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  #101  
Old 22nd March 2015
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I have ridden the bike a fair amount this and past week end. In doing so, I have collected a lot of info on the upper loads I am seeing in the rear and front suspension. Based on that data, I have experimented a bit to see how I could best setup the rear suspension for my riding weight. That will help me guide other “T” riders.

Pic 1: This shows the max range from the front suspension; it varied between 233 and 290. Based on the sag numbers, I can determine the riding envelope and can pick a suitable spring and longer damper rod to extend the length of the fork.


Pic 2: This shows the max range of the rear suspension; it varied between 657 and 690. Again, based on the sag numbers, I can determine the riding envelope and can project how the Frankenshocks will perform.


Pic 3. For the front suspension, I have ordered the front race tech springs. They are linear rate springs. I went with linear rate springs because the addition of oil will make the upper range progressive, so there was no need to get a progressive rate spring. It will probably be a week before they come in.


I also ordered the longer damper rods (thanks Madlin for the part numbers)
- Damper rods from 1200N, shortest one=47313-07
- Damper rods from 1200L, medium=45938-92: These are on the XL1200T
- Damper rods from 1200R, longest=45925-04: I ordered these.

I have also ordered and have received a set of front end preload adjusters. To keep the scratches to a minimum, I have not yet put them on the bike.

I have a 2000 XL1200C right fork coming in. It will be the tool I use to characterize the race tech emulator so I know what setting I will go with. I’ll probably test with 10, 15, 20 and 30 weight fork oil to figure out which gives me the performance I’m looking for. I want more rebound and less compression damping and with the race tech emulators, the rebound damping is set by the oil (heavier weight = more rebound damping). I will make the test jig next weekend and get some testing in (I hope).

Pic 4. The rear shocks are ready to go on. I will clean them up and check the bike geometry next weekend with them on the bike. This will let me see how to finish packaging the front suspension based on the taller rear to get the rake and trail numbers I was hoping for. I also need to see how the 1200S shocks work with the bags… or not.


Pic 5. The new spring rates are very similar to what came oem; perhaps the rear are about 6% softer. I’ll play with the geometry during the week just to take a closer look at the rates. But so far no show stoppers, I just have a bit more work to go. Perhaps a couple more weekends and the suspension work should be done.
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  #102  
Old 23rd March 2015
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You're setting up a mighty stiff front fork. Too stiff and harsh for solo riding, unnecessarily harsh for two up.

I outweigh you by 100 lbs in gear and tools in back pack and found the Race Tech recommendations of 95 kg spring, emulator, 20 w oil pre Race Tech recommendations way too stiff. I softened the forks up in steps, back to 10 w oil, Works Dual rate springs, and took the emulators out completely, and left the compression holes drilled out. Rode that way for a few years until Ricor Intiminators came out.

I have 2006 Roadster and I tried 5 w oil with the compression holes drilled out, emulators removed, and found the front wheel would get into wheel hop and loose traction over a particular set of braking bumps on my test rides, no problems with 10 w oil. A buddy had a 07 Roadster, did not drill out compression holes, did not use emulators, stock fork spring. He tried 20 w fork oil. I could see light under the front tire when he rode at highway speeds over concrete sectioned highways. His forks felt like molasses compared to mine.

Keep in mind the Roadster and (I assume) Custom damper rods have much smaller compression dampening holes than the damper tubes off short forks. So there are a lot of guys (with short forks) who say 20 w fork oil is OK.

My best guess is drill the compression holes in the damper rods, put in as much rider sag as you can get, 5w oil stock levels. This is as soft as it will get with the 1.0 kg spring. Test ride carefully, if you don't bottom out, you will know the spring is too stiff.
__________________
Former Ricor test rider for IAS Shocks, Intiminators and Vibranators. Works Dual Rate fork springs, fork brace, Avon Venom X tires, loosen drive belt, and set frame rails level to floor. Read the "7 Pages of Suspension" thread in the Suspension Sticky Index to learn how to fix your suspension.

Last edited by XLXR; 23rd March 2015 at 01:44..
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  #103  
Old 23rd March 2015
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XLXR, what level did you set the oil at when you ran your combination? When you put the emulator in, did you account for it and adjust the volume? It doesn't take much for the air spring to dominate the overall spring rate.

I am shooting for little to no contribution from the air spring, hence the higher spring rate. By staying with almost all spring and little to no air spring, it should be all nice and linear. If you look at the last pic, the new springs are about the same as what I'm running now.

I have 1.1 KG/mm front springs in my CB700SC and really like the ride. I hope my XL1200T turns out like my Nighthawk did. Its the best riding bike in the fleet.

Jerry

Edit: Added this graphic to show difference between the new spring vs oem setup. Also, 0.8 KG/mm = 45.0 lb/in and 1.0 KG/mm = 56.0 lbs/in. That is a 24.4% increase in stiffness. Take out the affect of the oem air spring, and they are comparable in stiffness. I will check it all when the new springs come in; your words of caution are heard and understood.
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  #104  
Old 23rd March 2015
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Quote:
XLXR, what level did you set the oil at when you ran your combination? When you put the emulator in, did you account for it and adjust the volume? It doesn't take much for the air spring to dominate the overall spring rate.
The Race Tech Emulators were my first fork mod back in 2006 and 2007. I can't tell you how many times I took the forks apart trying to soften them up. My idea was to keep softening them up until too soft, and then harden them up one notch from being too soft. I learned that in my dirt biking days. While I don't remember all the details, I can say I was well aware of effects of oil level/air spring. I generally start with stock oil levels, get rider sag, chassis pitch correct under average conditions, then the last thing is add oil level only as needed to prevent bottoming. I do remember never liking the Race Tech set up and focused on getting a smoother ride, at this time I can only assume I sucked out extra oil to return to stock oil levels after adding Emulators. I am pretty sure I would not have overlooked that.

I am also well aware of the differences between straight rate springs and progressive rate springs, that each has their own advantages and disadvantages, and that different riders of all skill levels have there own preferences.

I prefer suspension with a progressive rate for street bikes to better deal with inconsistencies and extremes of the road surface, but prefer straight rate for race bikes on more consistent surfaces. My goal with the Works Dual rate fork spring was to provide a soft initial rate to absorb small bumps to make the ride comfortable, but use the progressive rate to control bottoming during more aggressive riding or bigger bumps.

Quote:
I am shooting for little to no contribution from the air spring, hence the higher spring rate. By staying with almost all spring and little to no air spring, it should be all nice and linear. If you look at the last pic, the new springs are about the same as what I'm running now.
This is where yours and my opinions start to differ, based on the different aspects of straight vs progressive rate springs. 90% of the bumps a rider feels in normal paved roads are in the area of 1" or less. I want that first 1" of travel (after rider sag) to be as soft as possible. That is what provides long term riding comfort. With my Works Dual Rate fork spring for my initial travel, I have 34 lbs/in spring rate. You have 56 lbs/in spring rate. There are absolutely NO fork modifications you can do to get your initial travel as soft as mine, to absorb small bumps as well as mine. Except get a lighter spring.

I can also say from experience, that even if you changed to 5w oil and I used 10w, the differences in our spring rates are much greater than that change in viscosity.

Now look at final spring rates, yours 56 lbs/in, mine 60 lbs/in. Adding preload, increasing oil viscosity, especially increasing oil height, are all methods to fine tune the spring rate. Adding preload: I still have lower initial spring rate and smoother ride. Increasing oil viscosity: I still have lower initial spring rate and smoother ride. Increasing oil height: I will have to add less oil than you will. One advantage of air spring is that is has less stiction (internal friction) than a metal spring. So even if I have to add more oil to prevent bottoming, it will probably be less than you need, so I still win there (sure, by just a little bit).

Look at the graph above. Look at the intersection of 1" travel and 100 lbs fork load. There is about an 20 lb difference between the 1 and .8 kg springs. Grab a 20 lb hammer and beat yourself in the head with it. Stop when it hurts. When I was younger, no problem. Today at 60, I cannot tolerate anything but a soft ride.

Everything you are doing is "before Ricor Intiminators." Ricor Intiminators invalidates every assumption you make from this point on. They take the fork in the opposite direction you are going. The inertia valve blows off high speed compression dampening upon initial vertical wheel movement. For that instant, the weight, inertia/momentum, of the bike, and secondary hydraulic circuit in the Intiminators, is keeping it up in the air, letting the wheel to travel up as fast as other limiting factors such as stiction and inertia of sprung mass will allow. This has such a profound effect, by reducing front to rear coupling to such an extent that a lot of guys can actually reduce shock preload a notch or two. That results in even smoother ride.

Not only do I have a very comfortable bike to ride, due to my younger dirt bike riding/racing skills and current suspension set up, there has been only one guy who could out run me on a Sportster, he was expert level racer with a well set up XR 1200. So, my suspension is not soft and slow, it is very compliant, controllable, and allows for increased safety when pushing the limits.

I appreciate all the work you are doing, it proves what I have been saying for years. Keep in mind, I add my comments and explanations to help other guys understand suspension.

I can't remember if I said this in this thread or not. There have been guys who use a G-meter app available on I-Phones who have measured G forces before and after suspension modifications.

Last edited by XLXR; 23rd March 2015 at 08:42..
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  #105  
Old 23rd March 2015
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XLXR,

I do thank you for your thoughts as I post my mods. You have deep experience with the Sportster and I don't. But we both draw on lots of experiences that we draw on to guide our tuning. Having read almost all the suspension threads before buying, I think I understand your philosophy, and I would say we have similar thoughts. We have different strategies on how we get to the final results. That's why I post the graphs, etc, so you can see the path I am going. If I just posted my subjective thoughts, well, there would be different discussions going on.


The Race Tech Emulators were my first fork mod back in 2006 and 2007. I can't tell you how many times I took the forks apart trying to soften them up. My idea was to keep softening them up until too soft, and then harden them up one notch from being too soft. I learned that in my dirt biking days. While I don't remember all the details, I can say I was well aware of effects of oil level/air spring. I generally start with stock oil levels, get rider sag, chassis pitch correct under average conditions, then the last thing is add oil level only as needed to prevent bottoming. I do remember never liking the Race Tech set up and focused on getting a smoother ride, at this time I can only assume I sucked out extra oil to return to stock oil levels after adding Emulators. I am pretty sure I would not have overlooked that.
What did you use for the preload spacers? PVC, aluminum or steel tube?

I am also well aware of the differences between straight rate springs and progressive rate springs, that each has their own advantages and disadvantages, and that different riders of all skill levels have there own preferences.
Agreed.

I prefer suspension with a progressive rate for street bikes to better deal with inconsistencies and extremes of the road surface, but prefer straight rate for race bikes on more consistent surfaces. My goal with the Works Dual rate fork spring was to provide a soft initial rate to absorb small bumps to make the ride comfortable, but use the progressive rate to control bottoming during more aggressive riding or bigger bumps.
I prefer a linear rate suspension for the street; there are less variables I need to factor in as I ride. You cannot avoid a a number of road irregularities, but you can avoid most, so I make that tradeoff.

This is where yours and my opinions start to differ, based on the different aspects of straight vs progressive rate springs. 90% of the bumps a rider feels in normal paved roads are in the area of 1" or less. I want that first 1" of travel (after rider sag) to be as soft as possible. That is what provides long term riding comfort. With my Works Dual Rate fork spring for my initial travel, I have 34 lbs/in spring rate. You have 56 lbs/in spring rate. There are absolutely NO fork modifications you can do to get your initial travel as soft as mine, to absorb small bumps as well as mine. Except get a lighter spring.
I would say our strategies differ and these are driven by our preferences. You are comfortable riding on springs that transition from 34 to 60 lbs/in vs riding on straight rate springs. I only have a few hundred sportster miles under my belt, but I can tell you I didn't like the straight rate 45 lbs/in springs. They didn't have enough capacity. They also dive very easily under moderate braking (I should have added more preload which would have helped). The other thing I didn't care for is the transition under load progressive springs brings in turns. Do you know where the transition point is for your springs? Is it within 1" after preload is set? Is it 2 "?

I can also say from experience, that even if you changed to 5w oil and I used 10w, the differences in our spring rates are much greater than that change in viscosity.
I am not sure what you are trying to say here?

Now look at final spring rates, yours 56 lbs/in, mine 60 lbs/in. Adding preload, increasing oil viscosity, especially increasing oil height, are all methods to fine tune the spring rate. Adding preload: I still have lower initial spring rate and smoother ride. Increasing oil viscosity: I still have lower initial spring rate and smoother ride. Increasing oil height: I will have to add less oil than you will. One advantage of air spring is that is has less stiction (internal friction) than a metal spring. So even if I have to add more oil to prevent bottoming, it will probably be less than you need, so I still win there (sure, by just a little bit).
I think I will have less oil level than stock as I am looking to eliminate the air spring so I think you will run more oil than me. One aspect I find to be a factor is fork volume. On the Nighthawk, I had very long forks; almost 7" longer than the sportster. This allowed me to tune the air spring affect out. On top of this I am adding a longer damping tube (more volume). So may not end up with as much play - so I may have to go to a lower rate spring. But, for now I am heading gown the path of a higher rate spring.

Look at the graph above. Look at the intersection of 1" travel and 100 lbs fork load. There is about an 20 lb difference between the 1 and .8 kg springs. Grab a 20 lb hammer and beat yourself in the head with it. Stop when it hurts. When I was younger, no problem. Today at 60, I cannot tolerate anything but a soft ride.
My experience is once you are on the springs, the ride is good (once the suspension is set up). The motorcycle weighs in close to 600 lbs and I weigh over 200 with riding gear on, so 800 lbs or so. The way I would look at your set up vs mine: The baseline is 45 lbs/in from the steel springs. I am going to try a 11 lb/in greater rate and you chose a 11 lb/in less rate. With the weight on the front, I don't see a huge rate difference once you account for all springs in the fork (steel and air).

Everything you are doing is "before Ricor Intiminators." Ricor Intiminators invalidates every assumption you make from this point on. They take the fork in the opposite direction you are going. The inertia valve blows off high speed compression dampening upon initial vertical wheel movement. For that instant, the weight, inertia/momentum, of the bike, and secondary hydraulic circuit in the Intiminators, is keeping it up in the air, letting the wheel to travel up as fast as other limiting factors such as stiction and inertia of sprung mass will allow. This has such a profound effect, by reducing front to rear coupling to such an extent that a lot of guys can actually reduce shock preload a notch or two. That results in even smoother ride.
No disagreement, but everything I have read about the Ricor Intiminators speaks to the compression side. I have not seen anything on what they do for rebound damping. How do you adjust the Ricor Intiminators to adjust rebound damping? Also, how do they perform under moderate to hard braking?

Not only do I have a very comfortable bike to ride, due to my younger dirt bike riding/racing skills and current suspension set up, there has been only one guy who could out run me on a Sportster, he was expert level racer with a well set up XR 1200. So, my suspension is not soft and slow, it is very compliant, controllable, and allows for increased safety when pushing the limits.
I would guess you could easily out ride me too. But I suspect you would be riding on the top end of your suspension as the bottom end is too soft.

I appreciate all the work you are doing, it proves what I have been saying for years. Keep in mind, I add my comments and explanations to help other guys understand suspension.
rgr

I can't remember if I said this in this thread or not. There have been guys who use a G-meter app available on I-Phones who have measured G forces before and after suspension modifications.
I don't have my ram ball mount yet, but once I do, I will make use of the app as its on my phone too.

Jerry
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  #106  
Old 23rd March 2015
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This from a different site on the subject of math:

I was riding to work yesterday when I observed a female driver who cut right in front of a pickup truck, causing the driver to drive onto the shoulder to avoid hitting her.

This evidently angered the driver enough that he hung his arm out his window and gave the woman the finger.

Man, that guy is stupid, I thought to myself. I ALWAYS smile nicely and wave in a sheepish manner whenever a female does anything to me in traffic, and here's why:

I drive 48 miles each way every day to work. That's 96 miles each day. Of these, 16 miles each way is bumper-to-bumper. Most of the bumper-to-bumper is on an 8-lane highway.

There are 7 cars every 40 feet for 32 miles. That works out to 982 cars every mile, or 31,424 cars. Even though the rest of the 32 miles is not bumper-to-bumper, I figure I pass at least another 4000 cars.

That brings the number to something like 36,000 cars that I pass every day. Statistically, females drive half of these. That's 18,000 women drivers! In any given group of females, 1 in 28 has PMS. That's 642.

According to Cosmopolitan, 70% describe their love life as dissatisfying or unrewarding. That's 449.

According to the National Institute of Health, 22% of all females have seriously considered suicide or homicide. That's 98. And 34% describe men as their biggest problem. That's 33. According to the National Rifle Association, 5% of all females carry weapons and this number is increasing.

That means that EVERY SINGLE DAY, I drive past at least one female who has a lousy love life, thinks men are her biggest problem, has seriously considered suicide or homicide, has PMS and is armed.

Give her the finger?
I don't think so.

And somebody said I didn't know math and over think everything . . .Geeeeezzzzz

If this offended anyone, I apologize. But it shows we can use math in all kinds of ways...
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  #107  
Old 23rd March 2015
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I have to tell those statistics to my girl friend...
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  #108  
Old 23rd March 2015
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Quote:
That means that EVERY SINGLE DAY, I drive past at least one female who has a lousy love life, thinks men are her biggest problem, has seriously considered suicide or homicide, has PMS and is armed.

Give her the finger?
I don't think so.
That is friggen hilarious! I 'll give a longer response and answer your questions later tonight when I have more time.
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  #109  
Old 24th March 2015
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The previous discussion of straight vs progressive (or dual) rate springs is pretty typical. So is the discussion of a guy with experience with Ricor Intiminators and another who doesn't. Again, my main purpose here is provide a learning experience to readers who want to learn.

First point. Attempting to set up suspension in a straight line graph does provide a starting point of reference, but that straight line graph is in reality a very poor representation of the reality of suspension set up to match road conditions. The easiest way to explain why is to look at fork shaft speeds. Fork shaft speeds are literally how fast the wheel is able to move up and down in response to bumps and dips in the road, and in response to chassis movements such as brake dive (stoppies in the extreme) and rearward dynamic chassis pitch movements such as hitting the throttle hard (wheelies in the extreme).

Fork shaft speeds during actual riding conditions can vary from 0 inches/second to 300 inches/second. Brake dive, causes fork shaft speeds somewhere in the range of 3"/sec. 300 inches/sec is extremely fast, very rare, and perceived by the naked eye as just a blur, and Harley forks may not be able to move that fast under any circumstance. All the graphs Jerry has posted so far are extremely accurate and extremely enlightening to those who understand them. EXCEPT, none of the previous graphs reflect the suspension responses to the vast diversity of actual riding conditions. In order for that to be possible, computers, electronic sensors, G-meters, bank angles, dynamic chassis pitch measurements, tire loading calculations, on and on are necessary. Something that is possible, but extremely expensive, and limited the few who can deal with that level of complexity. Interesting side note: I have had two suspension engineers, of national caliber racing experience, tell me that at times all that information is useless, and sometimes the right suspension set ups resulted from an educated guess. Look at any national caliber race series. They all have the same info, but only one guy wins the race.

Some examples of actual real life suspension response to road bumps and dips. First is low speed and high speed compression dampening. Fork dive produces low fork shaft speeds. Hitting a square edge bump such as a big pot hole, or 6" high concrete curb at 60 mph produces extremely fast fork shaft speeds, assuming your rim, tire, fork tubes don't break. Actual fork shaft speeds are not linear, they vary from those two extremes, and are in direct response to all the various bumps, dips you hit, and at what speeds you hit them.

Now let's look at rebound. When riding over a bump that throws the bike up in the air, weight is off the tire, and the faster shock can extend to get the tire back in contact with the road, the better. In this case, excessive rebound dampening will actually hold the wheel up with the shock compressed and then the bike will fall back to the ground and tire hit the ground with the shock still partially compressed. That can severely limit the shocks ability to react to the next bump, or dip, in the road, because now your suspension is acting like a hard tail. In this case, you want minimal to no rebound dampening to let the shock extend as fast as possible.

Next case of rebound. Imagine hitting a big dip in the road. Tire is in full contact with the road, lots of bike and rider weight is on it, shock spring completely compressed. How much rebound dampening do you need now? Too little rebound dampening will let the shock spring extend so fast, the back end shoots up so fast and so high that you are thrown over the bars. In this case, you want a hugh amount of rebound dampening, which is exactly opposite what you need in the first situation.

So, I hope readers can now understand that in real life riding conditions, suspension response is not linear.

Hydraulic dampening provided by damper tube is also never linear in response. The faster the wheel moves, the faster oil is pushed through the holes in the damper rod. At high shaft speeds, hydraulic locking can occur. A common example of this is when guys increases oil viscosity too much and cause the tire to loose contact with the road over bumps or dips. Or adding too much oil, reducing the air chamber to such an extent that the forks lock up and limit travel. At low shaft speeds, damper rods may not produce any significant dampening at all. This is common when guys complain of excessive fork dive under front wheel braking conditions.

So, back to fork springs, straight rate vs progressive or dual rate. Remember when I stated that progressive rate springs have to be correct in initial rate, final rate and the transition zone between those two rates. I have the Works Dual Rate fork springs set up to provide a non-linear spring rate. However, the way I have them set up, I FEEL a linear response. How can that be???? Simple, the soft initial spring rate absorbs small bumps just like the final spring rate absorbs big bumps. So it does not matter what size of bump I hit, or what fork shaft speed is, the forks absorb the force of the bump, and that force is not transmitted to chassis or rider.

So, in my mind, the best suspension is where I can forget about the suspension completely. I cannot remember how many times I sat around the lunch table and listened to guys complain about how bad the roads were, how that one bump almost through him off the road. All I can do is shake my head and say I have no idea what you guys are talking about. One time after a long ride, I went to an empty table and sat down. All the other guys stood at the counter to order a beer, they couldn't sit down, too sore. As an old dirt biker, I love it when the road gets rough, pot holes, sand, water rocks, I don't care. But then I realize no one is following me any more, they stopped and waited until I turn around. I literally do not have to worry about road bumps or irregularities until they get to the point of blowing tires, cracking rims, or bending fork tubes.

Jerry, somewhere before you said you can live with stiff suspension because you normally can avoid the worst road bumps. In my mind, that is extremely poor suspension. Funny thing, it is quite common for guys who set up their forks correctly with Ricor Intiminators that they actually start aiming for the bumps they used to have to miss because they simply cannot believe how much better the forks non-linear response is.

Dinner time, and then I have to get some work done, so it will be a few hours and on the next page before I get my thoughts completed.

Last edited by XLXR; 24th March 2015 at 04:14..
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Old 24th March 2015
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Originally Posted by XLXR View Post
The previous discussion of straight vs progressive (or dual) rate springs is pretty typical. So is the discussion of a guy with experience with Ricor Intiminators and another who doesn't. Again, my main purpose here is provide a learning experience to readers who want to learn.

First point. Attempting to set up suspension in a straight line graph does provide a starting point of reference, but that straight line graph is in reality a very poor representation of the reality of suspension set up to match road conditions. The easiest way to explain why is to look at fork shaft speeds. Fork shaft speeds are literally how fast the wheel is able to move up and down in response to bumps and dips in the road, and in response to chassis movements such as brake dive (stoppies in the extreme) and rearward dynamic chassis movements such as hitting the throttle hard (wheelies in the extreme).

GIVE ME SOME TIME TO COMPLETE MULTIPLE ENTRIES AND COMPLETE MY THOUGHTS BEFORE RESPONDING.
Okay, but when you do, let me know why the CB700SC rides so wonderful on 1.1 KG/mm linear rate springs. I have oem VTR1000 cartridges and am running 10wt oil. The bike weighs in at about 525 lbs, so its 75 lbs lighter.

Standing by...

Jerry
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