Fork Spring Rates

New shock turned up today so fitting if i get chance over the weekend. I find the current spring rate too low and with a ground clearance problem i run mine with 0mm sag

What shock did you get? What spring rate? Length? Your weight?!

So i have just put the second hand stelvio shock that i received from Germany, very please so far as the shock was lovely and clean and like new, always a good sign. It raises the ride height by exactly one inch (25mm) and initial impressions when you sit on it is that it is a heavier spring. Preload set to halfway (oh how great to have a knob to turn to adjust). I believe that the spring rate is 11 kg/mm

Now going to set the damping as recommended for the stelvio and go for a ride. I have kept the forks dropped to the 5th circle on the top of the forks, i think i would probably end up there after raising it anyway!

There are a couple of big bumps on the the way to work (15 miles) so i will try it over those and se what the steering is like for the current setup.

Oh and i finally have some sag at the back, i have been running the previous shock without any to get it to turn and also give it some ground clearance and more travel in compression. Sag with new shock set to halfway for ride height is about 20-25mm

ok, so read the stelvio manual, they recommend 15 turns out for preload and 24 clicks out for rebound, here i go......

started a new thread called Stelvio shock for riding impressions

Just commented your experience on other thread - great stuff.....obviously what you do with your knob in your own time (in the privacy of your own bike) is your own business.....and whilst I am now envious and wish I had a big knob like yours (with a similar bigger shock), it's hard (metaphorically - not the knob, shock maybe harder) that we can't share these thoughts on a motorbike forum....well I can but might get a reputation!

As supplied and fitted I have 8mm static sag and 19mm rider sag. Spring is too stiff me thinks! I'll back off preload and see what I can get to but 40/45mm seems a long way from here!

Paulbrice, you have just shared your knob jokes for the world to see.

In fact the knob in question has a black ribbed end that is slightly too large to turn with contorting ones self when off the bike.

BBB888 Softer spring is the way forward, i think Ghezzi was advertising some that may suit on the other posting. The Stelvio is an 11.kg/mm and we tried some static pillion action today and i think that it will work well

Forks off and going back to k-tech for 9.5N springs. Will get 120N spring for Matris from BikeTorque ordered tomorrow. Then a bit of set up and hopefully I'm there. Personally don't think it's best at 329mm. Think I'll go to midway 334mm and see what that's like when I change the spring.

40/45mm sag. That's nearly 50% of the available travel on a Guzzi.

It's certainly a long way from the 19mm I've got as set up and delivered by Matris!

As a point of reference what is the OEM spring rate on the GRiSO ?

9.6kg/mm

Paul Brice I think you are in touch with BikeTorque re your Matris spring too. I have requested a replacement 120N spring which they now seem hesitant to agree and want to report back to Matris and see what they say. I pointed out that I bought a shock that they declared was bespoke to me and would arrive ore set for simple fitting and no need to adjust anything. Based on my sag measurement it is well outside their recommendeations and a softer spring is required. Will let you know what the response is after they have conversed with Matris. I also mentioned another rider at 78kgs with the same 135N spring as me at 103kgs which seems to contradict the idea that each shock is bespoke to the rider

Me thinks they got a container full of 135N/mm springs they wonna get rid of.

Biketorque tell me: QUOTE Matris feel that the 135nm spring supplied with this shock is the best spring to suit the bike, in this particular application they feel that the rider weight does not warrant changing the spring. Their advice is to use the adjusters on the shock to tailor the ride to suit your own personal preferences UNQUOTE. They also asked if I want to specify & get a different spring rate eg 120 nm; (MATRIS remain with recommended 135nm).

On the basis the Matris feels just like the original SACHS; I'm tempted to go softer spring rate down to 120nm. Plus I'm already over 700 pounds (UK) lighter at this point

Exactly what they said to me! And that they would as a gesture of customer service and good will order a 120Nmm spring if I preferred but only on the understanding that if I was not happy with that then they wouldn't change it again!
Quite p'ssed me off as all I want is the correct spring for my weight and riding style which i thought I had made absolutely clear at the point of placing the order and they agreed! I ordered on the basis that they and Matris know what they are doing! I now have my doubts.....
Quite a contrast to K-tech customer support - I had them revalve and respring my forks (9Nmm), much better creamier ride but a tad too much dive under braking. They were very helpful advised adding two clicks compression and two turns preload which helped but the forks became noticeably stiffer and less comfortable. So they said no problem just return them and we will change for 9.5Nmm springs at no cost. Not only that but they sent their parcelforce booking to collect on Monday pm and called me yesterday to say they had changed the springs reset the preload and damping settings to what they think will be best and they are on the way back to me for delivery to my office today. All at no cost! I cannot recommend them highly enough!
Incidentally Michael in the K-tech workshop told me they can supply springs at whatever rate required (he says the springs are all made by the same factory) so I think I will go with the 120N from Biketorque and if its wrong i will just deal with K-tech and buy any further springs/dampers or suspension components from K-tech as first choice! Looking at their results at the IoM TT I think they know what they are doing!
Incidentally it might be useful to have a survey of what rear spring rate people are using and their weight - something along the lines of:

BBB888 - 103kgs - Matris 46K - 135Nmm

And see what the consensus is out there on spring rate vs rider weight!

Quote Biketorque;

'As I explained yesterday, there is no such thing as ‘fit and forget’ suspension, and we do not advertise this because everyone has their own riding preferences: Valentino Rossi and Maverick Vinales both ride the same Yamaha Moto GP bikes on the same tracks, but I absolutely guarantee you that both bikes will be set up completely differently to each other in order to suit their riding style and preference. This is why the shock absorber has adjusters. Matris have built the shock to suit the bike combined with the information we supplied about your weight and riding, but this can only ever be approximate because every persons riding preference will vary: we are all different.

Talking to Matris about this situation they stick by the spring that they have supplied and suggest that you should use the adjusters to soften the ride. However, in our conversation yesterday you said that you did not want to do that, and you have repeatedly requested a 120nm spring, so as a goodwill gesture in the interest of customer service and to bring this matter to a conclusion I propose that we will purchase a 120nm spring for you and supply it free of charge in exchange for the 135nm spring currently fitted to the shock.

Obviously we will be supplying this spring at your specific request, so it is important that you are certain that this is what you want, as we will not exchange it a second time if you feel that it is then too soft.

I will place the order with Matris and send the spring as soon as it arrives. Once the new spring is fitted, please package the 135nm spring and let me know that it is ready and I will arrange for a courier to collect it from you so that you will not have the cost or inconvenience of having to arrange the return.'

To quote me; 'Arrogant, patronizing tw@t'!I didnt bother pointing out that a GRiSO is some way away from a MotoGP bike and its use is somewhat different - I specifically told him I avoided Motorways whenever reasonably possible and wanted a suspension unit that would work well on the less than perfect surfaces of average UK A and B roads.

Paul, maybe try the old spring 9.5kg/mm with the new shock? At least in the shot term you could solve one of the problems

or

by another spring directly from Matris either a 10.5 kg/mm or 11kg/mm

or

Buy another after market spring, when i was looking the Ohlins springs were £55 plus vat

or

Tell Matris it is not suitable for purchase and you want to send the whole thing back!

BBB888

My weight is 82kg, plus riding gear, Stelvio shock with 11kg/mm standard spring, very happy with it and it allows a pillion too (i had stopped taking my 15 year old daughter). If i wanted to play with springs i would like to try a 10.75kg/mm but in reality i would be nit picking.

Sidrat - thanks.
11kg is 108Nmm, 10.75 would be about 105Nmm.
The 135Nmm supplied on the Matris to myself (103kgs) and Paul Brice (78kgs) is 13.76kg!

I will post on the GuzziTech forum where I think there are lots of peeps with aftermarket shocks - Matris, Wilbers, Ohlins and see if I can find out what weight/spring rate they have. Hopefully a clear picture will emerge!

Good luck. I have to say i am very happy with the change i have made, it is a different and much better motorcycle now

Spring swap sounds good BUT how interchangeable are they in terms of a) just doing it and b) spring length and fittings like the fit to the pre-load adjusters ?

Paul, the only variable would be the outside diameter, the GRiSO uses an unusual size, to be able to fit in the swing arm. I would guess that the OD and ID are the same on both shocks for that reason.

You should be able to measure both and take off the original spring to see how easy it is to do

I had mine set up for nil Sag just to give me more travel.

Matris advised me 40mm - 45mm sag. I am not sure if this is total sag - from full extension bike off the ground to compression with rider static on board or whether it is the rider sag - ie. between normal position bike on the ground with no rider to bike on the ground with rider on board.
I had previously aimed as a general rule to have 10mm bike sag (from unloaded to sat on its wheels on the ground) and 30mm-35mm rider sag (from sat on ground without rider to sat on ground with rider). This would be 40mm to 45mm overall.
K-tech told me over the phone that they think I should have 115Nmm or 120Nmm rear spring.
Someone over on GuzziTech said he was 100kgs and had the same problem with springs and eventually got 9.5Nmm fork and 115Nmm rear shock springs and that was excellent.
Anyway, I am aiming to refit forks on Saturday and then play with the pre-load on the rear to see if I can get anywhere near 45mm sag and see what that rides like.

keep us informed as to how it goes