Formula 1 Meets Mountain Biking in Trek's New RE:aktiv Suspension 74

bturman
6/11/2014 10:48am

After five plus years of development, the minds at Penske Racing Shocks, Trek, and FOX are excited to introduce RE:aktiv, a new suspension design using regressive damping - a technology proven in auto racing that has never before been applied to mountain biking.

A chance meeting between Penske Racing Shocks' Technical Director Jim Arentz and Trek’s Director of MTB Frame Technology Dylan Howes at a NASCAR race, lead to the two companies talking about the potential for Penske’s custom innovations in the world of mountain bikes. Penske has been a major force in Formula 1, NASCAR, and Indy racing for many years, and Trek was eager to collaborate with them when developing this new design. After putting their heads together, the teams landed on the remarkable potential of regressive damping to achieve what inertia valves have been unsuccessfully attempting in the mountain bike world for years.

Comparison of traditional shim and orfice dampers to RE:activ, a regressive design.

RE:aktiv is a regressive damper that balances pedaling performance with big-hit absorption without feeling harsh. The valve is capable of delivering lots of low-speed compression damping, fluid high-speed compression damping, and an instant, seamless transition between the two. It provides a much firmer hold in straights and corners for incredible support, but when it hits a sudden obstacle, like the square angles encountered on technical trails, the shock’s hold instantly gives way to a plush, controlled progression.

The new design makes use of FOX's easy to use CTD settings.

FOX was brought into the process at a pivotal moment of the development process, applying their expertise and manufacturing know-how to the new shock to help bring RE:aktiv to market. The shock uses the new RE:aktiv damper technology packaged alongside Trek’s proprietary DRCV air spring and FOX’s easy to use CTD settings.

"The unique thing about Penske and Trek is that we've really only scratched the surface," said Penske Racing Shocks Director of Research and Development Bill Gartner. "Regressive technology helped with one compromise that was there in mountain biking but there's a whole other world of technologies that may apply. Not only from Formula One but all the markets we work with." Given the prestige and demand for Penske's suspension designs in auto racing, the mountain bike world should be very excited about their future involvement.

Trek is launching several new products this week, including a new RE:aktiv equipped 120mm travel Fuel EX 27.5, Carbon Remedy 29 (which we got sneak peek of last week) complete with a new 148mm rear hub spacing, and Lush 27.5 for the ladies. AJ Barlas is on the ground for Vital MTB and will be bringing you all the details you could want and initial ride impressions in the coming days. The entire lineup is expected to be available later this summer.

Related:
Trek
Vital's Voice
FOX
Rear Shocks
Trail / All-Mountain
74 comments

View replies to: Formula 1 Meets Mountain Biking in Trek's New RE:aktiv Suspension

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whitegoat
9 years ago
This looks great but you wont be able to appreciate it on a terrible trek.
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JMSharp814
9 years ago
Penske racing has been pushing regressive technology for several years now. They have had some success with it in F1 and in IndyCar, but an F1 car and an IndyCar are quite different from a mountain bike. Mainly in the amount of travel and the velocities seen on track. Traveling 3-5 mm and working within a small velocity window makes this technology a lot easier to tune. Plus add in the countless hours and money spent on specific rig and track testing along with data collection and equipment used to get this perfect regression at the perfect moment and you have created quite the nightmare for your average rider. Having some experience working with this technology, I am going to play devils advocate here and point out some issues I see with the technology and how it is being marketed here. First and foremost is the repeatability of the regression and the speeds at which the regressive part of the damper kicks in. There is no way a person weighing 120 lbs and a person weighing 220 lbs creates the same shock velocity for a given action. This would imply that each shock needs to be specifically tuned to regress at the perfect velocity for each riders weight and riding condition. Second, the graphs show a minimal amount of actual regression. On a 15 inch per second test, how much regression in force is actually seen? The video eludes to riders commenting on the tire staying in contact with the ground better, but if the regressive part of the shock is on the compression part of the damper, how is that keeping the tire in better contact. Rebound is what keeps the tire in contact with the trail, not your compression. Compression soaks up the impact but rebound is what lets the shock allow the tire to stay in contact with the ground. How does regressive compression improve tire contact? I could go on and on and back and forth. While I am all for progression, this one is adding a lot of variables to the mix. I can tell you there has been a lot of money and data collection involved in getting regressive technology to work and it doesn't work in every occasion. It is not the cure all. I feel like it can work and it could be effective in certain instances with the right tuning for the right rider on the right trail, but as a blanket build for all riders and rider abilities on all the different terrain, that isn't realistic. I say the actual amount of regression is small and we are more talking marketing gimmick here than actual functionality, because to do this technology right each rider would need a shock dyno and a data system to maximize the regression at the velocity needed for their riding style and terrain choice. Basically the shock built is a digressive with a lot of bleed and a steep nose. A dyno will show some regression, but I would be interested in testing one to see exactly how much regression actually takes place in force at a given velocity. I am certain I could build something with a shim or orfice shock that was very similar without using a regressive valve and still achieve the same feel.

And to throw it out there because another poster brought it up, off-road and motocross are not using this technology for the very reasons I pointed out above. The sweet spot for the regression is too small and hard to predict with the repeatability issues. One time it will regress at 3ips and the next hit will be 4-5ips. Very unpredictable and not consistent. Plus the time to dial it in to a certain track is very hard in off-road due to changing track conditions and amount of data needed to be collected to get it close.
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Dave_Camp
9 years ago
JM- thanks for the reply... To ease your concerns, EVERYONE who has ridden it thinks it's an improvement over the currently available shocks. Obviously there are a million variables (rider weight, style, speed, terrain, bike, travel etc.) however we feel like we have a good generic tune that will work well for most riders. It is not perfect. Nothing is.

You are absolutely correct in that we tuned a lot of the regression out of the curve. Initially we had a lot more regression, but it didn't feel good on the bike. We have a tune that offers a sharp nose for efficient pedaling, then a little regression to take the edge off bumps when riding in climb or trail modes. It works pretty darn good. Of course you will have to ride one to see for yourself and form your own opinion.
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JMSharp814
9 years ago
Dave, definitely no concerns here. I am confident that what I am saying is a legit argument. I agree there are a million variables with shocks in general but I definitely feel from my experience with regressive technology that to put a generic tune on something like this is doing very little justice for the general public. While I understand EVERYONE who has tried it has liked it, the exact technology you are comparing this shock build to is anything but "generic". Your marketing campaign directly compares to the build as technology used in F1 and IndyCar but those builds are anything but generic tunes designed specifically with thousands of dollars of testing for a certain velocity hit at the perfect moment.

I am not discounting the fact you may have hit on something by putting a steep nose on a compression build that effectively blows off on bigger hits. This technology is nothing new with off-road dampers. While most off-road applications use a very linear build, blow offs (basically a digressive) have been around for decades and offer a suitable alternative to the linear shock in certain circumstances. I honestly would like to ride one of these Treks with this shock but more importantly I would like to spend some time with a dyno and this shock to really get a true reading on the actual regression and consistency of it at different speeds and pressures. I'll supply the dyno and man hours, will you (Trek) supply the bike and the shock?
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matmanmoto
9 years ago
JM, I'm assuming you work for a Nascar team and therefore I feel your pain with working on a "shim" version of regression. That way was never intended to be a solution for regressive curves and was never sold as such due to it's constant inconsistencies. But due to Nascar's "strict" shock rules, this way was stumbled upon to be legal to run and was therefore used and still is!
However, all the other forms of racing, whether it be F1, Indycar, Motorcycles, Drag, sportscar, etc. use other specific forms of regressive methods to achieve a regressive curve. Nascar is the only one that uses that particular shim method. And unlike that method, the other forms are VERY tunable and predictable and are being run on a weekly basis in all forms of racing and WINNING.
A lot of testing was done to get where the RE;AKTIV ended up and you will have to ride it to see for yourself that it DOES work in this application. It's no gimmick or sales pitch whatsoever.
You must really hate working on regressives if you felt so strongly to write your original comment.lol Hopefully Nascar will soon allow other methods into the race series and you will see it's full potential. Take care! Wink
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JMSharp814
9 years ago
matman, your assumption on one thing is correct. I currently do reside in North Carolina where I am working with a Nascar organization so I am well aware of building regressive shocks using just a piston and shim combination. I will attest that I am not a believer in the method in Nascar. While I know Penske preaches teams are using it here, I would argue it is very rarely on a car and even less prominent, if ever has reached victory lane in Nascar.
I am assuming you work with Penske shocks and have been drinking the Kool-Aid of regressive dampers solving the racing worlds problems that they have been serving the past 3-5 years. Without going into a long drawn out explanation of my background and what I have done with shocks, I am well aware of the other regressive methods out there. When I was doing IndyCar dampers before I came to Nascar we used a 4 way adjustable ohlins that had a piston that would create a regressive curve on curb hits. I am well aware the stuff we are using in Nascar is very limited to what is out there in other forms of motorsports. I still will argue that it isn't as popular as Penske claims it to be. I know regressive shocks have won races, but week in and week out I would venture to say in all forms of racing from drag cars to snowmobiles, regressive dampers are in the minority and wins for it are few and far between. Yes, it has won, but you and I both know even junk can find victory lane.
This has gotten off topic a bit so I will try to reign it back in. I am not a fan of regressive shocks in general, that is no surprise. I still stand by my original post that it is something that is unpredictable and no matter how generic you have made it, a generic tune can not be most effective for every rider and every condition,with something like this. I also will argue it is a gimmick because in terms of force, the amount of regression is minimal at best from the graphs that have been posted. A digressive build with bleed would yield very similar results, but then Penske wouldn't be needed to develop that or be able to make money off a patented valve.
My offer still stands to you or Dave, or anyone else involved with this project, I'll gladly demo one and give a full report after spending some time on a dyno with the shock. It's easy to say it works and EVERYONE loves it in a cool video and article than to show actual dyno graphs and real numbers. The balls in your court to make me a believer.. If what you are proclaiming is legit, you'll have no problems sending one my way. I'll be waiting, but not holding my breath, if you get my drift.
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pinityafairy
9 years ago
Specialized has been using inertia valves with their brain system for years. Aside from the internal system opposed to piggyback setup that Specialized uses, what makes your system so different? Even the marketing is almost identical. Is that the way around patent infringement?
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tacubaya
9 years ago
How does this system differ from Propedal? Seems like its also a spring loaded valve that opens once you reach certain pressure threshold.
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Dave_Camp
9 years ago
They are a little similar, but Re:aktiv valve actually decreases in force as velocities increase (for a while). The damper curves that propedal makes are very different from the ones that Re:aktiv makes. The valves are also very different inside...
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Dave_Camp
9 years ago
It decreases force (in trail and climb modes only) from around 4ips to 10ips (medium speed hit) then the curve starts to turn up again as speeds increase and orifice damping takes over (the valve is fully open and the holes are the restriction).

It is fairly speed sensitive, so on an fast hit (50ips) peak, it reacts differently than on a medium speed hit (25ips) vs on a low speed hit (10ips). The curve kind of stretches out with increasing speeds.
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nismo325
9 years ago
Im no rocket scientist but looking at the graphs wouldn't this system lead to worse small bump sensitivity? and why still have three settings? I Don't care if my descend mode pedals good thats not whats its made for.... i have trail or lock out for that.
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Dave_Camp
9 years ago
Not exactly- small bump doesn't always mean small velocity. The shock velocity is more dependent on shape of the bump- even a small rock or tree root generates a medium/high shock velocity. The low speed inputs are all rider generated- pedaling, pumping, weight shifts etc. The goal of the damper curve is to resist movement due to rider inputs, while still being sensitive to terrain.
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Chader09
9 years ago
So, this is intended to reduce motion at the shock from common, seated pedaling forces? Assuming that and based on your velocity comment, I am guessing that the shock will still respond (compress) from rapid preload by a standing rider performing a bunny hop?

I like that idea since I prefer to use my suspension for some hops up ledges.

I am excited to demo one of these. I hope this shock finds its way onto the Remedy 27.5 because I want to stick with 140mm travel for my next bike.
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Dave_Camp
9 years ago
Yes- the biggest advantage is that the shock pedals efficiently while still moving when you need it to- hitting bumps, preloading for bunny hop etc.
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Mono_Hidalgo
9 years ago
I love when development is reached by mechanical solutions, because this is every time less common in this electronic world that we have today.
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k.raichev
9 years ago
@Dave_Camp. Guessing the shock is build around the trek`s frame linkage curve spec. From the approx graphs in the video i find similarities easily achievable with SPV/Control valve shock (Manitou/Progressive) on a progressive to linear linkage (earlier DW-Link/VPP revisions). The above shocks also had two rebound shim stacks (beging/ending) and a needle adjuster. Will be interesting to hear how the rebound is handled with the air spring of the new shock, which with varying spring pressure puts a lot of force to both ends of the rope(early / deep stroke), way more than with a coil spring i guess.
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Dave_Camp
9 years ago
I wouldn't say the damper was built around our linkage. It was tested and tuned on our linkage...

The rebound circuit is pretty much identical to previous DRCV rear shocks. It works like normal.
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LaBourde
9 years ago
Is this technology already used in motocross ?
If not, how could you explain this ?

How can a technology coming from the car racing be efficient in MTB ? Spring mass, load transfer, obstacles, speeds, ... many parameters seem to be really different.

"an instant, seamless transition between the two" seems to be pretty difficult to achieve.
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Dave_Camp
9 years ago
It's not used in motocross as far as I know. I think it would work well in moto, but just hasn't gotten there yet.

Think about it this way: F1 cars want stiff suspension for cornering, braking, accelerating and to resist against their massive downforce. They want the suspension to move when the car hits a bump or apron on track.

A mountain biker wants stiff (efficient) suspension for pedaling, braking & cornering. MTB rider wants the suspension to move when we hit something on trail.

This valve was designed for cars, but applies well to mountain bikes.
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Primoz
9 years ago
Nitpicking a bit, if we talk about F1 specifically, the tire is actually a REALLY integral part of the suspension. The proposed move to 18" wheels would completely destroy that.

As for the suspension and downforce, more or less every high downforce car uses a third spring to counteract the forces. The car is really stiff in double bump (which is worse when it comes to braking and accelerating weight transfer), while that third spring does nothing in roll (or single bump).
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Dave_Camp
9 years ago
True, and the tire is also really important to suspension on a mountain bike! Didn't know they were contemplating switching to bigger wheels.

I don't know much about F1 car suspension, but I do know that regressive damping was used as one way of controlling body motions without going to stiffer springs. Beyond that, I don't know much about the extra spring setups.
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Primoz
9 years ago
Oh, seeing we have a Penske engineer: how does the engineering work look like, do you guys use the metric or the imperial measurment system when desiging... well bikes (Trek), cars, shocks, etc. (Penske)?
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Dave_Camp
9 years ago
I'm not a Penske engineer- I work for Trek at our suspension office (which is not in Wisconsin). I like working in metric (even though I'm a proud American) and we use Solidworks CAD. Fox uses Imperial, so that is fun to switch.
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Arnoodles
9 years ago
It makes sense for Fox to work with imperial, seeing as most if not all machining is done that way. Metric makes more sense as a system, but since imperial is what is used by CNC machines it makes more sense to design that way as well.
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Primoz
9 years ago
I can assure you that you can write G code in milimeters. And at the end of it all it's just an option in the interpreter, the most important part of the CNC machine is how far the movement system must move. And that doesn't work in either metric or imperial units. If a stepper is used, you emasure steps (or half steps). Etc.

Also, i suspect a big part of the shock is not milled, but forged (the outer damper body, the kashimad part, and the top eylet), deep pulled (the aircan i suppose) and probably something else as well. Sure, there is milling also done, but as a final operation i suppose. But the point still stands, it's not an imperial world when it comes to milling, far from it. Maybe in the USA.
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Arnoodles
9 years ago
I actually worked at Fox up until recently. Every part you named is machined to some degree. The aircan and stanchion start as a tube that's closed at one end and are machined in two operations by lathes. The others probably start out forged or cast but are finished with machining. I'm not sure about the system that a CNC uses, however everything at Fox is done in imperial. I do like the idea of machines run on metric.
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jeff.brines
9 years ago
DCamp isn't only a good engineer, he's a good bike rider. Since he won't say it I figured I should... Always good to know the guy engineering something for your bike is a better, harder charging rider than you. So you have that going for you. Which is nice.
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Primoz
9 years ago
So Dave is the guy that made a bike at home (as the diploma/masters project) and got a job with Trek?

Anyways, did you swap around the sides of the crank and swapped out the axles of the pedals, screwing them in 'the other way around'?

EDIT: enver mind, i looked at allt he pics and saw the chainring is in the middle, so not on the cranks at all...
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lister_yu
9 years ago
First of all - I think it is very cool that you take the time and answer our questions.

mine is about the shock service - are there any changes in service intervals and can a normal dealer service the shock? It sounds nearly to good to be true and normally there is a slight downside. I already own fox parts and I am not very satisfied when it comes to service - maybe that's connected to the poor support in Austria and Germany in the past ;-)
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Primoz
9 years ago
Fox should really do the same as Rock Shox does. Service manuals on the internet and a completely serviceable shock. That would make servicing a whole lot easier (and cheaper).
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lister_yu
9 years ago
...and rethink what they are doing in Austria/Germany at the moment. But manuels would be an integral part - comparing a service on a rock shox and fox fork -> fox is a nightmare :-) imho

in Europe the availability of seals, parts and all the needs stuff is also a nightmare :-(
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Dave_Camp
9 years ago
No problem- I'm happy to answer any questions...

About the shock service- since this shock is manufactured by Fox, it is covered under Fox warranty and service. I know it went through and passed all their normal testing- durability and otherwise, so it should at least match the durability of other Fox products. I cannot comment on the Fox service in Europe.
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nickb01
9 years ago
Have you considered incorporating this technology in a Dh shock for the Session? I love my 9.9, but the one areai would improve is its ability to pedal, and surely it'd be easier to do as the hits would be more substantial?
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norbar
9 years ago
Also WTF Trek. Another axle size? Seriously. Why do people buy bikes from companies like Trek who make it that hard to like them.
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Nicholast
9 years ago
Because despite what you think, not every change to a "standard" is a gimmick. In fact, most aren't. Bikes are at the point in their development where giant leaps don't come along often or easily; everything you see is a polishing and refinement of what once was believed and implemented. A 6mm wider rear hub seems silly... unless you are the engineer with the test data to back it up. Trek wouldn't have bet the horse if it didn't matter; they are too large and invest too much in R&D for seat-of-the-pants changes.

FWIW, I am trying to get my hands on a new Remedy 29 Carbon. Should be a nice upgrade over my Stumpy 29 EVO Carbon.
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Primoz
9 years ago
AN engineer, that looks at the obvious test data and decides that it's a smart idea to incorporate a new, scarcely supported standard, should be shot. If not him then his supervizor or product manager.

Yes, it's stiffer. Yes, it's better. But where the hell will you get a new hub quickly, when this one gives up? This problem has been solved, you just need to use large diameter flanges and the effect is the same with no need to use special, weird standards that nobody uses.

Yes, a large flange hub crapping out will mean it won't be as stiff. But you'll still be able to ride. And trust me, that is worth a whole damn lot (tomorrow will be 2 weeks since my last ride because i'm waiting for a new derailleur hanger).

As for being too large, the large players are exactly the ones that can do this kind of stuff. Lok at their DRCV shocks. Or Specialized's 142+ and custom autosag/yoke shocks. They have the sales numbers that support custom hardware. Which just causes problems down the road.

EDIT: as for the new standards, KISS!
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Nicholast
9 years ago
I think you missed my point. The market demands the next generation of a product to be better than the last. However, if the product is already close to the technical limit, there is not much to be improved without making expensive changes for small gains. Unless, the "standard" is the limit. In that case, change the standard. That's refinement and happens in every industry, not just bikes.
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Primoz
9 years ago
As said, the standard was not the limit. If you need more stifness, use stronger spokes and rims or use bigger flanges all the while using the same hub standard. Have you seen an average rider? I'm far above average and i really doubt i'd percieve the difference in a blind test.

There are a lot more areas that need imrpovement than the stiffness of the rear axle, IMO.
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glucia805
9 years ago
Then why not use 150mm? It's already a standard in use if you wanted wider.

Also, we have plenty of useless standards for bike that where invented to "solve" problems, BBs anyone?
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pinityafairy
9 years ago
A remedy 29 carbon an upgrade over a Stumpy Evo 29 carbon?! I wouldn't expect that. In fact, the Remedy pedals better, but the Stumpy smokes it on the descents. If that fits your riding style and goals better, then fair enough. Don't think for a second that you are getting a better bike from Trek. Spesh is waaaaay better about warranty too.
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norbar
9 years ago
A bike with proper suspension design will pedal good without the need for fancy switches. Another XC oriented product trying to enter bigger bike teritory. We already have too many "enduro" bikes that turn and ride like xc bikes.
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Dave_Camp
9 years ago
True, but I'd argue that our bikes pedal pretty well with any shock. Also- you don't HAVE to turn the switch...
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Dave_Camp
9 years ago
Hey guys- I was the lead engineer on this shock. If you have any questions- fire away.

Edit- this was in response to earlier posts:
It is not SPV, and SPV did not perform like this.

Yes we tried to make descend mode to behave like a shim damper- that curve feels best for descending.
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