Suspension settings interaction

[steveb]

Less damping (counter-clockwise) = "Rebound faster"

I changed the phrasing a little bit, otherwise I entirely agree.

So it looks like I guessed correctly (had a 50-50 chance :^), and turned the screw in the proper direction to lessen the "Rebound Too Fast" issue (started with just an additional half turn clockwise).  I also show the same tire wear pattern that superfist found as a symptom for this problem.  I hadn't noticed it previously with my (primarily) solo riding , but it showed up on my last tour after riding >5k miles fully loaded plus passenger on a new rear tire during many very hot (100+) days.   On the shoulder of the tire, the leading edge of the tread/sipe pattern wore faster than the trailing edge, leaving a raised "flap" of rubber along the trailing edge.  I'm not really sure I understand how this happens.  
 

[skipperT]

I changed the phrasing a little bit, otherwise I entirely agree.

So it looks like I guessed correctly (had a 50-50 chance :^), and turned the screw in the proper direction to lessen the "Rebound Too Fast" issue (started with just an additional half turn clockwise).  I also show the same tire wear pattern that superfist found as a symptom for this problem.  I hadn't noticed it previously with my (primarily) solo riding , but it showed up on my last tour after riding >5k miles fully loaded plus passenger on a new rear tire during many very hot (100+) days.   On the shoulder of the tire, the leading edge of the tread/sipe pattern wore faster than the trailing edge, leaving a raised "flap" of rubber along the trailing edge.  I'm not really sure I understand how this happens.  

 
Are you trying to say that the edge of the rear tire had an uneven feeling when you place your hand on 2 sections of the tread? For example, one edge seems to be a bit lower/higher than the edge beside it?
 
That's called "cupping" when there are different "heights" or depths when the tread parts are compared with each other along the circumference of the tire.
 
Normal tire wear for a long ride without many corners and hot pavement.
 
Adjusting the suspension may help marginally, but I wouldn't get your hopes up that your next tire will wear dramatically differently because the rebound/comp is adjusted.
 
Running dual compound tires (OE are dual compound, but there are better ones out there IMHO) will help, as will checking your tire pressures religiously.
 
I've got almost 12k miles on Pilot road 3's, but have the typical straight road commute. I'm good with checking tire pressures and don't overload the bike. And my tires are still cupped as they get closer to the end of their life.
 
Is what it is....
 
-Skip
 
 

[steveb]

So it looks like I guessed correctly (had a 50-50 chance :^), and turned the screw in the proper direction to lessen the "Rebound Too Fast" issue (started with just an additional half turn clockwise).  I also show the same tire wear pattern that superfist found as a symptom for this problem.  I hadn't noticed it previously with my (primarily) solo riding , but it showed up on my last tour after riding >5k miles fully loaded plus passenger on a new rear tire during many very hot (100+) days.   On the shoulder of the tire, the leading edge of the tread/sipe pattern wore faster than the trailing edge, leaving a raised "flap" of rubber along the trailing edge.  I'm not really sure I understand how this happens.  

Are you trying to say that the edge of the rear tire had an uneven feeling when you place your hand on 2 sections of the tread? For example, one edge seems to be a bit lower/higher than the edge beside it? 
That's called "cupping" when there are different "heights" or depths when the tread parts are compared with each other along the circumference of the tire.
 
Normal tire wear for a long ride without many corners and hot pavement.
 
Adjusting the suspension may help marginally, but I wouldn't get your hopes up that your next tire will wear dramatically differently because the rebound/comp is adjusted.
 
Running dual compound tires (OE are dual compound, but there are better ones out there IMHO) will help, as will checking your tire pressures religiously.
 
I've got almost 12k miles on Pilot road 3's, but have the typical straight road commute. I'm good with checking tire pressures and don't overload the bike. And my tires are still cupped as they get closer to the end of their life.
 
Is what it is....
 
-Skip
 
------------------------
I've had cupping on other bikes and tires and this isn't it.  Wear is very even and consistent.  Every sipe on the shoulder of the tire is affected evenly with the leading edge smoothly worn, and the trailing edge has a thin narrow flap formed on it.  Check out "Rebound too Fast" in this link:    https://www.bikeminds.com/thethrottlestop/motorcycle-tire-wear-patterns-explained   The tire is still feeling good and should be good for several thousand more miles.
 
 

 

[skipperT]

Are you trying to say that the edge of the rear tire had an uneven feeling when you place your hand on 2 sections of the tread? For example, one edge seems to be a bit lower/higher than the edge beside it? 
That's called "cupping" when there are different "heights" or depths when the tread parts are compared with each other along the circumference of the tire.
 
Normal tire wear for a long ride without many corners and hot pavement.
 
Adjusting the suspension may help marginally, but I wouldn't get your hopes up that your next tire will wear dramatically differently because the rebound/comp is adjusted.
 
Running dual compound tires (OE are dual compound, but there are better ones out there IMHO) will help, as will checking your tire pressures religiously.
 
I've got almost 12k miles on Pilot road 3's, but have the typical straight road commute. I'm good with checking tire pressures and don't overload the bike. And my tires are still cupped as they get closer to the end of their life.
 
Is what it is....
 
-Skip
 
------------------------
I've had cupping on other bikes and tires and this isn't it.  Wear is very even and consistent.  Every sipe on the shoulder of the tire is affected evenly with the leading edge smoothly worn, and the trailing edge has a thin narrow flap formed on it.  Check out "Rebound too Fast" in this link:    https://www.bikeminds.com/thethrottlestop/motorcycle-tire-wear-patterns-explained   The tire is still feeling good and should be good for several thousand more miles.
 
 

 
Ok.
So your tires are wearing similar to the picture you linked?
 
Then we are talking about 2 different things. Pictures help, for sure.
 
Curious that the article doesn't mention cupping at all, and it's by far the most common wear that I see.
 
Hmmm.
 
-S

[johncw]

I've been thinking about suspension setup recently and wanted to make a couple minor adjustments to my shock. I found this article about tire wear patterns and how they read.  My stock tire was an exact match for "Rebound too Fast" after 5500 miles on the edge tread grooves.  The center tread was gone, so it's not like I didn't get the full life of the tire. On the FJ-09 rear shock we have preload and rebound adjustment only.  I could be wrong, but I want to think that increasing preload stiffens the spring and helps push the tire back out harder after suspension compression, so less rebound is needed.
I had my stock screw at the standard 1.5 turns out (right in the middle).  My preload was set to two clicks below maximum hardness.  Last night, I changed rebound to 2 turns from max to ease it up.  I also changed preload to 3 clicks from maximum hardness.  I didn't notice any appreciable difference in a commute ride, but I haven't pushed it in any way.
I suppose my questions is:  How does rebound and preload interact and do they affect each other? 

If your trying to remedy the sides of groves running across the tire standing up on one side, and scrubbing out on the other (so you end up with a saw-tooth effect), just be aware that is completely normal and all tires do it.
 
To understand why, get a pencil eraser (we call then rubbers in Australia but I appreciate that term has a different meaning in other countries), and holding it at say a 45 degree angle drag one end of it across the table.  Now push that same end of the eraser across the table.  When you dragged it, the edge was trailing, flexible and folded up.  When you pushed it the same edge was more rigid, dug in, and scrubbed away more.  That's what's happening with grooves running across the tire.  Just like the eraser the leading and trailing edges of grooves running across the tire respond differently as they pass over the abrasive road surface, so wear differently.
 
 

[koth442]

If your trying to remedy the sides of groves running across the tire standing up on one side, and scrubbing out on the other (so you end up with a saw-tooth effect), just be aware that is completely normal and all tires do it. 
To understand why, get a pencil eraser (we call then rubbers in Australia but I appreciate that term has a different meaning in other countries), and holding it at say a 45 degree angle drag one end of it across the table.  Now push that same end of the erase across the table.  When you dragged it, the edge was trailing, flexible and folded up.  When you pushed it the same edge was more rigid, dug in, and scrubbed away more.  That's what's happening with grooves running across the tire.  Just like the eraser the leading and trailing edges of grooves running across the tire respond differently as they pass over the abrasive road surface, so wear differently.
 
 

Great explanation, thank you.

[johncw]

I've been thinking about suspension setup recently and wanted to make a couple minor adjustments to my shock. I found this article about tire wear patterns and how they read.  My stock tire was an exact match for "Rebound too Fast" after 5500 miles on the edge tread grooves.  The center tread was gone, so it's not like I didn't get the full life of the tire. On the FJ-09 rear shock we have preload and rebound adjustment only.  I could be wrong, but I want to think that increasing preload stiffens the spring and helps push the tire back out harder after suspension compression, so less rebound is needed.
I had my stock screw at the standard 1.5 turns out (right in the middle).  My preload was set to two clicks below maximum hardness.  Last night, I changed rebound to 2 turns from max to ease it up.  I also changed preload to 3 clicks from maximum hardness.  I didn't notice any appreciable difference in a commute ride, but I haven't pushed it in any way.
I suppose my questions is:  How does rebound and preload interact and do they affect each other? 

Couple comments, purely intended to help ......
 
Forget looking at tire wear to set the suspension.  Tire wear WILL give you some guide about tire pressures, but not sag, rebound or compression damping.  
 
Adjusting preload has ZERO affect on stiffening or softening the spring.  All it does is raise or lower that end of the motorcycle.  It's important to get preload/sag correct as having the bike ride in the correct part of the suspension (roughly 1/3 of available travel), as well as having the correct front to rear height relationship is very important to handling.  However it doesn't make the springs 'stiffer', not one little bit.  Set the front and rear sag correctly, by static measurement in the workshop.  How to do it is well documented in numerous articles you'll find on the internet.  Once measured and set, don't touch it again.
 
So to your question "how does rebound and pre-load interact?  Simple answer, they don't interact at all.  As previously explained the sole purpose of preload is to set the static position of the motorcycle in the suspension travel.  Rebound is to control the rate of return of the compressed spring after it encounters a bump (or anything else that causes the spring to compress e.g. rear squat, front braking, cornering forces).  
 
So in practical terms, set sag by measuring and adjusting it in the workshop.  Set rebound damping on the road to get an appropriate balance between firming it up to remove any wallow in the corners on smooth roads, yet at the same time be fast enough to give an acceptable and compliant ride over rough roads.  It will always be a balance between these two competing objectives that only the individual rider can determine.  
 
Good luck, and if anything needs clarification don't hesitate.
 
P.S. and if your're scratching your head trying to figure why screwing up the preload doesn't stiffen the spring, consider your humble bathroom scale.  Does sticking a block of wood under the scale increase what the scale says you weigh (determined by how much the spring inside the scales compresses) or just increase your height when you're standing on the scales???  The preload adjuster is in principal no more than that block of wood.  Screwing up the preload adjuster just pushes against one end of the spring, bike just goes up, amount spring compressed remains unaffected (solely determined by the weight of motorcycle and rider it is supporting).
 
 
 

[pattonme]

Curious that the article doesn't mention cupping at all, and it's by far the most common wear that I see.

 
Because the article is talking about race tires which in a day or two of running will wear as much or more as street tires do in 15,000 miles. And also by virtue of the "extreme" forces being put into the carcass actually can show suspension effects.
 

[Guest autobiker]

The OE shock is a useless pile of junk. I've started a thread on that "other" FZ09 forum about comparative analysis of various rear shocks. I'll replicate it here hopefully later this week. It has f'all compression damping and the rebound even at fully closed is about the same as 1/2 way open on the K-Tech or Ohlins. 
A constant rate spring by definition moves the same X distance for same Y force no matter how much you preload it. What preload does is alter the balance point (pushing war between gravity and spring's potential energy) provided the spring doesn't have so much preload the shock is topped out. At that point then the 'Y' has to be big enough to overcome the potential energy.
 
Some good reading:
http://www.sportrider.com/technicalities-spring-rate-and-preload
http://www.worksperformance.com/html/tpl_desc.html

After reading this, I am tempted to turn the rebound screw all the way in (both fork and shock). But I read that the rebound screw also affects compression? Any truth in that? 

[betoney]

After reading this, I am tempted to turn the rebound screw all the way in (both fork and shock). But I read that the rebound screw also affects compression? Any truth in that?

Just curious, why set the damping all the way closed?  Put the bike in a tire chock, turn the adjusters fully closed and then press down on the handlebars or bounce the seat up and down and feel the effect. 
Maybe open 4-5 clicks from fully closed as a starting point then go for a test ride, and bring a straight slot screwdriver with you.
 
As for rebound affecting compression, I will let Pattonme give you a professional answer.
 

[com3]

Um...the fj doesn't have a rebound adjuster on the shock...only compression.
 
Dave Moss is a good friend of mine. He's been tuning all my bikes for the last 13 years.

[com3]

I've been thinking about suspension setup recently and wanted to make a couple minor adjustments to my shock. I found this article about tire wear patterns and how they read.  My stock tire was an exact match for "Rebound too Fast" after 5500 miles on the edge tread grooves.  The center tread was gone, so it's not like I didn't get the full life of the tire. On the FJ-09 rear shock we have preload and rebound adjustment only.  I could be wrong, but I want to think that increasing preload stiffens the spring and helps push the tire back out harder after suspension compression, so less rebound is needed.
I had my stock screw at the standard 1.5 turns out (right in the middle).  My preload was set to two clicks below maximum hardness.  Last night, I changed rebound to 2 turns from max to ease it up.  I also changed preload to 3 clicks from maximum hardness.  I didn't notice any appreciable difference in a commute ride, but I haven't pushed it in any way.
I suppose my questions is:  How does rebound and preload interact and do they affect each other? 

Couple comments, purely intended to help ...... 
Forget looking at tire wear to set the suspension.  Tire wear WILL give you some guide about tire pressures, but not sag, rebound or compression damping.  
 
Adjusting preload has ZERO affect on stiffening or softening the spring.  All it does is raise or lower that end of the motorcycle.  It's important to get preload/sag correct as having the bike ride in the correct part of the suspension (roughly 1/3 of available travel), as well as having the correct front to rear height relationship is very important to handling.  However it doesn't make the springs 'stiffer', not one little bit.  Set the front and rear sag correctly, by static measurement in the workshop.  How to do it is well documented in numerous articles you'll find on the internet.  Once measured and set, don't touch it again.
 
So to your question "how does rebound and pre-load interact?  Simple answer, they don't interact at all.  As previously explained the sole purpose of preload is to set the static position of the motorcycle in the suspension travel.  Rebound is to control the rate of return of the compressed spring after it encounters a bump (or anything else that causes the spring to compress e.g. rear squat, front braking, cornering forces).  
 
So in practical terms, set sag by measuring and adjusting it in the workshop.  Set rebound damping on the road to get an appropriate balance between firming it up to remove any wallow in the corners on smooth roads, yet at the same time be fast enough to give an acceptable and compliant ride over rough roads.  It will always be a balance between these two competing objectives that only the individual rider can determine.  
 
Good luck, and if anything needs clarification don't hesitate.
 
P.S. and if your're scratching your head trying to figure why screwing up the preload doesn't stiffen the spring, consider your humble bathroom scale.  Does sticking a block of wood under the scale increase what the scale says you weigh (determined by how much the spring inside the scales compresses) or just increase your height when you're standing on the scales???  The preload adjuster is in principal no more than that block of wood.  Screwing up the preload adjuster just pushes against one end of the spring, bike just goes up, amount spring compressed remains unaffected (solely determined by the weight of motorcycle and rider it is supporting).
 
 

 
 
 
I disagree with nearly everything you said.
 
Ps - preload does not change the ride height. It simply preloads the spring (which most are progressive springs these days, this affecting how stiff it will be in its initial stroke).

[pattonme]

After reading this, I am tempted to turn the rebound screw all the way in (both fork and shock). But I read that the rebound screw also affects compression? Any truth in that?

 
Sorry to have confused you. I was describing the slope of the rebound curve and observed value at 10 in/sec not that you wanted to maximize rebound by closing off the needle. It's "typical" of street use to have rebound rates in the ~6 in/sec speed. I'll have to line up the OE vs K-Tech curves to see where they end up.
 
What I can say though is that just 1 turn out on the OE shock covers a little more than 60% of the damping difference between fully closed and fully open. In other words, the best compromise setting is likely to be within 3/4 turn (and definitely inside of 1.5 turns) of fully closed.
 
@com3  posting wrong information doesn't help anybody. The FZ/FJ09 shock very clearly has a rebound needle adjuster (in theory it could affect comp too - but since the comp is so lacking basically doesn't) and the spring is a straight rate. Aside from cruisers and a handful of other models, it's actually uncommon to find a progressive spring on a shock anymore.
 

[betoney]

Um...the fj doesn't have a rebound adjuster on the shock...only compression.  
Dave Moss is a good friend of mine. He's been tuning all my bikes for the last 13 years.

Have Dave point out the differences between rebound and compression adjusters. 

[Guest autobiker]

Sorry to have confused you. I was describing the slope of the rebound curve and observed value at 10 in/sec not that you wanted to maximize rebound by closing off the needle. It's "typical" of street use to have rebound rates in the ~6 in/sec speed. I'll have to line up the OE vs K-Tech curves to see where they end up. 
What I can say though is that just 1 turn out on the OE shock covers a little more than 60% of the damping difference between fully closed and fully open. In other words, the best compromise setting is likely to be within 3/4 turn (and definitely inside of 1.5 turns) of fully closed.
 
@com3  posting wrong information doesn't help anybody. The FZ/FJ09 shock very clearly has a rebound needle adjuster (in theory it could affect comp too - but since the comp is so lacking basically doesn't) and the spring is a straight rate. Aside from cruisers and a handful of other models, it's actually uncommon to find a progressive spring on a shock anymore.

No worries, I didn't close the needle all the way. I backed off the fork rebound by 3 clicks and the shock rebound by 1/4 turn. I took the bike on a mix of highway and country roads, and it felt much better than before. It was more compliant over bumps and also more stable at high speeds. The suspensions didn't pack noticeably when I rode across speed strips, but the fork rebounded too slowly after going over bigger bumps or releasing the front brakes. I will experiment with small changes to find the sweet spot.
 
Thanks again for sharing your knowledge!