2015 Trek Fuel EX 27.5 and RE:aktiv Shock
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Given that Trek already offers their 27.5'' wheeled Remedy with a carbon fiber frame, it shouldn't came as a shock to see them add a 29er carbon model to the existing aluminum big wheeler platform. There is a more surprising bit of news, though: Trek is now offering the 120mm travel Fuel EX with smaller diameter wheels. Wait, smaller? Yup. The Fuel EX 29er is still available, but Trek told Pinkbike that they are aware that a 29er rider might be a very different animal than someone who prefers 27.5'' wheels: 'We have a philosophy that goes 'two riders, one trail' where, in regards to wheel size, we kept working towards rider-specific usage,'' John Riley, Trek Mountain Bike Product Manager, explained to us. ''Initially, we found that in the 140mm travel range there are really two different types of riders who are looking for a different experience on the trails. We also found that to be true of the 120mm Fuel EX platform.'' The type of rider that Riley is referring to could be someone who, while still wanting to feel fit and fast, might also not shy away from a fun bonus line on the side of the trail; the new Fuel EX platform that he's referring to is the 27.5'' wheeled rig shown here. It also should be noted that there is still a 26" wheeled Fuel model in the lineup for 2015, the $2,099.99 USD Fuel EX 6, meaning that Trek is offering their trail bike platform in all three wheel sizes.
Fuel EX 27.5
Have spent many, many hours aboard their Fuel EX 29er, flying down for two days of riding on the new 27.5'' wheeled version presented an excellent opportunity to compare the two. Now, the singletrack that we rode in Brevard wasn't the roughest, most testing type of terrain, but there's something about going through the trees at mach chicken that never gets old. Yes, there were plenty of Star Wars speeder bike references during the week. No Ewoks, though, just a few massive snapping turtles.
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 Trek calls it 'Matte Volt Green', and it might just be the safest machine to be aboard come hunting season in your local woods. This was my chosen stallion for Brevard's fast trails, the $5,249.99 Fuel EX 9.8 27.5. |
RE:aktiv Damper
The Fuel EX's FOX Float DRCV shock appears to be the same as last year, except for that small RE:aktiv decal stuck to it. What's that all about? You may have seen the press release a few days ago from Trek that talked about them working on new-to-mountain bike shock technology with the legendary Penske Racing, and while that blurb was heavy on the marketing, there is a real connection here between what Penske are putting inside the dampers that they provide for all sorts of auto racing applications and what is being used to control compression forces within the FOX shocks found on the new Fuel EX and Remedy platforms. And yes, the very same principles are being applied to the dampers that Penske builds for multiple Formula One teams, although a single one of those can cost more than what a Session 9.9 goes for. A lot more.
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| Same suspension layout as the Fuel 29er, but smaller wheels and new shock technology. |
The RE:aktiv design is essentially Penske's regressive compression damper shrunk down and stuffed into the FOX Float CTD shock. It consists of a completely different main piston design that, in very simple terms, employs a spring loaded valve (the special Smalley spring is pictured below) that can open to allow a lot of oil flow through the compression shim assembly. However, when the valve is closed the damper provides added low-speed compression for more efficient pedalling and, more importantly in my mind, more low-speed control that helps to keep the shock from pitching through its stroke when you're on the brakes or throwing your body weight around. This idea is to preserve the bike's handling.
The valve stays closed when the bike is stable, restricting oil flow and giving you a more stable chassis, until a pressure spike begins to open it. This typically happens when an impact of roughly three inches per second or faster occurs, which is actually a very minor hit. Penske worked quite hard at making sure that the system absolutely doesn't behave like a typical pressure release valve, though, and it was made very clear to me that one of the main goals of the RE:aktiv project was to create something that didn't behave anything like an on/off switch, but rather offered a more open and variable feel on the trail. Valve spring rate, valve plate design, and orifice size all came into play in the search for zero breakaway feel, and both FOX and Penske feel that they've absolutely nailed it. Part of this is also down to the velocity sensitive nature of the system: "When the valve starts opening you'll get very quick relief because there's a lot of flow area exposed extremely quickly before it regains control. That's the regressive element that
you're feeling,'' Jose Gonzalez, Trek Suspension Engineer, explained to Pinkbike. ''As the velocity increases, the spring tries to work against that force, but at some point the force overcomes the spring to allow for a lot of flow, so there's no harshness. At the same time, because you've got the flow area constantly varying depending on the force that's pushing on the spring, as well as the ports that the oil has to then flow through, you get high-speed resistance as the velocity increases.''Want to learn more about how the RE:aktiv shock works? Our look at the 2015 Remedy 29 Carbon includes more photos and information about the technology and the partnership between Trek, FOX, and Penske.
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| As the song goes, one of these things is not like other... |
On Trail with RE:aktiv
A little overwhelmed by the tech? Maybe you're as captivated by how RE:aktiv works as you are by your girlfriend's latest issue of Cosmo? I couldn't blame you for falling into either category - it's a hell of a lot of information to absorb, and, to be honest, it's probably not that interesting unless you're the kind of rider who stops to add or subtract a single click of damping or a few PSI to their shock every few rides... you know who you are, and you probably annoy the hell out of your riding buddies, but more power to you. What really matters is how this new RE:aktiv stuff performs on the trail. And even more importantly, how it compares to last year's non-RE:aktiv FOX Float CTD DRCV shock. Because finding out if the new shock is actually better than the old shock is all that counts, and because the only way to properly do that is to compare them back-to-back on the same section of trail, I had to do exactly that. Myself, a 2015 Fuel EX 27.5 with its new RE:aktiv shock, and Jose Gonzalez, Trek Suspension Engineer pictured to the right, with a handful of tools and last year's shock was all it took.
Most of the singletrack that I rode in Brevard was smooth enough to play billards on, which, don't get me wrong, is more fun to ride than playing tonsil hockey with Lucy Liu, but it isn't exactly ideal for evaluating new suspension. It took a while and I ended up having to import some large, pointy rocks onto the trail, but I soon had a worthy, if a bit short, section within an hour that suited my needs. This included a smooth climbing section, a rough climbing section, and then a rocky descent. The plan: start on the RE:aktiv shock before switching to the previous version (both run with the same settings), and then jump back to the new RE:aktiv shock in order to highlight any differences. What did all that back and forth prove?
 | What really matters is how this new RE:aktiv stuff performs on the trail. And even more importantly, how it compares to last year's non-RE:aktiv FOX Float CTD DRCV shock. |
Most of the singletrack that I rode in Brevard was smooth enough to play billards on, which, don't get me wrong, is more fun to ride than playing tonsil hockey with Lucy Liu, but it isn't exactly ideal for evaluating new suspension. It took a while and I ended up having to import some large, pointy rocks onto the trail, but I soon had a worthy, if a bit short, section within an hour that suited my needs. This included a smooth climbing section, a rough climbing section, and then a rocky descent. The plan: start on the RE:aktiv shock before switching to the previous version (both run with the same settings), and then jump back to the new RE:aktiv shock in order to highlight any differences. What did all that back and forth prove?
• Trail / Descend Mode - I don't think I'm alone when I say that I feel like a well sorted 120mm travel bike shouldn't ask you to reach for the pedal assist lever unless you're faced with a long gravel road climb. Sure, a 150mm+ bike might require some sneaky tricks, but a machine like the Fuel EX should be able to just get on with it, regardless of the shock being left open. The bike pedals well enough with last year's shock that there really isn't much to complain about in this regard, but I did note a slight increase in efficiency with the new RE:aktiv shock when spinning up the smooth climb - the bike's rear suspension simply cycled up and down less under chain torque and body weight movement. No, it isn't a night and day difference, and it is in no way anything like the firmness that an inertia valve system provides, but I'd say that it's likely a bit more "useable" for a trail ride because of this. Climbing up our little test section of rough singletrack showed that both the Trail and Descend modes feel very much like last year's shock, and I'd be hard pressed to tell the difference in a blind test. Actually, I'd be far more likely to spot the distinction between Coke and Pepsi before noting the difference between a RE:aktiv and a non-RE:aktiv shock on a rough climb. This isn't really a surprise, though, because the rocky ledges and holes of our test pitch were enough to open the regressive valve plate and allow oil to flow through, which in turn allows the shock to do its job.
Descending revealed a very familiar feeling, with the RE:aktiv shock coming across a lot like its predecessor on our short test lap when in either the Trail or Descend mode. That's not a bad thing, though, as I've never felt that it's left me wanting for anything more during my time on it in the past. Gonzalez did mention that it should be possible to lower the shock's pressure by 5 - 10 PSI due to how the regressive valving helps to hold the bike up in its travel, which in turn should create a more forgiving ride without sacrificing any ability to "push" against the travel when you're pumping the terrain. This is something we'll have to investigate on more familiar trails, but it does sound promising.
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| Consistency is key when doing back-to-back testing. That means carrying the same speed and hitting the same lines. |
• Climb Mode - Here's where it gets interesting. While the difference in performance between the new and old shocks when in Trail and Descend mode is certainly notable on a smooth climb, the truth is that it is also subtle enough that a rider who maybe doesn't know the difference between a shock pump and tire pump might not take note of it. Flip the little blue lever to Climb mode, however, and there's no way that anyone could mistake the RE:aktiv shock for the standard unit. It's firm on smooth ground, as it should be, but then manages to open up and take the edge off of impacts well enough that it could almost convince someone that it isn't the shock's firmest setting. Yes, it's still harsher than the two more forgiving modes, as it should be given that it takes a harder impact to open the regressive valve plate, but I'd say that it's far more functional than the Climb mode on last year's shock simply due to the fact that it offers both a firm and efficient ride on smooth ground, but can open up to dissipate hits. Back-to-back-to-back runs up and down our little test section revealed that while the older shock felt locked out, the new shock felt firm but allowed the bike to carry more momentum over the rocky ground. Interestingly, the RE:aktiv shock felt much more balanced and in-tune with the fork during this part of the testing, while the old shock, when in Climb mode, had the fork feeling harsh and underdamped.
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| Gonzalez swapping shocks on my Fuel EX 27.5 test bike while I did the important job of holding the bike up. |
Pinkbike's take:
| First, the downside is that, much like the DRCV air spring, RE:aktiv is entirely proprietary to Trek. The dirty 'P' word is one that gets many heads shaking, and, given the shock's unique upper mounting configuration, I can understand a lot of readers' apprehension to the idea, especially if you think you might want to run a different shock down the road. No one likes to be boxed in, even if said box works very, very well. Boxes aside, the bottom line is that the RE:aktiv shock pedals better when it's left in either Descend or Trail modes, but is also much more forgiving when in the firmest Climb setting. It's true that last year's FOX Float DRCV CTD shock was no slouch, and I've always thought that its two-chamber DRCV air spring allows you to get both sensitivity and big hit control, but the new RE:aktiv damper further increases its versatility. - Mike Levy |
Photos by Dan Milner and Sterling Lorence
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The original penske article has some good discussion on the inner workings
No problem! Definitely a legit question.
Boom. I give you "kashima" coating" $9.99
How long does it stay on for?
Basically a can a year/2.
Looks pretty gold to me...
But technology developments such as the above do not really justify those prices in my opinion.
As manufacturing costs / cogs should come down and economy of scale hit in. Whilst development costs might go up, it must be getting cheaper and cheaper to produce bikes nowadays.
The review states that in Trail and Descend mode the shock feels basically the same, maybe letting a rider get a slight bit more plushness out of a few less psi and a valve that still allows the shock to sit high in its travel.
But it makes a noticeable difference in Climb mode, a mode, which as stated by the author up front, shouldn't even be required on a 120mm trail bike if it is "well sorted".
I have the 201 EX9 and only ever use Climb mode for extended road climbs, otherwise the bike is in trail mode 99% of the time. Descend is just too soft, unless I jack the air and sacrifice other performance aspects of the fork and shock.
Trek, this is a great frame, the geo feels so nice… please do something about the suspension in Trail and Descend mode, where most all of your riders will use the bike.
psst: sorry to go off topic.
FOX, I don't need new cooler settings. I need reliability. Any thoughts?
Seriously? Why on earth would you need fatter stanchions on a 120mm bike? Revelation, Fox 32, Epicon, etc are all plenty stiff now that thru-axles are standard. Back in the days of QR axles I might have agreed with you, but there's nothing wrong with any of those forks at 120mm. Plus 120mm bikes are made to climb like goats, the tiny bit of extra stiffness wouldn't be worth the weight IMO.
DRCV could provide big hit control if the float 32 CTD wasn't underdamped. It nose dives and bottoms out too easily unless you choose to put a lot more air and have an harsh ride. 2014 flow divider does not make much difference to me.
Rear shock behaves not too bad but I am constantly afraid of blowing it.
It's a shame because the Fuel Ex (26'') is a very well balanced bike overall. I would expect the same of the 27.5'' .
They have essentially created another type of speed sensitive damper. However the spring and curve they have used allows them to essentially have very high LSC that does not negatively cross over to the mid and high speed compression. It has not eliminated the issue of more LSC = less traction internally (like they would have us believe) because this high curve is still very heavily damped. What they have done though is remove the negative effect it used to have on reducing the mid and high speed sensitivity by regressing the curve. It has just improved the LSC support and made the transition and into mid stroke smoother with more sensitivity and more traction after the initial stroke.
They have also slightly improved the way LSC is used, in that mostly increasing LSC can create a harsh point where it blows off this aims at keeping it as smooth as possible, although while you will not get the same curve with a shim change you can make the current dampers smooth like that too with the shims rather than the LSC external adjustment.
So in conclusion they have slightly improved the smoothness of LSC but most the improvement will be seen in the mid/transitional velocity performance.
If you look at the curve though the shock will need to be set up very well so the curve lines up with the right force input due to the regressive curve that regression needs to be initiated correctly.
I think he left the floater.
Get all that "middle activity" support for very little concidering price and...
www.pinkbike.com/news/north-carolina-dbinline-canecreek-video-2014.html