Join Date: Feb 2017
Thanked 36 Times in 34 Posts
A good starting point for sag is based on a rule of thumb. It is not gospel. As you get faster your sag likely will not look anything like it does now. Racers do not go by sag numbers or every bike would have a book that has numbers for every rider weight. Actually, I bet most racers have no idea what their sag is.
Since you're riding a 675 we can rule out bad suspension (unless it's faulty). Harshness could be old oil, bad setup of rebound and compression and/or sag, bad tires, messed up geometry, etc. Also, remember sag sets a preload on the spring and in turn changes ride height, which is why when you get sag you need to be sure the front and rear of the bike still is within heights that keep the proper geometry. Sometimes you will need to set the fork in the triple to another position to have the correct suspension travel and still have good geometry. Sag(set using spring preload) does not change the spring rate. 0.9 is a 0.9 no matter what the sag is set to.
Sag is set primarily to give you maximum suspension travel. The rule of thumb is usually about 2/3 left of suspension travel when you are sitting on the bike with full gear. Since most sport bikes have about the same length fork travel, the sag number is born.
I suggest you put a ziptie around one of the forks, and if you can, on the shaft of the rear spring. You generally want the fork/spring to compress as much as possible on your hardest braking without bottoming, but getting close. Not panic braking but controlled braking.
Most people setup their bikes way too stiff because that's what most people think high performance means. Hence why so many modified cars have such bad suspension setups, but that's another story for another day.
Also check the rebound and compression of your forks and rear shock. Keep a notebook and write down all settings. Also note how the bike feels and how the tires look. Make one change at a time and note the difference. You will learn pretty quickly how to adjust the suspension based on feel and tire wear.