be funny though if he has measured it on a stand...then took it off the stand to measure again, and it was the same..
I’m suspecting the same. How many guys can easily lift and hold the back of a bike while it’s being measured?
Most could by using the side stand as a pivot. If preload is backed right off and it is a original spring it sounds like the shock or the linkages are not moving properly. On the subject of sag there is static sag and rider sag both should be set as I understand it.
As others have said. Spring is too weak for his weight. I am 210lb without gear. I bought an old RSVR for track days. When I set rider sag the stock spring was wound up so tight there was no free sag. It actually contributed to a crash. First time on the track in 30 yrs, I did a track day at Laguna Seca. Dave Moss said “oh you’ll be OK on those old Q2s till you see where your head is at”. Wrong. 3rd session I got on the gas too hard at the apex of turn 3. The shitty PC3 on the bike made it very snatchy off closed throttle, and that, plus the weight transfer due to soft spring, unloaded the old Q2 on front and down I went.
Just checking, static sag = free sag, ie sag from the weight of the bike alone? Same thing different terminology?
Exactly terminology thing 3 numbers... 1 unloaded wheel off ground the full amount of travel which remains the same 2 weight of bike 3 weight of bike and rider
It's common to set a bike up so the rear shock is just topped out under the bike's own weight. I.E no static sag. Big heavy bikes tend to have static sag. That setting will give you about 25% total travel taken up with the rider on board. It's easy to check static sag with the bike on a paddock stand. Just push down on the seat a couple of times to settle it, then see if you can pull the seat unit upwards at all and look for movement on the swinging arm at the same time. I've done it loads of time on several bikes. I had the same thing when I bought my Evo. There was about 20mm of pre-load wound down on the spring and the rear suspension hardly moved at all when I sat on the bike. I've set it with about 3mm pre-load now. It's just topped out under its own weight and does sink a but more when I sit on it. The forks were the same. Pre-load backed right off on those now. They sink more when I sit on the bike but still don't bottom out even braking for hairpins on a trackday. Good luck .
As others have said - the correct way to set suspension is to aim for 25-30% rider sag. Be sure to measure it in both directions and take the mean - this corrects for stiction. There are lots of guides for setting sag on the web. If there is no free sag, the spring is too soft for your weight. All this assumes the fork oil volume is set correctly.
Here's my two penneth. The OP is talking about the rear suspension as he refers to adjusting the ride height and its almost ( repeat almost) impossible to have forks without free SAG. My definition of free SAG is the difference in the distance of the suspension fully extended and then compressed under the weight of the bike only, measured approximately vertically above the wheel spindle. Rider SAG is the difference between the suspension fully extended and then compressed with the weight of the bike with rider sat on it. The correct relationship between free SAG and rider SAG only works when the spring rate is correct for bike and rider. You can only set one of them and the best one to set is rider SAG, you have to take what comes as the other. The springs on 1098s and 1198 are really really strong as standard and so I think its entirely possible that the OP may be getting zero free SAG as he simply can't back off the pre load enough to give the bike a chance of compressing the spring a few mm (adjusting the ride height as alluded to wont affect this). When you are dealing with a really strong spring then it is better to set a bigger rider SAG just to get the suspension moving. So even tho he can still get 30mm SAG I still think the bike will be stiff. (I understand the weaker spring with too much pre load theory but I don't think it applies to this bike as the OP has backed off the pre load and 1098 springs are really strong( possibly too long)). So for me to get a better suspension action he probably needs a weaker spring. TB
I agree Topbox. Only thing I would say is that you always set rider sag, since that's how the bike is used - with a rider on board. Free sag is what you get - no adjustment possible except change the spring. Though OP (who probably left for good) says he is 215lb. i dont know Ducs at all (yet) - but would be surprised if its oversprung for a 215lb rider as standard, But who knows what spring is in there.
Is the correct answer. If there is no static sag (I.e. When you lift the bike at the tail, there is no movement in the suspension at all) then you have too much preload on the Spring. If you slacken the preload off a little to give static sag but then the rider sag is wrong, you have the wrong Spring rate. Ride height adjusters should not affect this in anyway.
