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Linear or Progressive?

How do you prefer your spring?

  • Give me all the progression, the more the better.

  • Make mine as flat as possible.

  • I don't understand the question.

"You're not bouncing off the bottom out, but you may as well be" -Henry Quinney

This line in the Pinkbike review of the new Unno Burn really struck me. What a great way to describe the feeling of an overly progressive suspension setup. At 40% progression, it was tough for them to get full travel on this bike during testing.

On my previous shock, the super deluxe, I used the Meg Neg air canister. I tried all combinations of positive and negative volume spacers and never seemed to find a setup I gelled with. It seemed like no matter the setup, it felt too soft in the first 60% of the stroke and then ramped up so hard that it would never bottom out. There is no bottom-out bumper in this shock, just an o-ring on the shaft, and I still never felt it bottom out even with 40% sag. If you never bottom out, you literally aren't getting the most out of the travel.

I've been on a mission with my personal setup since I mounted the 2024 Float X2 to my Enduro; to make the suspension as linear as possible.

The Float X2 is commonly ridden with the maximum number of volume spacers to give it more "Pop," and to address concerns about bottom-out progression. The suspension characteristics that I am used to people chasing after with the X2 go something like this;

"I want it poppy so It feels playful, and I don't want any harsh bottom outs."

For a long time, I saw this tactic used heavily as the go-to for anyone riding jumps or drops. However, recently I've seen people steering away from that approach and leaning more on higher air pressures and firmer damper settings with the bigger impacts absorbed by the bumper. In most cases, if you set up the damper to do its share of the work, and run proper sag, you don't have to rely on a wall of progression to deal with the force at the end of the travel. There are exceptions of course.

I took this approach when tuning my X2 for my Enduro. My fork, being a coil-sprung unit, is very linear in the way that it feels. The resistance and the response are much the same regardless of the position in the stroke. All telescoping forks will have some progression due to the space being compressed in the lowers. The trick I've been trying to pull off is getting the rear shock to mirror the fork in its progression.

After initially starting with two volume spacers in the X2, I've been experimenting with fewer and fewer. As I've reduced the number of spacers, I've upped the air pressure. Being well over 220lbs, I rode the max pressure of 300psi to see what kind I'd sag numbers I'd see. It didn't seem too stiff and sag seemed pretty decent at about 25%. However, the o-ring was a ways off the bottom, and it was evident that I should drop the pressure a little.

Interestingly, even though I wasn't getting enough travel, it still never felt harsh like when I was running deep sag and lots of volume spacers.

Dropping down to 287psi got me to 28% sag, and that felt better. I dropped once more to 275psi, and that resulted in 32%.

At 32% sag, I'm getting into the portion of the travel where I know the bottom-out bumper is engaging. The bumper in these shocks is there to be used, so I could probably still get away with a few less psi. Every psi dropped will increase traction, which is pretty much where my head is at currently.

It's really nice to finally have Fox 4 way dampers on both ends. The high and low-speed rebound options are super beneficial when trying to achieve balance. When compressing the bike into corners, and pumping through undulations, it's just so nice to have the fork and shock mirroring each other. I never was able to feel that with the previous shock, a very basic Super Deluxe.

While it can be daunting to figure out which knobs to click and which way to click them, it is just so nice to be able to separate out low and high speed circuits. It's been said before, but the best way to get to your own dialed setup is to wrap your mind around what is happening. To do this, it really helps to start your setup with the following sequence, on both ends simultaneously.

  1. Set the sag with minimal spacers. Aim for 18-25% in the fork and 28-30% at the shock

  2. With all clickers fully open, ride off a curb. Notice how, when the wheels hit the ground, the suspension oscillates, past the point of sag, and then back down. Start adding clicks (righty tighty) two at a time on the low-speed rebound adjusters. Notice how the oscillation calms down with every click that is added. Add clicks until the suspension does not overshoot the sag point on the return stroke. This will be too slow to ride, but it's good to know what too slow feels like.

  3. When you get to a rebound that feels just controlled enough to allow one overshoot but not more, you're in the right ballpark.

  4. Make the front and rear feel as similar as possible using just low-speed rebound.

  5. While coasting the bike around, bounce up and down slowly. Add low speed compression until you feel the suspension resisting your bouncing efforts just a little bit. Again, adjust the front and rear simultaneously.

  6. Set the high-speed circuits in the middle of their adjustment ranges. Once up to speed on the trail, open each high speed circuit one click at a time to see how it affects the way the wheel tracks track the ground.

Once you go through the sequence a few times, you should start to notice what feels right and wrong. As you move forward, record the end settings (from closed) so you have your baseline. You cannot track your settings too much, and you cannot know where you want to go without first knowing where you started.

So how do you tune for bottom-out?

Unless you are doing two-story drops, and 40 foot gaps on your typical ride, you don't need any more than 25% of the maximum volume reducers. Any shock with a significant bottom-out mechanism can deal with some pretty massive impacts. There is no need to up the progression and compromise the feel of the suspension where you most use it.

This clip was sent to me by a local rider who rides his DH bike in two primary scenarios. In the clip, he is riding his local freeride spot, Black Rock. He's using every bit of landing on the large step-down known as ET, and when he lands, you can hear his tire buzz the seat. In the other scenario, DH racing, he is bottoming maybe once a run on the biggest jump, so much more infrequently.

He wants the bike to be planted and tracking smoothly over rough ground, but also, he rides at Black Rock all the time so he wants more bottom-out resistance. What are his options?

  1. Increase spring rate. This will make it harder to bottom out, but due to the fact that sag will be reduced, he may give up some traction.

  2. Increase high-speed compression damping. This may also give up some traction but is not likely to change sag.

  3. Increase size and durometer of the bumper. An aftermarket bumper for his coil shock will allow the same spring and damper settings to be used while cushioning the bottom out more effectively.

These are the options on the table and it may in fact take a combination of the three options to achieve the most "uncompromising" setup. Or, he could choose to change his setup between racing and freeride and give up on the idea of the one dream setting that will work in all scenarios.

One thing is for sure, if you don't experiment, you'll never know what will work and what won't.

I currently don't need to prepare myself for any Rampage-sized impacts. I'm taking some time away from big hucks, and sticking to the ground. This has freed me up to optimize my setup for what I'm currently seeking out in the way of trails;

the loamers.

Last weekend I got to enjoy my very linear setup on some primo Oregon coast organic soil. Loads of traction, just enough pop, and a seamless transition between strokes are what I've become accustomed to. I love the feeling of opening the bike up and letting it steam right through anything in its path.

I will continue dialing in my setup as the winter progresses, as I think there is still potential to use more travel without losing control when it's all used up. My aim is to get to around 33% sag in the shock and use full travel 2-4 times per descent.

I'm trying to take a mental note of when I experience happiness on the bike, and lately, that occurs when I'm marveling at the capability of the machine to carry speed through bumps and find traction in tricky spots.

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