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Air shock tuning...technical

Sandwich

Pig my fish!
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May 23, 2002
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I'm looking to squeeze a little more performance out of my rear shock on my trailbike. I know this isn't the trailbike forum, but there are more suspension gurus here than anywhere else. Right now I have a Float R on my Cannondale Rush. To my knowledge the bike has a regressive shock rate that makes it perfect for a small volume air shock. Rather than sending my R off to PUSH and seeing what they can do, I've been looking at getting an RP23 to have some more adjustability. The problem is that most of them are coming with HV air sleeves. I'm kind of stuck with PUSH as the Rush has a weird shock stroke (1.75") and I don't inherently trust that I can just slap a spacer on any air shock and be good to go. If I get a HV air can, is there anything I can do to make it more progressive so the bike doesn't blow through it's small amount of travel? Is there any advantage to a spacer and HV air can vs. small volume air can?

Alternatively, can I swap my LV Float R air can and the HV RP23 air can, if they are both coming on 7.5" shocks?
 

Sandwich

Pig my fish!
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May 23, 2002
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Hmmm...that doesn't really help with my issue, but it does provide some insight into further tuning options. Those both look to be small air cans.

I think I need a 'pushing' as my rebound is currently fully opened, and I still wonder if the bike couldn't use a little less. Maybe I just like my rebound fast...
 

saruti

Turbo Monkey
Oct 29, 2006
1,145
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Israel
I just got my float R from a service center. (after opening it by myself.... all room got oil on the walls and everything.... my wife want to kill me... I forgot all about the air in the boost valve....)
the shock got new oil in it, the rebound got faster, and a new propedal screw.
the guy how serviced my shock is great and knows a lot about air socks.
my AM bike is also progressive/regressive (ironhorse MKIII)
so I wanted it to work better on the little staff and feel bottomless.
so he added a bottom out bumper
the bike really feels great now.

I think you can go with the bigger HV can
and add a bottom out bumper.
so it will work better in the small staff and feel bottomless.
 

Sandwich

Pig my fish!
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May 23, 2002
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Yeah I'm not inclined to crack open the damper internals. I probably COULD figure it out, but I think there's a high probability of me messing something up. I like the idea of being able to turn propedal off for downhilling which is why I want an RP2/3.
 

4130biker

PM me about Tantrum Cycles!
May 24, 2007
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Advantages of a HV would be more tuneability in the air volume department. I agree with Saruti on the bumper idea.
My RP2 needed to be more progressive, I messed with the air volume and pressure, but the bumper with lower pressure turned out to give the best overall improvement.
I'm pretty sure the air cans could be interchanged like you suggested.
 

Steve M

Turbo Monkey
Mar 3, 2007
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Yeah I'm not inclined to crack open the damper internals. I probably COULD figure it out, but I think there's a high probability of me messing something up. I like the idea of being able to turn propedal off for downhilling which is why I want an RP2/3.
Unless you have nitrogen charging equipment, including the Fox needle assembly (which they don't sell to the public) then you won't be able to rebuild it. IFP depths are super important (also not publicly available) and o-ring seals in the damper, should you want to change them, are very sensitive to durometer as well as the fact that you need to find the right size. Add to this the fact that all the parts in the damper need to be torqued to very specific values and you have a lot of reasons not to mess with the damper yourself.

I would not recommend a HV air sleeve (XV1 specifically - XV2 is even worse) on your bike though. Even with the -0.6 volume spacer, it's still only about the same spring curve as the standard low volume can.
 

Sandwich

Pig my fish!
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May 23, 2002
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Good to know, and thanks. I'll stick with the small volume can and go from there.
 

boogenman

Turbo Monkey
Nov 3, 2004
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BUFFALO
I got my RP23 pushed over the winter and switched to the LV can. It is a s hit ton better now. If you call them up they will let you know if you should change the air can or not.

Propedal is a joke, stick with your Float R. The push tune is worth every penny.

FYi: mine is 7.875X2.0

This is all the crap that Push took out and changed
 
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Sandwich

Pig my fish!
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May 23, 2002
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from my understanding, the floateR comes with propedal ON all the time, vs. RP2/3 where you can turn it off. I don't know if they can remove it, but I like having a lockout on my fork for climbing extended hills.
 

Steve M

Turbo Monkey
Mar 3, 2007
1,995
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Whistler
from my understanding, the floateR comes with propedal ON all the time, vs. RP2/3 where you can turn it off. I don't know if they can remove it, but I like having a lockout on my fork for climbing extended hills.
The Float R has fairly low Propedal settings, trying to balance being closed enough for good pedalling and open enough for good bump absorption, and consequently it's not amazing for either. Unfortunately no amount of custom tuning will fix the fact that it only has one LSC setting, so you'll always be compromising on the trail. I'd definitely suggest an RP23 (or CTD) Boost Valve shock if you can get your hands on one. You may have to shell out extra for a low volume sleeve but it will give you much better options than what you're currently on.
 

saruti

Turbo Monkey
Oct 29, 2006
1,145
67
Israel
Sandwich
what is the compression and rebound tune on your sock?
you can see it on the small stickers on the can.
my shock come with low tune both comp & rebound.
so I really liked it, except the bottom out... that now is fixed with the bottom out bumper