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Video: How Formula’s NeoPos dynamic air volume spacers work

how does the formula neopos soft air volume spacer work in a mountain bike suspension fork
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Formula may be a small company when it comes to mountain bike suspension, but they’re not afraid to go big with new ideas. Introduced in April (but in development since 2011!), the Formula NEOPOS dynamic air volume spacers offered a radically new way of thinking about air volume adjustments. By using a soft, squishy material that compressed along with the air inside your fork, they could provide the benefits of an air spring and adjustable volume, but in a way that (they say) more closely mimics the feel of a coil spring fork. Here’s everything you need to know about NEOPOS and how it works:

The NEOPOS spacers are a closed cell foam with air bubble trapped inside. That air compresses as the same rate as the air that you’ve put into the positive chamber. So, they change their size almost in direct proportion to how much your air compresses…to a point. The spacer material itself won’t compress, so it won’t be an exact correlation, but close.

how do Formula NEOPOS soft air volume spacers work

Because they change shape, they closely mimic a standard spacer through the first part of travel, but end up having less impact at the end of the stroke. Still enough impact to prevent a bottom out, but leaving you with a less harsh ramp, so there’s a more plush feeling overall. The chart below shows how it can deliver a similar end-of-stroke support by adding more air pressure, which is just one way of tuning it. Click image to enlarge:

how do formula neopos soft air volume spacers differ from standard hard plastic volume spacers in a mountain bike suspension fork

Want a softer fork on initial travel with a bit more ramp at the end? Use two or three NEOPOS spacers instead and keep the air pressure lower. It’s all about tuning for your type of riding, weight and trail conditions.

RideFormula.com

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Padrote
Padrote
4 years ago

I really don’t understand this graph. What’s the difference between “volume spacer” and “standard”? Also some numbers would be nice.

robert bullock
robert bullock
4 years ago

@padrote-volume spacer refers to the “tokens” or whatever that come standard with your fox or rockshox fork

RobertW
RobertW
4 years ago

Looking at the graph, I’m more convinced the standard plastic spacers are the way to go, but I’m willing to give the spongy ones a try.

Biscuit
Biscuit
4 years ago

I love that this is essentially the MCUs that Manitou/RockShox used as a spring medium in the mid-90s, also used to affect the spring rate here – things really do come full circle.

Tim
Tim
4 years ago

I’ve been using a similar system I developed myself over the last 18months in my RS-1. It works brilliantly because it reduces the last half of the travel ramp up. Fork feels more supple through the whole travel range.
The shore of the rubber is important but offers an additional point of tuning. I was quite amazed that Fox didn’t go this way with their volume reducers since those are a softer plastic than the Rock Shox VR
Great work Formula!

Tim
Tim
4 years ago

For those of you not old enough to remember, Rock Shox and Manitou used something like these as the main spring element in their forks starting around 1995- there was no air spring in the fork, just a stack of these guys around six inches long. They’d perform well for awhile, but had some deficits. First, they were affected by temperature- they’d turn not quite rock hard in the cold, and very soft in the heat; if you left them in your garage on hot days, they could also melt. Both of these things could happen to Formula’s product. If Formula’s air spacers get cold or hot within certain limits, they’ll have some effect on travel ramp up mid- to end stroke, as the ease with which they compress will change. If they melt, who knows what will happen- could that clog the fork’s internals?
Also, MCUs break down over time from being compressed and then rebounding, i.e. from being used. These Formula air spacers don’t do as much work as a proper spring (they only really get smooshed when the fork is halfway through its travel or so), so the process will happen more slowly. On the other hand, there might be only one or two of them in the fork, so the same impact will be concentrated on just a small amount of material, accelerating wear.

Antoine
Antoine
4 years ago
Reply to  Tim

they won’t wear fast i guess because they aren’t mecanicaly pushed just compressed slightly by the ambient air.

Tim
Tim
4 years ago
Reply to  Tim

Volume reducers are not the spring medium so direct compression as mentioned by Antoine is not going to happen and therefore will not affect performance across a temperature range. Also If Formula are using silicone rubber as I did then temperature performance is even less of a problem, as is mechanical wear.
Air springs work according to PV=mRT (Boyles Law). Each time the airspring is compressed heat is generated. The volume reducers actually absorb some of that heat which maintains the reducers compression performance as well as the airspring. Yes the rubber volume reducers will break down over time but very very highly unlikely to break up within the 120hrs of any standard fork service interval.

Andy
Andy
4 years ago
Reply to  Tim

@Tim ..the formula’s have literally nothing to do with the ones used back in the day…they are silicone foam not rubber.

Tom
Tom
4 years ago

This looks VERY intriguing, since when I install enough volume reducers to get the early and mid stroke “feel” I want, it gets difficult to use full travel.

Phil Rodeo
Phil Rodeo
4 years ago

I don’t get how the foaming of the material makes a difference. Generally, the air cavities inside the material should have the same pressure as the fork itself, and it should raise as the forks pressure rises with compression. I get that the material itself is compressed, too and probably has a different spring rate which can change the overall force-travel curve. But why not just use the non-foamed material?

Andy
Andy
4 years ago
Reply to  Phil Rodeo

Because they wouldn’t compress as the foam ones do. That’s the whole idea about it…duh.

Phil Rodeo
Phil Rodeo
4 years ago
Reply to  Andy

Yeah exactly, they wouldn’t compress as the faom ones do. But imagine one large, can-like structure of the unfoamed material. That would compress but it wouldn’t matter that there’s air inside because the air pressure inside matches the one outside, I.e. in the forks air chamber (as least in equilibrium case, might be different for fast hits). So whether the “can” is a can or just the same amount of material in a flattened out form wouldn’t matter. The only difference to a mostly static token is that the material itself is compressible. My question remains: why foam it? And also, no need for “duhs” maybe try understanding my point?

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