Fox Float DPS Rear Shock - Air Volume Spacers

[GrandPaBrogan]

The Fox Float trunnion-mount rear shock unit that came with my Giant Trance E+ 3Pro is the black 'DPS Performance' model. It has the 3 position switch (locked, firm, full movement), with only a basic rebound adjuster knob. But I think the air volume spacer kit for this shock is the same for the high-end DPS models with Kashima coating and both compression and rebound adjusters.



The issue I have with my shock is if I pump the air pressure up to get the recommended sag (14-17mm) the shock is too stiff and doesn't reach its full stroke (see pic above of stanchion O-ring) - so I'm only getting about 2/3 to 3/4 of the 140mm suspension travel I'm meant to have on my rear wheel.

I'm 85kg and I guess I don't ride aggressive enough for the standard Giant spec shock tuning. I don't do big jumps. I ride over medium drops, and also ride down old wooden staircases in some trails I venture into, so a stiff back end is no fun. The rear suspension is also jarring over high speed stutter bumps and rock gardens. If I lower the pressure so that the shock could get near the end of its stroke, the sag ends up being almost halfway down - so I've lopped-off the top half of my suspension travel. Yes it's plusher sort-of, but it has effectively become a short travel set-up.

I need more air volume in my chamber and change whatever is in there to a smaller spacer. It will allow me to raise the air pressure to get the right sag, but will also blow through most of its stroke.

Fox sells an air volume spacer kit for the Float DPS and it looks like this...

Has anyone performed a spacer swap/install before?

 

[ggx]

Wy not try it with no spacer at all (assuming theres one inside)?

 

[paquo]

i just did the seal service yesterday, it was straight forward, removing/changing the volume spacer would be even easier. On this page -https://www.ridefox.com/fox17/help.php?m=bike&id=568 it has an instruction video along with confusing charts but i think you may just need the float dps Air Spring Volume Tuning Kit: PN 803-01-250 listed or just remove the one installed ?

 

[GrandPaBrogan]

i just did the seal service yesterday, it was straight forward, removing/changing the volume spacer would be even easier. On this page -https://www.ridefox.com/fox17/help.php?m=bike&id=568 it has an instruction video along with confusing charts but i think you may just need the float dps Air Spring Volume Tuning Kit: PN 803-01-250 listed or just remove the one installed ?

I'll give it a shot. Found a video about the procedure... seems easy enough.

Wy not try it with no spacer at all (assuming theres one inside)?

I'll have to open it and see what's in there. I'm not sure if running it without a spacer is allowable - but if the spacer in there is already the thinnest, I might have to run it without and see.

Thanks guys.

 

[Lad]

You can run shock without spacers no problem, you cannot however exceed max. number of spacers specified by manufacturer.
You should find that info on Fox website.

 

[GrandPaBrogan]

Oh interesting! I can open it and get the spacer out without taking the shock off the bike!

It's got the middle sized yellow spacer (0.6 cubic inch), so I'm pretty sure running it without a spacer would be too much (too linear for the Maestro linkage ratio).



At a guess, I'd say the green spacer (0.4 cubic inch) is what I would need. There's not a lot of room in that slender chamber, so even a small change in spacer size will have a significant effect.

- - -

Oh by the way, I would never have been able to unscrew the shock cylinder if not for this plastic Pipe Strap Wrench. A plumber friend of mine gave it to me years ago (for opening pickle jar lids, haha) and it's come in handy so many times and in so many ways! Just so happen I saw one being used in another shock rebuild video, before I started. So I was prepared.

 

[GrandPaBrogan]

I was just about ready to buy the air volume spacer kit, but then I realised I would just end up with two identical YELLOW spacers. So I thought I might as well cut-up the one I've got to an in-between size and try that one first.



I removed half of the 'LIP' from 6mm down to 3mm. I just eye-balled it so that it was still higher than the shape of the green spacer - so hopefully it'll be close to 0.5 cubic inch volume. I guess I could've just cut it with a hacksaw, but best to keep the surfaces smooth and clean with a lathe.

I'll try it for a week and see how it goes. I might keep chopping it down until I get the tuning I want. I really don't like to open the shock too many times so I'm hoping this one works out.

 

[Mat_Ron]

I have the opposite problem as you, I am 250 lb and the shock bottoms out. I just ordered the kit so I will be increasing the size of the token/spacer. On the fork, I had the same issue that you are having with the shock and had to remove a token/spacer. It looks like I will need to remove another one as I am still not getting full travel when sag is set correctly. The Fox Rythm 36 comes with three installed. Odd that the bike comes with the suspension unbalanced front to back at least as far as rider weight is concerned.

 

[GrandPaBrogan]

^ Yes, we often take shock tuning for granted. And it's not just rider weight, but also how and where we ride that needs to be considered.

When I get a new bike, my immediate attention goes to changing the saddle, then the pedals, then the bars/stem and grips if needed. For me these have to be just right because that's the point of contact between me and the machine.

The tyres and shocks... that's the contact point of the machine and the ground I guess, and more often than not - I leave those for last, that's even if I bother. But I should pay more attention to it really because they're just as important... if not, more so.

I've done a bit of testing around the block with my modded spacer, and already the difference is noticeable. I'll chime back and post details of my findings.

Once you get your spacer kit and sort out the right one, you'd join me in wondering why we even waited this long!

 

[HikerDave]

The Fox Float trunnion-mount rear shock unit that came with my Giant Trance E+ 3Pro is the black 'DPS Performance' model. It has the 3 position switch (locked, firm, full movement), with only a basic rebound adjuster knob. But I think the air volume spacer kit for this shock is the same for the high-end DPS models with Kashima coating and both compression and rebound adjusters.

View attachment 22565

The issue I have with my shock is if I pump the air pressure up to get the recommended sag (14-17mm) the shock is too stiff and doesn't reach its full stroke (see pic above of stanchion O-ring) - so I'm only getting about 2/3 to 3/4 of the 140mm suspension travel I'm meant to have on my rear wheel.

I'm 85kg and I guess I don't ride aggressive enough for the standard Giant spec shock tuning. I don't do big jumps. I ride over medium drops, and also ride down old wooden staircases in some trails I venture into, so a stiff back end is no fun. The rear suspension is also jarring over high speed stutter bumps and rock gardens. If I lower the pressure so that the shock could get near the end of its stroke, the sag ends up being almost halfway down - so I've lopped-off the top half of my suspension travel. Yes it's plusher sort-of, but it has effectively become a short travel set-up.

I need more air volume in my chamber and change whatever is in there to a smaller spacer. It will allow me to raise the air pressure to get the right sag, but will also blow through most of its stroke.

Fox sells an air volume spacer kit for the Float DPS and it looks like this...
View attachment 22561
Has anyone performed a spacer swap/install before?

Perhaps you also could benefit from a custom tune.

 

[GrandPaBrogan]

Perhaps you also could benefit from a custom tune.

The Fox Float unit is Giant OEM and I think they already gave it a custom tune to match the Maestro suspension linkage. There's a decal that says, Custom Tune I.D. DTBL but I'm not sure what that exactly means. I'm not a good enough rider to be able to know which way to take it, so I'm inclined to just leave it to the custom factory spec. I just need to sort out the stroke reach for my usage.

 

[Crawford919]

Grandpa, I put this on my Trance while the stock shock was being sent back to Fox for a service due to a noise. It’s 185x55 and fit with no issues. It is valved for a regular MTB and is softer all through the stroke as compared to the stock one. It requires more air pressure to get the same sag but is very plush. Also I run stiffer rebound on this shock than the stock one because it feels too fast at the same clicker settings. Maybe just the feel you’re looking for? I’ll try to find the spec on the shock if you want? Bought it on eBay pretty cheap as a close out.

 

[GrandPaBrogan]

Previously in order to get the recommended sag of 14-17mm I had to pump it up to 240psi but the shock would only reach about 2/3rds of its stroke in my usage. Over rocks and scalloped stutter bumps, my fork would soak things up nicely, but then my rear end would buck me off my saddle. So I have to stand but the back end still bucks and the bike isn't as stable as it could be - bottom bracket jars against my footing.

Below left is what I've had to do in order to get a better ride from it. Below right is the way it rides now - after reducing the spacer.

I just got back from a trail ride this morning - that had rocks, exposed roots, multiple medium drops and long sweeping berms with stutter bumps. Hard to believe such a small reduction off the spacer can make a huge improvement. It's not just getting a deeper reach whilst having decent higher air pressure (no more excessive sag) - but also how nicely it yields in that space. It's plusher but not overly linear (still somewhat progressive). Over some moderate DH rock sections I can actually sit down now - front and rear wheel behaviour more closely matched. There's still about 8mm shock stroke left before bottoming out, so there's some headroom there for the odd hard hit. What a pleasure to ride - it's a different bike.

Oh and yes, @Crawford919 with the higher pressure, I also had to increase my rebound by a click or two. Wow, I think your's is the high end model with Kashima coating - good score! Post your shock spec any way if you can find it. It's all good info. For now I think I'll persevere with my version, because the simple mod I made thus far has already paid off big time. I also noticed that because the back end is now yielding as it should, I can pop the front wheel up easier with lesser effort. Wondering if you felt the same way when you changed your shock?

I'm guessing a smaller spacer might be worth investigating (might have to source a green 0.4 cubic inch spacer). At a guess I would say the air pressure for that will be higher again - maybe around 230psi, so it'll have lesser sag (better), but still attain the same reach but should be more linear (plusher). I'm hesitating to further reduce the modded spacer I have now, in case I want to revert back to it.

 

[Crawford919]

Not sure if you would like this shock after seeing your air pressures though. I’m running 140 psi on the stock shock and 170 on this shock. I weigh 175 lbs. I think if you ran 200 psi or more in this one it would feel like a pogo stick.
I paid $189 US. This was the eBay description of it:
2019 Fox Float Factory DPS EVOL 185 x 55 MTB Rear Shock Kashima, Trunnion Mount NEW

Brand new without retail packaging. Never installed or used in any way.

Lightweight, 1-piece EVOL (Extra Volume) air sleeve improves sensitivity and responsiveness
Dual Piston valve design improves compression flow & rebound
DPS (Dual Piston System)damper has three positions - Open, Medium and Firm
Trunnion mount
Factory Series Model with Genuine Kashima Coat

185mm x 55 Stroke Trunnion Mount
Finish: Anodized air sleeve and body with Kashima Coated shaft
Spring: Float Air
Adjustments: Open, Medium & Firm
Fox Tune: 2019, FLOAT DPS, Factory Series, K, 3pos-Adj, Trunnion, Evol Large Volume
Weight: 270g

 

[HikerDave]

The Fox Float unit is Giant OEM and I think they already gave it a custom tune to match the Maestro suspension linkage. There's a decal that says, Custom Tune I.D. DTBL but I'm not sure what that exactly means. I'm not a good enough rider to be able to know which way to take it, so I'm inclined to just leave it to the custom factory spec. I just need to sort out the stroke reach for my usage.

When Avalanche tuned my shock Craig called and we had an extensive discussion; he had concluded that the shock on my bike wasn’t what the linkage was designed for; the older narrow-body shocks. He recommended a reduction in negative volume which sounded crazy to me but actually worked very well for that bike.

He also asked a lot about my riding; the shock gets tuned for the rider, the trails, and the bike and it’s linkage design. Here’s his explanation of riders and styles:

Types of Riding Definitions

I mentioned tuning in case the volume spacer didn’t help, but it looks like you’re good. The bike manufacturer has no idea how and where you ride or what you weigh and besides I have a suspicion that the warranty department wants lower costs so they tune to protect the bike from hucking.

One big advantage of the Avalanche modification is a lot of low speed compression damping that opens up quickly when you hit something; that really helps with out of the saddle climbing; the bike stops wallowing and you get a ton of traction. ( I’ve ridden a Giant eTrance and realize that it has great rear-wheel climbing traction)

 

[GrandPaBrogan]

^ Yes, my Trance E+ climbs like a goat.

Interesting tuning terminology. It makes sense for suspension tuners to know. Based on that I guess I fall under All-Mountain/Sports Rider and prefer no higher than Grade 3 trails.

Pretty much middle of the road I guess, but at my age my son still insists that he’s impressed. I have very little motivation these days to shave seconds off my ride times as I make my way to the local cafe for a flat white and some marshmallows...