Am I expecting too much or is this easily fixed????

[Sport1200]

Went for a ride on my Sport 12 yesterday with a mate. This week I had my rear shock resprung and revalved and it is a totally different bike. It still however isn't a good handler. My ZRX1200R and particularly my GPZ900R would run rings around it, and the GPZ is 30 years old. I do like flogging bikes into corners but this one just doesn't feel safe at speed. (particularly bumpy corners)
Previous to the respring the bike was way too soft in the rear and loaded sag was 60mm on full preload. Now It is adjusted to 35mm around the middle of the adjuster as it should be. Front sag was (and is) 35mm and my understanding is that it should be 25mm or so. (not adjustable for preload the front???) So I am guessing I need a respring there too.
I have checked wheel bearings and steering head bearings and they are spot on. Haven't looked at swingarm bearings yet.
MY ZRX has 128000km on it on standard suspension and my GPZ 166000km, also on standard suspension. My Guz has 41000km and is an expensive bike. The others were cheapies. I am heavy at 140 odd kg, but the Japs steer and handle well and the GPZ I can't ride anywhere near its capabilities. I also own a GT550 Kawasaki which is my fave bike I own (I know I'm strange) and it wobbles around on its suspension but can be flogged through corners really well. Guzzi wobbles and it is scary. I am a bike instructor and have ridden all sorts of bikes (and own all sorts) and this one has me stuffed.
Have I bought a tourer and am asking too much of it? Should I respring the front and see how it goes? TIA!!

 

[PP-1753]

Tony, whether springing is right in the front is a subject often discussed. HyperPro had a spring/oil upgrade available some years back which put better handling back on the standard forks. Compression and Rebound also will need a bit of a fiddle. Compression is the L/H fork leg, Rebound is on the right.

Being a certified lardarse may make a huge difference in your requirements for springing up front, and I would suggest the front springs are way too soft for you. Also fork oil weight and amount is critical on these forks (allegedly these forks are better than the ones fitted to the Norges and Brevas). I find 390 ml of oil in each leg is about right for my weight (approx 90 kg) - 380 will give a softer ride, 400 will give a firmer ride. I use Penrite fork oil 5W - they also have 10W I believe. Different brands will all be different even for the same (supposed) weight.

Many variables here, I know. I find my bike handles quite well for me. But then again, I am not the world's fastest or best rider - adequate at best. I ride (usually solo) with very little luggage (tank bag, tail bag) or when I am off to rallies, probably have another 50 kg or so, on board. No handling issues noticed - but as I said, maybe I wouldn't notice it if it bit me.

What I do know though is that you probably should try a few things like compression/rebound and oil weight/amount before throwing money at it. A mate of mine has Ducati (I think) forks on his Bellagio and apparently that makes quite a bit of difference. Ducati/Aprilia forks may be an option if you want to tune your front end better.

Others having gone down this road, please speak up now!

 

[Android]

I have done the Hyperpro springs front and back, transformed the handling from a pogo horse to almost as good as my Ducati Multistrada .
They provide slightly thicker oil for the front and give you the basic settings for damping.
I'm 100kg and pillion slightly more, now I easily use my tires upto their edge with confidence on our bumpy english roads.

 

[Sport1200]

Thanks for that. Looks like a respring might be the go.

 

[Sport1200]

Looks like I may be partsly to blame: (MCN) : As a very broad guide a road bike should have 25-30mm of loaded sag at the front and 20-22mm at the rear.
I thought rear was 35. Need to readjust and remeasure.... Duh

 

[canuck1969]

That little difference in sag should not affect the handling as much as u are describing.

R u sure the rebound on the shock was not full opened or closed when the shock was serviced. Just double check it is at the correct setting first.

 

[Sport1200]

Dunno - have left it where it came from service guy so far. Ta

 

[canuck1969]

Not sure of the proper setting for the 1200 but I would fully close the rebound then fully open it and count the clicks. Then close it half way. Is a good starting point. Can also look in the manual but revalving and spring changes will change that stock value. There are ways to set the rebound properly by bouncing the rear end but leave that for later.

When you close it the first time, count the clicks so you can set it back to that "factory" point if needed.

 

[GuzziMoto]

A few basics to add. Adjusting preload does affect the sag readings and needs to be done correctly when possible. But changing preload does not change spring rate. A spring that is too soft before adjusting preload will be too soft after adjusting preload. In fact, how your sag ends up can tell you if your spring is too soft or too stiff (my money would be that your springs are too soft). If you set your sag to the desired value with you on the bike (usually 25% - 35% of total travel) you can then see how much the bike sags under just it's own weight. It should sag around 10% - 15% under it's own weight. If it sags to much without you on board it is too stiff a spring. If it sags too little without you on board the spring is too soft.
So, first set sag and confirm that your spring rates are about right. Then start playing with the knobs. Generally they should not be full one way or the other. If you don't have a good starting point, the middle ain't a bad place to start. Make changes to one adjuster at a time. Make changes that are big enough to feel the difference, but not too extreme that you are going from one end to the other. Make notes, keep track of what you do and how it affects the bike.
Years ago I rode a Breva 1100, I was amazed at what a marshmallow it was stock. But it didn't seem like it was fundamentally flawed, just that it was way too soft. I assume that could be adjusted out with a little work and maybe some upgrades. The frame is pretty rigid, so it should be do-able.

 

[kiwi dave]

If it sags to much without you on board it is too stiff a spring. If it sags too little without you on board the spring is too soft.

Isn't this about face?

 

[Brian UK]

I would have thought so.
If it sags too much before you get on, it's going to sag far more when you do.

 

[canuck1969]

OP said with the new spring he is at the required sag mid range on the preload. To me, that is about as good as it will get and sounds like the spring rate is within the range he needed for the weight he was applying. Is it enough if more weight is applied or he wants a smaller sag, all depends on the weight and how much more adjusting is needed. I don't think spring rate is his issue. 10mm of sag less will not cause what he is experiencing. This sounds more like rebound. We will have to wait to see what he finds.

To answer the OP questions about the front preload, you don't need to re-spring just for the sag. You can cut down or add to the spacer in the fork to adjust for the sag if needed, but I don't think you will need to.

 

[GuzziMoto]

Isn't this about face?

If you have springs that are too soft you will have too add a lot of preload to get the sag right with you on board. This will mean that without you on board it will sag very little. Thus, once you set the sag with you on board correctly, too little sag without you on board means your springs are too soft and too much sag without you on board means your springs are too stiff.

 

[kiwi dave]

I can almost follow this logic.

I dunno why sag without the rider is mentioned. I think it's meaningless.

 

[GuzziMoto]

I can almost follow this logic.

I dunno why sag without the rider is mentioned. I think it's meaningless.

No, sag without the rider is not meaningless. If you are trying to determine if your springs are too soft, too stiff, or right, sag without the rider on board is as important as sag with the rider on board. If you don't care about whether your springs are right for your weight or not, you could ignore sag without the rider on board. But if you want to check to see if your springs are right for your weight, sag without the rider on board is literally half of it.
Again, if you set the sag so that it is correct when the rider is on board, but the sag without the rider on board is too little than your spring rate is too soft for the weight it is carrying. If the sag is set right with the rider on board but the sag without the rider on board is too much then your spring is too stiff for the weight it is carrying. If you set the sag right with the rider on board and the sag is also correct without the rider on board then your spring is the correct rate for the weight.
If you don't know either sag, if you don't know the sag / haven't set the sag with the rider on board or you don't know the sag without the rider on board you cannot determine if your springs are the correct rate using sag.
In the suspension world it is common practice when doing sag to measure both the sag with the rider on board and the sag without the rider on board. The sag with the rider on board is often referred to as Race Sag. The sag without the rider on board is often referred to as Free Sag.

 

[GuzziMoto]

To explain further....
If your springs are too soft, to get the right amount of sag will require you to add a lot of preload. This will result in reducing the amount of sag under just the weight of the bike, i.e., without the rider on board. While the extra preload will decrease the amount the bike sags with you on board, the extra preload will make the bike sag very little under just its own weight. So while it seems backwards, too little free sag when the race sag is right means the spring is too soft.
If your springs are too stiff, it will take very little preload to get the sag with the rider on board right. This means that, with so little preload, your sag without the rider on board will be more than it should be.
That is why you can tell if your springs are the right rate or not by measuring the Free Sag (riderless sag) after you set the Race Sag (sag with the rider on board).
If you are never going to change spring rates, this might not matter to you. But even if you are not goingto change your springs if they are the wrong rate it can be useful to know. Perhaps, for example, you know that you springs are too soft. You can help compensate by running more preload than you otherwise would (resulting in lower than normal race sag numbers). More preload does not make the spring stiffer but it does raise the ride height, which could help keep a spring that is too soft from bottoming out. And / or you could run more compression dampening to help the shock deal with more weight than it is rated for.
It is up to you, but I think the better you know the better off you are.

 

[Sport1200]

Thanks for the replies gents. I think I have made some progress- at least with preload- I put the bike on full preload yesterday and come up with 26mm sag which is getting pretty close. (suspension knowledge is not my forte). With my partner on the bike (on her own) the sag is 11mm.... she is half my weight- 75kg. I have every intention of losing some weight soon so this might get me into the correct range. I haven't touched the dampening adjustment yet. I did take the bike out with my partner last night and it felt heaps better. I haven't gone flogging through corners solo yet but will be interesting to see how it goes. The rear is REALLY stiff when no rider is on the bike, but when riding it still has the nice ride it had previously as far as I can tell.
I measured one of my ZRX1200Rs for shits and giggles- never had a suspension issue with it- goes around corners well enough with its high mileage and standard suspension set on full preload- it has 38mm loaded sag. It does have the rear axle rotated to raise the rear. To me no need to change its suspension. I may fit the original shocks off my other ZRX that have much lower mileage on them.
My second ZRX I fitted Ohlins to ages ago- it has dial up preload like the Guzzi - no idea where it is set at- rides great as it is. I expected the Ohlins to make the ride harsh but it is like a magic carpet ride. It also has the rotated axle and the shocks are a little longer- raising the rear a bit more too. I may get enthused and measure its sag now too.
Pic is of my 1200s. One of my clients gave me the Bandit. (!) Was crashed but I have it ready to register- haven't painted it yet but may do a Katana kit on it so it looks like a Katana. (early 1980s Katana)