Pro Opinion: Active Suspension

Ya boi, the editor: As I’ve been doing this, I’ve published quite a few articles about various active suspension systems being cooked up in the bike-world. Fox have their Live Valve that they’re fine-tuning (I’ve actually skipped a shit load of documents related to this because it’s not really new). Shimano seems to be working on the same concept, although they don’t appear to be very convincing. Rockshox have something coming — we’ve even got a spy shot. And, Ohlins are dipping their toe into the game, as well (don’t sleep on Ohlins).

Explaining active suspension

I asked some professionals — manufacturers, tuners, mechanics — how they feel about these new magical systems. Obviously, they’re well versed in the suspension world, so I figured it would be cool to get their input, as well.

Jono Church – The Suspension Lab, Rotorua

How do you feel about active system on race bikes? Any discipline.

Personally, it would be pretty exciting to see some cool tech involved in racing. I’m a big Formula One fan mostly because of the level of engineering involved over other motorsports, so in my dream world of racing there would that extra layer of strategy involved with how you implement such a system. I’m imagining you could program different profiles for different parts of the track and they would switch automatically or you can cycle through them with a button on the handlebar. Back in the real world though, the deciding factor would be cost – I think you brought this up in your article but I do agree we don’t need another barrier for up and coming racers. It would need to be accessible at the same level as current bike parts or else the less well funded riders will be severely disadvantaged. Mountain bike racing is already prohibitively expensive for all but the very top riders as it is! And unlike the motorsport comparison, there are no feeder series or different classes with simpler technology that people can race in and still make a living or gain experience/sponsors before stepping up to the big time. If it was to be at the level you needed a dedicated engineer to set up the system it really wouldn’t work. From what I see teams can hardly afford to pay one mechanic a decent salary so I don’t see them bringing in even more specialists! To counter that though, a lot of those up and comers have little idea how to get the most out their bikes so the initial outlay may end up paying off by saving time getting a bike dialed in and not having to try and ride fast on a sub-par bike set up.

How do you feel about active systems on trail bikes?

I think it will be great, obviously its early days but I can picture it going in either direction depending on your inclination. If you love tweaking things all the time you could hopefully set up endless “maps” or profiles that change as you ride depending on whatever parameters you decide like pedaling, seat height, gear selection etc. Or go the other way if you are the “set and forget” type but want it to still work, you could set it to fully automatic, you wouldn’t even need adjuster knobs! So not only do you not need to worry about what they do, you wouldn’t even have to look at them!

How do you think these systems will effect your business?

Will you work on them or reject them? You might have figured out I’m pretty in to it so will definitely be working on them if I can. I used to be pretty scared of anything electronic, but last year I started getting in to electronics and computer programming partly because its interesting and I could use it for the Data Acquisition I already have, but also in the back of my mind I know we are only going to see more and more electronic systems of all sorts on bicycles. We already have them on e-bikes and one thing I worry about is a lot of the parts are just thrown away and replaced when something goes wrong. That’s not sustainable in the long term so manufacturers and customers won’t put up with the cost of replacing parts all the time. I think in a few years every good mechanic will need to know how to use a multimeter at a minimum. I guess the other possibility for someone like me is that if a customer really didn’t want to have to touch a thing, I could just log on to your dampers remotely and upload your new valve setting from anywhere in the world! And lastly – people love gadgets, if the market decides that’s where we are going you would be foolish to turn them away.

If you had the chance, would you put this type of system on your own bike?

Definitely. I never use lockouts because I’m completely incapable of remembering to open them but on certain bikes or tracks there are times it would help for sure. Also my 2 favorite types of riding are extreme opposites – slow, technical rooty trails or jumps, and my bikes normally end up favoring the technical riding so the jumping suffers. If it could switch to a decent jump mode instantly, or anything in between that would be awesome. Like if the Push 11.6 Dual Overhead Valve was an infinite overhead valve!

How much extra, as a percentage, would you pay for a fully active system compared to a conventional system?

I would expect to pay 50-100% more. Probably closer to 100%, or double an analog shock. Kinda depends if it lives up to the hype I’ve built up in my head though. 

Overall, do you believe you’ll have more fun with an active suspension bike?

For sure, if it can take away the need to puzzle over suspension yourself then it will be a lot more fun! Or if you are riding something high speed and out of your comfort zone it could switch to a setting that’s more stable so you feel more comfortable. I feel like the possibilities are endless and can only make things better because a bike that works well is more fun to ride, takes less energy and is faster! Making that more accessible to more people would be amazing.

Is there anything else you want to add?

Obviously I’ve projected a lot of my own hopes on to SRAM to deliver the system I’ve wanted to see, so we just have to cross fingers and wait for what actually gets released. But I didn’t even mention remotes! I can’t wait until the day we never have to work on a cable actuated lockout again. Aside from the fact I don’t see the need most of the time, the current systems are just so, so awful….despite there being an apparent steady demand for remotes since forever, they always feel like an afterthought. The ergonomics are awkward, they are fiddly to set up, they make a mess of the cockpit, the cables fray easily, they are highly prone to contamination which makes them too stiff to use, and if you have a push-to-unlock damper it will revert to being locked out if the cable loosens off or slips through! If you buy a bike set up with them its prohibitively expensive to remove or not even possible at all (looking at you Rockshox Super Deluxe!). Having a clean cockpit where the only cable is the rear brake but you still have the option to firm up the suspension from the handlebar sounds good to me. Scott could ditch the lever stack that looks like a squid and probably sell even more bikes! That alone would be worth the price of admission.

Harry – Workshop manager at a small indy shop in the UK

How do you feel about active system on race bikes? Any discipline.

It feels like it’s headed towards a formula one style competition, at the moment all race bikes are roughly speaking similar and provide similar benefits, once this sort of technology comes in it will make bikes drastically more efficient. There is a risk with this that it ends up like formula one where the teams with the most money (Mercedes and red bull) win the races really regardless of how good drivers are, referencing when George Russel raced a Mercedes last year and almost won. I think when not on race bikes people can do what they want, as it’s their decision and at the end of the day makes it all more efficient when pedaling and that. So I think regulations will need to be careful around their introduction to racing but not necessarily a bad thing if policed well.

How do you feel about active systems on trail bikes?

On trail bikes that people do not race I welcome the new technology, it’s up to people what they run. The easiest comparison would be the UCI racing rules and how people have frames that are the wrong proportions or the wrong weight to race in a UCI race. But as it’s their bike it doesn’t matter, at the end of the day ride what you like and have fun on it!

How do you think these systems will effect your business? Will you work on them or reject them?

As a local bike shop we are used to anything and everything walking through the door, and we try to help everyone that comes in. We’re not a stranger to electronic suspension as we are a pivot dealer, at the end of the day it is just something that will need to learn about to perform, same as anything else. So we will for sure be accepting them into the shop, especially as if it becomes more commonplace (Look at AXS) then you’re just turning down potential customers

If you had the chance, would you put this type of system on your own bike?

I think I absolutely would, I love my cutting edge gear, got GX AXS on release day and have got a brand new e bike on order which has a new motor and all new everything basically, I’m known as the guy in the shop who just buys all the shiny new things.

How much extra, as a percentage, would you pay for a fully active system compared to a conventional system?

Probably about 50-75% more, nothing crazy but there’s always a first adopters fee…

Overall, do you believe you’ll have more fun with an active suspension bike?

I think if the efficiency is increased then it will let me ride further for less effort, so more fun right?

Is there anything else you want to add?

Think that’s all, has to be regulated carefully in racing to not provide too much of an advantage. But on personal non race bikes then why not! Innovation is pretty much always good

Will Hilgenberg – Albatross Bikes

How do I feel about active systems on race bikes? Any discipline.

Active suspension systems are designed to squeeze out every last ounce of performance out of the vehicle they are attached to. As bikes that are designed to be raced are focused on being more efficient in the climb, more controlled in the descent, and more forgiving on the landing, then this will be of great benefit to any and all disciplines that are not weight-critical. Cross-country racing is the only discipline where it might not see as much acceptance as the addition of weight (which is inevitable with active suspension) is far more detrimental than it would be with downhill or enduro bikes. 

How do I feel about active systems on trail bikes?

Active suspension can benefit the average rider by potentially reducing the complexity of setup and improving the overall ride quality of the bike. The biggest hurdle to its acceptance is the cost which is a significant factor in the buyer decision. If the system is included in a top-level spec, I think it will only be a benefit to the consumer but the likelihood of it being seen at the price levels where it can help the most is slim at best.

How do you think these systems will effect your business? Will you work on them or reject them?

                Or as a manufacturer, will you develop your products based on these active systems?

As a manufacturer and frame designer, if we can design the kinematics to work well enough to not need an active system, then that is what we would prefer as there will not be any increased cost or weight of the finished bike. If this isn’t possible because of an existing patent or the overall package of the bike, then we absolutely will consider an active system to help solve some of these kinematic issues. For us, our goal is to design each bike with a focus on performance and we will use whichever system we need to achieve that goal. 

If you had the chance, would you put this type of system on your own bike?

If given the chance, I would gladly put this type of system on one of my bikes to see what it is capable of. There is always the potential that it can be used in ways that it wasn’t originally intended for and will be far more beneficial than I think it could be. You don’t know until you try it. 

How much extra, as a percentage, would you pay for a fully active system compared to a conventional system?

A 20-30% over the MSRP of a conventional system would be considered an acceptable upcharge for this kind of system as long as it provides the promised benefits. 

Overall, do you believe you’ll have more fun with an active suspension bike?

I believe that if you enjoy setting PRs, sending bigger features, and getting to the tops of climbs faster, then an active suspension bike could be more fun. If you are out riding to enjoy being outside, or just like to go for a spin with your friends, then there is absolutely no need for active suspension although it will still likely be fun since most cyclists tend to be gear geeks.

Is there anything else you want to add?

The biggest benefits of an active system are to fix suspension kinematic problems and to simplify suspension setup. Outside of those two uses, it becomes a marginal improvement over conventional systems while dramatically increasing price and complexity. Since we can’t put the genie back in the bottle though, active suspension systems will continue to be developed and improved for years to come and bike designs will continue to adapt to accommodate active system requirements.

Steve Mathews – Vorsprung – BC, Canada

How do you feel about active system on race bikes? Any discipline.

I’ve got no issue with it, but it’s worth distinguishing between actual technology that we’ve seen vs technology that we might see in the future. What we’ve seen so far aren’t fully active systems, they’re semi-active (ie active only in that they vary the damping resistance) at best, and most of the systems that have emerged to date (Live Valve, E:I, the new SRAM system and even the old K2 Smart Shock) are basically just an LSC adjustment at most. In the case of Live Valve and E:I, even calling them semi-active is a stretch – those are just automatic mode selectors. In the open mode, they’re just a mechanically damped system like any other. In the locked out mode, they’re a mechanically locked out system like any other. The transition between the two modes is what happens electronically and automatically, but that’s really all it does. The SRAM patent looks to be able to offer a range of LSC adjustment, but judging by the mechanisms in the patent you provided, it seems likely that it will move much slower than Live Valve (it’s literally a motor winding your LSC dial for you, I don’t see that being capable of 5ms response times from full open to full closed for example), so my prediction is that it will also be used much more like a mode selector, but you might be able to vary how firm each mode is, or have more than just two or three. Long story short, I don’t see it making any significant difference in racing any time soon. The pedaling efficiency advantages for XC are arguably outweighed by the weight disadvantages (these guys weigh their grips remember), the efficiency advantages for DH and Enduro are relatively miniscule, and what we’ve seen so far aren’t high-bandwidth systems that are going to increase grip, traction or stability by any significant amount. I completely disagree with your assertion that “active systems will ruin racing” unless active systems get a lot more advanced. Nobody’s even managed to make it work for motocross, where the power issues are much easier to handle and suspension behaviour is absolutely critical, and realistically the best anyone has managed in the automotive world has been quite low-bandwidth response to low frequency inputs (even the true fully active F1 systems from 1991ish). Those low frequency adjustments make a massive difference to cars, but not much to bikes.

How do you feel about active systems on trail bikes?

Again, let’s distinguish between actual current technology vs potential. Potentially, they’re awesome. But potentially, I’m a billionaire with ripped abs and a cure for cancer. So far it’s been basically an electronic gnome sitting in your bottle cage flicking your lockout levers for you. At some point though, I think they will be the future. 

How do you think these systems will effect your business? Will you work on them or reject them?

We’ll work with anything that the manufacturers adequately support with parts, tools & service information, and that enough people buy for us to actually justify working on. If SRAM’s system sells as few units as Live Valve then we might not bother, but it looks a bit more user-friendly and less bike-specific.

Or if a manufacturer, will you develop your products based on these active systems?

We might develop tuning products for them, we might not. We haven’t touched Live Valve partly because Fox haven’t published service information and partly because not many people seem to have actually purchased it. We aren’t going to develop tuning products and services for a product that only sells a few hundred worldwide a year.

If you had the chance, would you put this type of system on your own bike?

I’d try it for sure. I have my predictions about its benefits and limitations, but the devil is in the details. How they deal with miniscule battery capacity is the big one – you have to be extremely stingy about where you direct your power, or it just doesn’t last. Dampers can generate several kilowatts (ie multiple horsepower) worth of power very easily, it isn’t something you can just connect an AA battery to a valve and call it “active” unless it only needs to work for 30 seconds.

How much extra, as a percentage, would you pay for a fully active system compared to a conventional system?

Fully active meaning fully semi-active? It depends how well it’s done. So far, I’d pay more for a good conventional system.

Overall, do you believe you’ll have more fun with an active suspension bike?

You absolutely could, if it was done well. The actual execution matters a lot more than whether it’s electronic or not – who cares if you’ve got an automatic adjustment if the underlying spring and damping curves suck? 

Is there anything else you want to add?

I think the challenge of electronically controlled suspension is much greater than people realise with bikes. First, to minimise power consumption and keep battery weight down, you need a system that ideally doesn’t move if no power is applied, even if the internal pressures are changing significantly. 

Fox did this by using latching solenoids – it keeps the solenoid in the open position or the closed position with no power consumption, which works well in that context but once it’s in the open mode it’s just a fairly standard mechanical damper. K2 tried to do it with a piezo flapper valve bypassing the main piston, but piezos are extremely limited in how much force they can generate, so it was very easy to just push the valve out of the way (and many other aspects of that damper were very poor). 

SRAM are doing it by using a stepper motor and a dial – basically an electronic gnome turning your LSC knob – which is necessarily slower to adjust than Fox’s equivalent (I’d expect much too slow to respond bump-by-bump), but does let the LSC needle sit anywhere it wants without consuming power. 

Cannondale’s Simon actually tried to go completely semi-active but the power consumption was very high and it only lasted a couple of hours as a result. Not sure it even made it to production. What we’re seeing right now aren’t really active systems, they’re mode selectors. 

Secondly, there are physical limits on how fast you can respond. Our data logging shows that single milliseconds count when it comes to suspension movement relative to initial wheel accelerations. The chain of events for completely semi-active response is something like this:

1. Sensor takes reading, at given frequency, which may or may not be delayed by a filtering capacitor (say 10kHz, no capacitor, filtered with a 10-sample moving average filter, so minimum 1ms delay to get your sample – this is in line with the 1000Hz sampling Fox claim for Live Valve)


2. If sensor crosses a certain high-pass threshold (for acceleration, position or velocity for example), assuming processing time in the microseconds or nanoseconds, then send signal to the valve relay to begin moving. The key point here is that you need at least another 1ms to get this to happen, because you need at least two samples – one as a baseline/reference and another as your error signal. It may take longer than that, because the initial acceleration of the hub detected by an accelerometer may be below the high-pass threshold. 

3. Control signal goes to valve relay, which then needs to rapidly discharge a capacitor into a valve energizing circuit (which has its own capacitance slowing things down) to build force in order to accelerate the valve’s own mass against the viscous resistance of the oil and any other friction (eg seals) that it may have to overcome. This may take anywhere from 3-100ms to move an appreciable amount. It’s critical to note that valve motions are often not as fast as the claimed response times – you can certainly BEGIN motion very quickly but substantially completing it is basically what matters. When a bike is moving even moderately fast, let’s say 10m/s (36km/h or about 22mph, or 10,000mm/s), every single millisecond you’re covering 10mm of ground. 3m/s response (Fox’s claim for Live Valve, which I’ll take at their word, but which I’d say is absolute best-case) means you’ve moved forward about 30mm between sensing the impact (note: sensing the impact is not necessarily the same point in time as the impact actually initiating) and the suspension opening up. This is equivalent to the difference in horizontal axle displacement between hitting a 30mm high square edge and one that’s 45mm high, and necessarily results in an average analytical compression velocity of about 20% higher on that 45mm high root/rock/whatever because you now have about 150mm horizontal distance to lift the axle over the obstacle instead of about 180mm. In practice, you also get more tyre intrusion from the bump when that happens, so you get an even sharper acceleration (including a component not tangent to the axle path) and higher peak velocities than the predicted analytical value in reality, meaning greater changes in contact patch load (CPL) and higher bump forces delivered to the chassis/rider. That’s just with three milliseconds delay, which in my opinion is already an incredible achievement on Fox’s part to begin with. So maybe you can see why I don’t think it’s actually going to change anything in the race world, the frequency response is simply too low at this point to be much more than a convenient mode selector or adjuster-turner. That’s not to say those things don’t have their place – they absolutely do – but they aren’t going to change mountain biking into F1.

Photo Credit: US 6,406,048 by John Castellanos. A pivotless rear suspension system.

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