[englertracing]

What press

I think I'm fighting this same thing with the DPX2 on the rear of my SB5. The bike originally came with a DPS Float, that had practically no small bump compliance and was challenging pedaling through rough stuff. If I set it up for the right sag, there was no way I'd use full travel and it had no small bump compliance. Set for full travel and it had a little bit more small bump (but still a surprising lack) compliance but I could achieve full travel.

So I swapped on the DPX2, with a "lighter" damping profile, but it still isn't right. Small bump compliance is much better, but it wants to blow through its travel. I have the largest volume spacers in there and it still doesn't seem to help. 175 lbs geared up, for reference.

Setup:
160 psi
30% sag
2 clicks rebound
4 clicks compression
Largest volume spacer
Open damping setting
Evolv can

Not sure where to take it from here. 8 clicks compression? Rebuild & re-valve? It's better in the initial stroke, but blows through the mid/end stroke faster than it should, IMO.

Well,
Tbh I haven't messed with that shock at all.
But I'm wondering if the light tune was the wrong choice?

Is this the one that has open trail and lock or something like that
What happens if you put it in trail and open the lsc a few clicks?

 

[englertracing]

I think I'm fighting this same thing with the DPX2 on the rear of my SB5. The bike originally came with a DPS Float, that had practically no small bump compliance and was challenging pedaling through rough stuff. If I set it up for the right sag, there was no way I'd use full travel and it had no small bump compliance. Set for full travel and it had a little bit more small bump (but still a surprising lack) compliance but I could achieve full travel.

So I swapped on the DPX2, with a "lighter" damping profile, but it still isn't right. Small bump compliance is much better, but it wants to blow through its travel. I have the largest volume spacers in there and it still doesn't seem to help. 175 lbs geared up, for reference.

Setup:
160 psi
30% sag
2 clicks rebound
4 clicks compression
Largest volume spacer
Open damping setting
Evolv can

Not sure where to take it from here. 8 clicks compression? Rebuild & re-valve? It's better in the initial stroke, but blows through the mid/end stroke faster than it should, IMO.

Also are these numbers from closed? Or from open

 

[Adventurous]

Well,
Tbh I haven't messed with that shock at all.
But I'm wondering if the light tune was the wrong choice?

Is this the one that has open trail and lock or something like that
What happens if you put it in trail and open the lsc a few clicks?

Also are these numbers from closed? Or from open

It is the model with the open/medium/firm lever. Haven't run it in medium beyond a few miles of trail, as it feels like too drastic of a change and makes the rear end feel dead.

I grabbed the light tune with the idea that the OEM shock was a medium tune, and it felt like too much. It tended to skip over stuff rather than absorb it, and never really felt compliant.

All cited are clicks from open. Sorry.

 

[Westy]

It is the model with the open/medium/firm lever. Haven't run it in medium beyond a few miles of trail, as it feels like too drastic of a change and makes the rear end feel dead.

I grabbed the light tune with the idea that the OEM shock was a medium tune, and it felt like too much. It tended to skip over stuff rather than absorb it, and never really felt compliant.

All cited are clicks from open. Sorry.

Are you bottoming out the shock or is it just wallowing in the travel? If wallowing fewer pacers and more pressure/less sag will give you better support. Small bump compliance shouldn't change too much as the negative chamber controls that as much as anything.

 

[Adventurous]

Are you bottoming out the shock or is it just wallowing in the travel? If wallowing fewer pacers and more pressure/less sag will give you better support. Small bump compliance shouldn't change too much as the negative chamber controls that as much as anything.

It was my understanding that the spacers only controlled how quickly things ramped up to bottom. In which case, the largest spacer should be the most resistant to bottom out. So with my sag being right, and the compression in the ballpark, my only variable to change bottom out tuning was a larger spacer.

Instead, I appear to have wallowing and poor bottom out resistance. Like things are digressing faster than the spacer can compensate for, if that makes sense. Maybe I'm thinking about it wrong. More PSI + smaller spacer instead?

All I know is that I bottomed the ever loving bejesus out of it yesterday on a floaty 3' drop, which doesn't feel like it should happen.

 

[Andeh]

I think I'm fighting this same thing with the DPX2 on the rear of my SB5. The bike originally came with a DPS Float, that had practically no small bump compliance and was challenging pedaling through rough stuff. If I set it up for the right sag, there was no way I'd use full travel and it had no small bump compliance. Set for full travel and it had a little bit more small bump (but still a surprising lack) compliance but I could achieve full travel.

So I swapped on the DPX2, with a "lighter" damping profile, but it still isn't right. Small bump compliance is much better, but it wants to blow through its travel. I have the largest volume spacers in there and it still doesn't seem to help. 175 lbs geared up, for reference.

Setup:
160 psi
30% sag
2 clicks rebound
4 clicks compression
Largest volume spacer
Open damping setting
Evolv can

Not sure where to take it from here. 8 clicks compression? Rebuild & re-valve? It's better in the initial stroke, but blows through the mid/end stroke faster than it should, IMO.

Are those compression and rebound settings from open or closed? SB5 is only slightly progressive, so you will likely need both big token and more pressure to get bottom-out support.

Your pressure looks quite low, just by gut feeling. I've used 2 different DPX2s on 2 different bikes (a 210x57.5 trunnion with a 0.86 token on a Sentinel - barely progressive, and a 230x65 with a 0.2 on a MegaTrail - moderately progressive), weigh about the same geared and have needed pressures in the range of 210-235. The most recent time, I was at like 26% sag but had the rebound and compression pretty open, it tracked pretty well while feeling bottomless. On the Sentinel, the 1.02 token as a whole felt worse than the 0.86 (could bottom out both at equivalent sag, but was more wallow-y at sag).

A volume token will start affecting things from the very start. It changes the volume of the air chamber (reduces it). So from the same starting pressure, the pressure will ramp up faster in a given distance of shock/fork travel, since the chamber volume is smaller.

 

[Adventurous]

Spacer wise, I'm maxed out on purple for a 7.875 x 2.25 shock. Fox promises death and dismemberment if I try to use any larger.

 

[Westy]

It was my understanding that the spacers only controlled how quickly things ramped up to bottom. In which case, the largest spacer should be the most resistant to bottom out. So with my sag being right, and the compression in the ballpark, my only variable to change bottom out tuning was a larger spacer.

Instead, I appear to have wallowing and poor bottom out resistance. Like things are digressing faster than the spacer can compensate for, if that makes sense. Maybe I'm thinking about it wrong. More PSI + smaller spacer instead?

All I know is that I bottomed the ever loving bejesus out of it yesterday on a floaty 3' drop, which doesn't feel like it should happen.

Thinking back I had the same issues with my SB5 although with the stock shock. I ended up with spacers and higher pressure to prevent wallowing and bottom out. I resolved the small bump issue with a burlier tire and lower pressure. Might not be a viable solution for you as I think your rocks are pointier than my rocks.

 

[6thElement]

I think I'm at 230psi on my '21 DPX2 which is 7.5x2, double check your sag when fully kitted up to ride.

 

[Adventurous]

Ah, and there I was adding air to the shock and compressing it with the pump attached per Fox's recommendation, when the pump someway, somehow gets caught on the pedal while compressing, and yanked upon rebound, rendering both the pump head and the air valve stem FUBAR.

Oh, and then I pulled the air can cause it was making a noise, only to find one of the plastic rings that holds the quad seal in place on the piston head dislodged and got munched.

So all in all, it was a good day in the workshop.

 

[Westy]

Ah, and there I was adding air to the shock and compressing it with the pump attached per Fox's recommendation, when the pump someway, somehow gets caught on the pedal while compressing, and yanked upon rebound, rendering both the pump head and the air valve stem FUBAR.

Oh, and then I pulled the air can cause it was making a noise, only to find one of the plastic rings that holds the quad seal in place on the piston head dislodged and got munched.

So all in all, it was a good day in the workshop.

That sounds sub-optimal.

 

[CrabJoe StretchPants]

That sounds sub-optimal.

Surprisingly, the shock felt better after.

 

[Westy]

Surprisingly, the shock felt better after.

He could offer a tuning service

 

[CrabJoe StretchPants]

Avalanche Suspension

Avalanche Suspension gives you a competitive advantage with its custom tuned shocks and forks. Our Open Bath Cartridge systems are virtually maintenance free, guaranteed.

www.avalanchedownhillracing.com

 

[slimshady]

"Buy a Yeti" They said.

"it'll be fun!" They said.

I've read quite a bit of issues with the SB line shock's pressures for folks in the lower and higher weight brackets. As others said, I'd advise you to put a smaller spacer in there and upper the pressure a bit. 30% SAG seems excessive for that little travel.

 

[Adventurous]

"Buy a Yeti" They said.

"it'll be fun!" They said.

I've read quite a bit of issues with the SB line shock's pressures for folks in the lower and higher weight brackets. As others said, I'd advise you to put a smaller spacer in there and upper the pressure a bit. 30% SAG seems excessive for that little travel.

TBH, I never really noticed it while living/riding in CO. The gains in pedaling efficiency were worth it when it came to chugging up 1,000 ft+ climbs, just like the length and low BB performed great when descending.

I'm beginning to think the design just isn't optimal for the Northeast, and there's little I do can compensate for that. The low BB can be tricky pedaling in the chunk. The shock tuning doesn't offer enough small bump compliance to maintain traction pedaling through rocky/roots sections, while simultaneously blowing through travel on the bigger hits. Perhaps I'm at the point where a custom tuned air shock or high end coil shock would be the appropriate path, but the question is, is it worth it putting that kind of money into a 5 year old bike...

 

[slimshady]

I hear you, the age factor has its weight when evaluating upgrades. I was going to suggest a coil shoch (maybe you could get a used DHX2 off PB) but it might not be worth the hassle/cost. Some guys on emptybeer claim you could get away by long shocking the bike to 140mm by putting a 200x57 shock there. That might help with the low BB, but then again, you'll be throwing money to a bike you might consider selling in the near future...

 

[Adventurous]

I hear you, the age factor has its weight when evaluating upgrades. I was going to suggest a coil shoch (maybe you could get a used DHX2 off PB) but it might not be worth the hassle/cost. Some guys on emptybeer claim you could get away by long shocking the bike to 140mm by putting a 200x57 shock there. That might help with the low BB, but then again, you'll be throwing money to a bike you might consider selling in the near future...

Right now I do have a 200 x 57mm on there, and it's worked out great, in that regard. Eek out another 1/2" of travel with no downside. I have perused coil shocks on PB and eBay, just to see what's out there.

At this point, I'll probably be keeping this one for another 5 years, maybe forever, who knows. Bikes are so expensive and they change technology so quickly that it's a losing proposition to try and keep up.

 

[Andeh]

Don't get a coil for an SB5, it's not progressive enough. The DPX2 you have is perfectly fine, you just need to sort out the right pressures & volume spacer configuration.

 

[StiHacka]

I have perused coil shocks on PB and eBay, just to see what's out there.

Someone you know has a slightly used DHX2 in a box.

 

[Adventurous]

Someone you know has a slightly used DHX2 in a box.

7.875x2.0 or 7.875x2.25? Tis tempting...

 

[StiHacka]

7.875x2.0 or 7.875x2.25? Tis tempting...

 

[Adventurous]

Don't get a coil for an SB5, it's not progressive enough. The DPX2 you have is perfectly fine, you just need to sort out the right pressures & volume spacer configuration.

I'll do a bunch more fiddling before abandoning the DPX2. After all, it doesn't cost me anything at this point, unless it keeps munching hardware.

And are you referring to the shock or the bike not being progressive enough?

 

[Andeh]

I'll do a bunch more fiddling before abandoning the DPX2. After all, it doesn't cost me anything at this point, unless it keeps munching hardware.

And are you referring to the shock or the bike not being progressive enough?

The bike.

 

[Jm_]

The bike.
View attachment 158367

Great example of bike manufacturers throwing shit up against the wall to see what will stick (shock LC).

Like seriously, lets all just do something different, one of us is bound to nail it!

 

[Andeh]

Great example of bike manufacturers throwing shit up against the wall to see what will stick (shock LC).

Like seriously, lets all just do something different, one of us is bound to nail it!

Yeah, I'd like to know what drugs the Orbea engineers were on.

To be fair, most modern LR curve comparisons look a lot more similar because people figured out that linearly progressive feels pretty good and is easy to tune around. Although there's always a few weirdos (ahem... Ibis, Evil).

 

[Jm_]

To be fair, most modern LR curve comparisons look a lot more similar because people figured out that linearly progressive feels pretty good and is easy to tune around.

Yeah, for a coil shock...which bikes don't come with anymore.

 

[Adventurous]

Great example of bike manufacturers throwing shit up against the wall to see what will stick (shock LC).

Like seriously, lets all just do something different, one of us is bound to nail it!

Its an interesting chart that's for sure. I'm not sure what conclusions to draw from it however. Different philosophies on what the "ideal" curve looks like? Abandoning dynamics for aesthetic or patent avoidance reasons? Compensating for suspension behavior with shock tuning voodoo??

It would seem that the dynamics of two wheeled suspension would be fairly well understood by now, so their complete lack of consistency is surprising.

 

[Adventurous]

The bike.
View attachment 158367

At what point is the bike considered an ideal candidate for coil? I'm assuming there's some slope that translates to a coil friendly zone vs one that's better for air shocks.

And if I understand you correctly, throwing a coil on my SB5 would actually exacerbate the behavior I've observed, correct?

 

[Andeh]

Yeah, for a coil shock...which bikes don't come with anymore.

Huh? Plenty do now. Off the top of my head, Evil Wreckoning coil only, Yeti SB165 coil only, Santa Cruz MegaTower & Nomad have coil options, Norco Shore coil only.

At what point is the bike considered an ideal candidate for coil? I'm assuming there's some slope that translates to a coil friendly zone vs one that's better for air shocks.

And if I understand you correctly, throwing a coil on my SB5 would actually exacerbate the behavior I've observed, correct?

Yeah basically you're looking for the ending LR to be significantly lower than the starting LR. If the LR stays the same, the shock will move as easily at the end of the travel as the start of it. If the LR decreases, the shock moves less easily. A coil spring provides the same resistance force as it compresses, but an air shock provides increasing resistance. The formula I use is 1 - LRend/LRstart. There's no hard and fast number, but it seems to be <15% will bottom out too easily, and a lot of longer travel enduro bikes that are described as "coil compatible" are in the 18-25% range. There's a few outliers beyond that, like the Capra is ~35%, to the point where running an air shock, even with no volume tokens, can ramp up pretty harshly.

There's exceptions to this (some air shocks are tuned to behave in a nearly linear fashion, some coil shocks have hydraulic bottom out resisters or progressive springs), but that's my best at trying to explain it simply.

 

[englertracing]

7.875x2.0 or 7.875x2.25? Tis tempting...

They are the same aside from a plastic puck.
Changing this puck can be done without damper disassembly.

 

[englertracing]

RE the dpx2
this is what steve @ vorspurng says about it

"We keep getting asked when we'll be offering Tractive tuning for the DPX2. We aren't, and this is part of the reason why. .

These plots are with no valving at all on the main piston, all force coming solely from shaft displacement. What's the takeaway? The rebound adjuster hugely affects the range of the compression adjuster. The patented design layout of the DPX2 precludes the possibility of getting around this. .

All the oil displaced by the damper shaft has to go through either the LSC adjuster orifice or the rebound adjuster orifice in the base valve. Because neither of those have a shimmed or otherwise speed sensitive circuit, it's very difficult to get low to mid speed support out of this damper without risking high speed harshness, unless the rebound is valved quite firmly, so that the rebound adjuster can be run quite open. .

As a result, unfortunately we will not offer Tractive tuning for this shock, because it's actually not possible to achieve many of the damping curves we specify without redesigning about half the shock. .

Note that this DOES NOT mean the DPX2 is a bad shock. It means it's unsuitable for our tuning, no more and no less. It is however a reliable, lightweight and moderately adjustable unit that works reasonably well in stock guise (where both rebound and LSC are able to be run fairly open). Don't interpret this as a failure on Fox's part, it is simply designed to do something other than what we want to make it do."

 

[StiHacka]

And if I understand you correctly, throwing a coil on my SB5 would actually exacerbate the behavior I've observed, correct?

Not necessarily unless you go to the territory of big hits. What the coil gives you is low stiction and much more active initial stroke for small bump compliance so you can run the compression damping firmer for better mid-stroke support. Harsh bottom out can be solved with a heftier bottom-out bumper which always worked well for me on the Ibis.

I can bring the shock to a ride some day so you can try it on your bike - as long as I have light enough coil for your pretty legs.

 

[CrabJoe StretchPants]

I miss the good old days when I didn't know what any of this meant.

 

[Adventurous]

RE the dpx2
this is what steve @ vorspurng says about it

"We keep getting asked when we'll be offering Tractive tuning for the DPX2. We aren't, and this is part of the reason why. .

These plots are with no valving at all on the main piston, all force coming solely from shaft displacement. What's the takeaway? The rebound adjuster hugely affects the range of the compression adjuster. The patented design layout of the DPX2 precludes the possibility of getting around this. .

All the oil displaced by the damper shaft has to go through either the LSC adjuster orifice or the rebound adjuster orifice in the base valve. Because neither of those have a shimmed or otherwise speed sensitive circuit, it's very difficult to get low to mid speed support out of this damper without risking high speed harshness, unless the rebound is valved quite firmly, so that the rebound adjuster can be run quite open. .

As a result, unfortunately we will not offer Tractive tuning for this shock, because it's actually not possible to achieve many of the damping curves we specify without redesigning about half the shock. .

Note that this DOES NOT mean the DPX2 is a bad shock. It means it's unsuitable for our tuning, no more and no less. It is however a reliable, lightweight and moderately adjustable unit that works reasonably well in stock guise (where both rebound and LSC are able to be run fairly open). Don't interpret this as a failure on Fox's part, it is simply designed to do something other than what we want to make it do."

Curious design choice, but good to know in retrospect. I guess it's a good thing then that I've been running it pretty open for both LSC and rebound?

I added a solid 35 psi into the shock, and only got 4mm less sag out of it. So now I'm closer to 20% than 30%. We'll see how that fares.

Not necessarily unless you go to the territory of big hits. What the coil gives you is low stiction and much more active initial stroke for small bump compliance so you can run the compression damping firmer for better mid-stroke support. Harsh bottom out can be solved with a heftier bottom-out bumper which always worked well for me on the Ibis.

I can bring the shock to a ride some day so you can try it on your bike - as long as I have light enough coil for your pretty legs.

Im certainly willing to give it a squish. Last coil shock I had was an Avalanche DHS on my Turner RFX, so its been a while.

 

[TM_jimmy]

Ok no volume spacers,
Good start!
If you have the spares throwing them in your neighbors yard helps..

If I were you...
I would....
Back the hsc out, the hsc adjuster on these preloads shims, preloaded shims increases dampening through the whole range, and create a spike at low speed which must be encountered as all high speed movements begin as a low speed movement. Shoulda called it an "all speed except bleed adjuster", or "digressive piston preload adjuster"

So about that high speed adjuster, having it out more makes the shim stack behave in a more desirable linear fashion, this occurs somewhere in the 12-15 range somewhere 16 -18 or beyond the adjuster allows the stack to lift off the piston, meaning you no longer have any compression damping at all... and the lsc adjuster does nothing at all.

The other reason they can be choppy and or harsh is the design of the air spring, ive heard of tight pistons, and massively over greased negative chambers contributing to a bad feeling fork as well

You may find more Appropriate settings are
Putting your pressure back up to obtain sag
12 - 14 hsc
8-10 lsc
5-6 hsr
5-6 lsr

Just the observations I've made having a few of them apart and riding one for 2 years.

Did you measure how tall is the ring on that piston? Stacking some of those 10mm OD shims until there’s no room for preload might just work.

You loose the adjuster but gain an hsc stack with no preload, that you could also revalve.

If anyone has experimented with this let me know! I’d like to get rid of the harshness of that damper on successive hits.

 

[englertracing]

Did you measure how tall is the ring on that piston? Stacking some of those 10mm OD shims until there’s no room for preload might just work.

You loose the adjuster but gain an hsc stack with no preload, that you could also revalve.

If anyone has experimented with this let me know! I’d like to get rid of the harshness of that damper on successive hits.

I did something with the stack.
I put a crossover between the shims, so only the first two shims preload, and the gap decreases as you preload them, creating something of an adjustable two stage stack

 

[TM_jimmy]

I did something with the stack.
I put a crossover between the shims, so only the first two shims preload, and the gap decreases as you preload them, creating something of an adjustable two stage stack

Very interesting! Did that fix the harshness or improve overall feel?

 

[englertracing]

Very interesting! Did that fix the harshness or improve overall feel?

It's capable of a lot more support than the vvc, and is less harsh

 

[TM_jimmy]

I’ll give it a try, what shim size did you use for the crossover?