My Suspension

[BJ]

About 1.5 to 2 years ago I had a Brisbane suspension shop put Wilbers on the rear and they did some modifications (I know not what) to the front end. To be honest I was never happy with it and I have just taken measurements of the sag etc and my results are as follows:
REAR Wilbers 632/642
L1 Distance measured with rear off the ground - 240mm
L2 Distance measured with the bike on two wheels, no rider - 240mm
L3 Distance measured with me 85kg (no gear) sitting on the bike - 240mm
No wonder the back end feels like shit, skipping all the time.
Approx 8mm of thread showing above spring lock nuts.
FRONT
L1 Distance measured with front wheel off the ground - 166mm
L2 Distance measured with bike on two wheels, no rider - 144mm
L3 Distance measured with me 85kg (no gear) sitting on the bike - 130mm
Just before taking these measurements I backed out the preload probably about 5 turns.
When riding I have been watching the front forks to see if they are even going up and down.
My feeling is that they weren't.
Why it's taken me this long to check this stuff is beyond me. 
I feel the Wilbers will need to be taken back to the shop as I think the springs are Wrong!
The front end I can possibly live with if I can fine tune the adjustments.
Anyway, I would appreciate any advices from those with knowledge.
Many thanks in advance

[Blubber]

Whilst i am no expert regarding suspensions or their setup up.... you would expect some difference on an emprty bike and a full bike.

The rear measurements make it look like the rear shock has way to stiff springs.

A revisit to the same shop sound like a sensible option to me... after all... you payed them to set it up.

[grog]

Suspension and Springs - Sag
What's all this ruckus about suspension these days? It seems everyone is clued in that suspension setup can be a key to riding fast and safely, but how do you do it? No matter what shock or fork you have, they all require proper adjustment to work to their maximum potential. Suspension tuning isn't rocket science, and if you follow step-by-step procedures you can make remarkable improvements in your bike's handling characteristics.
The first step to setting up any bike is to set the spring sag and determine if you have the correct-rate springs. Spring sag is the amount the springs compress between fully topped out and fully loaded with the rider on board in riding position. It is also referred to as static ride height or static sag. My company, Race Tech, 951.279.6655 has an advanced method of checking spring sag that I'll describe.

If you've ever measured sag before, you may have noticed that if you check it three or four times, you can get three or four times, you can get three or four different numbers without changed anything. We'll tell you why this occurs and how to handle it.

REAR END
Step 1: Extend the suspension completely by getting the wheel off the ground. It helps to have a few friends around. On bikes with sidestands the bike can usually be carefully rocked up on the stand to unload the suspension. Most race stands will not work because the suspension will still be loaded by resting on the swingarm rather than the wheel. Measure the distance from the axle vertically to some point on the chassis (metric figures are easiest and more precise; Figure 1). Mark this reference point because you'll need to refer to it again. This measurement is L1. If the measurement is not exactly vertical the sag numbers will be inaccurate (too low).

Step 2: Take the bike off the stand and put the rider on board in riding position. Have a third person balance the bike from the front. If accuracy is important to you, you must take friction of the linkage into account. This is where our procedure is different: We take two additional measurements. First, push down on the rear end about 25mm (1") and let it extend very slowly.

Where it stops, measure the distance between the axle and the mark on chassis again. If there were no drag in the linkage the bike would come up a little further. It's important that you do not bounce! This measurement is L2.

Step 3: Have your assistant lift up on the rear of the bike about 25mm and let it down very slowly. Where it stops, measure it. If there were no drag it would drop a little further. Remember, don't bounce! This measurement it L3.

Step 4: The spring sag is in the middle of these two measurements. In fact, if there were no drag in the linkage, L2 and L3 would be the same. To get the actual sag figure you find the midpoint by averaging the two numbers and subtracting them from the fully extended measurement L1: static spring sag = L1 -[(L2 + L3) / 2].

Step 5: Adjust the preload with whatever method applies to your bike. Spring collars are common, and some benefit from the use of special tools. In a pinch you can use a blunt chisel to unlock the collars and turn the main adjusting collar. If you have too much sag you need more preload; if you have too little sag you need less preload. For road race bikes, rear sag is typically 25 to 30mm. Street riders usually use 30 to 35mm. Bikes set up for the track are compromise when ridden on the street. The firmer settings commonly used on the tract are generally not recommended (or desirable) for road work.

You might notice the Sag Master measuring tool (available from Race Tech) in the pictures. It's a special tool made to assist you in measuring sag by allowing you to read sag directly without subtracting. It can also be used as a standard tape measure.

Measuring front-end sag is very similar to the rear. However, it' much more critical to take seal drag into account on the front end because it is more pronounced.

FRONT END
Step 1: Extend the fork completely and measure from the wiper (the dust seal atop the slider) to the bottom of the triple clamp (or lower fork casting on inverted forks; Figure 2). This measurement is L1.

Step 2: Take the bike off the sidestand, and put the rider on board in riding position. Get and assistant to balance the bike from the rear, then push down on the front end and let it extend very slowly.

Picture

Where it stops, measure the distance between the wiper and the bottom of the triple clamp again. Do not bounce. This measurement is L2.

Step 3: Lift up on the front end and let it drop very slowly. Where it stops, measure again. Don't bounce. This measurement is L3. Once again, L2 and L3 are different due to stiction or drag in the seals and bushings, which is particularly high for telescopic front ends.

Step 4: Just as with the front, halfway between L2 and L3 is where the sag would be with no drag or stiction. Therefore L2 and L3 must be averaged and subtracted from L1 to calculate true spring sag: static spring sag = L1 - [l2 + l3) / 2].

Step 5: To adjust sag use the preload adjusters, if available, or vary the length of the preload spaces inside the fork.

Street bikes run between 25 and 33 percent of their total travel, which equates to 30 to 35mm. Roadrace bikes usually run between 25 and 30mm.

This method of checking sag and taking stiction into account also allows you to check the drag of the linkage and seals. It follows that the greater the difference between the measurements (pushing down and pulling up), the worse the stiction. A good linkage (rear sag) has less than 3mm (0.12") difference, and a bad one has more than 10mm (0.39"). Good forks have less than 15mm difference, and we've seen forks with more than 50mm. (Gee, I wonder why they're harsh?)

It's important to stress that there is no magic number. If you like the feel of the bike with less or more sag than these guidelines, great. Your personal sag and front-to-rear sag bias will depend on chassis geometry, track or road conditions, tire selection and rider weight and riding preference.

Using different sag front and rear will have huge effect on steering characteristics. More sag on the front or less sag on the rear will make the bike turn more slowly. Increasing sag will also decrease bottoming resistance, though spring rate has a bigger effect than sag. Racers often use less sag to keep the bike clearance, and since roadraces work greater than we see on the street, they require a stiffer setup. Of course, setting spring sag is only first step of dialing in your suspension, so stay tuned for future articles on spring rates and damping.

-Paul Thede

Magazine: Sport Rider
Issue : Aug

[Mick_J]

That's all very well grog but what is the starting position?  As far as I can see if the suspension is wound up too hard to start with your method will not work so I am assuming the starting position is with the suspension fully wound down to soft.

[grog]

MJGT, if its too hard no readings of course. Just back off and re check until in parameters. Thats what its all about, the correct readings.

[KoZi]

And this is that everybody have to do in their bikes 

[BJ]

Good article that Grog.

[GSX1400Convert]

It is a good article, but ............ this is all dependent on rider style as well.

In the tiwsties I use two different styles, one enhances suspension the other detracts. I have front dampning quite high, as is my preference, I always sit far forward on the seat, balls on tank, which probably explains the hasher dampning (which has nothing to do with the size of my goollies  ).

If I ride a corner bolt upright the 1400 feels rather vague and unstable, but is OK for the occasional bend.

But for surefooted spirited riding (lets say a tight left hander) I take half arse off the seat, place inside of the left knee on the head fins, or lower to ground, and move the top half of body forward, drop my left shoulder and elbow down, almost pulling the front end down. If I see ahead there is a slight right hander followed by another good left, I remain in left hander position and roll through the right hander, then drop down into the left hander. Same can be said for right handers, but opposite.

The body movement works the suspension so much better, even a bump though the corner doesn't seem to upset it as much as sitting bolt upright and the front end is far more stable.

We are talking about a lot of motorbike, and weight distribution is key to getting these old girls to corner. In all respects, it's about finding a riding style to allow you to ride around the feables.

I've seen blokes take there bike to the suspension 'experts' to get them sorted, and they still play around forever, trying to find the perfect formula. Let's face it, there is no perfect formula, it's a matter of adjusting your mindset, and therfore your riding style. I often laugh at Moto GP commentators who say, Rossi seems to have sorted out his suspension issues ......... really, or has he worked out how to ride around the problem? I'm not claiming to be the fastest rider out there, far from it, but do enjoy getting the most out of my bikes, be that through mechanical or physical means. 

OK, at this point I'll mention that I used to race speedway bikes. They have no suspension to speak of, and body movement is key to this type of riding .... and any other, for that matter IMHO.







 

[Andre]

@BJ  Sorry, I didn't pay much attention to your post at first. As @GSX1400Convert says there is no perfect formula. But there are working formulas that will help you dial-in a good compromise for you.

But if you got the wrong material all formulas are shite!

Only heard good things about the Wilbers Shocks in the German 14 forums. I have been looking at the Wilbers shocks for several years now and NEVER has the Wilbers configurator suggested the 632/642 shocks for the 14.  BTW there are 632 shocks and 642 shocks but no 632/642 shocks.

They offer 630 TS Road, 633 Competition S, 530 TS Road, and 531 TS Classic for the 14.

Their shocks are set up according to the info they ask you during ordering. That should be a good base for you.

I think it is best to order directly through wilbers.de as there are plenty of dealers who give you whatever they have sitting on the shelf. In your case the wrong shock with springs for the hippopotamus rider and his fat mama. And then tell you how much they labored to get it just right for you.

The front springs are a different story. They are handed out as a one-size fits all. I know 14 owners who found them too stiff and went back to the originals.

I happened to call Wilbers about the front springs as I want to try them out. Whatever they say, these are not progressive springs. They are dual-rate springs! Most (if not all) motorcycle spring manufacturers say that their dual-rates are progressives. Even linear springs can be called progressive if one wants to as they are progressive by FORCE but not by winding.  So nobody is lying but certainly not saying the whole truth. To my knowledge only Hyperpro has true progressive springs in their offerings. For the 14 the shorter and tighter wound area is 7.5 N/mm. The longer area is 11.5 N/mm. The original springs are 6.9 N/mm. You should be good with the originals IMO. Maybe play with oil viscosity and maybe oil level.

But who knows what that Brisbane suspension shop did to the front. Who knows which springs you have in there or the shop did its own evil magic to the originals (like setting installed preload too high). Something just isn't right there with your front.

L1-L2 on yours is 22 mm (5 rings visible?). My originals with 2 Rings visible L1-L2 is 32 mm. Incidentally that is the number Wilbers has given me for the originals. With about 105 kg I have L1-L3 42 mm while you with 85 kg have 36 mm. Wilbers states for their springs for the 14  L1-L2 30 mm and L1-L3 40 mm.

If anyone should care, it will be about a month before I can make my own measurement for the Wilbers front springs. Want to try them even though I am not unhappy with the originals.

[grog]

BJ, MPE in Caloundra will sort it, they did mine.They fitted Wilbers springs to front, checked out stock rear shocks. Made my bike perfect for my liking. Andre, springs must be stiffer as pre load was wound out a lot from them. Ive never touched their settings, bike very good over bumps. Been quite a while but remember being amazed by no more front dive. One of my best money spent.

[BJ]

I had MPE put Gazi shocks on couple years back. Same problem. Stiff as a board, wrong springs. Izzy from SuspensionRus Melbourne just sent me up some YSS rear springs and the change is huge. Bike feels really well balanced now and I haven't adjusted away from the mid range settings yet. I'm having fueling problem now. Will post under new heading.

[grog]

BJ, so much for my answer then. MPE were great for me, shit for you.

[KoZi]

@BJ I'm now looking for your first settings... First post... I understand that you changed the setting? It is very bad.
I set up more than few bikes of my mates and optimal SAG for road riding is 30-40 mm front AND REAR (ofc depends what is your riding style but in this range is very good). For occasionally track days I change it to 30-35 front and 25-35 rear.

In your case rear is to stiff... VERY STIFF. That should be correct to upper sag and also you have to check free sag. If SAG is set correct and you have no free sag then you have to change a spring.

Front on the SAG is ok. If you don't feel well it is hydraulic problem and you have to change copmression/rebound.

About aftermarkets items to our GSX is a long way to describe and compare each other... 

[BJ]

My current measurements
L1 wheel off the ground.         L2 bike upright, no rider.        L3 sitting on bike (for me, no gear)
Calculation aiming for 30 to 35

Front
L1 167.  L2 147.  L3 127
Calc 167-(147+127)/2 = 167-137 = 30

Rear
L1 385.  L2 372.   L3 346
Calc 385-(372+346)/2 = 385-359 = 26

Bike feels best it's been since I've had it.

Only my little fueling prob to sort now.

[GSXKING]

As others have said there is only guidelines and once you hit the sweet spot it's like a light bulb moment. Everyone rides differently which is the joy of individuality in motorcycling.
SAG is always the first port of call and then a tweak here and there can go really good or really bad it's good to keep notes of where your at with the adjustment.
I always start with everything in the most open position and move in from that point. It has a lot to do with how the oil moves through the valves. The more expensive your suspension units are the more adjustment you get.
I've only kept the standard stuff on my 2001, however I am considering Gazzi shocks to replace the 20 year old rear shocks. I have had them serviced over the years a few times. I have done front forks a few times. We changed springs to heavier weight and heavier oil early on to match the lift kit on rear shocks.