I know where the companies are, i was enquiring specifically about the rear spring. reason being, at jhp yesterday john said i needed to fit a rear spring of 7.5. this has i believe 75 on it. Well i have one of these, if its the one i can save myself £50+.
Andy b - not sure of your experience so I may be teaching granny to suck eggs etc....but Take care with advice from others. Make sure you set the bike up the way it suits you - Not John Hacket or the way neil Hodge has his set-up.
I fitted a heavier spring on Johns recomendation....less preload tension on a heavier spring is supposed to giving a more progressive ride response and better adjustability.
I hated the choppy ride, I spent months trying diferent adjustments with preload, rebound and compression. Eventually I went back to the standard spring.
Its a bit like the front steering head angle - some people will say ohh no leave it alone - nobody races with the steeper head adjustment. I love it, quicker turning without the rear of the bike high in the air gives me the confidence I need to get the power down early without the fear of highsiding.
My rear Ohlins has a 6.4Kg/mm spring fitted to it. My unit is off of a SPS and therefore meant for solo riding. Suits me on the race track with my 11 1/2 stone weight. If using a longer arm you will need a stiffer spring, if your using mag wheels you could get away with a lighter spring. Speeds envolved and types of surface will also help determine spring rating, as will the amount of available shock travel.