Do You Measure Fork Sag?

measure fork sag 3 times in 3 minutes and you will get 3 different measurements.

It's a reference point at best, but the best reference of all is a digital shock pump

cut the thing off, trust me, it will eliminate a form of anxiety from your life.

I like the oring for bottom out measurements only.  I’ve found some trail systems I wasn’t using as much travel consistently with my normal set up.  (Not that I bottom out my fork often anywhere but big difference between not using 10 mm and 40 on a 170 fork)

But I still only drop pressure by a couple psi.  Always just find a good setup on the stuff I like to ride most by feel and run it pretty much everywhere give or take a couple psi. 

I'll eyeball sag the first time I put air in a new fork, but other than that I really only use the O-ring to measure bottom out. Rear shock sag measurements are a frequent reference point for me, but I agree with other comments that fork sag measurements seem to be pretty inconsistent and thus not that helpful. My ideal fork sag is "not much."

I dont measure sag in the fork ever, i start with recommended and adjust from there, as soon as you turn a dial the sag changes in theory.

I do like to know how much travel i use though for giggles i call it the "yeeehaaaa bar"

Just calculate the mean 

To be pedantic, in theory, damping shouldn't affect sag because an (ideal) damper is supposed to resist changes in velocity rather than position.  In practice... It is recommended to measure sag with compression wide open.  The problem I have with sag measurements is seal stiction.

On the fork I just eyeball it and then see if it bottoms out when I do something stupid.

Nah 

Another vote for adjusting based on O-ring & bottom out.  On my DH bike, I really don't set the fork for sag, I set it for the track.  Certain tracks/parks are rougher than others, while others are mellower and I tend to go +/-5 psi accordingly when I see where the O-ring is ending up.  On my trail bike, I will set the fork based on standard/balanced sag-setting procedures but then ultimately adjust based on O-ring bottomoutness.

With fork sag I generally use the setup guide and adjust from there. With shock sag I use the O-Ring or bottom out bumper to measure. I normally measure three times to make sure I am getting consistent measurement for the static shock sag. 

I'll measure sag. I usually turn the crank to the bottom, stand on it and try to simulate "attack position", bounce up and down a bit to find the center of the sticktion and slide the o-ring. Then step off gently.

I think riding in the sag is good for traction, but I'm not sure I can feel that. I know from racing r/c dirt cars that sag is critical for traction on those things.

After sag is good, I'll use tokens/spacers to get the bottom out resistance I want. Then if I need more support in the mid-travel, I'll add some compression. That's the only thing I mess with from track to track typically.

I'm not a racer. I just ride for giggles. So I set my shock sag and just go by feel for the front. I don't check every ride or even after several. I just toss the bike in the back of my xterra and hit the trails.

I do get my suspension serviced at more or less proper intervals though.

I did it once on an old DHO because I was told that was the proper thing to do. A stiffer spring was already on order. I've only ever had one air fork, the last of the skinny legged World Cups. Never bothered checking the sag on that one. I just went by feel.

The results of this poll explain a lot. 

Yeah the results and comments seem completely at odds. I guess the kind of person who measures their fork sag is not the kind of person who comments, for whatever that conclusion is worth 😂

or someone is messing with the poll

I'll bite -

I used to set the standard 15-20% fork sag and could never trust my front end for anything but cruising well below trail speed. Way too much dive even with compression clickers full closed - which felt terrible. 

From there I started trying to run 10-15% which felt better but started to become pretty tough measure as I got closer to 10% so I just stopped measuring sag. 

Now I set me forks up for what feels most supportive when I push into the front for grip. Sometimes that means I rarely see anywhere near full travel and occasionally that extra 20-25mm or so saves my ass. 

I have not found a reliable way to measure sag on a fork.

That’s another misnomer for me, this concept that you should be using all of the travel on your fork no matter what trail you ride?

I mean surely if you ride a relatively smooth trail and only use 120mm of your 160mm, why should that mean that you should soften your suspension to use all of the travel instead of maybe you only need 120mm of travel for that trail?

I mean it’s not about how much travel you use, it’s about how the suspension is working for you, or am I just completely confused here?

I check sag on both fork and shock when first setting up. Afterwards make adjustments from there. Sag is a starting point, not the end all and be all. 

I have all my settings recorded along the way with notes of how the changes felt. 

I'll check travel usage on both ends to help keep front and rear balanced. 

I think there is a balance.  I wouldn’t want to drastically change things from what I consistently ride.  But i certainly think it’s worth tuning your bike within a reasonable spectrum for what you are riding especially if you are racing.

You’re 100% right. A mellow ride that has one drop to flat can bottom your suspension but a DH track with multiple successive hits might use 80-90%. Your spring rate (and rebound because it’s a function of spring rate) should not change track to track unless there are some really big hits or something like that. Minor tweaks to compression is really where it’s at. If you do major changes track to track your suspension is just not set up properly.

I hope Jordi reads this thread 

Using sag as a defining characteristic of your suspension is just absolute nonsense as far as I'm concerned. How your bike responds to both terrain and your inputs is what ultimately matters, and it depends SO MUCH on how your air spring behaves, and how your damper behaves, and how your spring and your damper are interacting, and where you want the dynamic ride height of your bike to be, and how you want it to bias front to rear in turns, and how much travel you want to be pushing into/how much you want it to push back with your inputs.... It goes on. Reducing all that to a single percentage that only matters when you're not even using your suspension is daft, especially because it's so inconsistent to measure.

Set your bike up for feel and ignore the bloody sag. Depending on what fork you make me run, I'll be at anywhere from 10% to 30% sag.

Sag isn't any more nonsense that the manufacturer's recommended pressure. 

Pick one as a starting point and tune from there. Document the changes and how they feel. Only change one thing at a time. 

It's a basic troubleshooting process and it's more important to be able to track changes and correlate those to the results than where your starting point was. 

Commenters know that the poll is mainly relevant to advertisers, since you're taking a measurement with your shock pump--or trusting a manufacturer's coil rate call-out--when setting spring rate? Also, sag is potentially even less meaningful for tuneable spring rate forks

I measure my fork sag using the o-ring, but I don't agonize about it. 30% or so, and we're good. I expect that percentage could change on a different bike, but on mine I'm happy at that sweet spot. 

Yeah, but both are only useful for a bounce around in your driveway before you further tweak it... in your driveway. Let alone finer adjustments once you've ridden on trail. Both are nonsense to use as gospel, which is what a lot of riders consider sag to be.

Agreed, 

Both are only a starting point. 

New to full suspension (been living in a cave) but seems like best ot set sage for the rear and note the pressure setting, then use mfg pressure as a starting point up front and sag, then adjust the front to balance the rear.  IF the rear is bottoming out too much ,then add pressure, if not using full travel, reduce pressure. All this aside from air chamber spacers that change the how progressive the spring rate is.  

OF course as you add pressure you may need to increase rebound and may be able to reduce compression for better small bump response.  

I really like having suspension I can adjust.  Part of the fun of riding. Had motorcycles both ways and my last MTB was ancient tech.

In the past, I checked sag (usually 3 times & averaging) when setting initial pressure, since the charts never seemed remotely close for me.  But for the latest round of RS stuff, the pressures suggested by the chart/TrailHead app has been pretty much spot on for me, maybe +/- 1 psi in fork and a few psi in the shock.  So I haven't bothered measuring it lately.

As other's have said though, the o-ring is useful for seeing how much travel you use on big compressions though.  Fork felt good with the baseline pressures but had lots of travel left.  So I cracked it open and removed the 3 (lol) tokens the previous owner had in it, used the same pressure, and still am almost never bottoming out but my hands feel much better.