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Hogarthd
07-17-2009, 07:12 PM
OK, I'm not a motorcycle expert by any means. My 2007 Tuono is my fourth bike if I'm counting my wife's Monster that I ride occasionally (and was purchased in my name!). I've been reading the Andrew Trevitt "Sportbike Suspension Tuning" b/c I feel that the Tuono's suspension is really REALLY stiff for me when commuting around and going on weekend joyrides, which is what I do on it 95% of the time. Here's my question:

Trevitt suggests 30-35mm of rider sag on the forks or even MORE for street riding. My initial measurement w/stock preload was 11mm. I cranked the preload adjusters all the way out to their stops and I'm at about 15mm right now. I haven't measured the rear yet b/c I need my wife's help, but it seems slightly better at default settings anyhow. Do I need new springs? Am I interpreting something wrong on the 30-35mm rider sag? Is it insane to have the preloads cranked all the way out in front? Also, for the rear, that locking collar is so tight that tapping on it with a screwdriver/hammer doesn't really budge it...I'm guessing I need the thing up on a rear stand to work the rear preload...I can't believe the T doesn't come with the rear C-wrench...my old SV650 even had one of those. The T toolkit is a cruel joke.

Also, the bike is for sale if anyone's interested - beautiful, black 2007 w/6300 miles and Akrapovics on it. $9K. I hope nobody wants it :(

thanks!

Hoagy

Biker_911
07-18-2009, 09:40 AM
You're probably measuring sag incorrectly. You need to measure the suspension fully extended with no weight on it. I did it by tilting the bike over on the sidestand with the front wheel in the air and getting the wife to measure for me. Then you need to put on your riding gear and take a measurement with you sitting on the bike. I did this by balancing the bike with my hand on the workbench. The difference in these 2 measurements is the sag measurement you're looking for.

rmcobb
07-18-2009, 10:22 AM
. I did this by balancing the bike with my hand on the workbench. The difference in these 2 measurements is the sag measurement you're looking for.

You really need 2 people to do it accurately, or at least some way to hold the bike up while you assume a normal riding position, providing you have a way to then get the measurement you need. By placing your hand on the workbench, you didn't get the actual load on the front forks as you would see in your normal riding position.

adyche
08-03-2009, 03:35 PM
Just playing with the sag on my 2007 R. I'm on the lighter range 75kg (170lb) so found the standard setting with 5 rings showing didn't give much sag so adjusted to 7 rings showing but doesn't seem to make a lot of difference maybe just under 30mm dynamic (from lifting front to load with rider). Tried my mates whos a bit porkier with 4 rings showing and that was about 25mm sag.

Wondered if anyone knew the relationship between rings showing to change in front sag.

Conversely the rear standard setting with 15mm of thread showing on the preload gave a bit much sag at 40mm. Confusing. I bought it used so wondered if it had stiffer fork springs or something.

I must say I think the handlings fine so maybe shouldn't bother but if there's something to fiddle with...

I assume all getting the right sag is about is setting the bike attitude right and putting the suspension in the optimum position of the travel for damping etc.

Alan.

Falco9
08-04-2009, 02:43 AM
Just playing with the sag on my 2007 R. I'm on the lighter range 75kg (170lb) so found the standard setting with 5 rings showing didn't give much sag so adjusted to 7 rings showing but doesn't seem to make a lot of difference maybe just under 30mm dynamic (from lifting front to load with rider). Tried my mates whos a bit porkier with 4 rings showing and that was about 25mm sag.

Wondered if anyone knew the relationship between rings showing to change in front sag.

Conversely the rear standard setting with 15mm of thread showing on the preload gave a bit much sag at 40mm. Confusing. I bought it used so wondered if it had stiffer fork springs or something.

I must say I think the handlings fine so maybe shouldn't bother but if there's something to fiddle with...

I assume all getting the right sag is about is setting the bike attitude right and putting the suspension in the optimum position of the travel for damping etc.

Alan.

There is no direct relationship between rings showing and sag as we are all a different weight. Obviously the less rings showing equates to more pre-load having been applied. You are spot on about why to do it though. Setting the static sag gives you a base point from which to tune your suspension to suit your riding style. Whats suits one of us wont suit another, we all ride differently and want different things from our suspension.

Without doubt setting your static sag is the best thing you can do to improve your bike for free.

Here is the Ohlins recommended way of measuring your static sag. With 2 of you it takes about 5 - 10 mins to do max

Measuring:
Preload on the spring/springs is very important,
because it affects the height of the motorcycle
and the fork angle. Consequently, handling characteristics
can be changed, even negatively.
Proceed as follows (it will be much easier if done
by two persons):
A Place the motorcycle on a stand.
B Lift up the rear end to a fully extended
position.
C Measure the distance, eg, from the
lower edge of the rear mud guard or
from a point marked by a piece of
tape, immediately above the rear wheel
axle, to the wheel axle. (R1)
D Make a similar measurement on the front
axle, e.g., from the bottom of the upper
fork crown to the front wheel axle.
The fork must also be fully extended. (F1)
E Allow the motorcycle (without rider) to
apply load on the springs and repeat
the measuring procedure. (R2, F2)
F Then take the same measurements
with the rider and equipment on the
motorcycle. It is important that the
rider has a correct riding posture,
so that the weight is balanced on the
front and rear wheel in the same way
as when riding. (R3, F3)
The measurements may not differ from the
following sizes:
Without rider:
Rear: 5-10 mm (R1-R2)
Front: 25-30 mm (F1-F2)
With rider:
Rear: 30-40 mm (R1-R3)
Front: 35-48 mm (F1-F3

Hope this helps

F9

adyche
08-04-2009, 08:11 AM
I appreciate weight affects sag and assume springs are non linear (?) but there could be a simple relationship between amount of change of preload distance to sag difference for the same weight of rider. I assume the front preload screw acts directly on the spring so all your doing screwing it out for example is altering the starting point upwards (unloaded) relative to the 'ground'. When you load the bike by its own weight and sitting on it you must compress the top of the spring to the same final position relative to the 'ground'. All you are doing is changing where the top of the spring is relative to the 'frame'. Assuming the forks are about vertical and no weight is transfered front to rear during the changes etc etc then the amount screwed out should be approximately the amount of sag added.

In my case if the above is true I need to screw out another 2 lines to 9 showing (!) if possible to get 35mm front sag. The screw won't be far of the handlebars !
Got the rear down to about 30mm sag by winding on about 5mm on the screw thread - guess the relationship is more complicated due to the spring acting near the swinging arm pivot - a lever effect. Think I'll go for a ride when it stops raining before more alterations !

Alan.

kzmille
08-04-2009, 09:03 AM
You are really over thinking it. Just turn the adjuster till you get the correct sag. If you can't get the correct sag with the range of adjustment available, you need different springs.

adyche
08-04-2009, 11:23 AM
You are really over thinking it. Just turn the adjuster till you get the correct sag. If you can't get the correct sag with the range of adjustment available, you need different springs.

You're right of course - just like to understand what's going on and can't always find someone willing to measure for me at short notice so getting it nearer theoretically could save multi adjustments !
Wouldn't seem logical to need different springs for my weight.
Its getting harder to get a spanner under the handlebars though & seems a bit of bother to move them to do adjustments.

A

wsmc99
08-08-2009, 12:43 AM
you are really over thinking it. Just turn the adjuster till you get the correct sag. If you can't get the correct sag with the range of adjustment available, you need different springs.

bingo!