Choice of spring rates is an interesting topic. All this talk of 90N springs got me thinking�

80N/mm = 8.2Kg/mm at the spring

Approximate linkage rate = 3:1 (3x the movement at the wheel compared to spring compression)

Rear wheel will roughly compress by 1mm for every 2.7Kg of weight added (we�ll use 3Kg to keep the maths straight forward.

Let�s assume the rear half of an unloaded bike is 100Kg so this will give you about 33mm of static sag. Add a rider of 100Kg, whose weight (for arguments sake) is split 30/70 front/rear, then there�s an extra 70Kg acting on the rear spring bringing the total to 170Kg. This will give a dynamic/rider sag of 57mm. Not quite the ideal third of suspension travel which would be around 65mm.

You would need to add approximately a further 25Kg of weight on the rear to reach the theoretical ideal of 65mm dynamic sag. This would equate to roughly an extra 35Kg of rider weight if you assume a 30/70 split.

Very roughly, based on a number of assumptions, an 80N/mm shock spring (zero preload) will be suited to 195Kg weight at the rear, 100Kg is the bike and 95Kg (70%) of the rider�s weight. Therefore this spring would suit a rider who weighs in at 135Kg (or a 90Kg rider with 32Kg of luggage).

A 90N/mm (9.2Kg/mm) will give 65mm of dynamic sag with 215Kg of weight at the rear, 100Kg being the bike and 115Kg (70%) of the rider�s weight. This equates to a rider weighing 164Kg (or a 90Kg rider and 52Kg of luggage).

All the above is based on no preload, so dialling in a bit will increase the payload further yet maintaining the same sag. 10mm of preload for example on an 80N/mm spring will buy you and extra 25Kg of luggage, or 37Kg or rider. On this basis, I would suggest that an 80N/mm spring is more than enough for any rider up to 120-130Kg (18-20 stone) in weight and certainly too much for a sub 100Kg (<16 stone) rider on an un-laden bike (who would need the 70N/mm standard option). Remember, you can always dial in preload, but you can�t take it away � you�re always best erring on the side of a lower rate than a higher one when selecting a spring. There�s probably a good reason Ohlins don�t sell a 90N/mm spring anymore� and that�s because hardly anyone actually needs one!

__________________

Thanks for the informatiin guys, i have been in contact with Kais and they do indeed do a 90nm spring with a free length of 230mm. Im just waiting in a price, and too decide if i actualky need it. After reading pleiades post, i had a rethink.

I guess my problem is the massive variations of load i expect my bike to hamdle, I am by my. Own admission fat, i carry luggage, i tow a trailer, i take a pilluon, i also do all of the above at the same time.

Then i want my bike to go trail riding too.
I Think i ask too much of a single set up.

I have projection 4 way dog bones set at 15mm (to. Match the added height of WP fork conversion. Could this have an effect on leverage ratio.

I removed the shock last night and added another 6mm preload, (quicker than doing 1/28th of a turn when fitted) and seems more like a reasonable sag, 70mm with rider.

This has imoroved all of the above riding conditions, so im sticking with it for now.
Thanks for your help guys, much appreciated.

__________________
To boldly go where no Tenere has gone before.

Maybe teknik motorsport (near Sydney / wrong side of the world ) can help you, they offer different springs for the shock:
From their website: "S46PR1C1 P/N YA 817. It comes with an 80N spring. Ohlins have discontinued the stiffer springs so we have more make in 85,90 and 95N. They are still Yellow so everyone knows you have an Ohlins!" I do not know if the sell the springs without an Ohlins shock, but hey, you can ask them.

See here: http://teknikmotorsport.com.au/Featu...ackage-upgrade

Ciao
Solitario

Just reread this pleides, i tbought the Ten had 200mm of rear wheel travel, and the stock shock offers 95mm stroke.

My ohlins has 94mm stroke. Would the ratio not be closer to 2:1??

__________________
To boldly go where no Tenere has gone before.

Once you’ve got the sag in roughly the right region (70mm is pretty good as a third of 200mm travel is 67mm) then the next thing to do to verify that the setup is ideal is to check the amount of stroke the shock is using.

On the centre stand (no load) fit a thin cable tie to the piston rod and slide it up to the bottom of the shock body. (Some shocks, like my Yacugar, have a rubber O-ring already fitted to check the stroke; the Ohlins might too?) Load the bike up with what you consider an “average” or everyday cargo (and fuel load). Go for a test ride on a route that covers varied terrain – road, speed bumps, a bit of off-road and some hard braking and accelerating. Hard acceleration is important; more weight is applied to the rear suspension under hard acceleration than even hitting the hardest of bumps due to the fact that all the bike’s and your mass is acting on the rear.

When you get back home, examine the position of the cable tie/O-ring and see how much unused stroke there is. If there’s lots (+20mm) you can take out some preload, if there’s a small amount 10-20mm you’re about right and if there’s less than 10mm then you need more preload (or a higher rate spring). Ideally you want the shock to be using all of its stroke, with just a little spare for unexpected impacts etc. Remember 10mm of stroke at the shock is roughly equivalent to 30mm travel at the axle.

Make any adjustments and repeat the same route and observe any differences. Re adjust and go again round the exact same route.

Maybe? But don't give up...

Continual adjustment of preload is the only way you’ll maintain the correct sag and use of the shock’s stroke with varying loads on a linear spring. Remote preload adjusters help here, but sadly not available for the Ohlins shock. Variations in payload/weight can be a reason to consider a progressive spring. Whilst I’m not a fan of progressive springs for forks (for reasons explained here), they do have a place on the rear as the spring rate increases in proportion to load, negating the need for continual preload adjustments. In fact you can’t really set sag on a progressive with the preload adjuster as all you’re doing is squashing out the lowest rate part of the spring which is why they are hard to set up and racers don’t use them and it is even more crucial you get the right spring rate range for your weight. If you get it right though, the joy is you never have to adjust preload apart from under extreme conditions.

Another thing you could consider is trying the linkage bones in another position? A 3mm reduction in hole centres gives a rise at the axle of approximately 10mm, which can help to maintain the bike’s attitude/geometry whilst running slightly more sag on the rear. For example, if you run 65mm of sag with dog bones at +15, the ride height will be the same as 75mm of sag with 3mm shorter hole centres (+25 position). The other thing shorter linkage bones do is reduce the leverage on the shock, therefore effectively slightly increasing spring rate. So in the example above, the 75mm sag on short dog bones (although the same ride height) will give a slightly “stiffer” feel and less shock travel will be used. Longer bones have the opposite effect, reducing leverage and giving an effective “softening” of the rear. Neither actually changes the actual rate of the spring itself, just the overall “effective” spring rate of the whole suspension system.

The moral is, don’t rush setting up the suspension. There’s a lot you can do and one thing affects another. Adjustments are free and relatively easy to do, they just take time, patience and copious note-taking. Take your time; try things out and test them and keep repeating the process over and over. You’ll get it right in the end. I reckon, since first tinkering with the stock suspension on my Z, it’s taken me the best part of three years to get it right, and even now there’s room for further fettling!

It's all good, honest fun though and satisfying when sorted. Happy spannering!

__________________