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Discussion Starter #1
I've been trying to sort out the suspension on my '04 ST4s since I bought it last August. I had it set up by one guy who did it wrong, then I re-set it myself and still wasn't satisfied. So I finally got an appointment last night with a local suspension expert, and we spend 2 hours working on the setup. He'd make some adjustments, I'd take it for a ride and tell him what I felt. He'd make some more adjustments, I'd go for a ride and report back. Finally, I asked him to take the bike out for a ride to see for himself.

Well, I'm happy to report that I'm not insane (about this particular thing, anyway). Ed said that felt the same things that I was feeling. The bottom line is that he is suggesting stronger springs both front and rear, and maybe re-shimming/revalving the forks. This concurs with NCRick's advide and others experiences on this list.

Now, I'm not a big guy (200lbs-ish in full gear), so I wouldn't expect to have to respring the bike. But he was saying that the suspension is spending too much time at the bottom of it's stroke where the damping becomes exponentially harsh, which is why the suspension can handle small road imperfections but is extremely harsh over any type of a right angle bump, regardless how small.

With front preload at max and rear preload almost at max, the bike now feels more under control, but very, very firm. Three of the 4 damping settings are close to what I originally had, with the exception of front compression which is much harder now to prevent the forks from bottoming. I'm still nowhere near satisfied, so I'll probably have this work done within the next few weeks and will keep you posted on the results.
 

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I could be totaly freaking out of line here. But rumor has it, Ducati sets it's stocker spring rate selection for a 165-170 lbs rider. So that is what I've heard...
 

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Discussion Starter #3
Another intersting note. I told Ed that I specifically bought the ST4s over the ST3 due to the upgraded suspension parts. His comment was that from what he's seen, Ducati spends money on the "bling" and not on the actual working parts. Take the forks. Ducati spent a lot of money to have the sliders coated in TiN, but the internals are cheap. Look no further than the location of the compression adjuster screw. You have to reach up through the axle to get at the screw, which is a dirt bike design. But on a dirt bike, and axle is offset from the fork so you don't have anything in your way. On most sport bikes, the compression adjustment screw is perpendicular to the fork and out in the open, but this costs extra money because it's additional machining operations and mechanism. But the gold coating looks cool...

He did say that the Ohlins shock is good, it just needs to be resprung.
 

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I can't argue with a suspension expert about the Showa internals being cheap. I can say that I had Lindemann install the proper springs for my weight (260 lbs), revalve for the higher rate spring, and do all his little tricks to reduce harshness and stiction. It was like night and day.

Jim Lindemann is a big fan of using the stock Showa parts, with minor modifications. He laughs at those that claim you must install their pistons or valves because their parts flow more oil. Take a look at his website for more detail. I hear good things about Race Tech too - I'm not saying Lindemann is the man. I'm saying the right rate spring, and valving that matches that spring rate is critical. Perhaps more members will post their experiences. I've never seen the Showa internals vs. Ohlins.

Like I said I'm not a suspension expert but his mods worked for me. The forks are compliant yet suck up the biggest, sharpest bumps. They have never bottomed (except upon returning to Earth- wink wink). And raising the oil level half an inch helped reduce that little problem. I can run right over railroad crossings and expansion joints, and the forks just soak it right up. Things that would have bottomed the fork, no longer bottom the forks. Yet the ride is much less harsh and I can see the fork moving up and down like crazy over the road surface.

I've checked front fork travel and I'm using it all. It may be bottoming but it's very gentle.

Another thing about the right rate spring: I went with a Penske shock and a 625 pound spring. To get the right sag I had to crank up the preload to over 20mm. Too much.

Finally I went to the spring Jim recommended: 800 pound. Now I have about 8mm preload and 33mm loaded sag. And the ride out back is more compliant. Why? Less preload means less of the spring is being used before you hit the bump. It rides better now with the 800 pound spring vs. the 625 pound spring. Rides better over not only huge bumps but small imperfections. I really wasn't expecting that.
 

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pazzoduc said:
I could be totaly freaking out of line here. But rumor has it, Ducati sets it's stocker spring rate selection for a 165-170 lbs rider. So that is what I've heard...
Which is why many of us have gotten a heavier rear spring, especially if we do a lot of 2-up riding. I can get exact numbers tonight if anyone is interested.
 

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Discussion Starter #6
Bill_Anderson said:
Which is why many of us have gotten a heavier rear spring, especially if we do a lot of 2-up riding. I can get exact numbers tonight if anyone is interested.
Bill - please do. Ed said that he had to look up what Ohlins recommended, so I'll compare his lookup to your spring.
 

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Badger_WI said:
Bill - please do. Ed said that he had to look up what Ohlins recommended, so I'll compare his lookup to your spring.
I had Circuit-1 tune the suspension on my ST4s 3 years ago, when I was a much heavier rider than I am now! They replaced the fork springs and rear spring and re-jetted the valves for the new spring rates.

Like someone said, the end result was like night and day! Before, it was like riding on jello in the corners. After, the ST4s is solid, stable, planted and a whole lot of fun!

I can't check the spring rate of my Ohlins rear because my bike is in the shop awaiting repairs after I lost a rear wheel bearing. I'm pretty sure it's rated at '150' though (and I think the stock Ohlins is '75', but I'm not as sure about that).

However, I lost a lot of weight and I'm still losing (I was 310 lbs, without riding gear, when I had the suspension tuned!). The suspension is way too stiff now, but it's still rideable. To be honest, I much prefer a stiff and harsh suspension to a soft and spongy one!

Since the original tuning, I've had the fork springs changed to a lighter rate, so I can adjust them. The rear is still the stiffest spring Ohlins makes! It's so stiff that I can't compress it much any more (I currently weigh about 255 lbs without riding gear). My rear preload is wound all the way out. I can't adjust preload any more!

Eventually, I'll have to get the rear spring changed again. I'm holding off until I've shed another 30-40 lbs in weight though. :D
 

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The Ohlins shock is great on the ST4s and respringing it is a breeze, needing no revalving unless you go WAY out of range.

Badger, it sounds like most of what your guy is saying is right on. I do not agree with the assessment of the fork internals being judged by the location of the adjuster screw. The screw coming in from the bottom imposes no limitation to the design. The compression valving is really crappy in the ST4s and is the same thing in an st4 or even an ST2.

I really can not stress enough the improvement you will get with the installation of the proper internals. We have actually installed Showa internals in those type of forks (stealing from 996 forks that have been "Pensked") and that is a nice addition for those on a budget, giving Gold Valve like performance and saving $100. With such a nice bike that has all the other right parts, to me is seems a false economy to try to save less than $300 by taking short cuts on the internals. We charge $540 for fixing those forks. For that price you get new RaceTech springs, Ohlins fork oil, Penske Compression and rebound valving using the 2 stage compression stack that has been developed specially for these bikes, our specially machined check assy. and the forks are totaly disassembled for inspection and cleaning. If you were to swap in the Gold valve instead of the Penske your looking at a total more like $380 and with revalved showa parts the toll goes down to $340. What if the inspection shows you need all new bushings, seals and wipers? Add about $85. The Gold valve option is what works in the ST2. Shipping is $20 each way and we turn them around in a day or two.

Any good suspension shop can fix these forks. We sell a lot of kits with the Gold Valve and springs to DIY guys. Cogent Dynamics was one of the very first shops in the county using the Penske kits and have worked hand in hand with Penske to dial the Ducati ST4-4s in.

For a lot more reasons than the fact that we do the work, I think this is the best mod you can do to the ST4s if your using the bike as a sport tourer or even sport bike.
 

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Rear springs by the numbers

Badger_WI said:
Bill - please do. Ed said that he had to look up what Ohlins recommended, so I'll compare his lookup to your spring.
I have no idea what these numbers mean, but here they are:
OEM = Ohlins 01092-31/95 L250
replacement = Ohlins 01091-39/110 L153

Please don't ask me to explain these numbers. All I know is that the replacement spring is for a heavier load. I remember from a prior thread that people said it is difficult if not outright impossible and dangerous to replace the rear spring yourself without a spring compressor tool.
 

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Bill_Anderson said:
I have no idea what these numbers mean, but here they are:
OEM = Ohlins 01092-31/95 L250
replacement = Ohlins 01091-39/110 L153

Please don't ask me to explain these numbers. All I know is that the replacement spring is for a heavier load. I remember from a prior thread that people said it is difficult if not outright impossible and dangerous to replace the rear spring yourself without a spring compressor tool.

Ah, I think the relevant numbers above are 95 and 110. I thought I might have been wrong about the stock Ohlins spring (I thought it was 75!). Anyway, my spring is a 150 and it is very stiff. :eek:
 

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I changed the fork spring, oil, and put in a Gold valve in my ST4s and found the improvements real nice. For me it was not a night and day change, but an improvement.

No matter the brand of suspension parts you put in, you will like the results.

Dave Harhay
 

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The stock Ohlins spring is normally a 95. The 95 is good for riders up to about 175 lbs. for those in the 180 to 210 range we recommend the 100 and 210 to 230 or so a 105 generally gets the nod. All this is dependant on the riders style, preference and bike setup/use. We would make specific recommendations in each case but those rates are a good starting point.
 

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This is a long post and is not really a rebuttal to any previous post, most especially not NCRick's (we are lucky to have such experience that is presented in such an articulate manner). My concern is simply to put the capabilities of the OEM forks in perspective, lest a rider think there is something inherently deficient with the components specified for their bike.

I weigh 210 lbs. naked and closer to 230 lbs. suited up. I can only speak from my experience with my 2002 ST4s but I would take reports of how undersprung the ST4s suspension is with a grain of salt. As long as you are getting proper sag measurements without needing excessive pre-load, then the OEM springs are good for your body weight. Maybe I was lucky and just happened to get firmer OEM springs than typical but they provide proper sag with about 1/3 of available pre-load dialed in.

Certainly fork damping can be improved with aftermarket fork valving but the harshness people complain about is usually the result of adding too much rebound damping in the forks. This simultaneously increases the compression damping and can make the forks practically unrideable over rough pavement. The key to avoiding this is to only add a minimal amount of rebound damping. It will be different for different forks as they do vary but I find harshness and the associated loss of traction starts to creep in if I turn them in any more than around 12 clicks out from fully in. In otherwords, I make sure the rebound adjusters are backed out at least 12-13 clicks. The fork compression damping adjuster does not cause the same type of harshness as early in the adjustment range but you still have to be careful about adding too much. The biggest benefit of upgrading the fork valving is that the damping can be utilized to reduce the speed at which the forks dive under braking, with the OEM internals this is not possible without adding too much harshness.

The bottom line is it's a mistake to try to control fork dive under braking with the OEM dampers. I just accept that my forks will dive a lot under hard braking but once they have compressed (which only takes a fraction of a second), the braking is well controlled. Even forks with lots of compression damping will dive the same amount under hard braking, it just takes them a little longer to fully compress, but not much. Heck, even factory MotoGP bikes dive quickly under corner entry braking, watch the race close-ups to see it first-hand. I think people often try to over-compensate for fork dive with the damping to the detriment of corner grip and even front braking grip over less than smooth surfaces. The idea of suspension movement in the first place is to maintain the tire in good contact with the road and too much damping of either comp or rebound will be counter-productive to this important goal and add uncomfortable harshness to boot.

Once you forget about trying to control fork dive with the damper adjustments, all you have to focus on about is controlling excessive oscillations (pogo motion). These oscillations will reduce grip and the ability to hold clean lines over undulating surfaces so it is important to control them but don't go overboard trying to completely eliminate them or you WILL lose corner and braking grip on imperfect surfaces and, with the OEM fork internals, you will add harshness. It only takes a little compression and a little rebound for this to be effective. This is one of those cases where if a little is good, more is not necessarily better. For maximum corner grip over undulating and broken surfaces you want to err on the side of too little damping rather than too much.

Having said all this I do admit I've been having a bit of a problem setting my OEM suspension to perfection recently. I think it may simply be time to change the fork oil and have the rear Ohlins gas recharged as the bike has over 27,000 miles on it. I do know that up to 18,000 miles the suspension worked exceedingly well without a hint of harshness except under very hard braking, well enough for me to corner aggressively over badly rippled and/or broken pavement with complete smoothness and control and excellent tire traction, even only using a sport-touring compound. By "corner aggressively" I mean my butt most of the way off the seat, shoulders offset by the same amount, knee held up off the ground only because my 'stich doesn't have knee pucks and riding on the edge of the rear tire, lean only limited by pipe and centerstand clearance with the front tire not even hinting at washing out over the bumps and broken pavement edges and the chassis movement so well controlled that my body could be completely relaxed over the bumps (no harshness). This is not to say the suspension can't be improved. Just that it doesn't (always) suck and most riders will not feel the need to upgrade forks or shock as long as their fork/fork oil are not worn out and they are adjusted properly.

It's also possible that some forks are defective. It happens will other components of the bikes, so why not the forks? I imagine most defects with the fork internals never get discovered because of the subject nature of the results. In other words, you will never get stranded because your forks are "defective". This could explain the widely varying opinions on how well the Showas work. Maybe the oil levels vary or maybe the OEM valving is easily fouled by the type of debris that can be created if the forks are not mounted at exactly the same level in the triple trees. I've heard people rave about the improvement of their Showa forks having done nothing but remove them, clean them out and replace the oil to the specified level.

Motorcycle magazine test riders have generally raved about the suspension qualities of the ST4s, even when ridden hard on the track. All their reports were done using OEM forks and internals. Motorcyclist said this after their extensive road testing:

"One of our test roads has a series of medium speed corners crisscrossed with buldges and ripples and overlaid with tar strips. On many bikes you're left to slow a bit just to get through the section. But on the ST4s you can carry on unabated. All the while, you're aware of the suspension stroking over the small and large bumps with little perceptable friction and all the control in the world. In fact, if you had to describe the Ducati's suspension in one word, it would be control. Although the spring rates are appropriately modest for sport-touring duty-the bike uses the majority of it's travel on gnarly/bumpy roads, as it should--the tires follow the ground with astonishing accuracy and manage the chassis with a firm hand. What then stems from the suspension doing it's job is heightened rider confidence. Hop on, go fast and have fun."

My point in posting that is not to say that Motorcyclist Magazine is the last word or their writers are suspension gurus, but to point out that the ST4s forks are not somehow so deficient (when properly adjusted and in good condition) that they cry out for help merely to go fast and maintain a plush ride. I don't really have time to quote more sources but editors by and large have raved about the ST4s suspension and I don't think this would be the case if the forks were inherently harsh and unforgiving. I haven't heard any of them complain about the Showa forks which were actually lifted from the 996 superbike.

And who said titanium nitride coating is "bling" factor? It's extreme hardness and resistance to wear is welcome addition on a sport-touring mount that might see a lot of miles. The slight reduction in stiction this provides is not nearly as beneficial as the resistance to rock dings and wear from grit and grime. Your fork seals should not fail as quickly because the titanium nitride is more resistant to dings and dirt abrasion. Anyone who calls this "bling" doesn't know what they are talking about. Chrome is hard but it doesn't hold a candle to titanium nitride.

Badger: My recommendation is to make sure the OEM springs give you the proper sag without requiring excessive pre-load and then experiment with lower damping levels. If you get it so it handles the type of conditions you ride and it works for you leave it be, if not, it's time to fix the problem. And that's what I'll possibly be doing this winter since my suspension appears to have degraded substantially after 27,000 miles. But don't try to tune it to be something it's not. It's like the magazine writer said, it'll be soft and compliant but give complete control and confidence, especially when pushing it hard over the gnarly stuff.
 

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Discussion Starter #14
Mike - You may recall a similer thread that I started last fall regarding the ST4s' suspension, and that I had taked it to a guy to have it set up. In retrospect, it was obvious that this first guy didn't know what he was talking about, so let's throw that whole thing away.

This second guy I worked with this week is a suspension expert; it's what he does for a living. He works for Showa, but is embedded at Harley-Davidson and does all of the suspension work for the new Buell and H-D bikes (design, testing, etc.). He also owns his own motorcycle suspension business and works with many local racers. He also used to race himself. The bottom line is that I believe this guy.

So, right now my front preload is completely maxed out, and rear preload almost maxed. We had the rear maxed at one point, but the shock was hitting the internal rebound spring so we backed it off a bit. If I recall, my sag numbers are around 32mm both front and rear, but I don't have the exact numbers in front of me.

What I have been unhappy about is that it felt like the suspension, especially the front, was working, but it was still transmitting most of the shock & bumps to me. I thought it was a damping issue, so I had both compression and rebound almost as soft as they would go (14 clicks), but this still didn't help. The ride was very, very harsh except over the smallest of road undulations. The front end also felt very vague especially going into a corner. All in all, the bike just did not inspire any confidence.

His explination was that towards the bottom of the fork stroke, the damping characteristics become exponentially harsh to prevent the forks from bottoming out hard. Because the springs are too soft for me, my forks are spending most of their time toward the bottom of the stroke, thus giving me a very harsh ride. This seems to make sense, and also jives with with NCRick has been saying. Having these two experts in agreement makes me feel confident in recommendation to respring the bike. I also had Ed ride the bike so that he just didn't have to rely on my feedback to make adjustments. He concurred with what I was feeling. The way we have the bike set up now makes it feel much more confident, but it is very "tight", still transmitting a lot of the road imperfections to the rider. So it's better, but it's still not right.

Believe me, nothing would make me happier than to simply adjust the existing suspension and get a compliant, yet confidence-inspiring ride. I really have no desire to drop $400 on a brand new bike to redo the suspension. But I feel the ST4s holds a lot of promise if I can work through these issues. Hopefully I'll get the work done within the next few weeks, and I'll let you all know on the results. With any luck, it will be like NCRick has been predicting...
 

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I have suggested to a lot of guys: "if it ain't broke, don't fix it." I like a softer spring on a street bike. Badger, IMO is reading the same things I do when I ride the bikes in stock form. I will take exception to what the showa guy is saying though. The forks internal damping is not position dependant at all. In fact, the bottoming cone that hydraulically cushions bottoming in many Showa forks are not present in this fork model. The damping system employed is a lot more like a damping rod fork in that it relies on a modified orifice to provide damping. The net effect is too little damping at slow fork speeds but too harsh damping once the fork speeds are up. I will try to post some photos later to better illustrate what is going on. In this particular fork, it is NOT just a matter of revalving, the compression valve must be replaced.
 

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Badger_WI said:
So, right now my front preload is completely maxed out, and rear preload almost maxed. We had the rear maxed at one point, but the shock was hitting the internal rebound spring so we backed it off a bit. If I recall, my sag numbers are around 32mm both front and rear, but I don't have the exact numbers in front of me.
I do remember the conversation but I don't remember you posting sag numbers like that with the pre-load maxed out! If those are correct, you definitely need new springs and it makes sense to match the damping while you have them open. I know that springs vary in firmness from sample to sample but have not heard of that much variation before. Maybe Ducati is shipping different spring rates or subsituting forks from another model (same forks but with a differnet spring inside) when they run out of the correct one. If so, shame on them.

You should definitely have your suspension guy measure the actual rate of the OEM springs when he removes them. That will help us determine why we are getting such different sag numbers with bikes that are supposedly identical. I've heard Duc superbike owners complain the rate of their OEM fork springs is too HIGH and at least one suspension expert say the same thing!

In any case, I bet you love your new suspension.
 

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NCRick, do you think it's possible my bike was delivered with 1.0Kg/mm fork springs? It was manufactured in June 2001 (right when the ST4s was being introduced). Maybe Ducati switched specs after the first few bikes were out the door.

I believe the published spec for the ST series is .84Kg/mm.
 

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Discussion Starter #19
NCRick said:
In fact, the bottoming cone that hydraulically cushions bottoming in many Showa forks are not present in this fork model. The damping system employed is a lot more like a damping rod fork in that it relies on a modified orifice to provide damping. The net effect is too little damping at slow fork speeds but too harsh damping once the fork speeds are up. ... In this particular fork, it is NOT just a matter of revalving, the compression valve must be replaced.
Interesting info, Rick. Ed did say that he wasn't extremely familier with this particular fork, but that he'd know more when he took them apart to replace the springs. I did tell him your opinion that the valving needed to be re-done, and he said that he would do that too.

Thanks for all the help and advice, guys!
 

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Mike, It is entirely possible, I have seen a lot of variations in the Ducati forks. I actually used a set of the ST4s springs for a friends Aprilia Falco. the light springs were perfect for his 140 lbs. I have a formula where you plug in the coils, length, wier dia. and OD to output the spring rate. It isn't perfect because you don't know the exact steel used but It seems quite close. We have been installing mostly .95 springs in those bikes. But for someone much over 200 lbs or who likes a firm front end, the 1.0 spring would be OK. Much of this stuff is down to rider preference. I admit to being rather obsessed by this stuff!
 
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