Setting sag with progressive springs...Help!

I know, I know, get rid of the progressive springs. I’m trying to convince my friends to do so. But until I do… I need some help.

Each time I help set their sag we get very strange numbers. :eek: The bikes are a ’00 KX125 (rear progressive) and a ’99 KX250 (now only the rear is progressive). Here’s the problem:

’00 KX125
Set sag for the intended 95-100mm race sag, but can only get 93mm max. Free sag remains in the 45-55mm range no matter what. His weight is 155 lbs. and it’s the stock 4.6 progressive rear spring. Recommended spring rate is 4.52.

’99 KX250
Set sag for the intended 95-100mm race sag. We get to 100mm just fine; however, the free sag is 50mm. If we dial in additional pre-load the numbers are 90-95 mm race and 30-40mm free sag. His weight is 130 lbs. and he changed the spring to a stock 4.6 progressive rear spring from a ’98 KX125. Recommended spring rate is 4.56.

Is this an inherent problem with progressive springs? When setting sag with progressives do you ignore the free sag setting and shoot for your race sag setting? Neither rider complains about stiffness now, although the rider with the KX250 did complain when he had the stock 4.8 installed.

Any help with the setups and understanding of progressive spring is appreciated.

Thanks,
Scott

No more progressives

Marcus,
Thanks. How do you know if you have the correct springs when using progessives, other than using a chart? I'm with you, I hope they'll go to straight rates soon.

Thanks Again,
Scott