progressive fork spring spacers

[flavor]

In looking at different blogs and help sites on length of spacers for changing stock to progressive fork springs. There seems to be a disparity in what the length that the spacers should be. Anyone have a definite answer on what length is correct.

[andyvh1959]

The length of fork spring spacers is not absolute for all riders and bikes. Its more a factor of how much "sag" is determined when you sit on the bike in its loaded condition. The process is done with the bike upright in unloaded and loaded conditions:
1. Lift the bike on a stand such that the front forks fully relax/extend. Measure from the front axle centerline to a fixed point on the forks, such as the bottom of the lower fork triple clamp. This distance is the Unloaded Fork setting
2. Prop the bike upright on the floor (however you do that) and measure that same distance. This is the Sag for the bike weight, or unloaded condition. In some cases it helps to lift up on the front a few times and let the fork settle to the bike load condition.
3. With the bike propped up, sit on the bike in your typical riding gear. May have to stand/bounce the suspension a few times to get the compressed loading.
4. Have a helper measure from the front axle centerline to that same point on the front fork. This is your Loaded Fork Setting
5. The difference in the Unloaded Fork Setting and the Loaded Fork Setting is the loaded condition, or sag.

In general the sag should be about 1/2". If your sag condition is greater, select a spacer length based on the spring rate. For instance, if your spring rate is 225 lb/inch, a 1/2" spacer creates a 112.5 lb preload, a 1" spacer creates a 225 lb preload. This sounds cumbersome, but it is the method used by Progressvie, Rach Tech and others to determine the fork preload condition.

Or, just use a 1" spacer and see how it feels. Then adjust to a shorter spacer if it feels a bit still, or a longer spacer if it seems to have little effect. Or, contact Progressive tech support for their input.

[flavor]

Thanks for the help.........as always

[andyvh1959]

Back in the 70's a common fork spacer technique was to use old air cooled Volkswagon Beetle valve springs as preload spacers. They are stiff enough to add preload, but still compress at higher loads such as big bumps and heavy braking.

[ldhthept]

Look at direction for Progressive spring install.

[Chuck A.]

Being of larger size frame I put 1 inch spacers in but believe a 1 1/4 would have still worked great. I ride the ruffer secondary roads most of the time.