I have the 2009 Honda CBR 600RR and setting it up for a dedicated track bike. I have done the fork internals, spring, valves, fluid and new seals and all cleaning and what not... Now for the rear shock im having a slight issue after the new spring was put on. I went with a very basic set up on the rear by just changing the spring and filling it with more nitrogen. I will replace the fluid and valving bit down the line... The OEM spring rate is 11.0kg and I need a 9.174kg spring rate "RACE TECH CALCULATION" But after the spring was installed it seems to be to wide to clear and fit through the swing arm. I measured OEM and NEW spring and they are 10mm size difference in width. "obviously thats the problem" But can anyone recommend a spring with my needed spring rate and sized properly to fit and clear the swing arm space to be installed? I take a guess that 07/08 differs in size of spring then the 09-12... ANYONE?
Why would Showa use X spring rate? Why WP Y rate? Why Penske Z rate? And Ohlin's another again? Therein lies the stupidity of any spring calculator basically...
I think with some shock brands you might use a 9.2 kg/f (90N) rate, if you were really light - most of this being empirical for me, as I am light!
Both the Blade & the 600 use heavier than a lot of after-market brands; but this is for their shock design. Not them getting it wrong, as such. Which is to say, change brands, or more to the point, fluid control from design architecture/theory, and the spring's rate cannot be the same - this has been the whole point of the last 35 years of shock changes - internal features - , and now entire ideas have been swapped about and actually come a full circle if we want to include 1960's F1 shocks in this!
So no, I do not subscribe to calculators. A waste of prerequisite knowledge.
Not my 07, it has a 91 N/mm (measured) spring on stock shock.
Racetech calc says it's perfect for me. Penske recommends 625lbs/inch (~110N/mm). K-Tech says 100N/mm. Öhlins comes with 95N/mm on it.
So yeah, racetech is not the only truth out there.
...a while back the Penske's were being delivered with 650's too; even ran 700's on some! As to your OEM spring, don't forget the coils are not striaght up from the base, so by nature it is progressive to some extent too. But the whole reason spring rates on same model bike are different is not lost on everyone right?