Setting sag is the first (and arguably most important) step to dialing in the suspension on your mountain bike. Sag is static ride height. That is, the amount your shocks compress when you’re in your regular riding position. The goal of this video and article is to dive deeper into how it can impact your riding comfort and control.
What’s my regular riding position?
If you tend to stay seated while riding mild trails, you should measure sag when you’re sitting down.
Conversely, if you’re a more aggressive rider (on the enduro or downhill spectrum), you should be standing in the neutral attack position while measuring sag.
What does sag do?
Sag puts you in the ideal starting riding position to engage the trail. It’s the resting point that you and your bike will continually return to for the duration of the ride. Here are some examples of what setting sag helps you achieve:
- You feel comfortable and controlled;
- The bike will compress and rebound through front and rear travel in a balanced way;
- Pedaling will be efficient;
- Braking won’t cause the suspension to lock up;
- Low speed body weight transfers will be controlled (braking, acceleration, moving around the bike);
- High frequency, low magnitude bumps will be absorbed (small bump sensitivity);
- High magnitude compressions and rebounds will be controlled (big hit control).
Is sag specific to each individual bike?
Yes. There are a number of technical terms like “anti-squat”, “anti-rise,” center of mass, and more that bike manufacturers design into their frames before tuning shocks with FOX. While we won’t go into the specifics of these terms today, know that they are reasons why a bike manufacturer will recommend a specific sag point for its specific frame.
The recommended sag point by your bike manufacturer is the place it believes will have optimal ride qualities for the majority of riders.
What if I don’t like the sag point recommended by my bike manufacturer?
You may find that your bike manufacturer recommends 33 percent sag for the rear suspension, but through testing and bracketing, you find that you prefer 27 percent. This is okay and completely normal.
Remember: the recommended sag point by your bike manufacturer is the place it believes will have optimal ride qualities for the majority of riders. You may or may not be the majority.
The most important thing you can take away from this is that it’s okay to experiment with your sag point for forks and shocks.
So, how much sag should I run?
Depending on who you talk to at FOX, you’ll hear or read a number of more specific recommendations. This is because everyone is different. It sounds cliché, but it’s very true in this case. Generally speaking, though, here are good ranges to stay within:
- Rear shocks: 25-33 percent sag.
- Forks: 15-25 percent sag.
How do I determine how much sag is right for me?
The amount of sag you should run is dependent on your set of expectations, riding style, terrain, and bike set up.
- More sag: Less experienced rider or take it easy on descents.
- Less sag: More experienced rider or ride fast on descents.
- More sag: Conservative and safe; prefer scenery and exploration; building skills.
- Less sag: Ride hard, fast, loose; racing; KOM attempts; climbing hard.
- More sag: High frequency, low to medium magnitude bumps.
- Less sag: Tarmac; smooth trail; jumps; drops.
Bike set up:
- More sag: greater than 150mm travel.
- Less sag: less than 150mm travel.
You’ll find that you fall in a mixture of “more sag” and “less sag” categories. It takes time to figure out what works best for you.
Here’s a practical example of how these categories break down. This is not a setting recommendation. It’s an exploration of these four categories to show how they result in an individualized setup.
Practical Example: Daniel’s Santa Cruz Megatower
- Expectations: Daniel rides hard – for an expert – but he’s no longer looking to take the risks to bump up to the pro level. Former racer; now ride for pure enjoyment.
- Riding style: Rides in the attack position with chest over the handlebars. Enjoys riding steeps and gapping jumps. Tries to corner as fast and hard as possible, to a point. If there is a long sustained straight section, he slows down for his own safety because he doesn’t want to deal with the increased risk anymore.
- Terrain: Redwood forest loam and dust; a few large compressions from jumps and drops; many medium magnitude, high frequency braking bumps, rocks, and roots at high speeds; steep descending grades.
- Bike set up: 160mm travel front and rear, 35mm rise bars, flat pedals, and strong wheels.
- Fork: 25 percent/40mm sag (with extra compression damping).
- Shock: 28 percent/16mm sag.
Sag is an important first step to setting up your suspension. It’s worth noting that a good sag point can be completely ruined by improper tire pressure and compression/rebound damping adjustments.
Fore-aft balance and sag:
- Your bike should compress evenly front and rear. One side should not compress quicker or slower than the other.
- Your bike should rebound evenly front and rear. One side should not rebound quicker or slower than the other.
Here are some quick recommendations:
- Use more compression damping if you are a larger rider, ride fast, and ride aggressively.
- In terms of what’s happening inside the shock, you need to control more oscillations and dissipate more heat.
- Use less compression damping if you are a smaller rider, ride moderately, and ride conservatively.
- In terms of what’s happening inside the shock, you don’t have as many oscillations to control.
Rebound damping should be as fast as possible without unsettling you or your bike. A good way to check is to do the test performed in the video starting at 1:44:
Rebound is what allows your shock and fork to extend back to a place where they can absorb the next bump. If your shock and fork rebound too slowly, you can experience harshness in the form of “pack down.”
We’ll be going into more detail around compression and rebound adjustments in future videos.
Like what you see? Check out all the FOX Academy videos for powered vehicles and mountain bikes here.
For the hardcore enduro rider or downhiller, check out DIALED.