CB1100RS static sag

[Olof_imp]

I've always found my RS fighting lean (needing excessive handlebar pressure to turn, from new) so yesterday I decided to tinker with the static sag (suspension position at rest with fully dressed rider on board, feet on the pegs). I aimed for roughly 1/3 of the suspension travel, a bit more at the front and a bit less on the rear. Wheel travel is said to be 107 mm at the front and 114 mm at the rear, so I should be looking for roughly 35 mm of static sag. I measured in two ways at each wheel for each setting - after collapsing as well as after rebounding (to account for stiction). I also took repeated measurements to account for measuring error on my part. The same numbers came up, so it seems that both I and the suspension behaved consistently.

At the front I found that static sag with factory setting (2 rings showing) was 52 mm. This was way too much and more than the preload could ever compensate for. I anyway decided to increase preload to 1 ring showing. This reduced the static sag to 47 mm. Slightly better but stilll off. I turned to the rear, curious to see if I'd get similar wild figures. With the factory setting (2nd position of 5 possible, 5 being hardest) the static sag was 39 mm. Also too much, but not as dramatic as the front. Increasing the preload to 3rd position reduced the static sag to 34 mm. At this point I had raised the bike 5 mm at both ends. Slightly deflated I decided to leave it at that, since I could not get closer to my target numbers anyway.

Not expecting much I then went for a ride as the weather was quite nice. To my surprise I found the bike slightly more neutral, calling for less handlebar pressure. No dramatic change - I still needed to put in some effort - but better. Logic tells me it was all in my head, but maybe not. Repeated runs gave the same feeling, a clearly nicer bike. Maybe someone can chime in here - what have you found? How does the CB1100 chassis work and what settings do you use?

 

[Tev62]

If you were measuring the front fork SAG linearly on the fork the true value of the front end dropping is actually less because of the rake angle of the front forks. The 5mm change in the rear is more vertical. So in effect you have raise the rear of your bike more than the front compared to where you started, and shortened your trail, thus making it a little quicker to steer. If you cannot meet your target 30% SAG I think it is more important to get your geometry right rather than aim for that 30%, so 35% or 40% even might be a good trade off for a better handling bike with a slightly reduced overall suspension travel. Jack up the rear preload one more notch and see if it improves the ride for you again, it has such an impact.

 

[dave]

As your tires wear you will feel a definite difference in the way your bike handles. Did you purchase your bike new?

 

[mvk24_imp]

While you're doing all that I also had to adjust my front suspension dampening from the factory after watching this video explain it.

It is long but you could cut to the 11:20 mark and watch him run through the entire process on just 1 of the bikes. Its a great visual

Sent from my SM-G965U1 using Tapatalk

 

[Jfro5687_imp]

Hi Olof. I agree with you, the RS does need a bit more counter steering input to make it want to drop into a corner (compared to the EX) but I quite like the unflappability trade off that comes with that. I’ve had bikes with a 200 rear tyre and they are much harder to turn in, until you get used to them of course. Appreciate your efforts on the settings, I watched Tev62’s vid and tweaked the rear preload up on my EX and that did work, you are not imagining it!

 

[jtopiso_imp]

I've always found my RS fighting lean (needing excessive handlebar pressure to turn, from new) so yesterday I decided to tinker with the static sag (suspension position at rest with fully dressed rider on board, feet on the pegs). I aimed for roughly 1/3 of the suspension travel, a bit more at the front and a bit less on the rear. Wheel travel is said to be 107 mm at the front and 114 mm at the rear, so I should be looking for roughly 35 mm of static sag. I measured in two ways at each wheel for each setting - after collapsing as well as after rebounding (to account for stiction). I also took repeated measurements to account for measuring error on my part. The same numbers came up, so it seems that both I and the suspension behaved consistently.

At the front I found that static sag with factory setting (2 rings showing) was 52 mm. This was way too much and more than the preload could ever compensate for. I anyway decided to increase preload to 1 ring showing. This reduced the static sag to 47 mm. Slightly better but stilll off. I turned to the rear, curious to see if I'd get similar wild figures. With the factory setting (2nd position of 5 possible, 5 being hardest) the static sag was 39 mm. Also too much, but not as dramatic as the front. Increasing the preload to 3rd position reduced the static sag to 34 mm. At this point I had raised the bike 5 mm at both ends. Slightly deflated I decided to leave it at that, since I could not get closer to my target numbers anyway.

Not expecting much I then went for a ride as the weather was quite nice. To my surprise I found the bike slightly more neutral, calling for less handlebar pressure. No dramatic change - I still needed to put in some effort - but better. Logic tells me it was all in my head, but maybe not. Repeated runs gave the same feeling, a clearly nicer bike. Maybe someone can chime in here - what have you found? How does the CB1100 chassis work and what settings do you use?

I struggle a bit to reach the ground with my feet, so I run prety low preload on both front and rear, trying to keep the bike low. So I don't have much set-up range.

However, a gamechanger for me was the new tyres. Going from the OEM (bridgestone) to the michelin I am running now (I think "pilot power CT2") made a huge difference. I guess is the section profile of the michelin, being much closer to a "V" shape (instead of a "U") make the bike to want to lean into the corners easily.

I have to say that having my preload so low, when I ride with a pilion, steering geometry must change a bit (longer trail), so the bike is harder to steer. So I should compensate with higher rear preload...

In short: rising the rear more than the front will make the bike quicker to steer, but the tyres will also make a difference.

 

[Olof_imp]

Tev, Dave, Jfro and jtopiso: thanks for all input. Good points on tires. Yes, the OEM rear is beginning to square off slightly but on the other hand it resisted turning from day one so I don't think that's the main culprit. Also good thoughts on sag and ride height. As a result I went out today and tested again. And the improved feeling was still there. Very nice balance (for the type of bike) between willingness to turn and line stability. I then went another notch stiffer on the rear shocks (position 4 out of 5, i.e. next stiffest): not really an improvement. Same same, if anything slightly more vague steering.

So, ideal preload setting for me (80 kg with gear, no luggage, OEM tyres) is:
Front: 4 mm preload adjuster showing (see pic)
Rear: setting 3 out of 5 (5 stiffest)

 

[Jfro5687_imp]

Just out of interest Olof what tyre pressures are you running?

I aim to set mine at factory 36/42 cold however I have discovered this morning (when checking my car tyre pressures) that the two pencil type gauges I use at home actually give a 2 psi reading difference! I checked all the wheels on my car and then my wife’s, every tyre exactly 2psi different. They are decent ones so that did surprise me TBH.

Now I’m pretty sure that would make a difference on a bike and because I know which gauge I’ve used on the CB I’ve realised I’ve possibly been running 34/40 in reality. I put 2psi extra in both front & rear and will see if I can feel any difference next time I go out. I’m making an assumption of course on the more accurate reading being the one I’ve gone for (based on the old dig your thumb into the sidewall test).

Anyone else found a noticeable difference running off spec either intentionally or by accident like me?

 

[Houtman_imp]

Pencil type pressure gauges are not the most accurate , I use a Motion Pro professional one .

 

[the Ferret]

One never knows if they are running the right air pressure because tire pressure gauges, even good ones, cant be guaranteed accurate. I have probably 5 different gauges, 2 of them " guaranteed to be accurate within 1/4 pound" and even they dont read the same. If the bike feels good when riding it, just use the same gauge on it everytime to fill it to the pressures that felt good.

They say you can go to a tire shop and they "may" have a master gauge that will check yours, but then again they may not. When I checked at my local multi store tire dealer, they did not, and they often use pencil gauges to check tire pressures, because it fits in the tire techs shirt pocket and they always have them with them. If you do find one to check yours, it needs to be checked periodically.

Tire pressures are not absolute critical, and can be run at various pressures. I've heard the tires need to be checked cold, at 68 degrees Fahrenheit for accuracy, and that pressure will be different every few degrees of ambient temp.

See on chart below set your tire at 40 psi at 68 degrees
at 50 degrees it will only be 38 psi

Cold inflation pressure - Wikipedia



Same goes for torque wrenches.

 

[Lord Popgun]

How can a torque wrench check pressure?

I usually put 2psi more that Honda spec and the bike seems to handle a lot better. YMMV.

I use a Motion Pro digital gauge, probably like Houtman’s. I hope it’s accurate.

 

[Tev62]

Just out of interest Olof what tyre pressures are you running?

I aim to set mine at factory 36/42 cold however I have discovered this morning (when checking my car tyre pressures) that the two pencil type gauges I use at home actually give a 2 psi reading difference! I checked all the wheels on my car and then my wife’s, every tyre exactly 2psi different. They are decent ones so that did surprise me TBH.

Now I’m pretty sure that would make a difference on a bike and because I know which gauge I’ve used on the CB I’ve realised I’ve possibly been running 34/40 in reality. I put 2psi extra in both front & rear and will see if I can feel any difference next time I go out. I’m making an assumption of course on the more accurate reading being the one I’ve gone for (based on the old dig your thumb into the sidewall test).

Anyone else found a noticeable difference running off spec either intentionally or by accident like me?

I have not had my CB long enough to comment on the tyre pressures and how they feel on that but my Tiger 1200 is very sensitive to pressure on the front, a difference of just a few PSI has quite an impact, the front end gets quite vague on losing a few.

 

[the Ferret]

How can a torque wrench check pressure?

I usually put 2psi more that Honda spec and the bike seems to handle a lot better. YMMV.

I use a Motion Pro digital gauge, probably like Houtman’s. I hope it’s accurate.

Lol torque wrenches like air pressure gauges can be accurate or not, and need to be calibrated periodically. I've had mine for maybe 15 years and have never had it calibrated, but then again I dont put engines together. It's probably close enough for an axle nut, but not much more technical that that at this point. I dont think I'd trust it for an oil drain bolt lol

 

[Houtman_imp]

I check my clicker torque wrench with a beam torque wrench as the latter stays more the same and I do not use the beam one much at all.

 

[Lord Popgun]

I understood what you meant Ferret. Just funning with ya

 

[GoldOxide_imp]

As with many gauges, I try to get a "consensus" between multiple devices. Sure: It ain't certified, but surprisingly I often get very acceptable variance (many times zero) that "feels good enough".

 

[Jfro5687_imp]

Thanks for the feedback chaps. It just crossed my mind reading Olof’s thread that before we dive into altering suspension maybe we ought to check our tyre pressures first, just in case the cause of whatever it is we think needs addressing is an easy fix right there under our noses.

 

[Olof_imp]

Thanks for the feedback chaps. It just crossed my mind reading Olof’s thread that before we dive into altering suspension maybe we ought to check our tyre pressures first, just in case the cause of whatever it is we think needs addressing is an easy fix right there under our noses.

Good point. I agree that when tinkering with setup it's good to only change one parameter between tests, and try to keep other - such as tyre pressure - as similar as possible. I never mentioned it since I have a morning routine since way back (from when I rode cheap wrecks leaking everywhere) to check oil level and tyre pressure, but in this I'm quite alone among my riding friends. Most seem to check monthly or less, typically at the gas station where they happen to be when the thought strikes them. No criticism, each have their own standards. These guys are fine on their bikes, never had a problem and happily label me as OCD.