i would imagine that 15mm rear would be your static sag there getting at. (i use 12mm static sag), ie. when the bike is taken off its weight. rider sag is with you sat on it and should be around 25-30 for road riding ( depending on preference), i set mine up for 18-19mm, but i use slicks which give more grip and work the suspension harder.
setting up the sag is the first and most important part of your suspension setup.
some guides are a pain in the ass, sometimes you just need to work it out yourself and set the bike bit by bit. if you do, alway always write down what the setting was and what its been adjusted to.
im still learning now, it takes ages to grasp it, obviously racing and my sponsor have helped me, and i dont mind passing my little knowledge on to help others on here, wether it be during meets or the trackday, just pm me.
Rear shock adjustment
Moderator: Staff
You have three basic adjustments on most modern sportsbikes:
Preload: This is how much you srping is compressed at a standstill. this is the spanner adjustment on the top of your forks (you measure it by counting the rings you see). on the rear shock this is the big metal collar on the top of your shock. You should set the preload to give the correct static sag - this is how much he bike sags from when the suspension is fully extended (i.e wheel of the ground), to when te bike is supporting its own weight, and then finally to when its supporting your weight (u sat on the bike in full kit).
Compression: as well as the spring suspension relies heavily on the flow of oil through valves within shork absorbers (and bike forks). Compression is obviously the adjustment that controls how quickly you allow your suspension to compress this adjustment is normally the screwdriver adjustment at the bottom of the forks and at the top of the shock at the back. To set up the correct compression at the front should increase the compression until you begin to get a judder on the brakes going into a bend, you should then decrease the compression just enough to get rid of the judder. At the rear you should increase the compression to prevent the vehicle squatting under accelleration.
Rebound - this controls how quickly you allow your suspension to extend after compression this is adjusted using the screwdriver adjustment on the top of the forks and on the bottom of the rear shock . If this is set to soft then the power of your spring will cause the shock to extent to quickly after being compressed so when u hit a bump or worse release the brakes after heavy braking going into a bend the vehicle will start to become unstable /bounce around. However if this is set too hard you will find that your spring can't recover quickly enough and so your tyres will skip over bumpy surfaces.
with compression and rebound adjustments you will hear and feel the screw click as you turn it. You should screw it all the way in and then count the clicks out to set it - so if the manufacturers setting say rebound 4 you would screw it all the way in and count 4 clicks out. You should only adjust one thing at a time when adjusting suspension and after each adjustment go for a ride an see how it feels before making another change.
Preload: This is how much you srping is compressed at a standstill. this is the spanner adjustment on the top of your forks (you measure it by counting the rings you see). on the rear shock this is the big metal collar on the top of your shock. You should set the preload to give the correct static sag - this is how much he bike sags from when the suspension is fully extended (i.e wheel of the ground), to when te bike is supporting its own weight, and then finally to when its supporting your weight (u sat on the bike in full kit).
Compression: as well as the spring suspension relies heavily on the flow of oil through valves within shork absorbers (and bike forks). Compression is obviously the adjustment that controls how quickly you allow your suspension to compress this adjustment is normally the screwdriver adjustment at the bottom of the forks and at the top of the shock at the back. To set up the correct compression at the front should increase the compression until you begin to get a judder on the brakes going into a bend, you should then decrease the compression just enough to get rid of the judder. At the rear you should increase the compression to prevent the vehicle squatting under accelleration.
Rebound - this controls how quickly you allow your suspension to extend after compression this is adjusted using the screwdriver adjustment on the top of the forks and on the bottom of the rear shock . If this is set to soft then the power of your spring will cause the shock to extent to quickly after being compressed so when u hit a bump or worse release the brakes after heavy braking going into a bend the vehicle will start to become unstable /bounce around. However if this is set too hard you will find that your spring can't recover quickly enough and so your tyres will skip over bumpy surfaces.
with compression and rebound adjustments you will hear and feel the screw click as you turn it. You should screw it all the way in and then count the clicks out to set it - so if the manufacturers setting say rebound 4 you would screw it all the way in and count 4 clicks out. You should only adjust one thing at a time when adjusting suspension and after each adjustment go for a ride an see how it feels before making another change.
so it turns out.........sometime i do give a f*ck
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TLS-Moose
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Nice summary 
the difference between static and rider sag also go's a fair way to identifying whether the spring rate fitted to the shock is correct for you.
Set the static sag correctly, then check the rider sag. If the the rider sag is virtually the same as the static sag, the spring is too hard. If the rider sag is more than that recommended the spring is too soft. Either will cause a compromise to the efficiency of the damper ......
There again all road bikes are a compromise, as the springs have to be factored to allow for pillions, baggage, defferent rider weights (
), etc.
andrew wrote:...............Preload: This is how much you srping is compressed at a standstill. this is the spanner adjustment on the top of your forks (you measure it by counting the rings you see). on the rear shock this is the big metal collar on the top of your shock. You should set the preload to give the correct static sag - this is how much he bike sags from when the suspension is fully extended (i.e wheel of the ground), to when te bike is supporting its own weight, and then finally to when its supporting your weight (u sat on the bike in full kit).
.............................
the difference between static and rider sag also go's a fair way to identifying whether the spring rate fitted to the shock is correct for you.
Set the static sag correctly, then check the rider sag. If the the rider sag is virtually the same as the static sag, the spring is too hard. If the rider sag is more than that recommended the spring is too soft. Either will cause a compromise to the efficiency of the damper ......
There again all road bikes are a compromise, as the springs have to be factored to allow for pillions, baggage, defferent rider weights (
), etc.Of all the things I have ever lost, I miss my mind the most .....
Handle stressful situations like a dog - If you can't eat it or play with it, pee on it and walk away
Handle stressful situations like a dog - If you can't eat it or play with it, pee on it and walk away
Setting your static sag (couple of mates plus tape measure required):
Step 1:
Rear – lift up rear of bike to extend shock, i.e. lever bike up on side stand. Measure between centre of axle and a fixed point directly vertical above axle i.e. sub frame. Make mark on sub frame and take note of measurement = L1.
Front – lift up front of bike to extend forks, i.e. lever bike up on side stand. Measure between top of dust cap to bottom of triple clamp = L1.
Step 2:
Rear – Sit on bike in full bike kit with bike upright (not on side stand) and feet on pegs. Have helper push down on the back of the bike and then let the shock extend slowly. Take another measurement in the same place as before = L2.
Front - Sit on bike in full bike kit with bike upright (not on side stand) and feet on pegs. Have helper push down on the front of the bike and then let the forks extend slowly. Take another measurement in the same place as before = L2.
Step 3:
Rear – As for step 2 but now have your helper lift up the back of the bike and then let the shock compress slowly. Take another measurement in the same place as before = L3.
Front – As for step 2 but now have your helper lift up the front of the bike and then let the forks compress slowly. Take another measurement in the same place as before = L3.
For both front and rear static sag = L1- [(L2+L3) /2]. Should be between 30-35mm (or 25-30mm for fast riders / racers).
If the correct sag cannot be obtained by adjusting the preload then new springs configured for the riders weight will be required (if sag is too low then a softer spring is required, if sag is too high then a harder spring is required).
Please note if the front sag is too high then preload can be increased by placing spacers on top of the fork spring.
For upside down forks measurements should be taken from the top of the axle clamp to the bottom of the dust seal.
Step 1:
Rear – lift up rear of bike to extend shock, i.e. lever bike up on side stand. Measure between centre of axle and a fixed point directly vertical above axle i.e. sub frame. Make mark on sub frame and take note of measurement = L1.
Front – lift up front of bike to extend forks, i.e. lever bike up on side stand. Measure between top of dust cap to bottom of triple clamp = L1.
Step 2:
Rear – Sit on bike in full bike kit with bike upright (not on side stand) and feet on pegs. Have helper push down on the back of the bike and then let the shock extend slowly. Take another measurement in the same place as before = L2.
Front - Sit on bike in full bike kit with bike upright (not on side stand) and feet on pegs. Have helper push down on the front of the bike and then let the forks extend slowly. Take another measurement in the same place as before = L2.
Step 3:
Rear – As for step 2 but now have your helper lift up the back of the bike and then let the shock compress slowly. Take another measurement in the same place as before = L3.
Front – As for step 2 but now have your helper lift up the front of the bike and then let the forks compress slowly. Take another measurement in the same place as before = L3.
For both front and rear static sag = L1- [(L2+L3) /2]. Should be between 30-35mm (or 25-30mm for fast riders / racers).
If the correct sag cannot be obtained by adjusting the preload then new springs configured for the riders weight will be required (if sag is too low then a softer spring is required, if sag is too high then a harder spring is required).
Please note if the front sag is too high then preload can be increased by placing spacers on top of the fork spring.
For upside down forks measurements should be taken from the top of the axle clamp to the bottom of the dust seal.
so it turns out.........sometime i do give a f*ck
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Mark-Blade
- Learner Driver
- Posts: 696
- Joined: Nov 20th, '04, 10:55
- Location: Exeter
I would never suggest anyone paying to have thier suspension set up unless they were going racing as i really don't thinks its worth it.Mark-Blade wrote:May be a suspension set up day is called for here? For anyone who want's it, done by someone who knows how to ??
I know I'd like to be shown. As was said earlier, if you have nothing to compare it with, how do you know it's at it's best?
Just a thought
i don't mind helping people out on an individual basis - but i'm no expert.
As for knowing if your bike needs it or not - well other than checking th static sag it is hard as we all get use to riding around problems but the key is to try to be analytical of what your bikes doing when u ride. Is the front end diving when you brake? Is the bak end squatting when you accelerate? Is the bike wobbling, wallowing or weaving in the bends? does your bike tend to run wide on the exit of bends? etc
Like i said its not easy and i'm pretty crap at being analytical of my riding / bike.....but i do try
so it turns out.........sometime i do give a f*ck
I have never adjusted suspension from its stock settings on any modern superbike I have ever owned.
A couple of times buying second hand bikes I have set them back to stock settings.
Hopefully this is not because I dont have a clue about suspension. (I spent years racing MX bikes and was completely anal about ensuring I had the right set up for me and was forever getting forks and shocks revalved)
but by and large if you are not overly heavy or overly light ( I weigh a couple pounds over 11 stone) most modern superbikes (certainly GSXR's) on stock settings are good for most of the people most of the time.
Also if your on a bike that is say 6 years old plus and it has never had its suspension serviced then you could adjust the suspension all day and your still never going to get over the base problem that the forks and shocks are tired and worn.
A couple of times buying second hand bikes I have set them back to stock settings.
Hopefully this is not because I dont have a clue about suspension. (I spent years racing MX bikes and was completely anal about ensuring I had the right set up for me and was forever getting forks and shocks revalved)
but by and large if you are not overly heavy or overly light ( I weigh a couple pounds over 11 stone) most modern superbikes (certainly GSXR's) on stock settings are good for most of the people most of the time.
Also if your on a bike that is say 6 years old plus and it has never had its suspension serviced then you could adjust the suspension all day and your still never going to get over the base problem that the forks and shocks are tired and worn.
jason does have a good point, anyone riding a brand new motorbike who is not too far either way of being average weight/ height will probably be ok with the manufaturers stock settings - as most people can't / don't ride that quick on public roads anyway.
However anyone riding a second hand bike will need to adjust / check their suspension as it will need stiffening up with wear, and also it maybe set completely wrong by the last idiot who owned it.
Also anyone who is very big or small could probably benefit from setting up their suspension (even on a brand new bike) as they will probably find the manufacturers settings to hard/soft.
However anyone riding a second hand bike will need to adjust / check their suspension as it will need stiffening up with wear, and also it maybe set completely wrong by the last idiot who owned it.
Also anyone who is very big or small could probably benefit from setting up their suspension (even on a brand new bike) as they will probably find the manufacturers settings to hard/soft.
so it turns out.........sometime i do give a f*ck
I'm not worried about exact settings, just want to be sure they're roughly right, so we're looking at around 30mm difference between full rider weight and zero weight?
Is that the same for the front and back? a few 'guides' I've read state the front should be around 30mm whereas the rear should be around 15mm?
Is that the same for the front and back? a few 'guides' I've read state the front should be around 30mm whereas the rear should be around 15mm?
