Description
Trek’s 2015 lineup is expected to be available late this summer, and it looks to be an improvement in many ways over their 2014 offerings. Perhaps the most striking addition is the new RE:aktiv equipped shock that will come standard on several models. In this slideshow we take a look at the new shock, the Fuel EX 27.5, a carbon version of the Remedy 29 complete with 148mm rear hub spacing, and a Lush 27.5 model for the ladies.
RE:aktiv is the result of a collaborative effort between Penske Racing Shocks, Trek, and FOX. Over the course of the last five years, they’ve worked together to put regressive damping, a technology proven in auto racing, into a mountain bike shock. In a race car application, regressive damping is designed to be firm when cornering but supple for sudden impacts. When applied to mountain bikes the goal is similar - to provide support when pedaling or pumping but open up when needed.
How? RE:aktiv was designed to be very sensitive to shaft speeds, and it responds accordingly. Most rider inputs create low shaft speeds, while bumps create higher shaft speeds. Inside the shock, the main piston is equipped with a special spring loaded valve. The faster the shaft speed, the more the valve opens up and the more oil is allowed to flow through. Trek says 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. Because of this Trek says RE:aktiv achieves what inertia valves have been unsuccessfully attempting for years by balancing pedaling performance with big-hit absorption without feeling harsh. The way it’s able to react so rapidly is by changing the surface area that the oil is pushing against, as illustrated below.
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. In the firmer Trail and Climb settings the spring force on the valve is higher, requiring a higher velocity impact to open up the shock. At really high shaft speeds (think big/sudden hits), however, the valve opens completely regardless of the compression mode. In theory this means that you could rally a rough section in Climb mode without worry and with more control than previous designs.
The initial ride on the RE:aktiv damper, contained within a DRCV FOX Float CTD shock on a 120mm Trek Fuel EX, left us impressed and eager to try it more the following day. The first ride, although short, gave a great tease for what lay ahead and we finished thinking how oddly vague the rear end felt—it reminded us of a recent fork that left a similar first impression. Don't take the vague sensation the wrong way, this was more a tribute to the shock doing the right thing, so much so that the feedback we’re normally accustomed to feeling through a bike had been dwindled down so much that the difference put me off. What it translates to, however, is rear suspension that tracks the terrain remarkably well, especially when coupled with the DRCV system. The first ride was spent in Trail mode, given the terrain ridden and gentle coaxing from the engineering team to check out the shock’s abilities in Trail and Climb—modes where the damper’s benefits were more pronounced.
The following morning was spent predominantly in Climb mode. While it firmed up the rear suspension, it was completely unlike any other Climb mode we’ve experienced before. Rather than simply coming close to fully locking out the shock, the RE:aktiv damper had the uncanny ability to firm up the suspension from rider input, remaining higher in the travel until an abrupt change in terrain, in which case the suspension would open up, absorbing the impact.
Despite there not being as much of an impact from the RE:aktiv damper on Descend mode, we still had to try it out. The bike still climbed very well when wide open and tracked the terrain incredibly well when the going got rough and speeds increased. While many riders may not mind flipping levers to help with long climbs, you can rest assured the Fuel EX 27.5 gets along just fine wide open too. So the question then is if RE:akitv is needed? The answer here is pretty obvious. The benefit is for those who prefer a firmer bike under pedaling efforts, yet when the terrain changes before you have time to flip the switch back to Descend it’s still able to offer a smooth ride.
This lead us to reconsider how the CTD compression settings on the RE:aktiv shock could be used. Rather than thinking of the Descend for going down, Trail mode as a firmer platform for a mix of up/down or smoother trail, and the Climb mode for road climbs, consider them more in relation to how the bike’s geometry is affected. Climb obviously gives the steepest head angle and tallest bottom bracket height, while Descend allows the head angle to slacken out, the bottom bracket to lower and the wheelbase to lengthen. These attributes can, for obvious reasons, be thought of similarly on many bikes with similar compression controls (CTD or otherwise), but the difference comes in the RE:aktiv damper’s ability to still let the shock work when needed, regardless of the setting.
We did also take the opportunity to try an optional Push volume reducer in the shock, not because we felt we had needed it yet, but to see how it was going to make the bike respond. An initial pedal along some flat terrain didn't provide any great discernible difference, but once we dropped into the first trail and on the first hit—a rock a number of group members opted to launch off—it was noticed and welcomed. The landing from the rock was more controlled and the suspension held higher in its travel, propelling the bike forward and down the trail, rather than the momentary delay that would have been felt without. After riding the rest of the day with the volume reducer, we concluded that it made the suspension better suited to aggressive riding, with a better mid-stroke and increased bottom out resistance, but didn't hinder the small bump performance and great traction the DRCV/RE:aktiv shock offers.
These are our first impressions, mind you, and a day and a half on the bike is by no means enough time to give any sort of conclusive information on the bike’s handling abilities. So far, though, we’re impressed and the shock does work as advertised. We’ll bring you long term impressions on familiar terrain in the future.
Visit www.trekbikes.com for more details.
Photos by Sterling Lorence, Dan Milner, and AJ Barlas
What Is RE:aktiv?
RE:aktiv is the result of a collaborative effort between Penske Racing Shocks, Trek, and FOX. Over the course of the last five years, they’ve worked together to put regressive damping, a technology proven in auto racing, into a mountain bike shock. In a race car application, regressive damping is designed to be firm when cornering but supple for sudden impacts. When applied to mountain bikes the goal is similar - to provide support when pedaling or pumping but open up when needed.
How? RE:aktiv was designed to be very sensitive to shaft speeds, and it responds accordingly. Most rider inputs create low shaft speeds, while bumps create higher shaft speeds. Inside the shock, the main piston is equipped with a special spring loaded valve. The faster the shaft speed, the more the valve opens up and the more oil is allowed to flow through. Trek says 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. Because of this Trek says RE:aktiv achieves what inertia valves have been unsuccessfully attempting for years by balancing pedaling performance with big-hit absorption without feeling harsh. The way it’s able to react so rapidly is by changing the surface area that the oil is pushing against, as illustrated below.
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. In the firmer Trail and Climb settings the spring force on the valve is higher, requiring a higher velocity impact to open up the shock. At really high shaft speeds (think big/sudden hits), however, the valve opens completely regardless of the compression mode. In theory this means that you could rally a rough section in Climb mode without worry and with more control than previous designs.
Initial Impressions
The initial ride on the RE:aktiv damper, contained within a DRCV FOX Float CTD shock on a 120mm Trek Fuel EX, left us impressed and eager to try it more the following day. The first ride, although short, gave a great tease for what lay ahead and we finished thinking how oddly vague the rear end felt—it reminded us of a recent fork that left a similar first impression. Don't take the vague sensation the wrong way, this was more a tribute to the shock doing the right thing, so much so that the feedback we’re normally accustomed to feeling through a bike had been dwindled down so much that the difference put me off. What it translates to, however, is rear suspension that tracks the terrain remarkably well, especially when coupled with the DRCV system. The first ride was spent in Trail mode, given the terrain ridden and gentle coaxing from the engineering team to check out the shock’s abilities in Trail and Climb—modes where the damper’s benefits were more pronounced.
The following morning was spent predominantly in Climb mode. While it firmed up the rear suspension, it was completely unlike any other Climb mode we’ve experienced before. Rather than simply coming close to fully locking out the shock, the RE:aktiv damper had the uncanny ability to firm up the suspension from rider input, remaining higher in the travel until an abrupt change in terrain, in which case the suspension would open up, absorbing the impact.
Despite there not being as much of an impact from the RE:aktiv damper on Descend mode, we still had to try it out. The bike still climbed very well when wide open and tracked the terrain incredibly well when the going got rough and speeds increased. While many riders may not mind flipping levers to help with long climbs, you can rest assured the Fuel EX 27.5 gets along just fine wide open too. So the question then is if RE:akitv is needed? The answer here is pretty obvious. The benefit is for those who prefer a firmer bike under pedaling efforts, yet when the terrain changes before you have time to flip the switch back to Descend it’s still able to offer a smooth ride.
This lead us to reconsider how the CTD compression settings on the RE:aktiv shock could be used. Rather than thinking of the Descend for going down, Trail mode as a firmer platform for a mix of up/down or smoother trail, and the Climb mode for road climbs, consider them more in relation to how the bike’s geometry is affected. Climb obviously gives the steepest head angle and tallest bottom bracket height, while Descend allows the head angle to slacken out, the bottom bracket to lower and the wheelbase to lengthen. These attributes can, for obvious reasons, be thought of similarly on many bikes with similar compression controls (CTD or otherwise), but the difference comes in the RE:aktiv damper’s ability to still let the shock work when needed, regardless of the setting.
We did also take the opportunity to try an optional Push volume reducer in the shock, not because we felt we had needed it yet, but to see how it was going to make the bike respond. An initial pedal along some flat terrain didn't provide any great discernible difference, but once we dropped into the first trail and on the first hit—a rock a number of group members opted to launch off—it was noticed and welcomed. The landing from the rock was more controlled and the suspension held higher in its travel, propelling the bike forward and down the trail, rather than the momentary delay that would have been felt without. After riding the rest of the day with the volume reducer, we concluded that it made the suspension better suited to aggressive riding, with a better mid-stroke and increased bottom out resistance, but didn't hinder the small bump performance and great traction the DRCV/RE:aktiv shock offers.
These are our first impressions, mind you, and a day and a half on the bike is by no means enough time to give any sort of conclusive information on the bike’s handling abilities. So far, though, we’re impressed and the shock does work as advertised. We’ll bring you long term impressions on familiar terrain in the future.
Visit www.trekbikes.com for more details.
Photos by Sterling Lorence, Dan Milner, and AJ Barlas
View replies to: First Look: Trek's RE:aktiv Damper and the 2015 Fuel EX 27.5, Remedy 29 and Lush 27.5
Comments