First Look: Sprindex's Adjustable-Rate Coil Spring

Nov 29, 2019 at 9:11
by Mike Levy  
Sprindex

Sprindex's new adjustable-rate coil spring system lets riders alter their spring-rate without needing to swap out coils or even reach for any tools. Instead, all you need to do is rotate the Sprindex collar by hand to add or subtract as much as 30 to 60 lb/in to the spring rate. It also consists of only a few extra parts, making it dead-simple to boot.

The design uses a proprietary steel coil spring, with three different overall lengths available to fit shock stroke lengths of up to 2.2 (XC), 2.6 (EN), and 3.0'' (DH) in length, and 290 lb/in to 610 lb/in coils are available. Thin Delrin adapters are used to adapt the coils to every major suspension brand's shocks, and all three models sell for $140 USD direct from Sprindex's website or your local shop.

Sprindex Details

• Adjustable-rate coil spring
• Material: Glass-reinforced polymer
• Provides approx. 30 - 60 lb/in adjustment range (depends on model)
• 290 - 610 lb/in spring-rate options
• Compatible w/ Fox, RockShox, DVO, MRP, Marzocchi, Cane Creek, Öhlins, RockShox, X-Fusion, and Push shocks
• Weight: 389-grams (2.6" EN, 350-380 lb/in)
• MSRP: $140 USD
• More info: www.sprindex.com

Views: 10,644    Faves: 3    Comments: 0




Sprindex
Sprindex
Tool-free coil spring-rate adjustment? You betcha.



If coils are so great, why aren't we all using them?

Given the popularity of coil-sprung suspension these days, along with the undeniable benefits of less friction and more traction, isn't it a bit odd that the vast majority of full-suspension mountain bikes come with air shocks? I mean, if these coils truly are better, why aren't they spec'd on all of our bikes? There's the fact that air is lighter than steel, but it's mainly because an air shock is far more adjustable. Using only a shock pump, a shop can have any of its air-sprung full-suspension bikes work for potential customers who weigh 100 pounds or potential customers who weigh three times as much.

As you can imagine, that makes it a whole lot easier to sell those bikes, and the shop doesn't need to keep dozens and dozens of different coil springs on hand.


Sprindex
The air shock on the bottom weighs 520-grams, while the coil-sprung shock in the exact same length, and with the Sprindex unit installed, weighs 861-grams.


Dialing back the cynicism a notch or three, you wouldn't be wrong if you also said that dead-simple spring-rate adjustment is air suspension's greatest asset. If you want just a nip less sag, all it takes is thirty-seconds to add 10 psi before your next ride, and the fact that it's so easy means that more of us will take the time to set-up our suspension properly. Or at least get closer to it. I suspect there'd be a ton of wildly over- and under-sprung bikes out there if everything used coils.

It's almost like an adjustable-rate coil spring would be a great idea, which is exactly what the folks at Sprindex have come up with.


How does Sprindex work?

To understand how Sprindex works, we have to understand how a coil spring works. They're just squishy, right? Well, yes, but also no; if you look closer, there's a bit more to it than that.

A coil spring is essentially a wound steel rod, much like the torsion bars found on many road cars. In that case, one end of the bar moves with the suspension while the other is fixed to the car's frame. When the wheel hits a bump, it's forced upward and that twists the torsion bar that's fixed at the opposite end.

In other words, it's the twisting steel that's absorbing (and storing) the force before the damper can dissipate the kinetic energy.
Coil springs twist when compressed, just like a torsion bar twists to absorb energy.

So while they look like boring, straight steel rods, a torsion bar is basically just an unwound coil spring. And the shorter the rod, the more force required to flex said rod. That means that a shorter torsion bar is stiffer than a long one made of the same material and gauge. Because a wound steel coil twists in the same way a torsion bar does, a shorter coil spring will be more difficult to compress the same distance than a longer one made of the same gauge steel. So if you could somehow lockout or deactivate a section of the coil spring, even just half a coil, you'd effectively be making the spring stiffer because it's effective length is shorter.

The easiest way to understand Sprindex might be to think of it as a simple way to adjust the effective length of the steel rod that, in the case, happens to be wound into a coil.


Sprindex
My test spring can be adjusted between 340 lb/in and 380 lb/in.


The glass-reinforced polymer Sprindex unit comes pre-installed on one end of their coil springs - it can't be purchased on its own. The bottom half is held in place in the last coil, while the top collar half turns and has fourteen indexed positions. The inner face of that collar also interlocks between the coils, and when the collar is turned all the way to the left, it's only working with a bit of a coil. Turn it all the way to the right, though, and it aligns with the bottom section to lockout half a coil and essentially makes the rod (coil) shorter.

Pretty damn clever.


Sprindex
Sprindex
See how the Sprindex is ramped and indexed? When you rotate the collar, the ramped section is run up between the coils to deactivate a section.


There are probably more than a few people out there having their own 'Why the hell didn't I think of that?!' moment, as well as more than a few questions...


What's spring-rate and why does it matter?

It's the amount of weight required to compress the spring by one inch, so if it says 400 lb/in on your spring, it means that you'll need 400 lb to compress it by a single inch. Two inches? That'll be 800 lb, please. The spring-rate is what holds the rider up, and it's also what largely determines how much travel gets used at each impact. If you're not using enough travel, it probably means that your spring-rate is too high and vice versa, and it's the first thing you dial in (before damper adjustments) when setting up your suspension.

Four factors determine the spring's rate: material, the overall diameter of the coil, the diameter of the steel wire used and, most relevant to our convo, the number of active coils. To alter the rate, Sprindex is effectively letting you activate or deactivate a small section of the coil spring.


How big is the adjustment range?

It depends. ''There are more active coils on the longer stroke springs and thicker wire on our stronger springs,'' Sprindex says on their website. ''The range depends on the percentage of active coils reduced and multiplied times the rate of the spring.'' Just some chill math, then. You're looking at somewhere between 30 and 60 lb/in of adjustment range, depending on the spring's length and rate. That's not enough to have a single spring work for everyone, of course, but it's more than enough for tuning purposes.


Sprindex
Sprindex
Delrin washers are used to adapt the coils to most shock models, as well as letting it rotate freely as it's being compressed.


Neato, but how is this different from preload?

The threaded preload collar on your coil-sprung shock doesn't affect the spring-rate because it's only partially compressing the coil, not altering the length of the coil (your wound steel rod). If you dial on a ton of preload, the only thing you'll be doing is raising the ride height of your bike and increasing the starting force required to activate your shock. More preload means less suspension sensitivity, and the general consensus is that you only want to tighten the preload collar enough to keep the coil from moving around.

If you want, you can combine your preload adjustment with Sprindex and it will work fine. That said, they recommend that you use their adjustment and modify the spring-rate to achieve the correct ride height instead. Less energy stored in the spring equals more supple suspension.


What kind of shocks does it fit?

With the included Delrin adapters and different diameter coils offered, you can get a Sprindex to fit shocks from all the names that matter, including Fox, RockShox, DVO, MRP, Marzocchi, Cane Creek, Öhlins, RockShox, X-Fusion, and Push models. Maybe some others, too, and you can check out the very long compatibility chart on their website to see if your shock is on the list.



Sprindex
This custom spring-rate-O-meter machine was used to verify Sprindex's claims.


But does it work?

The spring-rate-O-meter that I ordered off Amazon hasn't shown up yet, but a dozen donuts got me access to a very neat custom-made version assembled within a burly steel frame. A small car jack that serves as the lower spring perch is bolted to the bottom, while an adjustable upper perch is used to compensate for different length coils or add a nip of preload. A digital caliper is attached to that lower perch, and all you need to do is adjust the jack until it reads zero, then bring down the upper perch with just enough preload to hold it in place. The caliper tells you precisely how far you've compressed the spring, while a load cell on the lower perch tells you how much weight you're applying to the spring while compressing it with the car jack.

It's a clever machine, and while it's not lab equipment-precise, it's more than adequate for the day's job: Figuring out if Sprindex's claims are true. Can their little device, which consists of just two simple pieces, really offer an effective, tool-free coil spring-rate adjustment?

It sure can.


Sprindex
At the 380 lb/in setting, the Sprindex required 374 lb of force to compress it a single inch.


With the Sprindex set to 340 lb/in, and 10 lb/in of preload applied to roughly replicate it being installed on a bike, the spring-rate-O-meter's digital display read 348 lb/in when compressed by a single inch. Rotating the collar up to 350 lb/in saw the display change to 363 lb/in (don't forget about that preload), and each of the indexed 10 lb/in spring-rate settings tested after that corresponded to an 8 to 15 lb/in increase in the force required to keep the spring compressed by an inch.

At the test spring's stiffest 380 lb/in setting, and with the preload backed off to see how accurate the numbers are, the display read 374 lb/in. The spring-rate-O-meter probably isn't quite as accurate as a commercial-grade machine, but those numbers are pretty damn close. It also proved that Sprindex's adjustable, two-piece system does actually work as advertised.


Sprindex
Sprindex
Sprindex uses high-end steel for their coils that require less material for a given spring-rate. That means that in some instances they could be lighter than the stock spring it's replacing.


Out of the lab and back in the workshop, the Sprindex unit is installed just like any other coil - it slides down over the shock body, and don't forget to use those red Delrin washers that let the spring twist freely as it's being compressed. I installed it on two bikes, a Yeti SB165 and a custom-made 180mm-travel enduro rig that you'll get to see real soon; measuring the sag on both bikes throughout the Sprindex's adjustment range backed up the spring-rate-O-meter's findings.


Sprindex
Sprindex is slightly larger in diameter than the coil, so you'll want to make sure you'll have the room. It shouldn't be an issue on most bikes.


We're probably not going to see air suspension disappear anytime soon, and the Sprindex doesn't offer enough adjustment range to see a one coil work for any rider on any bike, but it's certainly a good tuning option for those who like to tinker. Wet day? Dial back the spring-rate a bit for more compliance. Fast day in the bike park? You might want to run a firming spring-rate for all those jumps you're going to overshoot. It could make sense for bike shops as well, with them no longer needing to stock countless coil springs.

I guess that leaves me with a single question: Why didn't I think of this?







302 Comments

  • 155 0
 Cool! Weird how it took so long to come up with such a simple yet ingenious solution Smile
  • 11 1
 applies to so many human inventions!!!
  • 26 25
 Definitely an interesting concept. I am curious to how accurate the spring rates are though.
  • 10 2
 @mixmastamikal: From some recent reading on springs I have seen that most are inaccurate, so probably no worse than other HS steel springs. I think this is the primary benefit of this system in that it allows you to compensate for inaccurate spring rates, but also to fine tune your spring rate. Very interesting and worth a try.
  • 18 7
 @dodgerpuppy: SAR/EXT coils are verified to be within 1.5% accuracy which are also "high-end steel". I am not sure why I am being down voted for asking a simple question. For 140 quid I would expect a decent amount of QC to go into a product of this type.
  • 1 0
 @mixmastamikal: act of faith, like with lots of other springs...
  • 31 0
 @mixmastamikal: I would say you are being downvoted because the article went into some detail to explain the test they conducted and the corresponding results.
  • 13 0
 @dodgerpuppy: We worked hard to make the rates as accurate as possible. The springs are as accurate as any fox Springs and better than most.
  • 4 0
 @richieschley: I believe that, but my main point is that, with this system, it is not really all that relevant. Personally, I think this is actually a great idea, as the vast majority of riders will be between available spring rates and this makes tuning that much easier. Great work; I’ll definitely be trying one on my next build with a coil!
  • 4 0
 @dodgerpuppy:

The accuracy of the spring doesn’t matter as much as achieving the right setup for you and your bike regardless of the number printed on the side
  • 7 0
 @liketoride1: I agree 100%, and this takes care of both issues, doesn’t it? The only reason the inaccuracy of the spring is important is that it can get you further from achieving that correct setup. If I need a 465 lbf/in spring rate but my 450 is actually 435 then it is an issue, is it not?
  • 8 2
 You guys are brutal. Ha ha but I get it. Using this single example for the values they tested and accounting for the preload they stated I got the following numbers.

Within 0.57% accuracy at 340 w/ preload.
Within 0.83% at 350 w/preload
And ~1.6% at 380 w/ no preload.
This is just one spring tested but if this is typical these are really good numbers. This seems pretty cool to me and could let you get sag super dialed. Could possibly be trying this in the bear future.
  • 6 2
 @mixmastamikal: Whats the bear future?
  • 21 1
 @schmichael325: haven't you heard? In the NEAR future we will be living in a dystopian hellscape over run with bears. Because the only way to outrun them through the forest will be on bike, getting a correct spring rate will be of utmost importance.
  • 7 5
 @mixmastamikal: you're being downvoted because asking simple, logical, accurate questions or stating facts of the technical nature for some reason enrages Pinkbikers. Even if you're right. It's the way of the internet. There is no logic in these hills!!!
  • 5 0
 @schmichael325: if you’re a polar bear, not so good
  • 5 4
 @mixmastamikal: they talk about inaccuracies with coils like they know exactly how much air they loose when they unwind their shock pump.
  • 8 0
 @richieschley: I like that you released it at U.S. Thanksgiving. Because after all the Turkey and dressing, we are sorely in need of a stiffer spring. Smile

You should call it the "Overeaters Chip"
  • 2 0
 @mixmastamikal: Talking about downvotes, see my comment in this thread and the one in the main thread about torsion springs. While i kinda get the negative votes in this thread, it beats me why the torsion spring comment was downvoted...

@thenotoriousmic: supposedly none, the blast of air is coming out of the hose with the schrader valve closing off. Putting the hose on is a different thing though.
  • 2 1
 @Primoz: Any guy that have torsion spring in his car can rightfully negprop your comment about cars not having them, I suppose.
  • 2 0
 @faul: I wrote there are cars that have them. Just like i wrote not many of them have them. I fail to see the logic in your reasoning to downvote my comment.
  • 1 0
 @Primoz: you also fail to acknowledge that emotions known as : mischief, malice, chaos & calamity don't take reason or logic into their bosom....they grope logic & poke reason in the poop chute
  • 2 0
 @thenotoriousmic: none, douchebag!
  • 1 0
 @mixmastamikal: being downvoted and having a valid point are not mutually exclusive.
  • 1 2
 @Primoz: for a fraction of a second while you’re unscrewing your pump you’l lose a bit of air. How much depends on how much pressure there is on the other side meaning it’s almost impossible to know exactly how much pressure is in your shock at least with a coil you know exactly what your spring rate is.
  • 3 0
 @thenotoriousmic: If you're hung up on the amount of air being lost by a schrader valve when unscrewing the pump, there are two options:
1. use a pump that can close off the valve before unscrewing, meaning you have 0 loss of pressure
2. design a better valve.

Since the valve is designed to multiple 100 psi (i wouldn't be surprised if it can hold 100+ bar as well) and is used in all manner of phase change cooling systems with temperatures going below -100°C and pressures being all over the place as well, it's supposedly also used in aircraft hydraulic systems, i don't think you can do much better than the ubiquitous schrader valve.

Plus, if you're worried about the amount of air leaking from the sock when pumping it, surely you pump it up according to ambient temperature as well? And adjust the pressure according to ambient pressure and temperature during the ride as well? Do you see where i'm going?
  • 1 2
 @Primoz: you can’t have zero loss because that valve is going to be open for a fraction of a second and that’s where you lose air.
  • 67 3
 For the “$140 for spacers” crowd:

1. Read the damn article.
2. Compare pricing to other coil springs.
3. Remember to read the damn article next time.
  • 6 4
 I was already outraging on them, brilliant post made me smile and chill, thanks
  • 1 11
flag themountain (Dec 2, 2019 at 11:21) (Below Threshold)
 DrPete ...even after reading the article ....its still smells like snakeoil. Come on ...a plastic insert for 140bucks ...you must be insane!
  • 7 0
 @themountain: there is an high-end coil spring whith it.
Go check msrp for an SLS or Fox light spring.
  • 9 0
 @themountain: refer back to my previous instructions. Hint: the spring comes with it.
  • 15 1
 By not using one coil you will reduce the total amount of travel available from the spring. As long as the spring has more available travel than the shock, it should be OK, but should be checked
  • 13 0
 The number of people commenting on this being the same as preload really highlights how poorly most people understand how their suspension works.
  • 1 0
 Different settings for different conditions for sure.
  • 9 1
 "I mean, if these coils truly are better, why aren't they spec'd on all of our bikes? There's the fact that air is lighter than steel, but it's mainly because an air shock is far more adjustable."
Maybe I'm missing something, please correct me if I'm wrong, but aren't alot of bikes spec'd specifically with air shocks as they lack the progressiveness in their kinematics? I see how this gadget can adjust spring rate but fail to see where it makes up for being super linear..?
Either way this seems like a very cool little adjustment gadget and it is sort of amazing nobody has thought of this until now.
  • 4 3
 #oncoil
Throw coil on everything, then complain about how terribly it rides!
  • 2 1
 @spaceofades: I've heard you can adjust for this with custom tunes, but not everyone can get/afford this luxury
  • 4 0
 Part of the problem with coil shocks is that there isn't one single correct progressiveness that can just be built into the frame. Different riders, terrain and riding styles require diffent amounts of progression. You can tune that with air tokens but not with coils. And trying to work around that issue with compression damping is not ideal and has negative side effects.
  • 2 2
 @Ttimer: Yes you can tune progressivness with coils, get a EXT with adjustable hydraulic bottom out control, or a damper that can except Avalanches new type of shape factor bumper system, job done, added progressiveness.
  • 1 0
 @Campagnolo123: The EXT Storia isn't adjustable but the Arma shock is.
  • 3 3
 Most people don’t realise they’re running a coil damper and not coil spring so they say things they don’t really understand like my frame isn’t progressive enough for a coil shock.
  • 2 2
 @Ttimer: yeah you can add a bigger firmer bottom out bumper for more progression same as adding volume spacers you can also use progressive springs or run a coil with built in bottom out resistance that’s before you even start on the compression tune and unlike air shocks you get support right through the travel not just at the beginning and end like with air. So the second your wheel hits something it’s doing it’s job.
  • 6 0
 I'm trying to nitpick, but this actually seems legit (leaving price aside for a second). Dialing a perfect spring rate could really be a pain. I just wonder about a durability of such a spacer, sandwiched between several constantly vibrating flexing pieces of metal. Hope to see this take off!
  • 9 4
 Here is an idea. Have a 2 piece spring, one for the main spring rate & a smaller one for the end stroke. Similar to a progressive wound spring but in 2 pieces so a rider can decide how much ramp they want or dial in to use a coil on 'air only' frames.
  • 5 0
 It was stock on the shockworks dh shock at the end of the 90s, worked really good
  • 39 7
 Its a cool idea, but science tells us that it doesn't work. Two springs stacked in a series act like two springs next to each other (in parallel), with both acting at the same time. The effect is that your spring rate is decreased without any progression because the springs are compressing together, not one after the other.
  • 10 0
 @dreamlink87: if you have a two same lenght spring with one with lower lbs/inch , they will not work the same. if you compress the two , will be for example a half of the low lb/i compress , and only a quarter of the other.
if you apply a low force , and have a big difference in rate , the first can eventually compress until it store enough force to move the second one.

in fact , that is use outside of the MTB worl , look at this : www.extremeshox.com/product/ext-tech-3r
  • 6 0
 @Megazzz: that’s pretty cool. I’ve seen crossover rings used in motorsport to get a dual rate spring, but not 3 rings on a single shock. I might be wrong but it looks to me that each of those springs has an internal collar that prevents the spring from continuing to compress after it compresses to a certain point. That’s a bit different than just stacking two or three springs, right?
  • 11 7
 @dreamlink87: springs can't be compressed infinitely. The softer spring bottoms first then only the harder spring is left- of course it works.
  • 4 4
 @dreamlink87: tell that to the automotive industry. www.vividracing.com/images/kwv3evox1.jpg
  • 4 4
 Coils already have that bottom out bumper that makes that last 20% progressive. You could swap different bumpers for different levels of progressiveness.
  • 6 6
 @dthomp325: that bumper is not a spring. At all.
  • 5 0
 @R-trailking-S: the way that two coil spring work stacked is weirdly complex (at least to me)

if you take a 200lb spring and stack a 100lb spring common sense would let you think that you now have a 150lb spring - it is not the case. its takes a differential equation to calculate the resultant rate.

as mentioned above in motor sports they often use dual spring with a cross over ring. this setup is nice as it can control your initial small bump absorption then ramp up quickly once your off the top spring.
  • 3 0
 @meathooker: You got it! Here is a good link for visual learners. www.crawlpedia.com/spring_rate_calculator.htm
  • 1 0
 @Megazzz:
The smaller springs in that case are compressing first. They seem designed to have very soft initial spring rate for a small part of travel, not a ramp up at the end of travel.
  • 2 0
 KING shocks use a similar set-up on their truck coilovers.
  • 3 1
 @R-trailking-S:

Why are you talking about subjects you don’t seem to understand? The softer spring is not an isolated system and will be acting on the secondary coil as it compresses, which compresses the harder spring.
  • 1 0
 @meathooker: What I've wondered about for a while is how a crossover ring setup on a mountain bike shock would work. Would there be a sudden transition at the cross over? If so, a progressively wound spring like MRP's might be the better choice.
  • 1 0
 @R-trailking-S: Sure, that definitely would work. However, we'd run into the problem of regularly binding the softer spring and that can cause all sorts of issues.
  • 1 0
 Even on the the longest MTB coil shock we have currently there is not enough room for a dual rate coil setup.
  • 1 0
 The DSD runt basically does this for air forks. I have one for my 36 and it works great to dial in different areas of travel. I believe MRP is currently working on a duel air chamber shock to bring that that adjustability to the rear of the bike.
  • 1 0
 @jason114: my 99 240mm shockworks shock says other
  • 1 0
 MRP have a progressive spring which is kind of like the 2 spring setup suggested...

mrpbike.com/products/enduro-progressive-coil-springs
  • 3 0
 @5afety3rd: that bottom out bumper is very much a spring. @dthomp325 is correct.

Progressive coils are just an expensive way of achieving what variable length bottom out bumpers already do.
  • 2 0
 @nickfranko: Doesn't change the fact that once the first spring bottoms it will merely act as preload on the heavier spring, leaving you with a higher spring rate at the end of the stroke.
  • 1 0
 @dreamlink87: You are correct. Spacers are used to prevent the weaker spring from coil binding and also to time the position in the suspension travel where the tuner wants to transfer the rate to the stiffer spring.
  • 1 1
 @gabriel-mission9: incorrect, you're only thinking about end stroke, not beginning or mid stroke. a progressive coil can be more sensitive early, siff midd/end AND you can have a very stiff bumber to help with harsh bottoming.

some would say all of that is just a way around proper high speed compression damping.
  • 1 0
 @dreamlink87: Does this mean that progressive springs don't work either or does that somehow work differently?
  • 2 0
 @5afety3rd: remove the spring from a shock and compress it all the way. The bottom out bumper progressively increases spring rate in the last 20% of travel, making it significantly more difficult to compress.
  • 4 0
 @meathooker:
It's not a differential equation to figure it out. Its the same equation as calculating electrical resistance of two resistors in parallel.
Req = 1/(1/R1 + 1/R2) or for your example
66.7lb/in = 1(1/200 + 1/100)

Two springs in series is softer than either of the two individual springs. It still works though as generally, you use a shorter spring specifically designed to coil bind (flat wire) for the softer rate. Once it reaches spring bind, only the higher rate spring is active.

"Progressive" springs essentially do the same thing. Some of the windings are closer together than the others. These windings bottom out on each other first, essentially "deactivating" those coils and the spring rate increases.
  • 1 0
 @dthomp325: i do this, every single day, with a shock dyno. and it's more like the last 5-10% to prevent damper damage. Air shocks use an o-ring and washer to do the same thing. it's not for tuning reasons or to make this progressive or to be relied on for spring duties. The bottom out bumpers get destroyed and replaced during regular service. the coil generally does not.
  • 1 0
 @MikeG156: Sounds like that's why only a couple companies are making progressive coils - the bottoming out of some of the windings could reduce their longevity relative to a non-progressive coil.
  • 1 0
 @dreamlink87:
Most cars use progressive wound springs. If the spring is designed to operate in that manner, it's not really a problem. They typically have a softer sleeve around the coils that bind though to protect them from wearing off the corrosion coating.

The reason why there aren't many progressive springs is because there are different bike frames out there and it's hard (impossible) to make a spring that works for all of them. It's easier to use a "linear" spring and then a couple different bottom out bumper designs can be used to adjust progression. Push and Avalanche Racing both have different bottom out bumpers designs depending on how much progression is needed. They can also have material cut out of them to change the spring rate curve of the bumper.
  • 11 6
 Just head over to Autozone and get these little spacers. 5 bucks... Smile

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  • 1 0
 Yes, but not as fine-tuneable. Interesting thought, though.
  • 2 0
 @dodgerpuppy: you could change the orientation within the coil loops for fine tuning
  • 6 0
 The easiest way to understand Spandex might be to think of it as a simple way to effectively manage your steel rod, which happens to be twisted into a coil in any case. .
  • 1 0
 underrated comment.
  • 7 0
 Perfect for the rider into cheeseburgers and fad diet plans.
  • 3 0
 I resemble that remark!
  • 5 3
 Neat product!

P.S.
@mikelevy you do know you could just have put a weight on the spring and measured how far it is compressed to get the springrate?
(Weight/(uncompressed - compressed length))

Did you measure of the springrate change was consistent across the usable range of the spring?
  • 7 4
 Didn't think that one through did ya? Try placing a 380lbs weight on top of a spring without it toppling. Or accurately measuring the compression for a lower weight...
  • 4 12
flag BobLogiii (Dec 1, 2019 at 3:42) (Below Threshold)
 @sebazzo: You weigh 380 pounds. Cool.
  • 2 5
 This! Would love to see a 2-axis chart with pound applied vs compression distance, measured at varying settings of their adjuster. Regular coil springs will show a linear curve but my (completely uneducated) guess is these will not.
It's fun theorizing about what curve I'd expect them to show but the proof is in actual physical measurements...
  • 4 0
 @Lankycrank: this is linear too. Just a different slope.
  • 1 0
 @Austink: I know they say it is. And probably it is! But I'd still like to see a real life test chart, comparing compression distance to pound increase. I was really struggling to understand how this is supposed to work (an offense punishable by downvotes! :-P ) and seeing the proof in the numbers will help me 1) eat my humble pie and 2) understand better. Cheers! :-)
  • 1 0
 @Lankycrank: the spring rate is constant on the coil itself. So regardless of where the device is set it is linear. By essentially cutting off part of the spring by limiting it with the device, you are adjusting the slope of the graph. It isn’t a progressive spring, it is just adjusting the spring weight by limiting the number of coils that are allowed to compress.
  • 1 0
 @Austink: Thanks – that makes total sense! Sorry, took a while for the penny to drop.
  • 2 0
 great idea! As many of us have experienced, adjusting the preload is not the right way to tune the spring stiffness. Sprindex does something completely different, altering the lenght of the spring you can actually modifiy the spring rate without loosing the zero-load. Simple but clever
  • 1 0
 This is an interesting concept for sure but how does it hold up out in the field?

Also are there any other options for progressive springs besides MRP? My bike is a regressive single pivot but my ride style lends itself to a coil shock. Any thoughts or experience here?
  • 3 0
 One solution for your single pivot would be an EXT shock. It's the only progressive damper on the market, and deals with linear and regressive designs like a champ! Give them a look. They truly are amazing. The Suspension Syndicate in Salt Lake, UT can help you out
  • 1 0
 A cheap experiment would be finding a old 5th Element coil shock and try that.. They were not high speed/ low speed but a beginning and end stroke compression. Add end stroke compression to make up for the regressive trait of your bike.
  • 4 1
 Reasons to use air sprung suspension:
1 weight savings
2 adjustability
3 pedalling platform
4 cost savings (it came with the bike at time of purchase)
  • 4 0
 Pedalling platform is present on Super Deluxe RCT/Ultimate in coil form and Fox DHX2 (in coil form), so that point is moot. And many bikes come with coil springs these days as well.
  • 1 5
flag Golden-G (Dec 2, 2019 at 5:17) (Below Threshold)
 @Primoz: pedalling performance of an air shock is superior to a coil shock. No comparison. Definitely not a moot point.
  • 2 0
 @Golden-G: How? If you flip the switch, you close off the compression circuit. Yeah, the air shock will have more friction in the seals, which is another damping factor. But nevertheless, the compression switch is the major force factor here.

Besides, good bikes don't need switches, so it doesn't matter if it has a pedalling platform or not or a coil or air spring.
  • 2 0
 @Golden-G:
Depends on what performance you are talking about.

Preventing the bike from moving while you stand and smash the pedals? I'd say that's "pedal platform" which actually comes down to the damper, not the spring.

Coils maintain better traction due to less friction. I've climbed lots of stuff on a coil that I always loose traction on my air shock with. If anything, I felt like the coil had the most noticeable improvement while climbing.
  • 1 0
 @MikeG156: Makes sense, with climbing you have relatively low speed, low impact movements when tracking the terrain plus the low speed nature of movement as well from pedalling, moving your CoG around, etc. The 'handling' aspect of suspension performance as opposed to bump performance.

With the small bump performance being more critical when climbing, having less seals that are all in an oil bath (damper circuit) as opposed to additional less well lubricated seals from the air spring will of course be only helpful.
  • 2 0
 That's a lot of words to say it changes where the spring is active... Ever cut the coils on a car? Then you know what that does to the spring rates! Yes, old 5.0L Mustang owners, not the same as real lowering springs...
  • 1 3
 Cutting coil does nothing to spring rate, it only makes it pretty hard to seat straight in the shock perch and is more likely damage it, why anyone would do that if you can buy lowering springs for less than 200dollars I sure as hell don´t know.
  • 2 0
 @Mondbiker: Cutting coils increases spring rate. But cutting most OEM springs leaves you with a too soft of spring for the amount of lowering it'll create, so lowering springs is definitely the way to go.
  • 2 0
 @acedeuce802: well, if you remove part ot the spring out it basically does the same as this device here than, just in much less sophisticated way, reducing number of active coils? As it doesn´t change any other determining factors such as wire dia, material etc.
  • 1 0
 How is it that I put a lot of thought into spring rate & sag-setting on my DHX2 only to find the collar has backed off and the spring is rattling around at the end of a run? At that point I twist the collar so it's 'pretty firm' and ride along until the next time....not very scientific. That's the thing about coils - they feel good, but intra-ride setup usually comes down to setup-by-feel. I'm def not getting the performance out of the thing and couldn't tell you where I'm at re: lsc/lsr/hsc/lsc. I just slow down rebound a bit and ride off a jump. Then I run into a guy who says "speed your rebound way up to recover faster in this stuff" This is why they sell a metric shit-ton of air shocks to the masses. Way easier for punters. Like me.
  • 3 0
 Why are there so many great things that I want to buy? I've only just got a Shockwiz 3 years too late, now this? Ha ha.
  • 1 0
 Was the shockwiz worth it?
  • 8 0
 It took 3 years for your friend to convince you eh. Only took 3 months for me to convice my buddy to buy it so I can... ...
  • 6 2
 @chyu: I rather get my suspension tuned by Voursprung for the Price.
  • 1 0
 @nedsded: It is a cool idea and before I read it I was wondering how it can be possible to alter the rate given the wire is not changed. I am happy to have had my eyes opened.
But I agree with you that a single coil on the right shock, properly set up, would be all you would need.
I guess the point of this is you get some tunability at the shop and also people like to tinker. Also I had a coil on my previous bike which was set up for me at 72kg. Two years later I was 82kg and it was definitely too soft. I wanted to go up a spring but I was too stingy to buy one so I went with a bit more compression damping instead. This bad boy would have allowed me to just perform a little twist to compensate for all the chickens and creatine.

One more question. Will it be available in colours @pinkbike? A lot of people have to have that Fox SLS spring in orange to match their bike!
  • 1 0
 Sucks you need the 3 way leave to do it tho @nedsded:
  • 1 0
 @nedsded: will update when I've used it, it literally just arrived.
  • 1 0
 So, why isn't it available to fit the sprint I already have?
And nothing to fit a 57mm stroke shock, they're missing a big chunk of the upgrade market by limiting selection so heavily.
  • 7 0
 It cannot really be mass produced for random springs. Each major suspension manufacturer seems to use different diameter for their branded springs. Also the "pitch" (Coils Per Inch) of the springs varies a lot depending on a combination of steel used, coil diameter, stroke, length and rate. In other words, they have to make that plastic limiting bit fit a specific coil geometry and that is all over the place with the springs people already have.
  • 1 0
 What are you saying? It clearly shows that the 65x142mm Sprindex is made to fit a 57mm stroke shock.... sprindex.com/pages/compatibility
  • 1 0
 @aj-allen97:
I'm saying a 142mm spring is too long for my shock.
  • 7 4
 If I understand the concept well that somehow prevents full compression of the coil so slightly reduce travel no ?
  • 7 0
 The length the coil can compress is further than the stroke so losing a bit of the coil length won't matter, just like pre loading the coil
  • 3 0
 Only if your spring fully compresses at full travel which is unlikely to be the case.
  • 1 0
 Another thing worth noting is that the closer you can get to the "correct" spring rate the closer you can get to the correct damper "tune" for you weight, style, terrain etc. thus improving performance even further.
  • 2 0
 Cool idea, but I'd need more spring coverage. For example, if you want a DH spring that can cover 375-400lbs you're out of luck.
  • 2 2
 Road cars more or less don't have torsion bars. Some do (Renault 4 being one example with offset wheels side to side to fit the two torsion bars under the floor of the), but mostly it's a mix of coil springs and air bags on the higher end of the spectrum.

While torsion springs have many advantages (low inertia, giving better suspension performance), they have a massive disadvantage in packaging. They are mainly used in race cars (even then not all of them) since there packaging is not such a big of an issue. They are integrated into the gearbox casing in the rear and the monocoque at the front.
  • 15 16
 Mike, you forgot about coil having another performance benefit: no rebound spike from the bottom out that vast majority of air shocks, if not all, suffer from. That makes the bike more composed and glued to the ground through big hits. Having said that not all coil shocks have been made equal.

The biggest problem with coils is their shaft diameters VS modern frames using yokes. It makes them a no no for many bikes, since the shafts just snap or at least keep developing play at the bushing.
  • 5 6
 Not sure what your on about but I’ve ever seen a coil shock break
  • 9 4
 @freeridejerk888: common problem on specializeds and older konas, especially with cane creeks. Yoke gives plenty of side load
  • 2 0
 @freeridejerk888: Happens actually quite a bit. Cane creek for example had to start making some versions of their CC DB COIL with a larger diameter shafts (9.5mm instead of 8mm).

It depends a lot on how the rear suspension linkages are designed. Some bikes just put a lot of side loads or twisting on the shock. then you get things like:
www.pinkbike.com/photo/17755119
www.pinkbike.com/photo/16387049
(pics from Jeffsy forum thread.)
  • 5 5
 So shitty cane creek shocks on poorly designed bikes. Makes sense @WAKIdesigns:
  • 3 1
 @freeridejerk888: poorly designed bikes maybe, but Cane Creek really isn´t at fault. The shock isn´t meant to take side loads, that just shouldn´t happen. It probably comes down to bearing play and poor bike maintenance in most cases.
  • 4 0
 This is true of pivot frames as well and even led to a recall of push 11-6 shocks. The EXT Storia runs a comparatively massive 14mm shaft to prevent this issue.
  • 1 0
 @freeridejerk888: you need to get out more. Even Friday fails from a few weeks ago shows a guy on a spec enduro snapping an Ohlins shock. It happens more often than you would think.
  • 4 7
 @freeridejerk888: you ride an intense, wouldn’t exactly call that a pinnacle of tech and geometry... Spec over Intense any day for me. Canecreek can be faulted for all inlines but CCDB Coil is the bees tits
  • 1 0
 No shaft problems with an EXT shock!
  • 1 0
 Apparently that’s normal for enduros to snap shocks @mixmastamikal:
  • 1 6
flag WAKIdesigns (Dec 1, 2019 at 11:47) (Below Threshold)
 @beaugnar: how’s your EXT, I am genuinely curious, not trying to be mean. The rumor has it they are leaking.
  • 2 0
 @WAKIdesigns: I do not know where you have the rumor from? Read the test here at PinkBike and the latest one on Bikemag.
  • 2 6
flag WAKIdesigns (Dec 1, 2019 at 13:44) (Below Threshold)
 @G1EXTStoria: you can figure it out if you work for EXT as your shouting username would suggest. it’s a small world. And I asked if it is true, I don’t know if it is. It happens to the best, lots of sht happened with Öhlins air units, Don’t lose your head here.
  • 1 0
 @WAKIdesigns: I have not heard of any leaking. Do you know where they are reportedly leaking from?
  • 1 3
 @mixmastamikal: I asked someone who sells almost everything: which shock should I get: Fox, CCDB, TTX22 or EXT Storia. Heard: Storia works super tits but we had one that leaked... I took CCDB Coil cuz I’m poor...
  • 5 0
 Ccbd is not very good. I’m surprised you went with them @WAKIdesigns:
  • 1 1
 @freeridejerk888: why not ? i owned a vast amount of shocks be it coil or air, my current cc db is by far the best (with fox shocks being always the worst). Very good sensitivity, brilliant control, great adjustability. (with unlimited mana i would have gone ext but the streetpricedifference is more than 300€ around here which i could not justify).
  • 2 4
 @freeridejerk888: is not very good? That is a bold statement. Problems turning the knobs right? It is definitely not pretentious anymore and some people don't like that.
  • 1 2
 Nope. Don’t have a problem turning knobs@WAKIdesigns: has one for a year and it never ever felt right. Many calls to cane creek later it was swamped for a jade. Felt better right away. A few shim stacks later and it was perfect for me. I have a super deluxe on another bike and that’s also blows cane creek out of the water. It just not for me. Maybe pay more attention to your kid and less on what rear shock somebody else likes
  • 3 3
 @freeridejerk888: yes that sounds like you can’t turn knobs
  • 1 2
 Can confirm waki has lost his edge @WAKIdesigns:
  • 1 3
 @freeridejerk888: what do you want me to do? Tell you to read the fkng manual or learn about basic testing like bracketing? It took me almost a month to set up my ccdb, then changed a thing or two, getting a quite good setup after 2-3 months that even the designer of my frame called really good after he took a few laps on it. The hardest was getting the rebound right. But unlike virtually every other shock out there, you can buy it and it can be set to suit your frame and what you think are your preferences. If you have serviced CCDB right and it still didn’t work, sent it on waranty andit still performed with no issues and then your Jade suddenly started working great is because someone did the base setup up for you by shimming it right for your bike and the weight of your ass. You just got a few clicks to play with to fine tune it.
  • 1 0
 @WAKIdesigns: while the ccdb is a decent shock, it's not magical and sometimes the adjustement range is'nt doing any good when the bike's kinematic doesn't match. And a well made shock with custom tuning will always be superior to a good shock with great adjustement range. you never set the hydraulic slope with knobs.
  • 1 5
flag WAKIdesigns (Dec 2, 2019 at 10:52) (Below Threshold)
 @faul: well, for most bikes CCDB will be as good as the best in the biz. At least in terms of what you are to do with the bike on the trail, not what you will see in some lab. The point of diminishing returns with nerding out on stuff like that is often closer than farther. Now on some bikes EXT or TTX22 (or insert whatever you find superior) can actually outperform CCDB in a perceivable and measurable manner but chances of that are so low that we may as well generalize that compared to stupid air shocks from RS and Fox (with exclusion of X2) CCDB coil is a rather evident upgrade.
  • 4 1
 @WAKIdesigns: I think the ccdb is a really great shock, especially for the money but to say that the ext and ttx "may" outperform it on "some" bikes just shows how clueless you really are. People, let's quit feeding the troll.
  • 2 3
 @mixmastamikal: except I rode it for a whole day... keep fueling your self preservation instinct and post purchase rationalization. keep this shit for your wife and friends.
  • 3 1
 @WAKIdesigns: Oh I bet you did. . . I am sure it was custom built for your weight, riding style and frame kinematics as well. I am sorry but it grows increasingly apparent with every comment that you are completely full of shit and just like to hate.
  • 2 4
 @mixmastamikal: no. I just happened to weigh the same and be pretty much as tall as the owner of the bike it was on. Sorry... oh, it didn't really make me Remy Metallier... I expected as much. Keep living in your litle world. What hate sort of hate are talking about, stop talkign like some emo imbecile. Do I hate EXT? No I have absolutely nothing bad to say about it. Hell I'd want one! Maybe I even will this year. You make some bizarre claim as if EXT was tons better than CCDB or DHX2 which it isn't. It can't be. And then you talk to me as if I compared DHX3.0 from 2005 to your beloved EXT. You know, i think Fox 36 Grip2 is better than Lyrik Ultimate. And so fricking what? My world doesn't fall apart like some whiny nerdy dweeb because I don't own one?Get some bloody perspective, zoom out, you have to know whether you are comparing apples to oranges, grapfruits to melons, or satsumas to mandarines, because you are just doin the latter mate... get a grip of how broad reality is
  • 2 5
 @mixmastamikal: www.instagram.com/p/Blx3UufhYCT I am so sorry for you... I'm suuuch a hater mheee mheeeeeee oooh can't take it, offended sbnowflake is melting mhwaaaaaaa mheeee, someone doesn't suck balls of EXT which I cherish so very much mhweee mhweeee. Compared my beloved EXT to a Cancreek, EXt lives matter, fight for Extgender rights noww mheeewwwww
  • 5 0
 @WAKIdesigns: Dude, the first comment you made related to the EXT is that there is some rumor going around that THEY leak, when you actually heard second hand from 1 person that they had 1 that was leaking and you don't even know how or where from. I have had both the CCDB and a Float X2 both custom tuned and very impressive but after trying both the Storia and Arma on multiple bikes that I have rode with several different shocks on I can say it is a different ball game entirely. You act like EXT is just doing custom tunes to a twin tube damper like everyone else and completely ignoring the completely unique technology they are using including hydraulic bottom out and progressive damping circuit. But hey "keep fueling your self preservation instinct and being broke rationalization. keep this shit for your wife and friends". I am done here.
  • 2 4
 @mixmastamikal: sorry mate you just came here to say how much you know about suspension and love your EXT. You just can't cope with someone not liking EXt, don't you? Because you just find it so ground braking don't you? I'd love to see you put that different ball game into action on one vs another. Yeah... keep it to your friends who will highly possibly not buy what you buy, no matter what it is. What we do care about though is that you like your bike. It is good to hear someone being proud of something. Why wouldn't we be? Unless you start telling it inot our face that youir shock is in os much totally different ball game. Some will get offended, some will think you are a lunatic. Like I do. BW, I prefer DHX2 over CCDB - it's a whole another game on jumps... but my bike came with CCDB because it is almost as good, within first world problems threshold and half the f*cking price... I know folks like you. We have a dude with Push Eleven Six... a dude with Enve wheels, everytime someone buys something expensive it's a game changer. Wow. What a pattern. I truly envy you. I got my Carbon Jack and I was like: f*ck, can't fit the dropper due to that stupid seat tube... and I wish it was alu... then I rode it and more I rode it the more I hated the Lyrik... and the Hope crankset. I can't I just can't be non critical and go tell everyone my bike is best! oh the kinematics! I bet your bikes have best kinematics out there...

Love ya
  • 1 0
 Exactly why my jade blows it out of the water. Seemed better for the frame I’ve tried a few cane creek equipped bikes and they just weren’t for me. @mixmastamikal:
  • 1 0
 @WAKIdesigns: it's amazing. Truly different than other shocks. I haven't had our heard of any leaking. We're they leaking from, just curious.
  • 1 0
 I'd like to see the slow-mo camera footage of the "huck to flat". If a rider has a lot of preload on their spring, wouldn't it be possible to shatter those plastic pieces?
  • 2 0
 Good question, but no, the plastic pieces won't get damaged even with heavy pre-load. However, now that the spring rate can be adjusted, no reason to overly preload. Preload messes up small bump sensitivity.
  • 2 1
 Lb/in, not in/lb. All through the article.

The RS Pike U-turn mechanism effectively does the same thing, increasing spring rate, but also shortening the spring.
  • 1 0
 It was driving me crazy too, enough to double check.

“ Spring rate refers to the amount of weight that is needed to compress a spring one inch. If the rate of the spring is linear, its rate is not affected by the load that is put on the spring. For example, say you have a 200 lb. per inch spring - it will compress 1” when a 200 lb. load is placed onto the spring. If another 200 lbs. is put onto the spring, the spring will compress another inch. At this point the load on the spring is 400 lbs. The rate of the spring, however, remains constant at 200 lbs. per inch.”
  • 1 0
 I am happy to see Springex gets it.

“For example, Sprindex adjusted to 360 lb/in spring rate performs exactly the same as a custom made ordinary spring that has a 360 lb/in spring rate.”
  • 1 0
 It's actually increasing spring rate BY effectively shortening the spring. One comes because of the other, not with the other.
  • 1 0
 @Primoz: I meant ride height, this obviously shortens the spring but keeps the ride height the same, the Pike lowered the ride height
  • 1 0
 @Bahh: That i agree. Though to nitpick, this thing changes the ride height as well, since the sag point changes Big Grin

(I'm going to hell.)
  • 1 0
 If this deactivates the last coil and a half, is there concern about bottoming out the spring before the shock has fully compressed?
  • 5 1
 If they thought about it for more than 5 sec, the spring you'll receive will have enough stroke to use the spacer maxed out without worrying.
  • 2 0
 What a time to be alive. Making airsprings feel as close to coils while making coils feel like airsprings.
  • 3 0
 @liketoride1: Everyone trying to combine the best from both worlds, who would have thought!
  • 2 0
 This is legit so genius in the simplest way it makes me want to order a coil for my SB130. Bravo.
  • 2 0
 Someone please put a cage around that 'spring-rate-O-meter' machine before OSHA sees this.
  • 1 0
 I had a friend who was testing this a it really works well. Its nice not to have to change the spring when you ride different trails.
  • 1 0
 Same thing as cutting a coil off of a spring for lowering cars if you do it right. Had a debate over that in statics with some other adult students.
  • 17 17
 It's a neat idea and everything, but am I the only one that thinks $140 for a steel spring and a piece of glass reinforced plastic is a little much?
  • 7 8
 must be only us germans.

imo 10-20€/$/... would be a good spot. but who am i to judge.
  • 27 0
 Light springs are usually around 120€ here so does not look out of line
  • 9 0
 Realistically the sales volume isn't gonna be that high so the margin per unit has to be higher.
  • 8 0
 When you factor in the spring it's hardly a massive additional outlay imo...
  • 9 1
 if you look at what fox sls spring or mrp progressive springs cost it´s ok. They do look pretty cheap though with that plastic collar, maybe they should make it in black rather than grey.
  • 3 5
 Honestly, I can buy 3 different steel springs with this price, or a titanium one...
  • 14 1
 @Monacchesi: of course, but you can’t alter each of those spring by 10lbs can you? Nor can you swap those springs tool free... nevermind do it 2 seconds trailside.
  • 8 0
 It’s a great bike shop service. Buy a new bike, use this spring to dial in for correct spring, then switch out to a standard spring.
  • 3 0
 @B650wagon: and find the one that fits you and then get it in ti
  • 1 0
 @optimumnotmaximum:
I´m sorry - I think i got the concept of the product now. forget what i just said (yesterday´s me is a moron)
  • 1 0
 This is neat. And you really got me intrigued about that 180mil rig you're teasing...
  • 3 2
 Hey @mikelevy spring rate is lbf/in and not in/lbf, I guess you flipped it without noticing
  • 1 0
 Perfect! Just after I ordered a couple of nukeproof springs on crc because black friday. Not coil at all! ????
  • 2 0
 Game changer product!!! Its rare, but sometimes it happens.
  • 2 0
 Damn. Why didn't I think of that?
  • 1 3
 The fail is the pricing and only offering it with a spring. It’s an injection moulded part. Sell us the plastic bits. I already have a spring, and it’s ti, don’t need another spring.

Once tooled up those plastic parts are dollars each. Could sell tons to all the coil spring riders out there
  • 5 0
 Your Ti spring has a different number of coils than a normal steel spring. Or the Fox SLS spring. Or their spring. Etc. You'd need a different part for every different spring offered and for every stiffness of it as well. Then you ca't control how the spring will behave - will you bottom it out or not. With offering their spring, they have that control.
  • 1 2
 Some pretty large gaps in available spring rates. Makes it a nice idea but a hard pass. I also feel like blocking the coils this way could bend the spring and wear the shaft bushing.
  • 1 0
 The effectively shorter spring should only be more stable, if anything.
  • 1 0
 @Primoz: Springs used on mtb shocks are close ended and square ground to keep them square and stable when compressed. Blocking the coils will make the spring act like a open coil and unstable without being supported by something else. That something else being your shock.
  • 1 0
 @Erotomania: The flat ground ends of the full spring are supported by the coil shock as well. And in this case the coil itself is supported. The thick part, not the ground off part.

Plus, stiff mounting of the ends of the spring also causes spring deflection, it's just in a different shape (the equation to determine the amount of it uses different factors depending on the mounting conditions).
  • 1 0
 @Primoz: No, the coil isn't supported, it is being blocked. It causes the spring to bend just like compressing a single coil would. MTB coil shocks aren't designed to stabilize the spring, and that's why they use close ground springs.
  • 1 0
 @Erotomania: Indeed, it's being blocked. By a coil-ish like piece of plastic, that goes in between the coils of the coil spring. Preventing in from moving. By... supporting it.

So you're trying to say by supporting it with a piece of plastic higher up in the winding it's not supported? And that a blockage is not a support? Can you please elaborate on that concept?
  • 2 0
 @Primoz: The coils are at an angle. The ends are tightly wound and ground level. If you block or "support" any part of a coil, it is now compressing to the angle of that coil and not the ground end. The plastic insert increases the spring rate, just like if you were to cut a coil off of a spring. In both cases you have an open ended spring, which is going to increase wear or damage the shock.
  • 1 1
 @Erotomania: you didn't say anthing right there, at least not anything to answer my question.

The tightly wound ends of a coil are also 'blocked' by your logic. Plus there are coil springs that are not ground on the end. Depending on the application, they work just fine. In most cars,t he supporting 'cup' is actually shaped in such a way to support a cut off end of the spring without any changes in winding pitch. So, kinda like what this does. And it works just fine.

So, if you want to make your point, please try again.
  • 2 0
 @Primoz: Man, this back and forth is exhausting. If you think it's a sound application, go for it. In other applications using a cup, its between rather strong suspension arms or between a strut. Struts support a spring, shocks do not. The cup on a open coil spring does not make it a closed coil. MTB shocks are shocks and not in any way robust enough to handle any side loading from a spring. The end treatment on mtb coil springs is about the best way to take stress off the shock. The insert may keep the spring from jumping out of the shock, but the active coil is still open ended.
  • 1 0
 @Erotomania: I'm running an air shock and will for the forseeable future. But that's beside the point.

The 'open ended spring' you're mentioning for cars is also used in the rear of many cars, where there is no strut or shock going around it. Plus the ~15 mm of shaft diameter of the strut in the front of a McPhearson shock is nothing compared to ~100 mm of diameter of the spring going over it. If you want to support the spring in the middle, you need to have a fairly tightly fitting rod going through it (that way you get spring rub, like it happens on MTB shocks).

What i'm trying to say is that i fail to see the point how some grinding can make the spring more stable than supporting it directly on the coil, directly on the shape of it. Even more so when that support is higher up, making the coil shorter and effectively more stable.
  • 2 0
 it used in motorcicles spring. is not a new inventions
  • 2 0
 I haven't been able to find any motorcycle equivalents. Could you perhaps point us in the right direction?
  • 1 0
 Highest spring rate for an Enduro rig is 500-550. What a bummer. I'm at 30% SAG with a 550. Any lower wouldn't be cool.
  • 3 2
 Can only imagine the crunching and grinding in a muddy ride. Pass.
  • 2 1
 How long before the 3D printer guys make this for a few bucks?
  • 3 0
 It is already a few bucks , the light coilspring costs the money
  • 1 0
 @optimumnotmaximum: Why do we need their spring? Did I miss that part?
  • 3 0
 @noapathy: Reasonable question. You need a spring that is wound to achieve the stated rate, but will not coil bind at full shock compression with the Sprindex device maxed out. Pairing their device with the correct spring is the only way the mfgr can be sure of that.
  • 1 0
 @RichardCunningham: Thanks. That actually makes a lot of sense.
  • 2 0
 Good questions. Our spring had to be custom in order to be designed to be properly stressed at full stroke when adjusted to the maximum spring rate. If you added the mechanism to your existing spring, you would highly overstress that spring. Additionally, the mechanism itself blocks about 1 full coil even when adjusted to the minimum setting, so adding the mechanism to your existing spring would increase the minimum spring rate by a lot. Our spring is made with the same expensive high tensile steel used in other "lightweight" springs.
  • 1 0
 I’ll buy it if you make it in black...
  • 1 0
 I don't always ride coil, but when I do, I ride Sprindex.
  • 1 0
 I ride Spandex Big Grin
  • 1 0
 It wont make your spring more soft, it only stiffens it.
  • 1 0
 Unwind it to zero and it will make it softer Smile
  • 1 1
 Before, Air shocks wanted to work like coil. Now, Coil shocks wanted to work like air. Make up you mind!
  • 5 0
 Its almost as if both options have pros and cons.
  • 1 0
 Is Marge Gunderson running Pinkbike now?
  • 1 0
 does it come in a metric version too?
  • 1 2
 My DVO Jade X that came on my Ripmo AF was adjustable by hand almost all the way down the threads (didn't go past 3/4 of the way down) Am I missing something?
  • 2 0
 Yeah. Preload vs. stiffness adjustment.
  • 6 9
 Texas sized 10-4 on this! Same thing as adjustable ride height coil overs for trucks. Its the same thing, only you use a spanner wrench to adjust the collar for ride height. What took so long? lol
  • 3 0
 That collar on a truck coil over is adjusting the preload, just like on every coil bicycle shock, so it's not at all like this.
  • 1 3
 One thing missing from the article-Sprindex is run by the two original owners of Crank Brothers. Let’s hope their QC is a little better this time around.
  • 2 1
 Well this has nothing to so with pedals so they should be fine. IMO everything that wasnt a pedal or a seatpost from CB was usually innovative and worked just fine.
  • 1 0
 @nouseforaname: I recently saw a CB pawl mechanism deform and break while pedalling easily up a fireroad on its third day of use.
  • 3 4
 Garbage product of the year. Ignorant market.

www.peterverdone.com/springs-cause-its-spring
  • 1 0
 holy shit what?

so you ride air sprung-bikes then?
  • 1 1
 @owl-X: I don't understand your point.
  • 1 0
 @pvd666: i guess i'm asking if you still ride coil-sprung bikes, and if so, do you test each one and re-label them with accurate numbers?
  • 2 0
 actually your link proves that this system that actually stiffens the spring rate is better than swapping springs that may be too off from rated rate.
  • 2 2
 I rate all coil springs that I use on bicycles or motorcycles. Any real performance shop would do the same. If you aren't getting your springs measured, you're probably working with novice shops.
  • 1 0
 @pvd666: if the bike's set up right, sag and all that, why would you need to consult with SI in Paris to pinpoint the true numbers? Like, my bathroom scale's off, but it's the only one I use so that seems okay...
  • 1 1
 @owl-X: That may be ok for you but I work with high performance setups and development. I need better and more predictable results than the average consumer. If 'just ok' works for you then you're all good.
  • 1 0
 @pvd666: cool. Just checking. Blog on!
  • 2 4
 A coil-spring is linear right?
So how does adding preload change the sensetivity of the coil?
  • 5 0
 Linear in that it requires the same amount of force for each inch that it compresses... a 400lb spring means it requires 400lbs to compress the spring one inch, then another 400lbs to compress it a second inch, then another 400lbs to compress it a third inch... a progressive spring like an air spring would require 400lb for the first inch, then > 400lb for the second inch, etc.

And this isn't adding preload, it's reducing the number of active turns meaning that the lower portion of the spring cannot compress so the portion of the spring actually moving is shortened. Reducing the amount of coils that can compress will increase the amount of load required to compress the spring the same amount because those fewer coils will need to compress further to achieve the same overall compression.
  • 4 5
 If you preload coil it´s like you have already compressed it, if you preload 500lb spring by 2.5mm it´s like 50lb already compressing the spring, so to actually compress it at all you now need to load it with 50+lb (+ whatever it thakes to compress shock itself, which differs but can be calculated from IFP pressure and shaft dia). With 0 preload only thing you need to overcome is friction from seals and force generated by IFP pressure.
  • 6 2
 @Mondbiker: incorrect, when you preload a spring the load is still distributed over the same number of coil turns so it still requires the same load to compress it one inch. By reducing the active coils, each individual coil has to compress more than originally intended, thereby increasing the overall force required to compress the spring one inch.
  • 2 1
 @badbadleroybrown: You either don´t know what preload is or I don´t know really...But it´s not that hard to try at home, feel free to do so and report back how it´s just as easy to compress preloaded spring and unpreloaded one, or just watch the video.https://www.youtube.com/watch?v=uUGRbaWlH8M
  • 1 0
 It would be nice if the testing included setting the longest spring to 600lb, and then measure the compression lengths for forces between 0 to 1800lb (assuming 3" stroke). That would give a good picture about the linearity of this solution.
  • 4 1
 @Mondbiker: I'm well aware of what preload is and of how it impacts the spring... it doesn't change the spring rate. Reducing the number of active coils does and isn't remotely like preload. Really not any way to say it more simply, but you not understanding that doesn't change that it's a fact.

No matter how much you preload a 400# spring, it's still going to require 400# to compress one inch. If you have 5 turns of coil on a spring and block one from moving, the other four will need to travel 25% further to achieve one inch of compression overall which raises the spring rate required to compress the spring by one inch...
  • 1 2
 @badbadleroybrown: I never said preload changes spring rate either, I said it affects break away force...
  • 1 0
 @Mondbiker: break-away force is determined by friction, not the spring. Completely unrelated to preload.
  • 1 0
 @badbadleroybrown: a preloaded spring will have a higher break away force. With no preload the force needed to start having travel is the force of friction or better yet, stiction (coefficient of stiction is higher than friction for most material, Teflon is one of the few that has both the same). With preload, until you get over the preload force plus stiction force, you don't move.

But yes, this does not add preload, this removes active coils and changes the spring rate. I think you guys have a general misunderstanding here.
  • 2 0
 @badbadleroybrown: this has got to be the best explanation about how this device works in the entire comments section (and the article for that matter)
  • 1 1
 @badbadleroybrown: " break-away force is determined by friction, not the spring. Completely unrelated to preload." Uhuh, I think at this point I will just leave this discussion.
  • 3 1
 @badbadleroybrown: you seem to understand how this product works, but what you're saying about preload doesn't make sense. Take a 400 lbf/in spring, preload it a full inch. now you have 400lbf stored in the spring (400 lbf pressing the spring seats apart), to compress the spring another inch you are going to need to apply 800 lbf. If you apply any less than 400 lbf the spring will not compress at all. This is why excessive preload makes a harsh ride, it feels a lot like (but is not the same as) stiction. Preload does not change the spring curve, just chops the supple bottom end of the curve off.
  • 2 0
 Granted, when you're at the sag point, the break away force is defined by stiction. With a preloaded spring the sag point will be different, but nevertheless, the stiction force will be the same.

For dynamic systems you usually look at oscilations around the neutral (i.e. sag) point, so the preload will just move your zero a bit, but not change the dynamics of the system, if the weight and spring stiffness are the same.
  • 2 1
 @arden0: read the last sentence of your post... you just explained it to yourself. In reality, you can't crank that much preload into a spring but, overall, you summed it up; you're not changing the spring rate you're just changing the point at which the bike sits in within that rate.

You can take your weight, the leverage ratio of your bike, your desired sag, and determine what % of that initial 400lbs you'll need to preload into the spring to support your static weight at your desired sag. Preload is a fine tuning adjustment to dial in sag and provide negative travel for the suspension. This approach limits the number of coils moving forcing each individual coil to travel further in compressing one inch than they otherwise would, thereby increasing the force required.

For a practical example, think of it this way... a 150lb rider runs a 300lb spring. If he throws on a 30lb pack and rides, no amount of preload adjustment is actually going to increase his 300lb spring rate so his new 180lb rider weight is going blow through travel and bottom out regardless of whether his sag is reset correctly. But if his coil spring uses 6 turns and he blocks out one of them from moving forcing the other five to travel further, he'll increase his actual spring rate to the 360'ish range and be able to ride with proper suspension support throughout the travel.
  • 1 2
 @badbadleroybrown: yeah, I understand, the sprindex reduces the number of effective coils, increasing the spring rate. I also understand preload.

I was just trying to clear up what you said about preload because it is wrong, at least missing some additional qualifiers and explanation...
"No matter how much you preload a 400# spring, it's still going to require 400# to compress one inch."
  • 2 1
 @arden0: see, you say that but you clearly don't understand preload if you doubt that no matter how much you preload a spring it will always still require the same weight to compress it one inch. All preload does is create a small amount of initial compression, it doesn't do anything whatsoever to change the spring rate. Whether you preload a 400lb spring by 1/16th of an inch or by 1/4" or by 1/2", that spring will require that spring still requires 400lbs to compress one inch total. That's a fact buddy, you either understand that or your definitely don't understand preload.
  • 1 2
 @badbadleroybrown: OK bro... again, I understand, please stop trying to explain. Your last comment gets at the root of the problem here; [a 400 lbs/in spring] "requires 400 lbs to compress one inch total." That last word wasn't in your previous comments and makes all the difference. You seem to be including the preload distance in your total compression distance, while anyone who talks about springs in a meaningful way would not. You're not wrong, but what you said seems likely to give people the wrong impression about preload.

To compress a preloaded spring by one inch you need to apply the spring rate plus the preload force. Using our 400 lbs/in spring, with say 50 lbs preload, you'll need to apply 450 lbs to compress it by one inch, and 850 to compress it by two inches.
  • 2 0
 @arden0: Are you sure that's correct ? I'm not doubting you but it somehow does'nt seem correct as regardless if the spring is preloaded or not its still going to take the same force to compress one inch is'nt it ?
  • 2 1
 @arden0: your inability to understand the simple concept of one inch of compression doesn't change the accuracy of my statement. Regardless of how much you preload a spring, it's not changing the spring rate. A 400lb spring will always require 400lb to compress each inch, regardles of preload. It doesn't become 450lb because you preload it... you don't add the preload force and putting 450lb would compress the spring more than one inch. You keep saying you understand and yet, you keep illustrating that you don't. A 400lb spring will compress one inch with 400lbs placed on it... preload does not change that.

Is English your second language, is there another language I can explain it to you in that you'll have a better chance of understanding?
  • 1 1
 @Campagnolo123: we're both correct depending on how you measure the spring travel. If you're just talking about spring compression compared to it's uncompressed, unpreloaded length, then yeah the spring will be compressed by one inch when the rated force is applied regardless of preload, but that's not particularly useful when talking about suspension and defeats the purpose of talking about preload.
If you want to compress the spring a full inch compared to it's preloaded length, you'll need to apply the preload force plus the rated spring force. If you want to compress a preloaded spring you have to first overcome the preload force, otherwise it won't move at all.
  • 1 1
 @badbadleroybrown: You can try french, I bet it'd be worth a laugh.
Just going to clarify your last post for any sad reader who made it this far; "A 400lb spring will compress one inch [compared to it's unpreloaded length] with 400lbs placed on it... preload does not change that."
  • 1 0
 @arden0: are you actually retarded or do you just play the role of a retard on pinkbike? The springs length doesn't change from being preloaded. A 9" x 3" spring is still a 9" x 3" spring regardless of how much you preload it and if that's a 400lb spring, it's still gonna require 400lb to compress one inch, then 400lb more to compress a second inch, then 400lb more to compress the third inch. No matter how much you preload it, that doesn't change.

We're not "both correct"... All this shit about "unpreloaded length" is just you trying to avoid being wrong by doubling up on being stupid. Preload works by compressing the spring to fine tune your sag point, it doesn't change spring length or spring travel or spring rate. A spring being compressed 1/8" by preload does nothing to change how much load it requires to compress one inch.
  • 1 0
 @Campagnolo123: to compress it any given inch, you need an additional 400 lbs of force, regardless of the force before. For the first inch with no preload, you need 400 lbs. With 50 lbs of preload, you need 450 lbs to move it one inch (effectively 1,5 inches).

Why the hell are we using inches and pounds???
  • 2 2
 DIE AIRSHOCK DIE
  • 11 0
 'the airshock the'?
  • 1 0
 Never gonna happen. In some linkage configurations it's so much better than a coil it's not even funny.
  • 2 0
 @onemanarmy: This is just my opinion but some frame manufacturers may well stop producing frames compatible for air shocks and start producing more for coil over dampers, then we can all gete the benifits of a coil shock, but this is just my opinion.
  • 1 0
 @onemanarmy: probably never gonna happen thats right. linkage configurations dont have to stay that way though. a nice constant progression around 20% overall has very little downsides paired with a coilshock. and the product tested here would allow a springrate from 430 -500 lbs on my specific bike and weight, thats all you can ask for. if you want to make your shock firmer you dont even need a pump ( and the fiddling with pressure). so its a great product for the future of trail -coilshocks.
  • 1 0
 @optimumnotmaximum: Current trend seems to be requiring MORE spring rate, not less.

Adding air to a shock takes like 30 seconds before a ride. Easy. Using the standard air pressures you should be able to get pretty close on the first go. Mess with it a bit. Sag it.... etc. Spend a few minutes getting it set up and then you know your pressure. If after riding it you think it needs more or less you figure that out. Then you know your pressures and you just check them every now and again. Really shouldn't change much.

I think people get too stressed out about it. Air pressure is the easiest part of setting up a fork/shock.
  • 1 0
 @onemanarmy: not sure what you mean by more springrate, if you mean bikes get more progressive i also think that this is the case (starting leverage rates seem also to be going up again, with some doing the opposite). More progressive layouts favour coil, while higher leverage rates help airshocks to overcome their stiction, although the 3.3 startingrate on my tyee was not enough to overcome the stiction issue of my dpx2. Even riding agressively one should not need more progression than 20% on a 160 bike with coilshock. And then if you ad an adjustable hydraulic bumpstop this should be even better. I have no big problem with handling airshocks, pumping up a shock to 300 psi is not fun though ( my tyee requiered 290-300, with me weighting just 170 pounds). My point was that this makes setting up a coilshock easier than a coilshock, even its not by much. I know airshocks have their fans and some bikes dont get along with coilshocks. They never feel right for me though.
  • 1 0
 I meant easier than an airshock obviously
  • 3 6
 Ingenious and legit product, but $140 bucks for plastic?
  • 2 0
 build your own then, it’s just plastics right? everyone with a 3d printer can build one, it’s just plastics, right? /s
  • 1 0
 Good question. Our spring had to be custom in order to be designed to be properly stressed at full stroke when adjusted to the maximum spring rate. If you added the mechanism to your existing spring, you would highly overstress that spring. Additionally, the mechanism itself blocks about 1 full coil even when adjusted to the minimum setting, so adding the mechanism to your existing spring would increase the minimum spring rate by a lot. Our spring is made with the same expensive high tensile steel used in other "lightweight" springs.
  • 1 1
 @Sethimus: It is about how much does it cost to make them. I'd bet they would sell way more if the price was lower.
  • 1 0
 @tacklingdummy: the spacer needs to be paired with a properly tuned coil, this is the reason for the cost. Go back and read the comments. There is a lot of nonsense and bickering but some good I go to be gleaned if you sift through.
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