Ducati Sporting Club UK > DesmoDue Race Series > DesmoDue - General Questions and Chat > Rear suspension units

[Iconic944ss]

The ST ride height adjuster sounds interesting but (if my failing grey matter is still functioning) the ST uses a vertical shox with rose joints and our 'modern classics' use an inclined and direct (linear) mounted unit.

sounds intreguing thou - any pics of said adjuster please.

I think it might be possible to manufacture a ride height adjuster to fit on the top shock mounting point but getting any more than 25mm adjustment could prove to be a problem.

ps - I dont think my WP shock is sufficiently improved over a std shock to justify the price (£280 I think I paid) but mine was leaking and the importer did a 'special offfer'. If I had my time over I 'd go for either an Ohlins or Penske - both get good ratings.

Frank

[skidlids]

Tim the standard SS shock is 328mm between fixing centres, one end fits directly to the frame just under the rear of the tank the other end bolts directly to the A frame part of the swingarm as it is a basic cantilever set up.
Each end of the shock has a eye fitting that are unadjustable, as the rear shock to wheel travel is approximately 1.9 to 1 then a shock length of about 235 to 240mm should do the job. With the standard shock at 328mm then there is not enough room between fixing centers to fit a proper adapter. I have thought about modifying one of the shock mounting points, the frame one seems the obvious one to do, where as the swing arm one is easier to take to my local fabricator and have him sort some thing, either of which I would first have to run by the comittee to see if it is within the rules.
My other choice is to use a shorter shock and a adapter/adjuster. I have a 290mm Paioli which woul give me 45 to 50 mm of space to fit an adjustable adapter in. As the shock only owes me £65 this is still a very cheap option and inside my budget, failing that I have an adjustable Penske that I'm sure I can get a mate to modify for me to get the right length, currently on its longest setting it is 320mm so basically I just need the adjuster bit to be 20mm longer, not to much of a problem to get made but as the shock is worth £250 plus then the budget is getting eaten up.

Kev

[paynep]

A quick question chaps -

what is the thinking behind altering the rear ride height?
I have looked for setup articles on the ss, but obviously have missed one.................

Cheers, Paul

[uncledunnie]

Domski,

I'm still interested, just need to clarify the following with you.

I've got a 620 Monster which already has an adjustable ride height rod, so I'm just looking for a shock upgrade/change. The unit fitted to my bike is a Sachs unit with rebound damping only.

The forks are Marzocchi I believe but since there are no obvious markings they may be Showa. I have been told the Marzocchi units are not easy to modify (??).

Thanks for the help.

Dunnie

[FiscusFish]

Originally posted by paynep
A quick question chaps -

what is the thinking behind altering the rear ride height?
I have looked for setup articles on the ss, but obviously have missed one.................

Cheers, Paul

One of the few problems with the SS is it's relatively slow steering. Once you get it over to the right lean angle then nothing short of running over anther DesmoDue competitor is going to put it off course but getting there in the first place requires a fair bit of effort.

One of the ways to change this is dropping the forks through the yokes a little. This is fine up to a point but eventually you're gonna run into ground clearance problems. The alternative is raising the rear ride height.

If money is really tight (from around £15) a later SSie shock off of eBay should bolt straight up and is around 12mm longer. Other than being newer and probably in better condition the extra shock length offers a noticeable improvement.

Darren

[ali]

Originally posted by paynep
A quick question chaps -

what is the thinking behind altering the rear ride height?
I have looked for setup articles on the ss, but obviously have missed one.................

Cheers, Paul

Hi Paul,

There was no specific article, it's just the SS tends to sit low in the back. Having had a 900SS and a 900SL I can testify that unless perfectly setup they can be a bit of a pig to muscle around corners, with a distinct tendancy to understeer.

As Niel Spalding wrote, it'll be better to get the whole bike slightly higher to help drop-in, so just canting the bike by dropping the forks through the yolks isn't really enough, hence the desire for ride-height adjustment.

[IGNORE]The problem is that the shock is mounted at such an angle that it requires a greater length difference than a vertically mounted shock would. In order to gain 10mm of vertical difference you'd need about 25mm of adjustment on the shock, and there are those that'd contest that 10mm vertical on an SS is just the start..... [/IGNORE]

Cheers,

Ali

[Edited on 18-2-2005 by ali]

[skidlids]

Originally posted by ali
The problem is that the shock is mounted at such an angle that it requires a greater length difference than a vertically mounted shock would. In order to gain 10mm of vertical difference you'd need about 25mm of adjustment on the shock, and there are those that'd contest that 10mm vertical on an SS is just the start.....

Cheers,

Ali

How do you work that out Ali, my 916 shock is mounted to a rocker that gives a ratio of about 2:1 where as the cantilever set up of my 600SS has a ratio of 1.9 to 1, 20 if I add 10 mm to either shock the 916 rear will be lifted 20mm w.r.t. the rear spindle and the 600SS by 19mm w.r.t the rear spindle, the angle of the SS shock will actually determine the rising rate part of the ratio as it travels through a slight arc.

I have tried a few places for a SSie shock but no luck, Jim at Bike Enders thought he had one but it turned out to be a shock off a ST4 which after digging it out he then put on Ebay

[ali]

Originally posted by skidlids
How do you work that out Ali, my 916 shock is mounted to a rocker that gives a ratio of about 2:1 where as the cantilever set up of my 600SS has a ratio of 1.9 to 1, 20 if I add 10 mm to either shock the 916 rear will be lifted 20mm w.r.t. the rear spindle and the 600SS by 19mm w.r.t the rear spindle, the angle of the SS shock will actually determine the rising rate part of the ratio as it travels through a slight arc.

I appear to have made the same school boy error again.....

I always get the ratio the wrong way around, but then physics was never my strong point!! Come to think of it I can't remember what was???

Thanks, again, for the correction.

Ali

[skidlids]

To get a rough idea of ratio is easy on any bike Find out how much rear wheel trave it has, usually stated in the specs and then look at the stroke of the shock.
If there is about 120mm of rear wheel travel and 60mm of stroke on the shock then the ratio is around 2 to 1

Ali your original schoolboy method would give a shock stroke of 240mm, would certainly make for a very long shock well over half a meter long

[ali]

Originally posted by skidlids
Ali your original schoolboy method would give a shock stroke of 240mm, would certainly make for a very long shock well over half a meter long

Which is exactly what I'm intending on using! That should place my bum about 1m above the rest of my body, thereby giving the Heinz BB Turbo chance to work...

Skids, thinks he knows a bit about physics just 'cos he works with particle accelerators!