Rear Shock Advice
Stellar HDF Member
Joined: Feb 2010
Posts: 3,121
Likes: 489
From: sunny florida
Dave as much as it kills me Iwill try one last time in very simple terms to explain this to you . Let's say we have a shock with a 3" stroke , and the bike rides best for us with 1" of sag . We set the bike up this way , the shock still has 3" of stroke however our zero (starting point) that we like is 1" down from top out. If the spring compresses at 100lbs. per inch at our starting point it will now take it 200lbs to move it another inch and so on. If I set the bike up for a 200lb , 225lb & 250lbs rider using the same spring at 1" of sag I'd do this by adding or reducing preload(tightening down on or loosening up the spring tension) to get to zero for each rider. What you are not taking into consideration is to get to my zero starting point when you push down on the spring the spring is under load and pushes back. So for each of the 3 riders the resistance pushing back would be different if they all started at 1" of sag . Once it is set for your weight , weight no longer plays a effect in moving the shock , it is now a combination of your weight and energy from you going over bumps or hitting holes. So in this illustration if the 200lb rider rode the bike set up for the 250lb rider he wouldn't have his 1" of sag and it would take more energy to compress the shock and it would rebound quicker , likewise if he was riding it set up for himself by adding or reducing preload it will now take more or less energy to compress the shock and it will like wise rebound faster or slower . This spring is not stiffer or softer it is working at the rate of the spring , however your shock will be firmer or softer depending on the adjustment.
Stellar HDF Member
Joined: Dec 2005
Posts: 2,598
Likes: 52
From: South Jersey
Does it make any difference if the shocks are set up upside down like my Revo's? The oil portion (cylinder) of my shocks is on the bottom. Also I have a dampening **** with increments from 1 to 6. I was told by the manufacturer that the lower the number makes it rebound faster with #6 being the slowest. How should I play around with the dampening adjustment? I have tried them all but wasn't able to tell dramatic difference between them.
Stellar HDF Member
Joined: Feb 2010
Posts: 3,121
Likes: 489
From: sunny florida
I don't know if putting them upside down will effect them , on shocks I am familiar with it would not effect them , what the damping adjustment does is it opens or closes a needle valve that causes either more oil or less oil to go through and not by pass your shem stack which will stiffen the shock and slow or speed up the rebound
Stellar HDF Member
Joined: Dec 2005
Posts: 2,598
Likes: 52
From: South Jersey
I don't know if putting them upside down will effect them , on shocks I am familiar with it would not effect them , what the damping adjustment does is it opens or closes a needle valve that causes either more oil or less oil to go through and not by pass your shem stack which will stiffen the shock and slow or speed up the rebound
Stellar HDF Member
Joined: Feb 2010
Posts: 3,121
Likes: 489
From: sunny florida
Closing the needle valve forces more oil through the shim stack , opening it lets oil by pass the shim stack , so when it is closed and more oil goes through the shim stack this creates resistance which will stiffen the shock Edit : so opening it will let oil by pass the shim stack and soften the shock
Last edited by tj316; Feb 27, 2016 at 05:07 PM.
Dave as much as it kills me Iwill try one last time in very simple terms to explain this to you . Let's say we have a shock with a 3" stroke , and the bike rides best for us with 1" of sag . We set the bike up this way , the shock still has 3" of stroke however our zero (starting point) that we like is 1" down from top out. If the spring compresses at 100lbs. per inch at our starting point it will now take it 200lbs to move it another inch and so on. If I set the bike up for a 200lb , 225lb & 250lbs rider using the same spring at 1" of sag I'd do this by adding or reducing preload(tightening down on or loosening up the spring tension) to get to zero for each rider. What you are not taking into consideration is to get to my zero starting point when you push down on the spring the spring is under load and pushes back. So for each of the 3 riders the resistance pushing back would be different if they all started at 1" of sag . Once it is set for your weight , weight no longer plays a effect in moving the shock , it is now a combination of your weight and energy from you going over bumps or hitting holes. So in this illustration if the 200lb rider rode the bike set up for the 250lb rider he wouldn't have his 1" of sag and it would take more energy to compress the shock and it would rebound quicker , likewise if he was riding it set up for himself by adding or reducing preload it will now take more or less energy to compress the shock and it will like wise rebound faster or slower . This spring is not stiffer or softer it is working at the rate of the spring , however your shock will be firmer or softer depending on the adjustment.
Stellar HDF Member
Joined: Dec 2005
Posts: 2,598
Likes: 52
From: South Jersey
I don't know if putting them upside down will effect them , on shocks I am familiar with it would not effect them , what the damping adjustment does is it opens or closes a needle valve that causes either more oil or less oil to go through and not by pass your shem stack which will stiffen the shock and slow or speed up the rebound
Road Captain
Joined: Aug 2015
Posts: 578
Likes: 522
From: Durango CO
Lower numbers allow more oil to flow causing it to rebound faster.
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Intermediate
Joined: Aug 2010
Posts: 39
Likes: 2
From: Mid-Atlantic
I've got the JRI 13" shocks, I love them! But, I'll say they came with about a 10 page manual on how to set the "SAG"!! I read it, set the bike up as per directions, measured it, re-read the manual, re-measured it and so on until the lightbulb finally "clicked on"
Figured out how to fine tune them after my break in rides over the next month, and that was at least year ago....dun forget all of how it works, but still have the directions! Sometimes you just have to play with it until it makes sense
Figured out how to fine tune them after my break in rides over the next month, and that was at least year ago....dun forget all of how it works, but still have the directions! Sometimes you just have to play with it until it makes sense
Stellar HDF Member
Joined: Dec 2005
Posts: 2,598
Likes: 52
From: South Jersey
Is that a correct understanding?