Hyperpro replacement springs
 

I've just had the fork and shock oil changed on my f4i, but I think the springs are worn out because I'm having trouble setting the sag and preload. My mechanic suggested I replace the springs.

Has anyone had any experiences with the hyperpro progressive springs?

Go to RaceTech site. You can type in your weight and it will give you a suggested spring rate. Straight rate springs is what I've always been told or read about, to use for more consistent & predictable handling. There was a Penske shock on ebay for the F4i, which would make a world of difference, for the better of course.

Springs don't wear out. If you could set correct sag before, you can again if its put back together properly. If you could never set sag to being with, then yes springs are the correct step to take. Normally requires a valving change too though, would have been better to do while the suspension was apart already. I agree progessive springs are not the way to go, solid rate springs are a better choice.

Yeah, they do.