Suspension Settings - Demystifying LSC/HSC and LSR/HSR
Hi, I'm Shannon! Welcome to my 'idiot' guide on suspension set up. Suspension set up for me is super important and something I spend a lot of time getting dialled in right for my bikes. It took my years of messing around and trying out different set ups to make me realise what works better and what doesn't (for me anyway). I hope this helps you get more out of your suspension/bike!
What is the main purpose/goal of suspension tuning?
The primary goal of suspension tuning is to enhance your control over the bike, allowing you to navigate turns, brake effectively, tackle jumps, and ride confidently across various terrains and weather conditions.
A well-tuned suspension helps you stay on your chosen line with precision and stability, adapting flawlessly to the challenges of each ride. You will gain confidence on the bike, it'll perform better and the impact on your body will be minimised.
The set up can vary between each bike, depending on the fork and rear shock manufacture, bikes linkage type (4-bar (probably one of the more popular types), VVP (Santa Cruz), Single Pivot, the Yeti Switch Infinity, High Pivots and many more.
Setting Sag
First step: lets talk 'Sag'
Setting sag is the most critical step in suspension setup, serving as the foundation for how your bike handles. Sag measures how much the suspension compresses under your weight and riding position, directly influencing performance. Typically, sag is adjusted to 25-35% of the suspension’s stroke length, tailored to your riding style and terrain.
Nailing the sag setup is absolutely key... too little or too much can throw off your bike’s suspension performance, geometry, and overall handling. Think of sag as the starting point for a balanced, responsive ride, primed to tackle any trail conditions. Always do this before anything else. If you have the wrong level of sag, every other adjustment you make will be incorrect.
Too much sag = leads to 'wallowing' into the travel and causes fork 'diving'. You'll be using up too much of the fork travel just riding along and will be more likely to bottom out unnecessarily.
Too little sag = harsh top end feeling as the fork is having to work harder to absorb even the smallest trail imperfections.
When setting your sag, you would do this without making any adjustments to the dials on your fork and shock (rebound and compression). Ideally, have all dials opened up for the most accurate sag setting.
Remember: Increase air pressure to decrease sag. decrease air pressure to increase sag
What you will need:
A shock pump! There's many available, we'd recommend one from Fox or RockShox. They are not brand-specific so you can buy whichever you like. Look for a big dial for easy reading.
Fork: Sag Measurement
For fork sag, the general target is between 15-30%. Many forks have sag indicators printed on the stanchions, making it easy to check. If yours don’t, use a ruler or tape measure. The length of the stanchion is the amount of travel your fork has. This simple calculation gives you the amount of travel your fork should compress into when you're stood on the bike in a balanced position.
https://www.youtube.com/watch?v=dh2Q7Fu2pfA
The video providing by Fox is a light-hearted watch to the below instructions. Typically with a Fox fork they recommend between 15-20% sag. With Rockshox it's a little higher, a lot of people run between 22%-28%.
Preparing: Ensure all dials are open and if your fork has an o-ring, push this down to the bottom of the stanchion. If your fork doesn't have an o-ring, then simply use a cable tie or tied elastic band as a replica.
Getting started: If you look on the back of your lower fork leg, there should be a manufactures starting guide for their recommendation on air pressure, corresponding to your weight. Use this as your starting point. Set the sag with your usual riding gear on as this would provide a more accurate measurement.
Introducing some air: Remove the valve cap from the fork, which can be un-screwed by hand. Typically located on the left hand leg, then screw the pump onto the valve (just like a car or bike tyre valve). As you put around 30 PSI into the fork, push down onto the fork with the handlebars to help the air circulate around the forks air chamber. Then repeat to the recommended pressure.
Calculating: Get a friend to hold the front of the bike while you gently climb onto the bike without disturbing the forks o-ring too much. Stand up in your usual riding 'attacking' position and gently bounce to break the seal on the fork and settle back into your attacking position. Don't hold in your front or rear brake. Push down the o-ring on your fork stanchion.
Retrieving your measurement: Remove yourself from the bike carefully not to move the o-ring which will be showcasing a measurement.
Where you see the o-ring leveling, will be your sag measurements (in percentage). If it is sitting 25% or more, remove some air via the valve, though be careful as less is more, if there is less than add in a few more pumps of air and repeat the steps above.
Shock: Sag Measurement
Shock sag works pretty much the same way as the fork, you need to repeat the same steps as above, but on the rear shock.
However, a rear shock would have a higher air pressure due to the riders weight mostly being situation through the center of the bike.
Shock manufactures tend to have a guide on what they would recommend in their shocks for your weight. For example you can check out some for Rockshox and Fox. Your bike manufacture may have their own specific guide available on their website - if so use this as a starting point, every suspension design is different.
As a rule of thumb 30% is the typical sag value that you are aiming for. This will give optimal balance and will allow the rear suspension to perform at its best. This is often a slightly higher sag value than on the fork but is generally the sweet spot when it comes to the rear.
Compression Damping
Compression damping is a key factor in your bike’s performance, directly affecting traction, comfort, pedalling efficiency, and resistance to bottoming out. Fine-tuning this setting allows your suspension to respond effectively to the unique challenges of the trail, enhancing both control and ride quality.
When adjusting compression damping, consider the size, shape, and speed of the obstacles you encounter. Square-edged hits, like rocks and roots, deliver sudden, high-force impacts that cause the suspension to compress rapidly. This is what high speed compression (HSC) damping adjustment seeks to control.
On the other hand, smoother, rounded bumps exert less force, resulting in slower, more gradual suspension movement. The same is true for your own bodyweight movements. We need to control how the suspension reacts to these forces and this is what low speed compression (LSC) compression damping affects.
Dialling in your compression damping ensures your bike can adapt to these varying conditions, keeping your ride balanced and responsive.
Not all forks and shocks have individual adjusters for low and high speed compression or low and high speed rebound. Only the very top end models will have all four adjustments. Its common for their to be a single rebound adjuster on many forks and shocks.
A simple understanding is below I find helps:
HSC: Plushness / resisting bottom out and harsh impacts
LSC: Suppleness / pedalling efficiency
HSR: Lively pop / G-out control
LSR: Plush / firm
When we talk about open and closed we are referring to whether the fork/shock's damping circuits are open (no additional damping provided) or closed (full amount of additional damping provided). Guides from manufacturers will talk about starting your adjustments from a fully-open or fully-closed position.
Low Speed Compression (LSC)
(-) / Open: this would keep the suspension lower in its travel during riding. When you adjust (-) to let the suspension move more easily through the early and mid-stroke, providing a softer and more supple ride.
(+) / Closed: adjusting the dial clockwise will allow the suspension higher in its travel during riding, resulting in a firmer feel on rough terrain. This can enhance efficiency and help maintain momentum over rolling terrain and through corners.
High Speed Compression (HSC)
(-) / Open: opening HSC enables the suspension to compress more rapidly through its travel, allowing the tires to maintain consistent contact with the ground. This enhances traction and control, particularly when navigating challenging terrain like square-edged roots and rocks.
(+) Closed: closing the HSC assists with big impacts, providing the suspension to absorb a lot of force. This comes in beneficial to help support big impacts.
Low Speed Rebound (HSR)
(-) / Open: opening up the HSR creates a “lively & responsive” feel by allowing the shock to rebound more quickly after deep compression. This enhances your ability to launch off jumps and generate momentum while pumping through the trail, giving your ride an energetic and responsive character.
(+) Closed: closing the HSR will assist you in reducing that feeling of being too far forward over the bike, 'bucked' is a good word to use, making you feel off balanced.
The benefit of adjusting this setting slows down the internals during bottom outs, compressing into a jump or hitting some real rough terrain like rock gardens.
High Speed Rebound (LSR)
(-) / Open: the more 'open' you make your LSR, the more of a 'plush' sensation you will achieve, along with traction making the bike feel more planted and in control.
(+) / Closed: closing off the LSR will act as a stabilization feature, slowing down the suspensions return speed. It typically allows you to help maintain traction, but decreasing the feedback sensation while completing technical climbs.
Real World Testing
Figuring out what works and feels best for you can take some patience and playing about. I find riding one particular trail that has a bit of everything (rock garden, drops, berms and high speed sections) works best. It's taken me years to be able to get to the bottom of what feels good and how to get the most out of my suspension.
'Bracketing' is a term used for riding the same trail and making suspension adjustments after each run. I would recommend writing these down as they can be easily forgotten, for me anyway! Less is more though, so be patient. Once you're dialed you'll hopefully feel like more of a hero and can also help your mates.
I would start in the middle of each setting and make small adjustments on how you feel the bike is responding, changing a single setting each time.
