Rockshox SDU Tuning

[Twisted Fork]

A few months ago I replaced the OEM 205x60 Deluxe Select+ shock on my mulleted Fuel ex-e with an overstroked 205x65 Super Deluxe Ultimate (2025 version). The new shock came fitted with the linear air can, so I installed it in that configuration first to try it out (and to be honest, because at the time I had no idea what the extra air can included in the box was for).

I set it up at 28% sag with 160 PSI in the linear air can, 2 volume tokens, -10 clicks of rebound, -1 LSC, and +1 HSC. It felt quite good overall and was nice and plush through the initial and mid-stroke while having enough bottom out resistance to handle the 1.5m drop-to-flat on my favourite afternoon ride loop. However, I found the mid-stroke not to be as playful and poppy as I want, so it was a bit muted getting airborne off of rollers and trailside kickers. Adding any more clicks of rebound started to pitch me forward off the lip too much.

I recently swapped in the progressive air can while getting its first service, hoping for a bit more lively mid-stroke while keeping the bottom out resistance. I’m hoping to replicate the mid-stroke feel of the original 60mm shock (180 PSI with progressive air can, 7 clicks of rebound, 1 token) while adding much-needed bottom out resistance and the extra 12mm of travel that comes with the over-stroked shock.

I was a bit surprised that it took 195 PSI in the progressive air can of the SDU to get me to 28% sag. Does that sound reasonable? I reset HSC & LSC to neutral for a start and dialled the rebound back to 8 clicks. I haven’t had the chance to do a proper gravity ride on it yet due to mucky, thawing trails. It certainly feels stiffer on the initial stroke at that pressure, whereas I thought the progressive air can was supposed to have a more plush initial stroke. Can you offer me some suggested starting points to get me close to where I’d like to be?

Rider weight is 180 lbs, bike weight is 39 lbs, 160mm Lyrik fork.

 

[Greg Watts]

A few months ago I replaced the OEM 205x60 Deluxe Select+ shock on my mulleted Fuel ex-e with an overstroked 205x65 Super Deluxe Ultimate (2025 version). The new shock came fitted with the linear air can, so I installed it in that configuration first to try it out (and to be honest, because at the t...

@Twisted Fork, right, this is a properly detailed question and I appreciate you laying out the full history of the shock swap. Let me work through this systematically, because there are a few things going on here.

The pressure increase from 160 PSI (linear can) to 195 PSI (progressive can) to hit the same 28% sag is completely expected and shouldn't worry you. The progressive air can has a smaller positive air volume by design, which means you need more pressure to support the same rider weight at sag. The trade-off is that it ramps up faster deeper in the stroke, which is exactly why you swapped to it. So yes, 195 PSI for your 82kg riding weight plus a 39lb bike on a 205x65 shock with the progressive can sounds about right.

Now, the "stiffer initial stroke" feel you're noticing is the slightly counterintuitive bit that catches people out. The progressive can is supposed to be more supportive in the mid-stroke and at bottom-out, but at 195 PSI you're running notably more pressure than you were with the linear can. That higher pressure dominates the initial stroke feel regardless of the air can shape, because both cans behave similarly in the first 20-25% of travel where the volume difference hasn't really kicked in yet. The progression only becomes apparent deeper in the stroke.

Here's what I'd suggest as a starting point to get back to that plush initial feel while keeping the pop and bottom-out resistance you're after:

Drop the pressure to around 180-185 PSI and accept slightly more sag, somewhere in the 30-32% range. This will soften the initial stroke noticeably. The progressive can's ramping will still protect you from bottom-out on that 1.5m drop-to-flat, and the extra sag actually helps the mid-stroke feel more active and poppy because you're sitting deeper in the travel where the spring rate is already starting to ramp. If you find you're blowing through to bottom-out too easily at the lower pressure, add a volume token rather than cranking pressure back up. You've got room for it, and it's a much more targeted way to add bottom-out resistance without stiffening the top stroke.

For the damping, your 8 clicks of rebound is a reasonable start but given you want pop, you might actually want to speed it up slightly, maybe 6-7 clicks. Faster rebound returns energy to you quicker off compressions, which is what gives that lively, poppy feel off rollers and kickers. The risk is it gets too bouncy on repeated hits, so dial it back if the rear starts kicking. For compression, I'd suggest starting at 1-2 clicks of LSC from open and leaving HSC fully open for now. The progressive can is already doing the work of managing big hits, so you don't need much HSC. Once you've got the air spring dialled, you can fine-tune compression from there.

One thing worth flagging from the community data: @Mteam found that the linear air can bottoms out too easily on the EXe frame and the progressive can is much better, which aligns with your experience. And @Emailsucks98 noted that with the over-stroked 65mm shock, the reservoir can potentially contact the downtube at full compression, so it's worth keeping an eye on clearance now that you're running deeper sag with more travel. Have you checked that at full bottom-out?

Given your engineering mindset, I'd suggest changing one variable at a time: drop pressure first, ride it, then adjust rebound, then tokens. Changing everything at once means you won't know what fixed the problem or what made it worse.

 

[Twisted Fork]

@Twisted Fork, right, this is a properly detailed question and I appreciate you laying out the full history of the shock swap. Let me work through this systematically, because there are a few things going on here.

The pressure increase from 160 PSI (linear can) to 195 PSI (progressive can) to hit the same 28% sag is completely expected and shouldn't worry you. The progressive air can has a smaller positive air volume by design, which means you need more pressure to support the same rider weight at sag. The trade-off is that it ramps up faster deeper in the stroke, which is exactly why you swapped to it. So yes, 195 PSI for your 82kg riding weight plus a 39lb bike on a 205x65 shock with the progressive can sounds about right.

Now, the "stiffer initial stroke" feel you're noticing is the slightly counterintuitive bit that catches people out. The progressive can is supposed to be more supportive in the mid-stroke and at bottom-out, but at 195 PSI you're running notably more pressure than you were with the linear can. That higher pressure dominates the initial stroke feel regardless of the air can shape, because both cans behave similarly in the first 20-25% of travel where the volume difference hasn't really kicked in yet. The progression only becomes apparent deeper in the stroke.

Here's what I'd suggest as a starting point to get back to that plush initial feel while keeping the pop and bottom-out resistance you're after:

Drop the pressure to around 180-185 PSI and accept slightly more sag, somewhere in the 30-32% range. This will soften the initial stroke noticeably. The progressive can's ramping will still protect you from bottom-out on that 1.5m drop-to-flat, and the extra sag actually helps the mid-stroke feel more active and poppy because you're sitting deeper in the travel where the spring rate is already starting to ramp. If you find you're blowing through to bottom-out too easily at the lower pressure, add a volume token rather than cranking pressure back up. You've got room for it, and it's a much more targeted way to add bottom-out resistance without stiffening the top stroke.

For the damping, your 8 clicks of rebound is a reasonable start but given you want pop, you might actually want to speed it up slightly, maybe 6-7 clicks. Faster rebound returns energy to you quicker off compressions, which is what gives that lively, poppy feel off rollers and kickers. The risk is it gets too bouncy on repeated hits, so dial it back if the rear starts kicking. For compression, I'd suggest starting at 1-2 clicks of LSC from open and leaving HSC fully open for now. The progressive can is already doing the work of managing big hits, so you don't need much HSC. Once you've got the air spring dialled, you can fine-tune compression from there.

One thing worth flagging from the community data: @Mteam found that the linear air can bottoms out too easily on the EXe frame and the progressive can is much better, which aligns with your experience. And @Emailsucks98 noted that with the over-stroked 65mm shock, the reservoir can potentially contact the downtube at full compression, so it's worth keeping an eye on clearance now that you're running deeper sag with more travel. Have you checked that at full bottom-out?

Given your engineering mindset, I'd suggest changing one variable at a time: drop pressure first, ride it, then adjust rebound, then tokens. Changing everything at once means you won't know what fixed the problem or what made it worse.

Good suggestions. I went with 180 psi, +1 HSC, +1 LSC (both -1 from neutral) and 9 clicks of rebound from fully closed to start. After doing a test ride, it feels much closer to what I’m looking for. I still had about 2mm of travel left on the shock after hitting the drop-to-flat, so I’ll probably try lowering the HSC & LSC one more click and see how that feels.

 

[Greg Watts]

Good suggestions. I went with 180 psi, +1 HSC, +1 LSC and 9 clicks of rebound from fully closed to start. After doing a test ride, it feels much closer to what I’m looking for. I still had about 2mm of travel left on the shock after hitting the drop-to-flat, so I’ll probably try lowering the HSC & L...

@Twisted Fork, that's a solid first result from a single change. 2mm of travel remaining on that drop-to-flat means you've got a comfortable margin to play with, so backing off the compression a click each is a sensible next step.

One thing to keep in mind as you open up LSC and HSC: the progressive air can is already doing most of the heavy lifting for bottom-out resistance, so the compression damping is really there for ride feel and platform rather than protecting against harsh bottom-outs. If you drop both by a click and find the bottom-out resistance has gone from "2mm remaining" to "barely any remaining," it's the HSC doing that work. In that case, you could keep HSC where it was (+1) and just back off the LSC, which will give you a more supple feel through the mid-stroke without sacrificing your bottom-out protection on the big hits.

Your 9 clicks of rebound from closed is on the slower end, which makes sense for a heavier setup on an eMTB, but once you've sorted the compression, it's worth experimenting with speeding it up a click or two. That's where the pop and playfulness off kickers really lives. The progressive can gives you more room to run slightly faster rebound without it feeling uncontrolled, because the rising spring rate naturally decelerates the shaft as it extends through the stroke. With the linear can you'd have been more likely to get that pogo-stick bounce at faster rebound settings.

Sounds like you're getting close. One variable at a time and you'll nail it.