M900 suspension question

[koko64]

I'm surprised you can get static/rider sag of 10/30 with 20mm preload on the spring.




[/quote]

Did you expect higher or lower numbers?

You know, just when I think I'm gaining a handle on suspension principles, a different but very valid logic appears.

I guess it's the decision about one's primary objectives and what area should be compromised, e.g. comfort Vs control.

[Speeddog]

Usually with a soft spring and lots of preload to get acceptable rider sag, static sag is very small or zero.

For street riding, it's indeed a matter of how you want to compromise.
And it's very subjective, and dependent on rider preference.

Racetrack, it's all in pursuit of lowest laptimes.

[scott_araujo]

S2R800 is the new style linkage, which seem to need a spring about 1.0 kg/mm stiffer than the old style linkage.

Are the DSS bikes the same linkage geometry as the S2R bikes?  Wondering if shocks/springs between S2R and 800 Dark can interchange even though the swingarm is different.

Scott

[Speeddog]

Are the DSS bikes the same linkage geometry as the S2R bikes?  Wondering if shocks/springs between S2R and 800 Dark can interchange even though the swingarm is different.

Scott

AFAIK, late model DSS and SSS are same linkage geometry.

I've got both styles 'in the house', so I can measure tomorrow....

[scott_araujo]

Thanks   I'd like to upgrade my rear spring on the existing rear shock of my 800 Dark.  So few people do it there's little data.  If I can at least cross over with the S2R guys that helps.

Scott

[He Man]

Im pretty sure they are the same.

manglebug has a late model DSS bike where the shock failed and i sent her my SSS shock which looked exactly the same.

I dont remember what happened, but im pretty sure she installed it and went on riding with it.

[scott_araujo]

But if I recall from her shaved seat tutorial pics she's about half my size  

I think you're right though and they are the same.  I think the aftermarket adjustable link for the rear is the same for both bikes which would also support that.  I should stop being lazy and go look up the part numbers for both shocks online.

Scott

[koko64]

Went for a good 130 mile sport ride yesterday. The roads included pretty much every kind of road, corner and bump. There's great variety East and North East of Melbourne for that sort of thing.

I have to say I was impressed with the shock's performance. It's nice to feel what the rear tyre is doing! Planted with plenty of feedback, tracking on line, on the sport side of firm with good pitch control. The front feels more planted because the ride height increase I made at the back now works as intended. I will tweak the preload and the damping a little over the next few weeks.

The bike is composed now. No more bouncing off line, no more "rocking horsing", no more collapsing of the rear into bumps and unloading the front. There is good stability considering how sharply it steers. I can't speak for the later Monsters, but a well set up early Monster (888 chassis) can be a razor sharp back road weapon.

It makes me remember the 'Sport Rider' article (Feb 1996, p53) which stated, "Tremendously tight, exact handling package", and, "this 900's back road prowess is astounding", and "laser accurate steering". That article made me buy my first Ducati, a new 1995 Monster in 1996. The only new vehicle I've ever purchased.

It's good to have one again.

[koko64]

Bikes pretty much sorted.

Just a note to say thanks to everyone who contributed their ideas and suggestions.

It was good to have a sounding board and I hope this thread was of use to others.

Cheers

[ajw85]

Isn't the free length of the Eibach spring 7"?
Does that extra .3 inch make a big difference over the stock spring?

[stopintime]

Isn't the free length of the Eibach spring 7"?
Does that extra .3 inch make a big difference over the stock spring?

My WP spring is about an inch longer. It was explained to me that a longer spring will behave better, with a more even resistance, throughout it's range. If it's noticeable for me? I don't know, but it sounds logical.

[Howie]

My WP spring is about an inch longer. It was explained to me that a longer spring will behave better, with a more even resistance, throughout it's range. If it's noticeable for me? I don't know, but it sounds logical.

If the spring is a linear spring the rate stay the same.

[stopintime]

If the spring is a linear spring the rate stay the same.

Isn't the resistance stronger when it's near fully compressed than when it's at it's full length?
Surely, it must be

[koko64]

Peter Verdone Design website is very informative about the technical aspects of motorcycle suspension.

The site under the sub heading "Springs" mentions a Dan Kyle test which supports the idea that even linear springs behave a little 'progressively' as they are compressed, so according to those guys you're correct. Also, the shorter springs behaved progressively much earlier than the longer springs.

Peter Verdone also has a PVD Wiki site with various projects.

[junior varsity]

for the non-engineery types, springs go with hooke's law, like bears go with candybars:

http://en.wikipedia.org/wiki/Hooke's_law