Re: OEM vs RT data
Thought I'd add to this a little.
Finally checked the sag on the front and rear suspension right before removing the stock forks and replacing them. Sag is a simple measurement of suspension fully extended vs the suspension at its average height after being settled from both an extended position and a compression return. You average the 2 numbers it settled at to remove stiction which is the drag of all of the components. Sag = "difference from fully extended" - "average settled height".
Anyway my 08 with 8k miles on it came in like this with me at 188lbs w/out gear:
Front sag = 43mm (compresses 1.7" from me sitting on it)
Rear sag = 29mm (compresses 1.1" from me sitting on it)
R6 forks installed:
Front sag = 31mm and adjustable +/-20mm
Rear sag 29mm
Several articles say that 25 to 35mm is good for the street while racing applications head closer to 20 to 25mm. So this is my starting point for this season and to be adjusted as needed. . .
As you can see the stock front springs are dropping a good deal just from me sitting on it and its soft progressive rates compress easily hence the higher numeric stag# in the front. Having it closer to matching (31) should make it take bumps and surface imperfections in the corners much better if both ends of the bike have closer to the same sag and spring rates.
A 2004 R6 was the doner bike with 3400 miles on it. The rates for the front are:
Spring rate K1: ___________8.3 N/mm (0.83 kg/mm, 46.49 lb/in)
vrs stock FZ6 dual rate of:
Spring rate K1: __________7.40 N/mm (42.25 lb/in) (0.75 kgf/mm)
Spring rate K2: __________11.80 N/mm (67.38 lb/in) (1.20 kgf/mm)
What does all this mean: The FZ has 5.1" of travel. The second rate comes into play near the end of those 5" when the nose is diving hard under braking (1.20 kgf/mm). Granted many are buying Race Tech Springs to firm things up and most are opting for 0.95kg/mm. But as most of you know the stock FZ springs use up a good 3.5" of travel over minor bumps and braking.
I know I may end up swapping springs but these forks make it easy to dial in the sag as well as adjust both compression dampening and rebound dampening. Time will tell where we land with the springs. . . How will this impact cornering; with less initial rake from the nose being higher it will change how it feels. However, these forks are a 1/2" shorter 12.5mm. SOoooooooo, if you were to look at the sag vrs ride height -the numbers really come back to the same numbers in terms of rake or angle on the nose because the relationship of the steering head to the axle is very near the same as it was with the softer springs (@43mm) vs 31mm (& shorter forks 12.5mm). Make sense?
Edit: hey if you don't want to swap parts but want to help the bikes nose, at least add some new spacers to the front springs to fix the sag so you can ride safer. . .