Rear Spring Preload/Sag issue (Wilbers)

Thanks. Contradicts what I had always thought as well but I'll do as Matris suggest to see if that makes the 135N spring more compliant before I swap it out for 115N or 120N.
Matris did not come with c-spanner to suit which surprised me for a shock costing over 700 of our British pounds. I have a couple from previous bikes but not sure they'll fit the Matris diameter. Anyway will get busy with adjustment at the weekend and report back

Hey Brendan, I just ordered 115nm spring but will be september before they get it due to italian holiday period, Adam told me it's relatively easy to change the spring with a suitable compression tool (which I don't have at moment - will get them to do it); but at least means there are other options if our second choice spring doesn't work out. I'm now convinced having tried all combos that the spring rate is too high and means I need to back off pre-load to almost top of shock to get even close to 35-40mm SAG; and even then the suspension is way too hard - so softer spring should put preload and sag in right range


Also, inspired by Keiths Stelvio shocking experience I upped the length by 15mm to see if that improved anything in the dumbbell ratio side. Apart from looking cool, more clearance and dodgy sidestand; the handling on flat out didn't improve especially steering on high speed bends, and somehow it made my knees sit in a different position that felt odd.

Let us know how you get on

I just got my replacement 125N/mm Matris spring this week and will put it on this weekend - took 3 weeks or less from when I ordered. Came in black.

The vehicle spring compressors are too big for this so ratchet strap method coming up.

paulbrice wrote:

Also, inspired by Keiths Stelvio shocking experience I upped the length by 15mm to see if that improved anything in the dumbbell ratio side. Apart from looking cool, more clearance and dodgy sidestand; the handling on flat out didn't improve especially steering on high speed bends, and somehow it made my knees sit in a different position that felt odd.  

Let us know how you get on

Paul, 15mm increase is a lot, the selvio spring is only 10mm, giving about 25mm at the saddle. Have you read my update to this?

Yes, just went the full banana to see what it could do for suspension...I'll back it down to almost as delivered because the handling & balance is perfect there

Well I have backed my preload off 4 turns which I think equates to 4mm on the basis of thinking 3:1 ratio will give me 12mm more sag, at least that's my theory. Now off on hols so haven't even managed to remessure but have left the locking ring up at the top of the shock and will try to adjust as necessary to get 40/45mm sag when I get back. BikeTorque also suggested winding out comp and rebound damping as recommended by Matris. Can't remember the exact no of clicks they suggest but have their email, but again will do it when I get back. If that does the trick all well and good, although my instinct is that I will need the softer spring - about 120Nm I think for 103kg.....will see how it goes and let you all know!

Update - I have struggled to get the Matris set up and despite backing off preload, adjusting sag to meet recommendations by Matris, changing damping to Matris suggested settings and then to their updated recommendations I simply couldn't get the rear to work and it was way too hard. Bike Torque (Matris agent UK) have been excellent and in fact offered to refund the price paid for the Matris shock if I returned it which I have now done - my view being that the shock is mis-described as 'bespoke' to each individual as both my shock (100kgs) and Paul Brice's shock (74kgs) arrived with the same spring rate and settings.
So I have now visited MCT Suspension in Stowmarket and had a Wilbers rear fitted and a front and rear set up. The bike is utterly transformed. Creamy ride, firm but compliant and far far easier to change direction side to side. What was also interesting is that I had the forks done some months ago by K-tech who fitted 9kg springs, which seeemed to almost bottom out under an emergency stop 9and probably woudl bottom out under a real emergency stop) so swapped them out for 9.5kg springs, and with a thin tie-wrap could see that the travel was about 95-98% with just a couple of mms before it would bottom out when I tested braking from high speed. Felt stiff too but planted. MCT adjusted and set up with 100mm air gap (k-tech setting was 140mm air gap) and backed rebound out to zero (!) - never thought that would work. But its superb, and the travel now has 1 - 1.25" free whilst also feeling far more compliant and comfortable - no idea why less travel should feel far more complaint and comfortable but it does! Total cost - £168 and I think is the best £168 I have yet spent on a motorcycle! I highly recommend MCT to anyone in the UK looking to get their suspension set up, but book early he told me he only has a couple of slots left in August and is now taking bookings for September......well worth it!
Lovely test route too - left out of workshop, right at mini roundabout and then 'Laguna Seca' through the Suffolk countryside!
Incidentally for shock removal he jacks up at the exhaust junction underneath and just ahead of the swingarm, long socket in to undo top and then the bottom and out comes the shock - took 10 mins if that! New shock goes in and small adjustment on jack to line up linkage and bingo all back together in 10 mins too!

Fantastic you finally got sorted Brendan; sounds like you've found the right set up and a decent supplier !......I'm still on the Matris (118 nm spring) and happy with (what I thought were - see later) relatively soft settings front & back - only long high speed corners with rolling dips gives slight too much suspension; all the rest kills road bumps but still firm.

Only odd thing I'm still trying to understand is that although I think and feel like front end is soft and yielding, when i saw everyone else's set up in Brecons last week; I'm running more preload than any but still getting loads of travel & handling short hard bumps at low speed etc....Not sure if it's because I'm running with very low compression damping or if the minor change in cartridge last time I had forks serviced is changing the behaviour

I’ll post my settings later, but forks are set with wide open zero rebound damping. I guess they have enough in built damping and don’t need any more.
K-tech fitted 9.5 springs and 140mm air gap. MCT have reduced to 100mm air gap - have added 40 MM oil.
What surprised me is that my previous travel was all but the last 2mm or so on the forks but now has around 25/30m[You must be registered and logged in to see this image.]
m travel remaining but feels way way more compliant and comfortable. It’s a dark art methinks. Darren at MCT did say ‘you have to understand it’ to be able to set it up correctly!

Post above should read k-tech, 140mm air gap, and 25mm - 30mm fork travel remaining under hard braking.
Will post details from my desk tomorrow. Bike is transformed. Darren at MCT said he could reengineer original rear shock for about £150 which would be huge improvement too, and he can rework forks to improve further but the law of diminishing returns applies - small further improvement at more cost so suggested I stick with what I have for now. Wilburs was £200 more than Matris but to me feels way way better. Darren charged £168 inc VAT and was about 1hr 20 mins in workshop then a test ride then hand over for me to test. Highly recommended