Thought I should update the thread with some new info.
Bought myself some new springs and fitted them yesterday. I went for Öhlins springs (of course) with a spring rate of 9N/mm. These springs have exactly the same diameter as original and are 299mm long.
http://ohlins.com/Our-products/Motorcycle/Products/Hypersport/08713-90/
I started checking the spring rate on the new Öhlins springs, mostley to validate my method of measuring the rate on the original springs.
Weight/displacement
10kg / 11 mm => 0.91 kgf/mm (8.9 N/mm)
20kg / 23 mm => 0.87 kgf/mm (8.5 N/mm)
Given my measuring method using a ruler I think the results shows my previous measurings are reasonable.
After installing the springs I started looking at static sag and preload settings.
No preload:
Free sag - 15.9 mm
Ride height - 31.3 mm
3 "rings" preload (should be the same on both the tyga preload adjusters and original):
Free sag - 11.6 mm
Ride height - 26.5 mm
6 "rings" preload:
Free sag - 6.4 mm
Ride height - 20.7 mm
I ever felt the need to measure the sag with full preload setting.
The sag measurements were done by using cable ties on the fork leg and measuring the position after both compressing the fork and after rebound, then using the mean value of those two.
Next step will be to look at the rear suspension, raise/lower the front/rear, oil level in the forks, rebound dampening and least compression dampening settings.
I will take the bike to a track next weekend, and perhaps let you all know how the new setup felt after that. Until then I have some more work do to.
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MC21, GP-Replica (Daijiro Kato, Telefonica Movistar Team 2001)