Suspension Tech Thread

Joely Boy

Joely Boy

Hey guys, just wanted to get some opinion and feedback on what suspension settings we are running. At the moment I'm only using stock internals.

With what I've been reading on sag I have heard some conflicting info, for example before, as a general rule of thumb I would have worked with between (for front) 20mm - 25mm track and 25mm - 30mm street. Then for the rear would have been 25mm - 30mm track and 30mm - 35mm street.

But I have recently bought some DVDs by Dave Moss (Catalyst reaction) and a book called "sportsbike suspension tuning" by Andrew Trevitt where both are basically promoting the use of more sag in the front as opposed to the rear. One of the reasons stated was that alot of modern bikes are now fitted with "top out" springs or more sag (in the front) in an effort to keep the front wheel on the road especially when exiting corners.
Dave moss states between 38 - 50mm front with 38mm rear for street and 32mm front with 28mm rear for track (ballpark)

I was running about 32mm front and 38mm rear but have picked it up to 27mm front and 33mm rear just for experimenting but am not happy with the feel or the lack of fork travel now so will be doing some more testing.

Later when I'm happy with my sag settings (I might even find out that it was good where I had it) I wouldn't mind finding out what rebound and compression settings others like and anything else like fork tube height, ride height etc and yes I know that weight/tyres/wheelbase/riding style/ etc all make a difference but it can't hurt to throw it around and hopefully some of us might learn a thing or two along the way ..
Joely Boy

Joely Boy

Just had my 07Sd measured on a G.M.G. computrack. to find out the real geometry numbers.

Rake=23.8 degrees
Trail=97 mm
Offset=28 mm
Swingarm angle 7.8 degrees

All measurements taken with bridgestone bt016 tyres
forks even with top of triple clamp.
rear free sag 10mm ,front free sag 21mm

These rake and trail are pretty aggressive, but the swingarm is kind flat.
maybe that's why KTM didn't put a ride height adjuster on the shock. Jacking up the rear to get a good swingarm angle ( around 12 degrees) would change the trail to around 95 mm and be scary at high speed (imho)

It's also important to check to free sag numbers. along with rider sag numbers to see if you have the proper spring rates.

FWIW. my weight is 205 pounds, and my current set up is

Shock 10mm free sag 35 rider, 17.9 nm spring
Fork 21 mm free sag. 37 rider sag. one fork leg 9.5nm the other 9.0nm springs

The forks and shock have been re-valved (less high speed comp. damping) same rebound damping as stock, with a slight increase of mid valve damping, ( helps with pitch control front to back).
For me the suspension is perfect on track, and not too harsh on normal roads and freeways.

My damping adjuster are; fork Comp. 15 out, rebound 3 out.
Shock L/S Comp. 18 out. H/S Comp 2 turns out. rebound 9 out.

HTH Regards . Tim