So you have your fork dialed in, now its time to setup your rear shock. Christina Chappetta runs us through a simple guide to setting up your rear suspension and achieving baseline sag, rebound and compression.
Better to do the rear suspension seated I think - its only a small adjustment in how you calculate it for much better results. On most frames Ive come across a seated 35% is close to 30% standing. Its way more consistent to set up, so even if you don't quite like the 35% rule, you can adjust it for your taste and then get the same result over and over. Standing up gives inconsistent results as tiny movements in your position give different readings.
Agree 100%. Also dynamic riding position is way different to static one "on the parking lot", so using something that is always the same(seating position) and then adjusting from there is much prefered way of setting up my bike for me.
This is exactly why I constantly make incremental psi changes after the initial set up! Sure my position on the bike is consistent when I set sag, and I’m careful not to do a final bounce when I dismount. But it takes me about four tries to get something consistent. And it’s not very consistent. Christina’s videos are the best! Now I guess I should go back to the Tuesday tune and find out exactly why we set sag.
I fully agree. Not that it matters but Doddy checks it seated on GMBN and I've seen world cup sag checks seated. For consistency (for myself) I prefer it. I just do it seated, ungeared at roughly 30% (geared up, seated at 35% would probably be more ideal) and go thru my setup as normal. If bike feels good and isn't bottoming constantly, great. I know I can repeat it and adjust sag a small amount if not. Since the fork is easier to check sag with the o-ring and how you get off the bike, I do that at 20% in a neutral standing position. And then adjust based on ride feel again.
To expand on this: If you set sag to 30% on your AM rig while standing, it'll be about 34-35% while seated and will pedal like shit because the anti-squat won't be where the manufacturer intended. Worth pointing out that because women have a higher % of their weight in their hips than men, Christina in particular might not end up as far off as the average man does by setting sag while standing.
@iduckett: sag isn't actually how you set bottoming resistance, Sag is mostly about bike geo and downward travel to operate how the manufacturer intended. Your sag setting should have nothing really to do with your relative aggression level or terrain as it's just about body weight & weight distribution. You should use the damping and the air spring compression ratio (i.e. volume reducers) to control bottoming, so this is what adjustments you make for terrain and your personal send-it level.
@SATN-XC: forks are much harder, and since rockshox ditched their fork markings that made theirs harder too. I would say start with recommended pressure and adjust from there if in doubt. Unlike rear shocks the forks behaviour is consistent on all bikes (with the same fork) so the manufacturer recommendations tend to be fairly close to what most would want. Even allowing for pump accuracy it's a good starting point.
@Thorjensen: yes for sure. Drop your saddle, sit down on the saddle feet flat on the ground. Lift your feet off the ground to hover for a second, then place them back down and your done. Aim for 35% this way and your good as a starting point that works for most people.
@SATN-XC: no it doesn't really work. Static friction and damping means that you don't generate enough force to get consistent results. That's the same problem you see (to a lesser extent) standing up for rear shocks.
Setting sag is about getting a repeatable adjustment that you like as opposed to a specific number or body position. Most shocks recommend 25-30% 'standing' sag dependent on the shock, but x% standing is just y% seated, so you can flip between the two, as long as you make the adjustment for the position.
The crucial part is to be confident that if you do it twice you'll get the same result, and then just experiment from there.
@SunsPSD: Right - but too little spring rate and you will be bottoming out. I meant it more as a validation that your sag is in the right ballpark. I also have coil f&r, so no volume spacers for me!
@benpinnick: That have been my go to way from my first FS. The new thing for me is the 35% sag on the Aeris 9 and not 30%. And I know that it's just a reference point to start from but I cant remember ever bottomed out with 30% running Zero Volume Reducers. I have to try it out
So helpful! Recently-ish (been salmon fishing too much...) picked up a mid travel frame with a DHX2 coil and I need to figure out how to squeeze all 135mm out of it for my fat ass. Been tweaking things and taking notes but this is such a clear stepwise process about how to figure out the right tune.
Thank you Christina! Feel like this and the fork tuning video will get a lot of bookmarks!
If you have a coil and need to figure out travel amount on your own without trying to pry your bumper up, take an elastic band and loop it around the shock shaft and through the elastic's loop. Pull to tighten it. Voila - you have a sag-o-meter. Use a pick or toothpick to remove it.
These two articles have really displayed how mismatched the internet mtb crowd's basic technical knowledge is from their self-confidence in same and obsession with numbers. No one (suspension manufacturers, frame manufacturers, mtb media) is saying to set sag at 30 plus or minus 0.5%. Put another way, no one is saying adjust your springs to achieve a sag to the nearest one percent. It's not a precise process. Most people's shock pumps aren't going to be accurate to 1 psi, even if the display makes you think it is. Most people's rulers may read to the nearest millimeter reasonably well but the way individuals use the ruler on any given occasion likely won't be accurate to the mm. All of y'all in the Well Actually crowd with two threads of blah blah blah you set up suspension better than the next rider, it's false precision. You're kidding yourself, and wtf cares if you sit down to set sag. It's a starting place the very next step is to adjust away from.
Manitou Mara Inline shock have fixed negative air which is set when you screw on the air can on to the shock body.
Manitou forks (R7, Mattoc, Mezzer, etc.) doesn't require balance air chambers step because you pressurize both together at the same time. When you connect the shock pump to Manitou fork. Shock pump connect to both positive and negative air chamber right away. Since both negative and positive air chamber is connected together to the shock pump it is effectively disabling both until you remove the shock pump then the positive and negative air chambers will start to work again.
You will the have to add a bit more air as the pressure in the main chamber will have dropped slightly as it moved into the negative chamber to balance it out
My main takeaway from the Race Tech suspension bible (recommended read!) - friction -> spring -> damping. Set up in that exact order. Optimisation of friction and spring along with halfway useful ranges of damping make 90% of achievable performance. I spent lots of time focussing on my springs afterwards, both in rate and curves and it paid out massively, far more than any damper tuning ever did. Not even to mention burnishing your bushings!
How do you do anything about friction without disassembling the shock/fork and replacing seals, grease and oils with the best possible/lowest friction/viscosity of each?
Your point is fair and race tech bible is indeed the shiz. However, if you've ever swapped from a crap damper like a Charger RC to a more advanced unit like an RC2 or RCT3, or from a fit4 to a grip...
You just can't make those kinds of improvement in feel and ride-ability with a spring change or bushing treatment.
Older bikes with slack seat tube angles would show big differences in seated vs standing sag. Modern geometry has made that difference far smaller. On my 78 degree seat tube enduro bike the seated and standing sag are only marginally different both front and rear
A really easy starting point for air suspension it to match the psi in your fork to your weight in kilos, and your weight in pounds in the shock.
So if you weigh 75 kilos/165 pounds, you put 75 psi in the fork and 165 in the shock.
A nice little relationship based on coincidence here is many bikes have a leverage ratio of 1:2.2, which is the same ratio of Kg to Lb.
As I said, starting point! Just like the 'your weight in pounds/8' for front tire pressure and add 3 for the rear - starting point. If you are really fast or are a plough king, the above will be too soft.
I'll also add that whatever your pressure, that in an attack position while bouncing up and down on your bike, if you are on an XC bike and you moved the o-ring 50% on your fork, then you should also have moved the o-ring 50% on the shock. On gravity bikes you want to the fork's o-ring to have travelled less than the rear as you want the fork to be slightly stiffer as you will be pointing downhill when the real action happens.
In my (little & humble) experience in setting up bikes using linkage software and dynamic sag measurements, I found rear suspension is always going to be soft when using the described method. It’s a very descent starting point - but with modern bikes fairly high starting leverage and somewhat progressive linkage 30-35% on the shock equals to 35-45% on the rear wheel (depending on frame design of course) - which is just way to much for faster riders. I’d aim for no more than 28% on the shock (Seated (dropper down!) or standing doesn’t make a significant difference on modern bikes with seat angles steeper than ~77deg)
This is nice but tells you what's already on the internet. I would like to see a much bigger tech piece about bike suspension set up. Including Data analysis and the general aim like, springrate and how that changes the dirstribution of used travel, front/rear balance, suspension speeds etc. ... How that plays together with overall bike geometry. There motioninstruments.com/blogs/blog/20-faster-same-bike-same-rider-proper-suspension-setup-using-data is an interesting article about the benefits of proper suspension set up.
What all of these shocks and forks need is an adaptive / dynamic release tech; the faster and deeper the suspension compresses, the slower the release is while accelerating as it approaches back to the sag point.
@iridedj: You all missing my point, this should have no adjustment, should be dynamic and "self adjust" as the shock moves probably controlled by a chip and with a little motor inside to control the oil flow dynamically. Comprende?
Hi Ohlins, Brand new Forbidden Druid LTD. build here, TTx2 rear and the rebound damping at full slow is an absolute laugh. It seems like there is none at all. Very little noticeable range of rebound changes between the end points. I fully understand the faster you ride concept of valving, however, in the Northeastern US there is a lot of rocky, slow, tight, tech. And the rebound adjustment on whatever this tune is, is far too fast at fully closed (OEM spec’d not aftermarket) jnn7I have emailed the North Carolina location and waiting on a response. Mind you on the Druid they recommend a sag amount that is typically close to many DH bike settings 30-35% for sag. If the spec’d shock can’t offer a fair rebound (or compression) sweep range for that matter..that is a
I've had Ohlins shocks in the past and I find the rebound damping is a little different to setup than I'm used to. What is your rider weight and air pressure?
Many many many riders have no clue what any of this means....or even own a shock pump. The 5 regulars I ride with don't own a shock pump, don't know what the little o rings are for and certainly can't tell you what any of the knobs do. Just go out and ride , they don't care and neither should you.
"The best suspension you've ridden is the best suspension you know." Those "knobs" make a huge difference to the quality of your ride. A properly set up suspension is a joy to ride, and vice versa.
@woofer2609: you aren't wrong...but again the average knuckle dragger doesn't care. My buddies are good riders with good bikes, they just have different focus. For one they are rarely on PB and two their bike shop "takes care" of them. I mean ride your bike with the climb switch on for a few days, it is still fun. Perfect no, fun yes, all a matter of perspective.
your 100% right, doing 33-35% seated (geared up) is spot on
Sure my position on the bike is consistent when I set sag, and I’m careful not to do a final bounce when I dismount. But it takes me about four tries to get something consistent. And it’s not very consistent.
Christina’s videos are the best! Now I guess I should go back to the Tuesday tune and find out exactly why we set sag.
Worth pointing out that because women have a higher % of their weight in their hips than men, Christina in particular might not end up as far off as the average man does by setting sag while standing.
Sag is mostly about bike geo and downward travel to operate how the manufacturer intended. Your sag setting should have nothing really to do with your relative aggression level or terrain as it's just about body weight & weight distribution.
You should use the damping and the air spring compression ratio (i.e. volume reducers) to control bottoming, so this is what adjustments you make for terrain and your personal send-it level.
Would you say that the 35% seated "rule" goes for ex. Bird bikes "wink ;-) wink ;-)
Setting sag is about getting a repeatable adjustment that you like as opposed to a specific number or body position. Most shocks recommend 25-30% 'standing' sag dependent on the shock, but x% standing is just y% seated, so you can flip between the two, as long as you make the adjustment for the position.
The crucial part is to be confident that if you do it twice you'll get the same result, and then just experiment from there.
I have to try it out
Thank you Christina! Feel like this and the fork tuning video will get a lot of bookmarks!
This is consistent with all brands and models? Thanks.
Manitou Mara Inline shock have fixed negative air which is set when you screw on the air can on to the shock body.
Manitou forks (R7, Mattoc, Mezzer, etc.) doesn't require balance air chambers step because you pressurize both together at the same time. When you connect the shock pump to Manitou fork. Shock pump connect to both positive and negative air chamber right away. Since both negative and positive air chamber is connected together to the shock pump it is effectively disabling both until you remove the shock pump then the positive and negative air chambers will start to work again.
Step 2: There's so much we can do.
Step 3: ....
So if you weigh 75 kilos/165 pounds, you put 75 psi in the fork and 165 in the shock.
A nice little relationship based on coincidence here is many bikes have a leverage ratio of 1:2.2, which is the same ratio of Kg to Lb.
As I said, starting point! Just like the 'your weight in pounds/8' for front tire pressure and add 3 for the rear - starting point. If you are really fast or are a plough king, the above will be too soft.
I'll also add that whatever your pressure, that in an attack position while bouncing up and down on your bike, if you are on an XC bike and you moved the o-ring 50% on your fork, then you should also have moved the o-ring 50% on the shock. On gravity bikes you want to the fork's o-ring to have travelled less than the rear as you want the fork to be slightly stiffer as you will be pointing downhill when the real action happens.
I’d aim for no more than 28% on the shock (Seated (dropper down!) or standing doesn’t make a significant difference on modern bikes with seat angles steeper than ~77deg)
upload.wikimedia.org/wikipedia/commons/thumb/4/46/Dunning%E2%80%93Kruger_Effect_01.svg/1024px-Dunning%E2%80%93Kruger_Effect_01.svg.png?20230915204651
Brand new Forbidden Druid LTD. build here, TTx2 rear and the rebound damping at full slow is an absolute laugh. It seems like there is none at all. Very little noticeable range of rebound changes between the end points. I fully understand the faster you ride concept of valving, however, in the Northeastern US there is a lot of rocky, slow, tight, tech. And the rebound adjustment on whatever this tune is, is far too fast at fully closed (OEM spec’d not aftermarket) jnn7I have emailed the North Carolina location and waiting on a response. Mind you on the Druid they recommend a sag amount that is typically close to many DH bike settings 30-35% for sag. If the spec’d shock can’t offer a fair rebound (or compression) sweep range for that matter..that is a
Those "knobs" make a huge difference to the quality of your ride. A properly set up suspension is a joy to ride, and vice versa.