Tuesday Tunes with Vorsprung Suspension

For those that missed it, here's a look inside the FOX Float X2 and Cane Creek DB Air CS shocks. Steve's discussion includes the major similarities and differences between the two, plus well educated opinions about durability and function.

Tuesday Tune #3: Air Spring Volume Spacers



"Air springs and volume spacers are one of the things we get asked about most frequently. This week on The Tuesday Tune we're use real world spring data to take a look at exactly how volume spacers work, how to understand them and how to tune your spring curve so that you aren't endlessly chasing your tail."







This is also a good opportunity to look back on a Vital feature detailing how to get the most out of your RockShox suspension:

The Tuesday Tune Ep 4 - Springs vs Dampers

This episode covers the fundamental differences between springs and dampers:

https://youtu.be/QuPL9x2UcZQ?rel=0&showinfo=0

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The Tuesday Tune Ep 5 - High and Low-Speed Damping Adjusters - Pt 1

Here's the basic theory behind high-speed and low-speed damping and how your adjusters work. This is Part 1 of the HS/LS topic, next week Vorsprung will be delving more into rebound curves and how to adjust high and low speed damping for maximum benefit.

https://youtu.be/JEBNlHXUGdE?rel=0&showinfo=0

The Tuesday Tune Episode 6 - High and Low Speed Damping - Part 2

https://youtu.be/E7veBt1Maj8?rel=0&showinfo=0

This week's Tuesday Tune follows up on the last episode's focus on High and Low Speed Damping and delves into some setup concepts to be aware of. We take a look at the practical ranges of velocities that adjusters actually affect and how to understand that in a way that translates to relevant on-trail adjustment. Also covered is the process of bracketing, which is a relatively foolproof method of setting up each adjuster individually. Bracketing can be used on any external adjuster irrespective of how much you know about the effects of that adjuster - all you need to do is decide whether each change is better or worse than the previous setting. Easy!

There are a few things we need to put out there as well about using this information:

1. Obviously any changes you make to your suspension will change the behaviour of the bike. Be smart about this - don't make big changes then go and immediately send it off the biggest jump you can find without spending time getting used to the setting first.

2. Time matters a lot. Keep the time between changes to your suspension to a minimum, so that you have the best memory possible of the previous setting. Multiple adjustments in a single run are a good way to do that. Comparing setups hours or even days later is a really easy way to confuse yourself.

3. Trust your FIRST impression of any change - it is usually the most accurate one. You'll get used to anything over time, and what felt terrible initially may begin to feel normal as you get accustomed to it... even though it was terrible.

4. Getting someone else to make the changes for you, without telling you what they changed in order to eliminate placebo effects. Then re-read point number 1 above.

5. This is not intended to be a complete or comprehensive coverage of all possible setup methodologies. We do simplify and cut out information just to be able to squeeze it all in. If your on-trail experience does not agree with what you expected based on something we've said, your on trail experience should always take precedence as there's almost certainly a rift in the theory as it has been communicated or understood. In other words, trust your own perceptions.

6. Check your tyre pressures. They make a lot of difference.

The Tuesday Tune Ep 7 - The Less Obvious Aspects of Sag



This week on the Tuesday Tune we're going back to basics - sort of - and looking at some of the less obvious and less commonly discussed aspects of sag setup.

We aren't here to tell you what is the "right" amount of sag - no single number is correct, and what works best varies hugely according to the frame/fork/shock/rider/ability/terrain variables. For this reason, discussing specifics needs to be done in context - 15% sag on your Pike is fine, but that's extremely stiff on the back end of your V10, for example. This video is aimed at those who already have a basic grasp of sag, so we aren't going to show you how to measure it, but if you want to learn more about that, DVO have a short and sweet guide here - http://bit.ly/2hBq1qG

What we are looking at though is what the relevance of sag is, why it's useful as a transferable and comparative value even between different riders on different bikes, how to make sure your measurements are consistent, and what the practical limitations of sag are, both in terms of measurement and relevance to performance. Although it's far from being the be-all and end-all of proper spring rate setup, sag is very useful as a starting point and a baseline indicator of spring rate relative to body weight.

The Tuesday Tune Ep 8 - Why We're Riding Telescopic Forks



For over 100 years, telescopic suspension forks have adorned the front end of motorcycles - and more recently, mountain bikes. For just as long, alternative systems have been proposed, built, tested, sold and usually also abandoned. Most of these alternatives have been some form of linkage fork, using short links, swingarms and pivots just like the rear suspension of your bike. These have invariably been touted as solving problems that telescopic forks have always found it difficult to address, the most notable of which is brake dive - so how did it come to be that we're almost all still riding telescopic forks in spite of their accepted shortcomings?

After all, if you could remove brake dive from the equation as a variable, it should be much easier to find spring and damping rates that allow for better bump absorption and traction since the need to compromise on sensitivity in order to support the fork under hard braking is eliminated.

This is a more complex question than it may first appear. After all, nobody is using telescopic forks for the rear suspension - that idea died with the old Manitou frames. Why is it that we can easily accept linkages as a viable system for minimising unnecessary motion of the rear suspension under acceleration/braking, but not for the front? What is it that linkage forks are yet to get right in order to achieve the level of performance and commercial success that their respective engineers always thought possible?

We suggest that the answer lies in two related aspects: the steering axis's relationship with axle path, and the number of design variables. This week's Tuesday Tune is about understanding how telescopic forks came to dominate the market in spite of their widely known and inherent compromises in performance.

Note: there won't be a Tuesday Tune video next week due to the holiday break. We'll be back in a couple of weeks to bring you more tech ramblings!

The Tuesday Tune Episode 9 - Single Tube and Twin Tube Shocks



"Pretty well all the shocks currently on the market in the mountain bike world are one of three basic forms:

1. Inline/monotube, eg Fox's Float RP23/CTD/DPS series, Rockshox's Monarch RT3 or X-Fusion O2
2. Single-tube (with separate or piggyback reservoir), eg DVO Jade, Fox RC4, BOS Stoy, Ohlins STX
3. Twin-tube (again with separate or piggyback reservoir), eg Cane Creek Double Barrel series (including the Inline), Ohlins TTX, Fox DHX2 and Float X2

The major defining difference between inline/monotube shocks and the single-tube type, as we're discussing them here, is that monotube shocks only have a single damper piston, and the IFP charge is the only thing providing pressure to force oil through the piston in compression. We won't be discussing those today. Single-tube types with a base valve (a second compression circuit usually mounted in the reservoir bridge, and which is usually the external compression adjustment) are a common configuration for mountain bike shocks. Twin-tube dampers are often visually similar to the single-tube dampers (CCDB Inlines being a notable exception) in terms of layout, but there are some differences.

This week on the Tuesday Tune, we're looking at what some of those differences are, where the twin tube concept came from and how the different layouts tend to behave as they currently exist."

The Tuesday Tune Episode 10: Oil Considerations



This week on the Tuesday Tune we're delving into suspension fluids to discuss some of the demands placed on them and how the manufacturers develop the properties that are necessary to meet these demands. Since we at Vorsprung Suspension aren't chemists, we invited Alex Marangoni, Canada Research Chair, Professor of Soft Material Sciences at the University of Guelph and the scientist behind Whistler Performance Lubricants to explain a few things to us:

1. What the major demands on suspension fluids typically involve
2. What base oil types are used and their properties
3. Some of the compromises involved in oil design
4. How oil properties change with temperature and over time

From the workshop's point of view for servicing, we consider three main factors in the most relevant priority order when selecting an oil for a given application:

1. Viscosity - how thick the oil is, and its resistance to flow through shear
2. Viscosity Index - the thermal stability of the oil and ability to minimise changes in viscosity as temperature changes
3. Lubricity - its ability to reduce friction.

Each of these factors has to be considered in terms of its relevance to the oil's application. For example, fork splash bath lubricant needs to lubricate first and foremost, and forks in general are more sensitive to stiction than rear shocks as the rear shock has the leverage of the suspension linkage to help overcome its friction. Conversely, rear shocks see more heat than forks, so thermal stability becomes a bigger concern.



Following those three primary considerations are secondary considerations, in no particular order:

1. Oil durability - oil breakdown through thermal and shear stress occurs over time.
2. Environmental concerns (side note - WPL's oils are biodegradable and non-toxic... but they taste terrible and eating or cooking with them is still generally not recommended)
3. Price
4. Anti-foaming characteristics (for open bath/emulsion dampers only)
5. Other factors affecting performance such as adhesive additives ("tackifiers") that can drag oil past seals

The Tuesday Tune Episode 11: Adjusting Spring Rate vs Adjusting Compression Damping

https://youtu.be/EJELsCkYEDI?rel=0&showinfo=0

This episode of the Tuesday Tune is dedicated to one of the questions we regularly get asked: whether the rider should adjust spring rate or compression damping to achieve a desired effect. This week in the Vorsprung Suspension workshop, we're looking at some of the considerations that determine whether you might want to adjust your spring rate (eg. air pressure or coil spring stiffness) or adjust your compression damping.

A large part of the difficulty in differentiating between the effects of compression damping and spring rate is caused by the fact that the forces generated by the spring are acting in the same direction as the forces generated by the compression damper. As a result, increasing spring stiffness and increasing compression damping both have overlapping effects in that they both make the suspension feel firmer in some way. However, because the spring is an energy storage device, whereas the damper is an energy dissipation device, the way that they generate these forces and the way that affects the feel of the bike vary considerably.

Because of this, increasing compression damping has effects that overlap with the effects of increasing spring rate in some ways (bump harshness, travel usage etc), but also overlap with the effects of decreasing spring rate in other ways (stabilizing/deadening the bike). We take a look at how you can understand these effects so that you can pick the most appropriate adjustment to make when you feel that your suspension isn't quite performing at its maximum potential.



As always, the purpose of this is to explain some concepts, and it is important to realize that every fork and shock has adjustments that behave in slightly different ways, so this is far from a conclusive array of "If XYZ then do ABC" statements. Not all adjusters are effective everywhere in their range of clicks (some adjusters stop doing anything before the dial stops turning), and the variation in damping forces that they can produce can be drastically different from one product to another, as some adjusters offer a broad range of adjustment and others are very much for fine-tuning within a narrow band. In other cases, you may run into limitations with stock air spring curves when running above or below certain air pressures, that cause disproportionately large issues once you firm them up or soften them beyond a certain extent.

The Tuesday Tune Episode 12: Leverage Rates



Mountain bike frames have various forms of what we broadly refer to as suspension design, but more specifically could be termed kinematic design. Kinematic design refers to the ways which each member of the suspension linkage move, particularly relative to one another. In other words, the suspension kinematics are the geometric motions of the linkage, before we start introducing force or mass to our considerations.

Anyone who's ridden more than a couple of different mountain bikes is well aware of how different the rear end of the bike can feel, even with the same travel and when using the same shock. Variations in leverage rate, among other things, are a very large factor in determining how the suspension performs, so this week in the Vorsprung Suspension workshop, we're looking at the ways in which variations in the leverage ratio can affect the feel of the bike, and why small changes can result in fairly large differences.

Leverage ratio is typically defined as the ratio of mechanical advantage that the axle has over the shock. This can be an instantaneous leverage ratio at a single point in the travel, or an average leverage ratio obtained by dividing wheel travel by shock stroke. Plotting the instantaneous leverage ratio against travel gives us a leverage rate curve. The difference between ratio and rate is that the rate describes how the ratio is changing throughout the travel. In the motorsports world it is more common to use the term motion ratio, which is the same thing but inverse - it is obtained by dividing shock stroke by wheel travel.

When considering the overall wheel rates - that is, the spring rate and the damping rate when measured at the wheel - it is necessary to understand the spring and damping characteristics of your shock as well as the leverage rate characteristic of your linkage. Some frames work really well with the linearity of coil shocks and relatively poorly with progressive air shocks, and vice versa, and it is this interaction between the leverage rate and the shock's spring characteristics that is primarily responsible for this. An in-depth discussion of how air springs, particularly those of our own products, interact with various leverage rate curves can be found here.

Please note a few things here:

1. As usual, the devil is absolutely in the details. Generalizations, including some of the things we refer to in the video, are not applicable to every variant of any particular linkage design, and this is a long long way from being a comprehensive breakdown of leverage rates.

2. A certain acronym or name for a linkage type does not mean all frames of that type perform or feel the same. They can vary hugely.

3. We're not here to tell you what system is "best". There is really no objective way to assess that - everyone's preferences and priorities vary, and what works well for someone who likes a super firm feel doesn't necessarily work well for someone who wants the plushest thing out there.

4. If you'd like to see what your own bike's leverage rate is like, download a program called Linkage and measure up your own bike to see how it stacks up. Note on using this program: there are a great many existing files out there and a lot of them are a fair way off the mark, particularly on bikes with very short links. Don't rely on clicking on points on a photo for accurate inputs - that can be accurate enough for single-pivot bikes with no linkage, but on anything else it's more than likely going to be misleading. Use a measuring tape to verify distances between points on your suspension if you want accurate results.



Terminology worth knowing:

Linear leverage rate: this would be better termed "constant leverage ratio", as this is what delivers a linear force vs displacement curve at the wheel (if using a linear spring).

Progressive leverage rate: also known as a "rising rate", this creates a force vs displacement curve at the wheel that is progressive, ie an increasing wheel spring rate even if using a linear spring.

Digressive leverage rate: the opposite of the progressive leverage rate.

The Tuesday Tune Episode 13: FOX's "Budget" FIT GRIP Damper



It seemed like only a matter of time until one of the major manufacturers developed a light, cheap, reliable fork damper with true shimmed valve performance. FOX's primary trail bike offering, the FIT4 damper cartridge - functionally an updated variant of its largely unloved CTD FIT cartridge predecessor - has got low friction nailed, along with (slightly) more support and somewhat more useful compression adjusters. The expanding bladder system and SKF damper seal head means it gives up nothing to anyone on the smoothness front. All in all, while it's not for everyone, it's not bad.

However, while the CTD FIT cartridge attracted its share of criticism from riders and the media, it was a beacon of sheer brilliance compared to its Open Cartridge brother, found in the Evolution Series CTD forks. Cheaply made, with little regard to durability, smoothness, outright performance, adjustability or even serviceability, the Open Cartridge CTD damper may well be the product that FOX are the least proud of ever producing. Being fair and putting this in context though - initial expectations were relatively high, because FOX usually do their homework quite thoroughly, and it caught a lot of consumers off guard when they purchased a bike with FOX plastered all over it, that didn't deliver the performance or durability they were expecting from the FOX brand name. You'd be more than a bit upset if you bought a Mercedes AMG that blew up in the first week you owned it too. Had this kind of thing come from some of their competitors - and it routinely does - perhaps the media and market response would have been a bit less negative. Nobody wants a Koeniggsegg that's slower than a Ford Mustang though.

Regardless, a lack of shimmed rebound and a pressed-together compression assembly, with an oil-ingesting seal head and lack of effective volume or pressure compensation meant that there really was no polishing that turd - it couldn't be made to be reliable or to perform very well without changing pretty well every part in the entire damper. And that wasn't for lack of trying either - we prototyped dynamic bleed compression assemblies and shimmed rebound pistons for these, but the cost of fixing every issue simply became too high to be realistic.



Anyway, the good news is that FOX have listened and built the FIT GRIP damper for their more budget-conscious forks. Calling them low-end would be doing everyone a disservice because FOX don't actually cater to the low-end market per se, but they are FOX's lower-end damper right now.



Our conclusion? Simply put: it's a MASSIVE improvement over the previous generation Evolution-series Open Cartridges. While the compression assembly is a little basic and doesn't have a true shimmed valve as such, the adjustment is effective and the lockout/climb switch is cleverly executed. Meanwhile, the rebound assembly is a fully functional and effective shimmed valve with a wide range of adjustment. As you'd expect from its lower price point, it's not quite as refined as the FIT4 or RC2 cartridges, but with decent performance and being designed in such a way that we expect better reliability than ANY other damper they currently make, FOX have done a solid job on the FIT GRIP damper.

Vorsprung just dropped a wealth of suspension knowledge on their Youtube channel. Grab a tasty beverage and dig in!
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Episode 14: Myth Busting

https://youtu.be/NlRKdl_S42s?rel=0

This week in the Vorsprung Suspension workshop, we decided to clarify a few things. There are many common misconceptions regarding suspension (including the concept of a "correct" setup!), so we arbitrarily picked a few to clear up, from foamy oil to midstroke support. No rhyme or reason, just ranting and rambling.
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Episode 15: The Concept of Correct Setup

https://youtu.be/lTvpVM3JN_M?rel=0

"How do I set my suspension up correctly?"
"How do I know if my suspension is set up correctly?"

There's a good chance you've asked that at some point in your bike riding life if you're a mountain biker, either to yourself or somebody else. We get the question at least once a day here at Vorsprung, so we would be remiss not to address it head on.

The long and the short of it is that the correct suspension setup is the one you're happiest with, according to whatever criteria you use to determine that. Just want a smooth ride above all else? Or are you willing to take some punishment for the sake of cutting seconds off the stopwatch? Clearly, the two are going to result in some differences in setup. This week on the Tuesday Tune, we're discussing simple questions you can ask yourself about whether your suspension is performing the way you want it to, to help you narrow down the characteristics that could do with improvement, and to help you understand where compromises in your setup may begin to arise.
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Episode 16: Bump Compliance and Harshness

https://youtu.be/fN4re79q8QU?rel=0

For better or worse, Vorsprung's location in Whistler gives us exposure to some of the harshest, most violent conditions bikes ever see. From A-line's infamous braking bumps (that the trail crew, fortunately, iron out a few times a year!) to the sheer brutality of In Deep, there are plenty of reasons why many riders here end up feeling like their hands are broken after a few days of riding.

Consequently, one of the biggest issues we deal with on a day to day basis is minimizing ride harshness. To achieve this, it is necessary to understand the physics behind bump absorption, which is what we are delving into on this week's Tuesday Tune. Rather than simply handing you a set of instructions saying "reduce X, increase Y, set Z to extra medium", we're presenting an introduction to the fundamental ways in which your suspension responds to encountering a bump. We hope that by doing this, that you can relate this to your own adjustments and find yourself making more productive changes when you are adjusting your setup.

This week's video is pretty heavy in theory, and it does assume that you are familiar with the basic functions of a spring and a damper (if you aren't, check out our video on the functions of springs and dampers).

As usual, this is just the tip of the iceberg when it comes to in-depth analysis, and should not be considered anything like a comprehensive explanation of everything to do with a smooth ride. Many factors not directly related to your mechanical suspension can influence the perception of harshness (and hand pain), including rider variables such as strength, fitness and fatigue levels, as well as cockpit setup and brake configuration. Tyre pressure is invariably part of the equation, and should always be the first thing to check when something feels exceedingly rough. It's also worth noting that your priorities for suspension setup may not be the same as the next rider - some people want the smoothest ride possible, some people want the fastest thing they can hold on to on steep terrain, most people lie somewhere in between. Setup is all about finding the compromises that work best for you.
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Episode 17: Moar Shimz

https://youtu.be/cKd5RqLBECc?rel=0

Alright, here it is; shim stacks. Shimmed valves are the most common form of high-performance valve in suspension dampers, and the raison d'être for many forums and indeed entire websites to exist. Some say they control the flow of oil, others say they are responsible for controlling the flow of karma throughout the cosmos. Being light, simple, compact, highly tunable and relatively cheap to manufacture, shimmed valves very often turn out to be the right tool for this particular job.

So what we've put together here is a very brief overview of the simplest form of a shimmed valve. Within this video are many technical omissions for the sake of simplicity so that we can focus on the very basics of a single-stage (non-crossover), unpreloaded, zero-float shim stack, and garner some insight into the way that the actual shims function.

We feel that the simplest way to understand a shim stack is as an unpreloaded spring holding a valve closed, and it is predominantly the stiffness of that spring that determines how much pressure it takes to open the valve a certain distance—this dictates the relationship between pressure drop (damping force) over the valve and volumetric flow rate (determined by shaft speed) through the valve. A shim stack of this configuration will deliver quite a linear force vs velocity characteristic over the majority of its operating range, up until the point at which it cannot open any further to increase the available flow area. Other variations on this type of valve can deliver substantially digressive or progressive curves, but we aren't covering those here.

This video certainly isn't comprehensive, it provides exactly nothing in the way of precise methods of calculation, and it makes many generalizations, simplifications, and omissions for the sake of explaining the stack's function and demands within a short video. However, hopefully, you'll find it interesting and informative one way or another.
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Episode 18: Setup for Pros and Mere Mortals with Remy Metailler

https://youtu.be/DcsbLgceUMg?rel=0

For the last episode of the Tuesday Tune for this winter, we've brought bike park destroyer Remy Metailler in to the Vorsprung Suspension workshop to discuss setup, and the differences in setup priorities for pro riders like Remy compared to the rest of us mere mortals.

Remy is one of the most precise riders out there when it comes to consistency and specificity in suspension setup and feedback, which is why we have worked closely with him over the years. Unlike many people, he's definitely the kind of rider who'll make changes to his setup very frequently according to the specific demands of his riding on that day, which requires both a methodical approach and the ability to trust your own perception of what works well for you.

Like many pro riders, Remy's aggressive riding means that a lot of thought needs to go into the compromises between the compliance that gives comfort and traction, and the support necessary to hold up on steep terrain and big hits without destabilising (or damaging) the bike.

The focal point of this video is this: The common point of all suspension setup—where every single rider, from the novice to the pro, is in the same boat and needs to make the same decisions—is working out where your priorities lie and what constitutes an acceptable compromise to you. As an (unrealistic and extreme) example of compromise—anyone who wants literally zero fork dive is looking for a rigid fork (or a linkage fork!), which obviously isn't going to do much for bump absorption. Conversely, if you want to be able to plow through braking bumps all day without feeling like your hands are arthritic, you might find that the setup you need in order to achieve that feels a bit soft in other situations.

Working out your priorities is often a matter of taking note of what bothers you most with your current setup and addressing that. Sometimes, improving a factor you're already satisfied with doesn't improve the perceived ride quality much, whereas addressing deficiencies always does.

In this video we touch on a few subjects relating back to a couple of our previous videos (particularly The Concept of Correct Setup and Less Obvious Aspects of Sag) to explore some of the nuances of setup, particularly when it comes to figuring out your own ideal setup.

With peak riding season over, Steve at Vorsprung is kicking off his suspension education video series again. This time it's all about rebound damping. What is it? What amount is ideal? What happens when you have too much or too little? All that and more...

Episode 19: What Your Rebound Damping Does

https://youtu.be/nVZnyrnqzcQ?rel=0

Welcome back to another season of The Tuesday Tune!

This week in the Vorsprung workshop, we delve into the basic ways in which rebound damping affects the behavior of your suspension, and some of the fundamentals regarding grip, stability and the considerations involved in optimizing the two.





Questions, comments and feedback are always welcome.

Episode 20: Preload and Sag



Coil springs require a certain amount of preload to hold them securely in place, but how much should you run? This week on the Tuesday Tune, we go right back to the basics to take a look at the function of a preload adjuster and its purpose, as well as the carryover mentality of preload adjustment from the motorsport world to mountain bikes.

High and Low Speed Rebound Adjustments - Episode 21



This week in the Vorsprung workshop, we take a look at how HSR and LSR adjustments work, how they interact and suggest some tuning methods to help you get the best out of your damper.

Quite notable with these adjusters is the huge overlap between the effects of the two as well as the interference they each have with one another. When tuning these, simplification is important, and we show you why that is and how to make setting up your rebound damping as simple as possible.

There are, as always, a few notes:

1. Simplification to remove variables can be beneficial because it allows you to get to 95% of the potential performance ceiling very easily, as opposed to a theoretical 100% of the performance ceiling that is very difficult to find.

2. Advanced tuning of these two adjusters can go beyond what we suggest in this video - the difficulty though is understanding exactly what interference effects you're causing.