Hyperpro progressive fork springs?

[justplainbill]

Are there reasons suspension experts are not recommending fork springs wound progressively?  I understand they are not suited to racing, but would seem to be a good choice for street riders without racing aspirations.  The OEM FJ-09 springs are dual rate (similar to progressive) and if you are in the right weight class, evidently not a bad set-up (ignoring criticisms of the compression circuit). 
 
Progressive fork spring manufacturers claim you get a plush ride that still soaks up hard bumps, as well as providing improved braking, better handling, stability and road holding. Not sure if they cure warts or acne...
 
The only manufacturer I found offering progressive fork springs for FJ-09/Tracer is Hyperpro.  Pricey compared to single rate springs.   No FJ-09 reviews, but I did find some positive comments from street riders (Aprilia Futura, FZ1, and ZR-7 forums) on Hyperpro springs and spring kits. 
 
Any ideas? Experience?  Suggestions?  I'm trying to learn what I can and relate it to my own riding experience on the FJ and pick an optimum solution for a choppy ride over expansion joints, cracks in the roadway and potholes.  
Thanks,
 
Bill

[xlxr]

Here is how I explain it. Racers like straight rate springs because they feel more consistent. And they can use increasing oil height in the fork to provide a progressive feel. Straight rate springs have only one parameter to get right, one single spring rate (assuming the spring has correct travel, free length, diameter).
 
Progressive rate springs have to have 3 parameters correct, initial spring (soft) rate, final spring (harder) rate, and the transition zone between the two different rates. That makes it far more complicated to get one spring that works how you want it to work. For example, assuming 5 inch travel forks, the first inch is rider sag, leaving 4 inches useful travel. Lets assume the same initial and final spring rates are used in the following example. A transition zone up high in the travel will feel soft in the initial inch of travel, but then stiffen up in the last 3 inches of travel. Or if the transition zone was in the final inch of travel, the forks would feel soft for the first 3 inches of travel, but then the last inch of travel in the high spring rate zone may not be enough to prevent harsh bottoming.
 
In addition, racers who are very perceptive can feel the mismatch in the dampening characteristics as spring transitions through the different spring rates. This makes it more difficult for them to tune the dampening curve exactly how they want it. Keep in mind, top level racers may change dampening curves for different tracks.
 
For street riders, my response to this problem is that the difference between the initial and final spring rates is too much for the dampening curves. However, keep in mind street bikers ride over a much broader range of bumps/dips/road rash than racers, which is where a properly set up dampening curve will have to be averaged out with properly selected spring rates and transition zone to provide smooth ride over small square edge bumps, and still resist harsh bottoming.
 
Next you have to consider how preload/rider sag and spring rate(s) interact. It is entirely possible to have a too soft initial rate so that when you sit on the bike, the initial rate of the spring completely compresses, coil binds, and then the only spring rate the rider feels is the harsher final rate.
 
As a result of these factors, there is only a limited amount of different progressive rate springs available and they are usually meant for average weight riders. If you are too light, or too heavy, the standard progressive rate spring may not work well for you.
 
Harshness over small square edge bumps, typically less than 1" high (or a dip 1" deep), such as when riding over concrete sections on highways, imparts high shaft speeds of forks or shocks. High end shocks have high speed compression dampening adjuster for this, and have the ability to be tuned with a much higher spread between high shaft speeds and low shaft speeds.
 
I weight 270 lbs in gear. I had to maximize preload in both shocks and forks, but still had way too much rider sag. Problem was the stock shock had so much excessive high speed compression dampening, and excessive stiction, when new that the shock was essentially hydro-locking over those small, harsh, square edge bumps and providing an extremely harsh ride even though I was way too heavy for the spring rates.
 
Bottom line, if your current suspension has excessively high - high speed compression dampening, or excessively high stiction, progressive or softer springs may not help much.  For me, custom suspension is on order.  I don't have any direct experience with Hyper Pro springs.
 

[Guest fzrcraig]

I use Progressive (the design and the manufacturer) fork springs on my race bike along with gold valves. It is the best front end I have ever experienced but this is more coincidence as I agree that straight wound would have made it easier to fine tune. I just got lucky.

[justplainbill]

That's a very technical and abstract analysis xlxr, most of which was over my head but thank you for it. But away from the abstract, two questions come to mind: first, since the FJ-09 comes from the factory with dual rate springs and the damping circuits and valves were designed or selected for dual rate springs, wouldn't the FJ fork seem to be a better candidate for progressive springs than linear ones? (Ideally of course the fork would benefit more from dual rate springs with different rates for different rider weights/loads.) Second, wouldn't it be safe to assume HyperPro is aware of the complexities you pointed out and has taken steps to mitigate them? I have no idea what they could do to mitigate them but unless they and other makers of progressive springs have survived for years selling snake oil to gullible motorcyclists - there must be something to it.
 
All that said, my bike just turned over 1300 miles and on a hundred mile ride yesterday the usual harsh jarring I experience on our roads was appreciably less than usual. So I spent this afternoon setting front end rider sag (40 mm) and set the rebound damping screw three turns out, then ran up and down my dirt test road with mega stutter bumps, rocks and other impediments and since my retina's didn't detach, I was pretty pleased with the results . It's too soon to say for sure, but I'm not certain I will need any aftermarket front end work. But if I do, I'd like to do it once and get it right. And if there is merit to progressive springs for the FJ-09, other riders might benefit from knowing it too.

[wordsmith]

Any ideas? Experience?  Suggestions?  I'm trying to learn what I can and relate it to my own riding experience on the FJ and pick an optimum solution for a choppy ride over expansion joints, cracks in the roadway and potholes.   Thanks,
 
Bill

I'm pursuing the same Holy Grail, Bill.   And if I may - what weight are you, fully-kitted to ride, please? [em]Wordsmith[/em]
 

[xlxr]

The main questions you should ask Hyper Pro are their springs meant for a rider your weight and skill level, and are they meant for stock or modified forks. If you can't find somebody who has tried their spring, you may have to be the first to find out and report back.
 
On my FJ 09, the stock shock was extremely stiff. If your shock is as bad as mine was, changing fork springs will not help at all. Sometimes getting the forks right, makes the shock feel even worse.
 
 

[justplainbill]

Any ideas? Experience?  Suggestions?  I'm trying to learn what I can and relate it to my own riding experience on the FJ and pick an optimum solution for a choppy ride over expansion joints, cracks in the roadway and potholes.   Thanks,
 
Bill

I'm pursuing the same Holy Grail, Bill.   And if I may - what weight are you, fully-kitted to ride, please? [em]Wordsmith[/em]

Layered up for winter rides Wordsmith, 220 - and 210 in summer. For my little foray up Sedge Canyon (dirt) road, I was dressed more for summer. 

[justplainbill]

The main questions you should ask Hyper Pro are their springs meant for a rider your weight and skill level, and are they meant for stock or modified forks. If you can't find somebody who has tried their spring, you may have to be the first to find out and report back.  
On my FJ 09, the stock shock was extremely stiff. If your shock is as bad as mine was, changing fork springs will not help at all. Sometimes getting the forks right, makes the shock feel even worse.
 

HyperPro is a Dutch company and the US distributor is EPM Performance Imports in New Jersey.  I have no confidence that I'd be able to get accurate information from the distributor (sales outlet). And apart from the language problem, my experience dealing with corporate types on technical consumer questions hasn't been good either.  I was hoping one of the guys making their living selling suspension services and parts might have some info on progressive springs to share.  I know that Forks by Matt sells Hyperpro rear shocks -- which use progressive springs. But if he sells Hyperpro fork springs, he isn't listing them. (Maybe he keeps them next to the Playboys, under the counter...and only brings them out when asked and no children are present.) 
As for the rear shock - I've given up on it and have a low mileage Hayabusa shock on the way to replace it.  You're right, as the front improves, the rear seems to worsen. 
 
 
 
 

[wordsmith]

I'm pursuing the same Holy Grail, Bill.   And if I may - what weight are you, fully-kitted to ride, please? [em]Wordsmith[/em]

Layered up for winter rides Wordsmith, 220 - and 210 in summer. For my little foray up Sedge Canyon (dirt) road, I was dressed more for summer. 

That's appreciably more then me, at about 80kg fully-kitted (summer, winter, here all the same).   80kg is about 176lbs.   Cannot you go on a crash diet, Bill, lose a fair bit, and try again with the suspenders?   You seem to be fairly systematic, which is what I think this matter needs...  Thanks.  [em]W[/em]
 

[xlxr]

220 lbs is 40 or more lbs heavier than the standard rider weight of 180 lbs and probably getting to the point of needing at least one spring rate heavier than stock for forks and shocks, that is the information you need to ask Hyper Pro. I would try the Hayabusa shock, max out fork preload, raise the oil level a bit and see what you think.
 
I am totally guessing here, I have a lot of experience on suspension with other bikes, but none with FJ 09, yet.  
 
You can go to Race Tech and other suspension companies and see what they recommend for fork spring rates.  Race Tech says 700 kg/mm stock fork springs.  Entering 220 lbs rider weight, they recommend between .95 or 1.0 kg/mm spring rate.  These are straight rate springs.  Race Tech offers 6 different spring rates.  180 lb rider is .90 kg/mm fork spring.
 
Hyper Pro offers one spring, SP-YA09-SSAO11, but I could not find their explanation of what spring rates that represents.  Progressive rate springs should have two numbers, for example .85 / 1.2 kg/mm with the first number representing the initial (soft) rate, and the second number representing the final (hard) rate.  (I completely made up that number.) 
 
Based on these comparisons, and assuming the Hyper Pro spring is for average weight riders (160 to 180 lbs), it may not be heavy enough for  your 220 lbs.
 

[justplainbill]

Layered up for winter rides Wordsmith, 220 - and 210 in summer. For my little foray up Sedge Canyon (dirt) road, I was dressed more for summer. 

That's appreciably more then me, at about 80kg fully-kitted (summer, winter, here all the same).   80kg is about 176lbs.   Cannot you go on a crash diet, Bill, lose a fair bit, and try again with the suspenders?   You seem to be fairly systematic, which is what I think this matter needs...  Thanks.  [em]W[/em]

Don't say "crash" it makes me cringe. And I don't think I could pare off 40 pounds before your FJ is worn out W, so you'd best get your 14 mm spanner and flat blade screwdriver and try for yourself. 

[wordsmith]

 ... so you'd best get your 14 mm spanner and flat blade screwdriver and try for yourself. 

Just waiting (and hoping) for some more inputs from others here, Bill: might save me some blood, sweat, and tears. [em]W[/em]
 

[justplainbill]

220 lbs is 40 or more lbs heavier than the standard rider weight of 180 lbs and probably getting to the point of needing at least one spring rate heavier than stock for forks and shocks, that is the information you need to ask Hyper Pro. I would try the Hayabusa shock, max out fork preload, raise the oil level a bit and see what you think.  
I am totally guessing here, I have a lot of experience on suspension with other bikes, but none with FJ 09, yet.  
 
You can go to Race Tech and other suspension companies and see what they recommend for fork spring rates.  Race Tech says 700 kg/mm stock fork springs.  Entering 220 lbs rider weight, they recommend between .95 or 1.0 kg/mm spring rate.  These are straight rate springs.  Race Tech offers 6 different spring rates.  180 lb rider is .90 kg/mm fork spring.
 
Hyper Pro offers one spring, SP-YA09-SSAO11, but I could not find their explanation of what spring rates that represents.  Progressive rate springs should have two numbers, for example .85 / 1.2 kg/mm with the first number representing the initial (soft) rate, and the second number representing the final (hard) rate.  (I completely made up that number.) 
 
Based on these comparisons, and assuming the Hyper Pro spring is for average weight riders (160 to 180 lbs), it may not be heavy enough for  your 220 lbs.

With the exception of spring companies asking for my base weight which is 197 pounds (not with gear), you are spot on for their recommendations; Race Tech says fork springs need to be 0.95 Kg/mm, Sonic 0.90 Kg/mm.  For the rear shock spring, RT likes 11.5 Kg/mm (which I did use when I put a Sachs unit on my NC700, and will use for the Hayabusa shock).  
This: http://www.promecha.com.au/springs_advanced.htm is a discussion of springs you will certainly appreciate (and understand better than I). 
Per the FJ-09 service manual, Yamaha factory fork springs are dual rate, with the first 85 mm of travel rated at 0.70 Kg-f/mm and the remaining 74 mm of travel rated at 0.95 Kg-f/mm.   The setting I found successful on my test yesterday, left two rings showing on the fork pre-load adjusters. If needed, I'll raise the oil level from 179 mm (to 140 mm?) after giving the current settings a good trial.
 
Thanks to your contributions to this thread xlxr, I am coming to believe the reasons suspension tuners don't recommend progressive springs is partly because they cater to racers and those with racing aspirations and linear rate springs are better (at least more predictable) for track use.  And it's partly because progressive (or dual rate) springs are very complicated, with limited choices available from spring manufacturers. So, stick with what you know works.
 
But for the FJ, that may be throwing the baby out with the bath.  Yamaha went to some effort to use the more complicated dual rate spring layout on these bikes (and maybe even matching fork innards) and by converting to linear springs and making costly changes to valving and fluid circuits, tuners may be giving up something worthwhile for their non-racing customers.      

[pattonme]

 a choppy ride over expansion joints, cracks in the roadway and potholes.  

Damping. Damping. And Damping. 
Springs just 'mask' the issue. If you have a weak spring (eg. initial rate of OE) the damping gets worked harder since the wheel moves farther (less push back from the spring) and thus displaces more oil per unit time which highlights damping characteristics.
 
Harder springs slow the wheel down but also transfer some of the energy into moving the chassis upward instead of letting the chassis maintain "little to no" movement while only the wheel is madly moving up and down.
 
The factory picked the cheapest option that could conceivably cover as broad a range of rider weights as they could muster. The higher rate portion is to help deal with the initial rate being much too soft so as to provide some bottoming resistance on weight transfer.
 
"Progressive" springs are rarely that, typically they are dual or maybe triple rate. They are more difficult to get right because in order to achieve sag goals, maybe you're past the initial rate or on the threshold of the next rate so you end up riding around on the rate that is much too high. Eg. if your weight calls for .85kg/mm and your spring goes from 0.7 to 0.95. Once you've left the too soft 0.7 part of the stroke, you're now way into the too stiff section.
 
Straight rate means you've removed this unnecessary compromise and confounding factor. It also simplifies shim stack builds - a stack for 0.7 is a few shims shy of one built for 0.85 and another few shy of one intended for 0.95. The likes of Andreani, Matris and other "budget" cartridge providers have one configuration for all spring rate applications and instead force the user to crank down on the bleed circuit to achieve the rate of rebound. True, the non-savvy user doesn't question this but the better tuners aim to let the user retain maximum adjustment range.
 
The modern, big-money solution to these various tradeoffs is Electronic Damping.
 
 

[pattonme]

I know that Forks by Matt sells Hyperpro rear shocks -- which use progressive springs. But if he sells Hyperpro fork springs, he isn't listing them.

 
Not sure what led you to believe I sell Hyperpro shocks. I only carry JRi, Ohlins, Nitron and maybe soon K-Tech. The JRi shocks use a Hyperpro shock spring since they are the only ones who make a 5" spring (Technically Eibach has them too but good luck getting one). The rate on it is straight, however.
 
I very much doubt there is any "special thought" given by a fork spring supplier that has progressive springs in their catalog for a given bike aside from initial rate, final rate, and stroke depth of the transition. The KYB suspension was done poorly and cheap.