Updated again: Cogent Dynamics Monster S4Rs Ohlins revalve

[MonsterHPD]

Hi MonsterHPD, thanks for the nice chart. Could you comment for us on what it demonstrates?

Hi,
Sure. I just put them there as a comparison to the charts on your stock and modified shocks. The format is slightly different, but the units and system of the graphs are the same.
The blue curve is the shock for my M800 and is OK for road riding and track riding (at the pace I´m capable of and willing to risk on it).
The red curve is the track bike, which I have softened up now by reducing both clamp shims by 1 mm. Only riding it will tell how that came out.     

[Moronic]

Okay I get it - thanks. Interesting.

So it looks to me like your blue-curve Monster shock is a lot softer on compression than mine at similar settings. But about the same on rebound. Sounds comfy.

What compression setting do you tend to run at? I spend a lot of time within a few clicks of my minimum compression setting. Looking at your Monster curve, that makes sense.

Do you ever wish for more compression damping?

One other thing i notice is that yours is much more linear at the low-speed end - my curve has that sharp ramp up to 1.0 in-sec and then it settles down.

Whereas your Hyper shock is much firmer than mine in both dimensions.


Do you know how the linkage affects things? Are the M800, Hyper and S*R linkages relevantly similar?

[Speeddog]

M800 and S4R are the same rockers and pushrod, frame pivot points are the same.

AFAIK the swingarm pivot points are in the same spot.

HYM and MTS are most low/forward on rocker pivot.

They may have a different swingarm pivot location too.

[MonsterHPD]

Well,
 I ride the M800 mostly alone and on smaller roads where speeds are not so high, but the road can be quite bad. In fact, about 10km of my regular ride is what I use as my suspension test road. No matter what the people responsible try to do to it, it´s always BAD.
So I go for comfort front and rear. Even quite soft, a well-set-up Öhlin (as I´m sure any other quality damper) feels quite OK.  I don´t exactly remember where I have the adjusters, but something like in the graph. (12 to 14 clicks for both). For track riding, I usually firm things up: Reduce sag, more damping comp and reb, maybe around 10 clicks out). I always try to find the right setting from the soft side since too soft is always pretty obvious, too stiff can feel just fine if the track surface is reasonably smooth. It takes a couple of stints to find what seems to work, and as the day progresses, some further stiffening up may be necessary.
Sometimes my buddy (90+kg) borrows the Monster to drive some lady around the track. In effect, that doubles the load and actually works much better than you´d expect, even without further adjustments. Much to my surprise, really …

My track bike is a 749R frame and as such has the linear linkage and the corresponding shock. Due to the shaft bore in the HYM1100 crankcases, the pivot is raised slightly.
 The 3 Ducatis I know reasonably well have significantly different set-ups:

Monster / ST: progressive linkage (around 40% total), shock length 305 mm, stroke 66 mm, spring 100 N/mm. Mine was a DU0462  (old 900-2002) or DU5034 (M800, originally OE for the S4RS). Same shock fits the ST´s, same linkage etc (DU0150, the shock I once had came with a 95 N/m spring).

749/999: Progressive linkage (even the R´s etc), the rocker looks very much the same as the Monster / ST rockers .  I don´t have the spec sheet for 999 shock, but it has a stroke of something  like 75 mm, and came with very soft springs (64 N/mm on many bikes, I have a bunch of them lying around by now …). I think the Biposto came with a 90N/mm spring. I don´t  know how progressive that linkage is, but since the rockers look (or even are) the same as Monster / ST, I expect them to be pretty similar. 

749R: Du to Supersport reg´s, these bikes came with the linear linkage and a shock 305 mm eye-to-eye, stroke 56 mm and a 120 N/mm spring (at least my shock had that). As it came, it was rock hard (at least for me with an empty weight of some 60 kg). I also don´t know how “linear” this is, but the rocker looks definitely different, and it feels very different.  Still not sure if I like it …   
I don´t know if any of this helps, but there it is, anyway. Feel free to inquire further, gla if I can be of any help :-)

[Moronic]

Thanks Speeddog, that helps make sense of the divergent curves for the two bikes.

MonsterHPD, thanks for all the info. You are running on your Monster the same rear spring as I am currently. Although I am about 20kg heavier. Still seems to be plenty of spring for me.

Yes, I like your suggestion that the adjustments be set by increasing from soft. As you say, very stiff can feel okay when it's smooth.

[Speeddog]

My philosophy is to have the spring do as much of the heavy lifting as possible, and add just enough damping to keep it from being bouncy.

Not the best setup for track riding, but that's not what it's for.
Works good for me, and the roads we have around here, YMMV.
And I grew up on long-travel dirt bikes.

My S4 had quite heavy damping that felt really good when the road was smooth.
Small sharp frost-heave bumps in a fast right-hand sweeper convinced me that the OEM settings weren't going to be a keeper.

[MonsterHPD]

My philosophy is to have the spring do as much of the heavy lifting as possible, and add just enough damping to keep it from being bouncy.

Not the best setup for track riding, but that's not what it's for.
Works good for me, and the roads we have around here, YMMV.
And I grew up on long-travel dirt bikes.

My S4 had quite heavy damping that felt really good when the road was smooth.
Small sharp frost-heave bumps in a fast right-hand sweeper convinced me that the OEM settings weren't going to be a keeper.

Speeddog,
that´s about exactly my approach, even if I´ve not put into words like that. It´s important to remember that the damping does not do any lifting at all, it only slows movement.
BTW, the frost-heave experience is the same around here.

One final note on springs: Many years ago I tried an 85 N/mm spring on the Monster. I don´t remember in detail exactly what was wrong, but the spring was definitely too soft; I suppose I could not get the sags reasonable.
Also, with the very progressive nature of the linkage, at least in theory too soft a spring could land you too far into the suspension travel, effectively making the suspension harder du to the progressive linkage (in spite of the spring beeing softer).
Anyway, 95N/mm or 100 N/mm seem to work, can´t really distinguish between those two.   

[Moronic]

I am probably with you guys completely on all this but I do want to put up my hand for compression damping, which lets you run a softer spring and can help a great deal to stabilise the bike when you are going for it.

The overdamped stacks that Ohlins has specified for some Ducatis including mine has given it a bad name.

On the rebound side, yes I too prefer just enough rebound control to keep the bike mostly settled. I know mine works because about a year ago I caught a slippery patch on a cold tyre at the exit of a third-gear suburban left-hander and I could feel the rebound operating to resolve the near-highside that followed. It was lovely.

A well tuned compression stack is a great thing. And it works with the soft rebound side. It resists the bike's settling into hollows and onto humps, leaving the spring with less work to do and the rebound with less spring to control.

But yes, it has to be gentle enough to let the wheel move freely over frost heaves. Once the main stack is right, having some adjustment on the fly is a great help as well.

[Speeddog]

That's the balance, compliance vs. 'platform'.

I consider the soft spring / more damping to be The Official Ohlins Tuning Philosophy.

It's the fore-aft pitching stiffness that's primarily at play.
The bike will get into and out of corners better, as the geometry changes less and/or slower.



I've experimented very little with the rate progression of the rear.
Too expensive and difficult to measure, to start with.

I've experimented quite a bit with the progressive nature of the forks.
Brad's talked about it quite a lot.

The 'too-soft springs with too much rate progression' is basically the OEM fork setting for most Monsters.
They don't bottom out noticeably, they just get so stiff so quick that it stops movement (not so different from bottoming out, for all practical purposes).

If you're relatively light, 150 lbs or less, it's kinda OK, as you don't spend so much travel in rider sag, and you're OK with less spring rate as you're lighter.

The fundamental weakness is that the normal suspension travel is then rather short.
And it gets worse quickly as you get heavier.
Theoretically you can preload it up to get the sag with rider to a good number, but it just moves the un-usable travel from the top of the stroke to the bottom.

Straight rate springs and lower oil level get you into a more usable range of progression.

As a street rider, I find the limitations of less pitch stiffness are more acceptable than the harshness on sharp edges.
I don't fling the bike around, and I try to ride big round corner lines (must look like a very slow version of JLo  ).

[MonsterHPD]

I suppose the damping vs. spring situation is mainly about finding a solution one´s happy with. As is most suspension work, really, I don´t think most members on this forum will ask the stop watch if the suspension change made it better or worse.

One thing to keep in mind, I believe, is the different nature of damping force and spring force: Spring force is linear against movement (installed in a bike shock, non-linear as dictaded by linkage) and not affected by damping speed. Hydraulic damping force is not affected by position (again, modified as dictated by linkage) but proportional to damping speed squared. This "Vsqared" effect is basically what is compensated for by a good shim set-up.

As with springs, I personally prefer going on the soft side with the damping, especially on the street, since my aging body really dislikes the beating frost heaves and such dishes out otherwise.  Fast people on good roads or a track might want a firmer set-up, or just plain like it so.