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Im planning to rebuild my suspension on a 07 zx10 this winter and need help from suspension tuners. Ive been researching and have decided the first thing is to decide if I need a progressive or digressive valving in the forks. Im not worried about brand, I feel there are many good products and services to choose from. All I do is street riding. I do like to ride as hard as my skill will allow from time to time and ride on some very rough farmer market roads. Any information on this would help.
 

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Discussion Starter #3
I was refering to the force vs. dampining. the amount of dampining in relationship to the amount of force applied applied when hitting bumps
 

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I think I know what he is talking about although the terminology might be different. If he is talking about what I think he is talking about, "progressive" damping gets stiffer more than in proportion to the speed of fork movement (not road speed). "Digressive" isn't the right term for the opposite situation but the name of the right term slips my memory right now.

"Progressive" damping implies soft low speed damping and firm high speed damping. This is like the old damper-rod forks. The other slipped-my-mind-what-the-name-is implies firm low speed damping which "blows off" beyond a certain compression speed and doesn't get much stiffer at high speed.

For roadracing and cornering etc, the latter is normally what you want. You want firm low-speed damping to minimize pitching and floating and maintain good chassis control, but you want not-too-firm high-speed damping so that sudden (but not very big) bumps and pavement irregularities don't transmit so much force into the chassis that they upset the balance.

BUT, there is a tradeoff. "Firm-then-blowoff" characteristics are not good for resisting bottoming under extreme conditions, e.g. landing a 12-o-clock wheelie hard, or hitting a really nasty big bump. Those conditions could let the suspension go right to the bottom and slam off the travel limit.

Most stock forks nowadays that have cartridge dampers use "firm-but-blowoff" but then start to go progressive again beyond a certain compression speed and then go REALLY firm on the compression damping in the last 20 - 25mm of compression before reaching the mechanical travel limit. You can feel this if you have the forks put together with fork oil but without the springs installed.

In roadracing with such forks, you can either remove that increased compression damping or you have to stay out of the last 20mm or so of compression travel because otherwise the high compression damping will cause problems. Doing the former (remove this function) means no more landing hard 12-o-clock wheelies and no more going really fast over an angled set of railroad tracks because it WILL bottom. Doing the latter requires a compromise of higher-than-otherwise spring rates to reduce the amount of travel that you use.

So, what's the answer?

Simple ... it depends.
 

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Digressive valving? Is there such a thing for suspension? Why would you want LESS damping when MORE force is applied? Makes no sense to me dude and I don't know of anyone who offers that.

As far as I know, all the valving options are progressive but can be taylored to provide a specific damping force based on the applied input force (i.e.- configured for a particular riders weight and riding style). But it's still all progressive in nature: MORE FORCE = MORE DAMPING which is what the suspension is there for.
 

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Im planning to rebuild my suspension on a 07 zx10 this winter and need help from suspension tuners. Ive been researching and have decided the first thing is to decide if I need a progressive or digressive valving in the forks. Im not worried about brand, I feel there are many good products and services to choose from. All I do is street riding. I do like to ride as hard as my skill will allow from time to time and ride on some very rough farmer market roads. Any information on this would help.

For Your needs, because of rough old roads, being quite different than the smoothish closed course road race tracks that the bike is kinda considered for, by the manufactures. I'd highly recommend you just tell Race Tech what you want, and because of their history in off road racing, they will select a shim stack for your requirements.

I had Tony in R&D, do just that. My Riding is on old roads, one in particular I have to believe is the roughest paved road that exists. Being a wagon trail that got a hard surfacing maybe 120 years ago, and then patches on top of patches ever since.

I'm an Ex-Desert racer, and have made the conversions to my ZX-10 (flat tracker handle bars, Scotts Damper, and the suspension being the main items here), to ride it like flying a desert bike, where the pavement is so rough, the bike is launched and stays launched as long as the speed is maintained in the areas of visability.

Pirelli Diablo Corsa III's work better than the other choices here, and your suspension has to be "tuned" to the tires, so switching around on tires will just keep things screwed up (never set-up), So... if you haven't done the tires yet... that should be done, and tell Tony what You have there.

Good Luck on this, it transforms your bike :cool:
 

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Discussion Starter #9
I have been studying this for several weeks and have found Race Tech to be using the digressive vanvling. Traxxion is using it also. From what Ive found Da Kyle is using a more progressive valveing with ohlins. There are three possible form of valving Ive found digressive, progressive, and regressive. If you have a x,y graph that represented the dampining and travel of fork the progressive would be represented with a line almost straight equal to both x and y. Digressive and regressive would be represented by a line that arched up or down respectivly in relationship to x,y. Since the track is very different from the road and several very good companies offer different options ,each Im sure they feel the best, I was looking for a unbias opinion or someone with knowledge on the issue.
 

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thanks Phastone That exactly what Im talking about. Im wondering though if on the road the stiff intial dampining would make road riding difficult. Thats why Im looking for some direction before I dump a couple of grand.
 

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Thanks Im a ex cross country rider myself. Im allready runnning the Diablo tires and have been pleased with them so far. Havent got many miles though. What option did you use for your rear shock and did you go with the 25mm kit or just a revalve?
 

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thanks Phastone That exactly what Im talking about. Im wondering though if on the road the stiff intial dampining would make road riding difficult. Thats why Im looking for some direction before I dump a couple of grand.
No problemo. I can't say for sure but just going by how the digressive valving works, I'd say you're correct about the harshness on the street.

Like louemc said, your best bet would be to call race-tech up and tell them what you're looking for from your bike. Myself, others around here, and even numerous ama guys are going to race-tech for their suspension lately. They're very good at listening to you and coming up with a solution for your needs. :thumbsup:
 

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Okay, re-read my post again, what they are calling "digressive" damping is the same as what I described in the other post; there is firm low-speed damping but the damping force pops open the shim stack beyond a certain level and the damping force stays more constant at higher shock speeds.

Yes, the firm low-speed damping will transmit more harshness, but unless you are looking for a floaty Buick smooth ride, it won't make street riding more "difficult". In fact it should make riding on bumpy roads easier. (By the way, I had a set of Bilstein shocks on a car that I previously owned, and in that application I HATED them, too much NVH - noise vibration harshness - they made my CD changer skip. Felt awesome as far as cornering was concerned. Ride quality ... not so much!)

The bad thing is resistance to bottoming under extreme conditions. The article that was linked to referred to rally-car suspensions. Those resist bottoming by a combination of the spring rates and REALLY long suspension travel.
 

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Really there is not answer to which type of valving is better then the other. In my opinion it has to do with your particular style of riding and what you are comfortable with. I have Racetech Valving and Springs in my forks and and Ohlins rear shock. I have a progressive compression setup in front because I like to late brake and trail brake into corners. I like the front to dive early and settle. But my bike is a trackbike only. It really depends on what type of riding you do and when and how you will use your suspension.
 

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We have some bloody rough roads over here, I'd go with a slightly progressive setup for the road, digressive sucks, like it has been pointed out, hard on the small slow stuff, then soft and too much bottoming on the big stuff.
Really,unless you're doing the valving yourself, just tell the experts what you're gonna do with it and leave them to it. It takes a lot of testing and trial and error to get it right, not to mention hours of dyno time. Have faith in the company you choose, if they're any good, they'll sort it for ya.
 

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Thanks Im a ex cross country rider myself. Im allready runnning the Diablo tires and have been pleased with them so far. Havent got many miles though. What option did you use for your rear shock and did you go with the 25mm kit or just a revalve?
Not sure who's post your replying to... but if it was one of mine... I had Race Tech
re-shim stack/compression-rebound separator valve/springs/oil, service. (the stock forks and shock) front and back.

There were several choices in routes to go (like Traxxion forks and Penski shock), but....I wanted the same people to do the front and back, and Race Tech had the Dirt (rough surface) history, that I had the most confidence in. :thumbsup:
 
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