I have 412s on my Sportster. They are set at the least amount of preload. They have the standard springs in them. I am 180 lbs. The first few bumps are absorbed, but after that the shocks are stiff and do not seem to give any. Any ideas? Thanks.

 

If that was the normal behaviour I'm pretty sure no one would buy them.

 

Try adjusting your preload to another setting and see if it still happens. Could be any number of reasons thats happening

 

My guess is you have them completely bottomed out...
You need the Heavy Duty ones espesially if you have the Preload set so low.

 

I have the HD 412's on my 1200L never had that problem I suggest you contact Progressive customer service for help/advise

 

I'm 210 and the preload is on the 2nd to highest (412's 11 1/2 inches). Move it up a notch.

 

The damping and spring rate can not change from one bump to the next, so the sensation you are feeling is likely bottoming out (shock uses up all of the available travel). Add preload to both shocks (one setting at a time) and test ride.

Assuming you are not hauling a passenger the standard rate spring is correct for your weight. Althought you did not give us shock length, please keep in mind shorter shocks will never supply the ride quality that a taller shock will.

 

Progressive has several spring choices,,3 or 4 I think,,

The condition you speak of sounds like "Shock Packing"
A shock that Is compressed fully that has a spring that Is NOT strong
enough to rebound quickly enough to reset In time for the next bump.

It's acting like It has too much rebound damping. This makes a shock "Pack"
As In remain lower after each bump when they come very rapidly.

If more preload does not correct this a Stronger spring will.

NOTE: You must set proper rider "Sag" first with the springs you have
to know what you need.
Know how ?
Jack the bikes rear, tire hanging.
Measure shock length fully extended.
Set Her down.
Get a LARGE freind,,and a third to measure.
Squat the bike,,bottom It out and measure shock Length.
The Difference Is Total travel.

Break out the calculator,,It's math time.

You get yer riding gear on and have a buddy straddle
the front and hold the bike level.

Sit the bike feet and kick stand up.

This shock compression Is "Rider Sag".
It should be between 1/4 and 1/3 TOTAL travel.

Adjust preload accordingly and go ride It,,
Not around the block,,go do 5 miles.
If you still experience Shock pack you need a stronger spring.

If you have 75/110 rate springs you may need 90/125 for Instance.
(No Idea If Those Numbers are correct) Just an example.
Just going heavy duty may be too stiff.

Call Progressive,,they will fix you right up.
Them's Is good people XD

FYI the Shorter the shock the stiffer the spring all things being equal.