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Discussion Starter · #1 ·
Finally got around to properly checking and adjusting the sag on my bike. My son helped me out.

I weigh 195 lbs., so before installing my panniers and engine crash-bars, or doing any real sag measurements, I’d previously tested and guessed and had set the preload to 19 clicks – up 12 full clicks from the factory setting of 7 clicks. (And I’d double checked by dialing all the way down first until it bottomed out at 0 (confirming it was at 7 from factory) and then dialing back up to 19. I also tested the whole range for preload and found my bike has exactly 35 full-click (one full turn) settings from bottom to top).

I thought I’d share my findings because I’m convinced anyone who’s running at the standard factory setting of 7 clicks from bottom is probably riding too low unless they weigh under 150 lbs. (all geared up and with panniers, etc. if they have them). And it makes a difference in ride performance.

I set my bike for 30% sag. (30% appears to be the consensus for Adventure Bikes).
This equates to ~2 - 13/16 in. (7.16 cm) of the 9.4 in. (23.88 cm) rear travel range.

Moving on to accurately measuring my rear sag after installing panniers and engine crash-bars:

All geared up and with pannier rack (but no panniers) and engine bars and with my preload set to 19, my sag was just over 8 cm (1 cm too far - about 34% sag).

Adding the empty panniers (about 15 lbs.?) brought the sag to just over 9 cm. (38% sag).

I added 4 clicks to the preload for a setting of 23 clicks from bottomed-out to give me my 30% sag (just over 7 cm) with panns, engine bars and full gear.

So, it turns out that my initial setting of 19 clicks (without panniers or crash-bars and total weight of probably around 200 lbs. with full gear) was probably close.

These measurements were done with empty panniers. So, if I add a lot of weight to the panns, I’ll have to reassess. But at this point, I only have 12 clicks up remaining; but I'm guessing the clicks are not all equal and the further up the scale, as the spring tightens, there may be more tension/ stored energy within each click, i.e., the clicks get stronger as they go up—but I’m only guessing).

So, I’m set for now with 30% sag.

But my point is that if you weigh more than 175 lbs. geared up (hẹll, if you weigh much more than maybe 150 or 160lbs) or esp. if you have panns, boxes or crash-bars installed, you should probably be adding some serious preload to get your sag right. It does make a difference in handling. After riding around with the panniers and bars with my preload set to 19 (nearly 40% sag), I noticed an appreciable difference in ride and feel after adjusting up to 23 clicks (30% sag) – esp. in leaning and turning--cornering. And the bike and I feel more “connected” to the ground. The ride just feels better.

The numbers:
The 2018 Africa Twin Adventure Sports has 9.4 inches (23.88 cm) Total REAR TRAVEL.
30% of 9.4 inches (23.88 cm) is 2 – 13/16 inches (7.16 cm).
That’s the distance you are shooting for when measuring how far your rear end drops from NO WEIGHT on rear wheel to you and your gear on the bike.


BUT... Every rider is different, of course, and some may prefer more or less sag. Do what feels right for you, but do experiment with the preload if you haven't already. And do the measurements--you'll need a helper. Google search reveals several good videos and articles explaining sag and how to set your preload correctly. And BigKev has written a bit about his experience with sag too.

Now with the rear sag properly sorted, maybe I will experiment and see about any changes to front suspension and rebound and compression damping--my guess is that this stuff is a bit more subtle though, and at least I have the big one out of the way.

Just my two cents.

Safe travels, guys.
 

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Good post Gary, I am intending to do the same this weekend (if the weather will allow it).

I have a question; we do usually adjust the rear sag; what about the front? Shouldn't it also be checked and adjusted as the load increases?
 

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Good info from garyh.
The sag is important as it sets the ride height, bike ride attitude and therefore the riders attitude to the bars, wind etc. I find if I jack it up too far I feel less comfortable as the seat feels more inclined forward.
As for how the bike handles its the damping that affects the suspension characteristics and as you have compression and rebound to play with front and rear its a more complicated game.
On my ATAS I am running 23 clicks rear pre load and factory front pre load, rider 105 KG, and a top box

I have not touched damping yet and would be interested to hear if others have on the ATAS
 

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Nice write up.
AT's rear shock spring is known to be too soft, probably good for "asian" weights, less for EU or USA, especially if touring with pillion and/or fully loaded panniers. In this last case, I doubt you can reach a proper sag with the standard spring.
 

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Discussion Starter · #5 · (Edited)
Petros, I think the rear sag is most important to get right first. But I have to say, with the rear sag at 30% for me, overall, the bike feels pretty good. I plan to experiment some with the front end and rebound and compression damping next, but I'm honestly not in a hurry to do anything there because I like the ride as it is now, a bit on the soft side and it feels pretty good off-road too.
But I think if you get the rear sag where you want it, making changes to the front height will throw that geometry off and you’ll have to go back and compensate.

Kev, it’s that sitting attitude, the geometry of the bike, back to front, that makes, for me anyway, a better ride—the bike feels more connected and I notice a difference in cornering. I think the damping and rebound affect the overall smoothness of the ride—going over bumps and whatnot—most. (But if you really dig in and tighten up compression and damping, it probably will have a serious impact on cornering and quick maneuvers too).

I haven’t made any adjustment to rebound or compression yet. But then, I like a bit softer ride and I think it’s set pretty soft from the factory.

Deltabi, I fear you might be right, and with maxed out panniers and a top box, I might run out of upward room on my rear preload. It will be close, that’s for sure.
 

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Discussion Starter · #6 ·
I think the damping and rebound effect the overall smoothness of the ride—going over bumps and whatnot—most. (But if you really dig in and tighten up compression and damping, it probably will have a serious impact on cornering and quick maneuvers too).

I haven’t made any adjustment to rebound or compression yet. But then, I like a bit softer ride and I think it’s set pretty soft from the factory.
I should clarify here, from what I have learned anyway... adjustments to compression and damping can have an impact on cornering, but mostly I think, with racing bikes and on the track. For adventure bikes, I think any adjustments we make to compression and damping will be for overall ride comfort as it applies to shock movement over bumps, etc. But if you're doing a lot of really fast riding around corners or winding roads, these adjustments could probably help if you are experiencing problems going into and out of turns.
For me, the bike handles the roads pretty well with its existing settings. But I'm not going nuts around corners or doing a lot of fast riding.
But it all starts with getting your sag set properly. That's the base and the first thing that should be done.
BUT... I am not an expert! I'm just going from what I'm reading and my limited experience.
 

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I waited too long to check the suspension setting.
Big mistake! What I assumed was that the bike came with correct factory settings
but they were all off!
Going through front and rear clickers and putting them to stocks setting is time well spent.
.
I set everything to stock values as it should have been and then set preloads without playing too much with others.
So happy with the results.
 

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Discussion Starter · #8 · (Edited)
I waited too long to check the suspension setting.
Big mistake! What I assumed was that the bike came with correct factory settings
but they were all off!
Going through front and rear clickers and putting them to stocks setting is time well spent.
.
I set everything to stock values as it should have been and then set preloads without playing too much with others.
So happy with the results.
Hmm. I found my rear spring preload where it was supposed to be, but I haven't checked the others settings. After getting my sag/ rear preload sorted, the bike feels great, but you make a good point: I should check my front and rear rebound and compression damping settings. And the front preload.
There's a reason shock manufacturers give us a recommended initial setting. The shocks are designed to work best for most in this range.

Oh well, I enjoy fiddling with my bike--it's my new hobby. :smile2:

Ps. This is a good overview of suspension tuning--A Dave Moss Masterclass.

https://youtu.be/Ikjw4IheeF4
 

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Garyh - I understand what you say regarding the bike feeling better with more pre load.
Its worth a few more words perhaps to go into suspension functionality.
Changing spring pre load should only make one difference and that is ride height. The suspension characteristics should not change provided the suspension does not bottom out. I have often heard people say they have 'stiffened up' their suspension by increasing pre load, that is not correct. The suspension will be no stiffer with more preload, however its total movement will be less for a given load. The clue is in the 'pre'. With more pre load you need to apply more load to get the suspension moving but once moving the spring should react as it did with less pre load as its spring RATE has not changed.
Actually pre load does make one other change - it changes chain tension as the swing arm is operating over a different part of its arc.
Damping is what stiffens up suspension (as well as changing the spring) and controls suspension rate of movement. Compression damping is slowing down the rate at which the suspension compresses when you hit a bump. Rebound damping slows down the rate the suspension extends when you hit a pothole.
Wind up your damping and the bike will no doubt handle better for fast riding on twisty roads with normal road defects. Keep that setting for cruising and it will be harsh

Anyway, not trying to lecture those that know its just that its easy to think that winding up a spring makes things stiffer - that's the job of damping.
 

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Discussion Starter · #10 ·
Yes, I agree with everything you said, of course! I was alluding to the same things, but guess I wasn't very clear. Preload/ sag doesn't stiffen up the ride or shock--that's damping.

Except maybe you allow for less enhanced handling characteristics from the sag/ preload setting (the geometry of the bike/ rider and furthermore, where the bike rides in the suspension stroke) than I do. From my experience (and reading) a proper sag setting has a real impact on handling. For me, honestly, it's a big difference. Going from 40% to 30% (in my testing) was pretty noticeable--the improvement in handling--the bike seems more receptive. Maybe I’m imagining *some* of it, but there is a real improvement just from getting my geometry on the bike/ the bike’s geometry (and where the bike rides in the suspension stroke) to where it feels right for me. I rode it fairly hard in my testing--quick take-offs, stops, cornering, etc.

But most importantly, getting the sag/ rear preload right is the first step to any other changes in suspension.

Safe riding!
 

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Yep I think we both agree Gary.
Must admit I am a bit reluctant to start playing with damping. Maybe I will just give it the 'bounce test' to see how many cycles it takes to come to rest - If I am strong enough !
Anyway our roads are now well salted so thats my ATAS tucked away for 5 months. I think I need a CRF250 Rally for the winter ?
 

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Me too - the damping has been spot on for me and I have fiddled with it a couple of times in 22k miles but always come back to the factory settings. And this is from someone who spent a couple of years trying to get the NC750X suspension tolerable.
My bike isn't getting tucked away though Kev. The 5 national parks within striking distance of us just cannot be ignored in our winters when there are no tourists in them :)
Mike
 

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Thanks for posting this. I weigh about the same, so 19ish clicks seems like a pretty good starting point for me. What brand of panniers are you running?
 

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Discussion Starter · #14 ·
Thanks Todd,

I installed Touratech Zega Mundo Panniers. You can see my post about them and the Hepco & Becker engine guards I installed in the Parts and Accessories sub-forum:
https://www.africatwinforum.com/for...ine-guards-touratech-zega-mundo-panniers.html

But do take the time to measure and set your sag, you won't regret it. With a helper, you can complete the whole process and get it dialed in in less than 1/2 hr. There are lots of good videos and articles out there explaining how to measure and set rear sag.

ADV Pulse has a straight forward article on setting rear sag for Adventure Bikes: http://www.advpulse.com/adv-prepping/quick-tips-how-to-set-your-rear-sag-on-an-adventure-bike/

And MC Garage has a good video on front and rear sag: "Suspension Tech: How To Check Motorcycle Suspension Sag | MC GARAGE TIPS."

And there's a lot more. Check out the "Dave Moss Tuning" YouTube channel.

Good luck man and ride safe, Gary
 

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Discussion Starter · #15 · (Edited)
Maybe I will just give it the 'bounce test' to see how many cycles it takes to come to rest - If I am strong enough !
Too right about needing strength to check the forks. But with all my might (and with my son’s help, pushing down together) the front end seems pretty good. Rebound: goes down and comes up, just the one bounce, settles. The movement and the feel seem just about right to me, in a cold state. (If I’m comparing it to what the experts are showing in their videos, esp. vis-à-vis rebound).

And at the back, at static sag, bike upright with just its weight on the wheels, the bike feels about the same, seems well balanced—the compression and rebound, front and back—in movement and tension.

Well enough, that I don't think I want to mess with rebound and compression damping just now.

I do find it a bit disconcerting that it is *so loose* at the back when it’s on the kickstand, i.e., with weight off the shock. I can, literally, push the rear end down with one finger. With barely any strength, you can push down on the pillion and get the bike bouncing like a basketball at the rear—only slight exaggeration. This might be exacerbated by how high I have the rear end set for my sag. If it were lower, it would move as easily but maybe not as much.

But to summarize, the rebound feels and looks just about right on my ATAS. The compression seems maybe a bit on the tighter side, which oddly belies the ride, which seems, to me, fairly nice and soft, the way I like it (but maybe that’s because the bike and I weigh so much). Anyway, no changes to compression and damping for me in the near future.

But something I did pick up on in my reading and viewing the subject of compression and rebound damping: keep an eye on your tire wear. Odd tire wear can be an indicator of problems.

Edit: My son and I also together pushed down near the center of the bike, to watch the front and back working together, from static position. And it does seem quite even, well matched, same movement at front and back.
 
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