which is more in line with Fox's recommendations. FWIW
I had lower pressure than that when the fork had problems with stiction from the seal of the air piston. I would check that out if I were you... Just my 2 cents
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
2,066
1,437
SWE
Currently I am running 40 psi to get small bump compliance (one token) with a few bottom outs per ride, I'm looking to fix that. (180-185 loaded riding weight)
Ok! :drag:
Either you ride only sitting on the saddle at a moderate speed or Fox did not correct the tolerance issue they had previously with the main piston seals...
If the later, I would recommend going for a Luftkappe upgrade if you want small bump sensibility and midstroke support.
 

Sorgie

Monkey
May 20, 2005
265
80
Rochester
From MRP's website:
  • Isolate and tune bottom-out with minimal changes to initial and mid-stroke.
https://www.mrpbike.com/rampcart/



50 psi for your weight seems way too low. I had around 70psi for 160lbs which is more in line with Fox's recommendations. FWIW
I had lower pressure than that when the fork had problems with stiction from the seal of the air piston. I would check that out if I were you... Just my 2 cents
You didn't read down far enough.
Fox 36, Version D
This new model goes beyond our previous offerings and includes parts
to convert the stock air-spring into an independent positive and negative chamber arrangement similar to the Fulfill™ spring found in our Ribbon and 2017 Stage forks. Once installed, you can now vary the pressures in your two chambers; increasing your negative spring rate to improve small bump sensitivity (a common complaint with the stock spring). This, in addition to the control you have over bottom-out and ending-stroke performance, gives you a radically more sophisticated air-spring that’s incredibly straightforward to tune and adjust!

Those pressures get me to 20% sag per Guerrilla Gravities recommendations. Seems to work for me. I'm guessing the increased negative pressure makes it go through the initial travel a little easier.
 
Last edited:

Happymtb.fr

Turbo Monkey
Feb 9, 2016
2,066
1,437
SWE
You didn't read down far enough.
Fox 36, Version D
This new model goes beyond our previous offerings and includes parts
to convert the stock air-spring into an independent positive and negative chamber arrangement similar to the Fulfill™ spring found in our Ribbon and 2017 Stage forks. Once installed, you can now vary the pressures in your two chambers; increasing your negative spring rate to improve small bump sensitivity (a common complaint with the stock spring). This, in addition to the control you have over bottom-out and ending-stroke performance, gives you a radically more sophisticated air-spring that’s incredibly straightforward to tune and adjust!

Those pressures get me to 20% sag per Guerrilla Gravities recommendations. Seems to work for me. I'm guessing the increased negative pressure makes it go through the initial travel a little easier.
Ok, I missed that difference, sorry about that!

From what I can see from the additional parts, the original piston and its seal are not changed and the fact that you get 20% sag with 50psi for 180lbs is a clear indication that something is wrong. Check the guidelines from fox https://www.ridefox.com/fox17/help.php?m=bike&id=553#settingforkairpressure you should be around 75psi... A too low pressure makes the fork really divy, requires a lot of ramp up to not bottom out easily and often ends up with too much compression from the damper which make the fork harsh.

If your current setup works for you then just forget what I wrote. I don't mind!
 

Sorgie

Monkey
May 20, 2005
265
80
Rochester
Ok, I missed that difference, sorry about that!
No worries. I see what you're saying about the pressures. I can't remember what I ran before the swap, but it is definitely less than I ran in the stock configuration. It feels great though. Really plush and only bottoms when I would expect it to. I think the saying is "If this is wrong I don't want to be right". :D