Suspension Guru's

[ianp5uk]

Well you can skin a cat a number of ways and the sag has to work with valving. All the same my point remains that you have to make clear what sag you're talking about - with or without rider.

 

[(RIP) Kaister]

static sag has nothing to do with valving - its only spring related.

Valves control speed of damping pistons


static sag is with rider in normal kit - its only a starting point tho'

my 660 is setup full soft spring on the rear and full hard and thicker oil on the front. - works for me and feels great for the road .

Lots of people complain the suspension is crap - i think they don't know what they're talking about

 

[Giles]

All the same my point remains that you have to make clear what sag you're talking about - with or without rider.

static sag is with rider in normal kit

Correct! Any time I've had a suspension set up, I have gingerly sat on a bike being careful not to bounce it as i've got on, and gone from there ....

 

[ianp5uk]

static sag has nothing to do with valving - its only spring related.

I said the sag has to work with the valving not that the damping changes the measured sag! Although it could if you don't take account of stiction.
The whole system works together. Exactly how depends on how the shocks are built. But sag will change internal air or gas pressure preload which is progressive, changes the travel available and can change the pressure on the valves effecting compression damping depending on how the particular shocks are built. Then it is possible you could even introduce or change the onset of cavitation - maybe not a factor in normal use but could be if you take it off road.

Giles lamb:
You have taken quotes out of order and hence context. My suggestion that it needs to be clear which sag is being discussed was made prior to Kaister defining what he means by it. Rasher and others were sometimes just saying sag. Why do you gingerly sit on the bike? I can see why if the guy is referencing the sag with stiction included but that could vary from bike to bike. You may as well jump on, measure, bounce, measure bounce a few times and take an average. That way you would eliminate stiction effects.

 

[Giles]

I said the sag has to work with the valving not that the damping changes the measured sag! Although it could if you don't take account of stiction.
The whole system works together. Exactly how depends on how the shocks are built. But sag will change internal air or gas pressure preload which is progressive, changes the travel available and can change the pressure on the valves effecting compression damping depending on how the particular shocks are built. Then it is possible you could even introduce or change the onset of cavitation - maybe not a factor in normal use but could be if you take it off road.

Giles lamb:
You have taken quotes out of order and hence context. My suggestion that it needs to be clear which sag is being discussed was made prior to Kaister defining what he means by it. Rasher and others were sometimes just saying sag. Why do you gingerly sit on the bike? I can see why if the guy is referencing the sag with stiction included but that could vary from bike to bike. You may as well jump on, measure, bounce, measure bounce a few times and take an average. That way you would eliminate stiction effects.

My understanding of static sag, and the way I've set up track bikes (and for that matter mountain bikes!) is slacken everything off, use a couple of cable ties around fork legs and rear shocks and gently get on the bike so it accurately soaks up your weight but no more. (hence don't jump on at and allow it to bounce..). Rasher says static sag is a bike with no rider. That's not my understanding, I've always interpreted it as rider + bike.

Maybe I look at it too simplistically?

Maybe some peepes are over complicating it?

 

[Engineer]

Chaps

On medium to firm acceleration I have noticed a tendency for the rear wheel to skip a bit too much when going over bumps/ undulations in the road.

What bit do I need to fiddle with to dial this out

1. Either increase or reduce the rear spring pre-load.
2. Either increase or reduce the amount of rear spring rebound damping.
3. Either increase or reduce the amount of front spring pre-load.

4. Any or all combinations of the above

Hope that helps

 

[ianp5uk]

My understanding of static sag, and the way I've set up track bikes (and for that matter mountain bikes!) is slacken everything off, use a couple of cable ties around fork legs and rear shocks and gently get on the bike so it accurately soaks up your weight but no more. (hence don't jump on at and allow it to bounce..). Rasher says static sag is a bike with no rider. That's not my understanding, I've always interpreted it as rider + bike.

Maybe I look at it too simplistically?

Maybe some peepes are over complicating it?

I'm desperately trying to get my head round suspension because I'm so far away from a standard person; 6'3" and 110Kg. So every bike is wrong for me as standard. I viewed sag measurement much the same as you did until a few weeks ago when I had some instructions for measuring it from a suspension tuner. I was shocked at the difference stiction made. It was making a 5mm difference on forks. Hence h advised me to average readings from pushing down then relaxing and pulling up and relaxing.

Anyway the whole thing was bugging me as to what is going on so I started studying shock and fork operation. It turned out a whole lot more complicated. Although suck it and see still works well. However sometimes things aren't obvious. E.g. harsh bumps don't necessarily mean the suspension needs softening in some way so it's worth trying things that appear counter intuitive because EVERY thing is interlinked on bikes.

 

[GS TRV]

This is a GS for goodness sake not a race prepped R1

 

[Giles]

Personally, I am not that hot on suspension either!

My understanding is, that probably the most important thing to get right, is your static sag. So that's you, sat on the bike, taking up an amount of it's available travel. Now that amount will vary from bike to bike depending on the bikes suspension. R1 ?? WR450?? Both completely different in terms of suspension travel. So be wary when google ways 35mm or whatever, cos thats probably a standard for the average sports bike. (And the average weight of a japanses bloke probably..)

I am into mountain biking in quite a big way!! To set my static sag on there, I adjust my forks and rear shock so that 1/3 of its available travel is my static sag. So, thats cable ties round the forks and rear shock, gently get on and off.. see how much of the travel my weight is using and adjust the preload...

But that's a push bike!!

I've set up a track bike before, but I've done it at a tuning shop. Not quite the same process as the mountain bike, because here the set up bloke looked up the manufacturers proposed settings. But these aren't fractions or percentages of available travel, they're set measurements. (Set up for track?? Set sag for 30mm... or what ever..). But again, say it's a jap sports bike, (in my case it was a zx6) and those static sag measurements will be based on the weight of your average male jap.

How does your BM suspension compare with the average sports bike suspension? Don't ask me!! I would have though it would be quite a bit softer, and would allow for further travel, but i don't know. Thankfully I have ESA! (Phew)

If, you've buggered about with your settings and havent got a clue where you are now with your preload, and what you've done with it, it might not be a bad idea to chuck £30 at it and go to a shop and get it done that way.

Whilst I understand the principles of rebound and damping, to be honest, On previous bikes I put 'em mid way between min and max and didn't feck about with them!

 

[Rasher]

Ohlins define Static sag as riderless bike and with rider as "ride height" which gets confusing as this is not related to a ride height adjuster. I prefer to uise the term rider sag.

Basically there are two measurements bike without rider and bike with rider.

Both should fall within a range, if they do not then the spring rate is incorect and needs sorting first and foremost as with an incorrect spring rate trying to get a good setup is a bit like pissing in the wind.

Once this is all sorted you should move on to damping adjustment, the whole thing is a confusing black art that keeps many professionals in work - and they often argue about this shit.

Much info is available for setting up sportsbikes, far less about GS's and even less about paralever and funny front tends - although one Ohlins manual I have does recommend running a bit more sag for non-paralever shaft drive bikes as they rise under acceleration.

If anyone is interested I can get images of the manual posted up

 

[casperfelix]

The answers to date remind me (a little) of when I had my APE and used to frequent an RSV1000 site: What with getting the sag right and then doing the preload and the compression and the tyre pressures and so on and so forth it was dark before you were ready to get riding.
On my GSA I just tweak the ESA and enjoy. Pure luxury - and it grips the road quite well.

 

[Giles]

Ha! Now yer know why Rossi is famed as being brilliant at being able to diagnose a bikes set up. Oh to be able to pull into the pits and say ''hey guys, the front is chattering a bit in turn three and coming out of turn seven it just doesn't want to turn quickly enough.. can try dropping the forks by 5 mm, backing off the preload a tad and two clicks on the rebound ...."

Now yer know why people love their ESA!!

 

[Bem]

Chaps

On medium to firm acceleration I have noticed a tendency for the rear wheel to skip a bit too much when going over bumps/ undulations in the road.

I wonder if we are all getting too carried away with the technicalities and not spotting the differences between bikes here? The "tendency to skip" on a GS is not the same as that on a full-bore sports bike. At different stages and times my GS`s have wallowed but surely that is because they ride in a different way? Apart from losing the front on a well gravelled corner when getting a bit excited, I am certain that my GS`s have given me much more feedback prior to impending disaster than any previous superbike, or current borrowed litre machines.

Shaft Drive v. Chain drive handling argument brewing!

 

[Rasher]

Shaft Drive v. Chain drive handling argument brewing!

I was expecting the GS to feel entirely Alien after 25 years of sports bikes and have been amazed at how similar it feels, not sure what I was expecting, but certainly not for it to feel so "normal"

Thing I notice most is the woble on throttle blips, I take that and any bouncing / wallowing to be "character"

Much as I would like better quality suspension (less choppy) I do not expect the rigid planted feel of a good sportsbike and not having to f*** about applying lube to the chain / removing lube from the rest of the bike certainy makes up for the slight loss of finesse.

 

[APE]

I wonder if we are all getting too carried away with the technicalities and not spotting the differences between bikes here? The "tendency to skip" on a GS is not the same as that on a full-bore sports bike. At different stages and times my GS`s have wallowed but surely that is because they ride in a different way? Apart from losing the front on a well gravelled corner when getting a bit excited, I am certain that my GS`s have given me much more feedback prior to impending disaster than any previous superbike, or current borrowed litre machines.

Shaft Drive v. Chain drive handling argument brewing!

Having ridden GSs with and without Ohlins I can confirm that the 'wallowing' can overcome by fitting Ohlins or Wilbers. This is down to the quality/ build of the OE parts. However the tendency to 'skip' is down to to the chassis imo and cannot be eradicated. If you do not ride the bike hard or weight 100+ kgs you probably wouldn't notice this though. The bottom line is you can't make a GS handle like a sports bike - it's like comparing a 4x4 with a sports car.

 

[Timolgra]

Having ridden GSs with and without Ohlins I can confirm that the 'wallowing' can overcome by fitting Ohlins or Wilbers. This is down to the quality/ build of the OE parts. However the tendency to 'skip' is down to to the chassis imo and cannot be eradicated. If you do not ride the bike hard or weight 100+ kgs you probably wouldn't notice this though. The bottom line is you can't make a GS handle like a sports bike - it's like comparing a 4x4 with a sports car.

This is most noticable on a GS by riding up a steep rocky climb and trying to keep the back end gripping