Flight Attendant, RockShox' new wireless electronic suspension system launched today, and it's big enough news that it warrants two separate articles. If you want a comprehensive rundown on how Flight Attendant works, check out Mike Levy's article and video here. If you're more interested in how it performs out on the trail, keep on reading.
First, the quick synopsis of what Flight Attendant does: it automatically makes suspension adjustments depending on what a bike and its rider are doing in order to maximize efficiency. The system takes information from sensors in the fork, shock, and cranks, and uses it to decide what compression setting the suspension should be in: Open, Pedal, or Lock, or even a mix, where the fork might be in one mode and the shock in another. The analysis happens every 5 milliseconds, although the time it takes to actually open or close the fork or shock does takes a little longer than that.
Efficiency is often associated with cross-country bikes, which is why it was a little surprising to find out that Flight Attendant is aimed more at longer travel options where pedaling performance isn't typically the top priority. The idea is that Flight Attendant should make it possible for a longer travel bike to have greatly improved manners while climbing, all without losing anything on the descents - I like to think of it as the 'having your cake and eating it too' concept.
I was lucky enough to get my hands on a Specialized Enduro with the new bits on it four weeks early, giving me just enough time to put in a solid thrashing before issuing a verdict. Testing took place on Vancouver's North Shore, in the Whistler Bike Park, and on a wide mix of terrain around Bellingham, Washington. Conditions were also mixed, and ran the gamut from dry and dusty to soggy and sodden.
I should note that while I've racked up enough hours on the system to feel comfortable calling this a review, it's still too early in the testing process to comment on long-term durability – if any issues arise in the future we'll be sure to issue an update. For now, the focus here is on how the system functions and feels out on the trail.
Different colored lights indicate what is being adjusted. In this case, it's the shock's low-speed compression.
Set Up
Getting the Flight Attendant system up and running requires a strong cellular or wi-fi signal, at least if you want to access the in-app tutorial, so it's best to avoid go too deep into the bush before performing the necessary pre-flight procedures. The most important step is the calibration of the system. Calibration is only done for the initial setup – it's not something that needs to be done before every ride.
The app includes step-by-step instructions, but calibration basically involves sitting on the bike so that the amount of sag can be detected, and then tipping the bike towards the non-drive side in order to give the sensors the information they'll need to determine the bike's position in space out on the trail. The lights on the top of the right fork provide visual indicators to make things easier, and from beginning to end the process only takes five minutes or so.
For my 160 lb weight I ended up running 210psi in the shock for 30% sag, and 59 psi in the Zeb fork.
Flight Attendant does take up more space on a frame, which is why it'll initially only be available on select models from a handful of companies.
AXS App
The app that I was using during testing was a beta version, so I can't issue an absolute verdict as to how well it works. I can say that there were some frustrating moments when the app was having trouble recognizing all of the AXS components – I ended up getting caught in a few endless loops before deciding to do a full reset and start over again. Hopefully those bugs are worked out for the final version.
Thankfully, once Flight Attendant is calibrated and set up there's really no need to open up the app again – all of the adjustments can be performed via the buttons on the top of the fork's control unit. The only time you'd really need to use the app is to reassign which AXS lever is used to put Flight Attendant into override mode. Override mode is accessed by holding down the selected AXS lever for two seconds. That switches the system into the pre-selected mode – fully locked out is the default option.
I ended up choosing the fully open position as my override mode rather than fully locked out. That way, I could basically turn the system off and have everything open whenever I wanted. I didn't end up using it all that much, due to how 'smart' Flight Attendant is, but I appreciate having that option close at hand.
There's an app for that...
Adjusting your compression damping is possible via the Flight Attendant / AXS app, or on the fork itself.
Flight Attendant Performance
Let's start with what it's like to live with Flight Attendant out on the trail. Within a couple of pedal strokes the Flight Attendant system wakes from its slumber (if it doesn't wake up, a quick push of the AXS button on the fork should do the trick). The 'bzzt, bzzt' of the fork and shock servos doing their job lets you know it's receiving information, along with the green light on the top of the fork that illuminates with each mode change.
The current Specialized Enduro isn't a terrible climber, especially considering how much travel it has, but it is a bike that benefits from being able to firm it up on uphill or rolling terrain, especially to help minimize the suspension movement during out of the saddle climbing. With Flight Attendant, any concerns I may have had about the Enduro's pedaling efficiency were completely erased.
At one point, thanks to a slight miscommunication, I ended up on an XC ride with two buddies, one on a Specialized Epic and the other on a Transition Spur. To help bridge the gap I bumped up the Flight Attendant's Bias level to the firmest position, which made it so that it placed more of a priority on being in the fully locked out setting, and then proceeded to pedal my brains out.
Did those electronics completely level the playing field? Definitely not, but they did take one of the advantages of those shorter travel bikes off the table. The Enduro's weight and geometry meant that it still wasn't an even match, but it was nice to be able to stand and sprint without any mushiness, and then when the suspension automatically opened up on the descents I was able to reap the benefits of bringing that big bike along.
The fact that Flight Attendant's default setting is open rather than closed is what sets it apart from something like Fox's Live Valve, and I'd say it's one of its biggest strengths. I was a little hesitant at first, worried that the suspension would firm up or open up when I didn't want it to, but I never encountered any unexpected mode changes while descending (or climbing for that matter). It fades into the background, aside from the noise when the modes change, and the algorithm does a great job of adapting to terrain and pedaling input changes in a way that's not distracting or jarring.
The Bias adjustment feature is a nice touch - it makes it possible to fine tune what the system is trying to achieve. My preferred setting ended up being one firmer than the default middle position, which is one away from the setting that places the highest priority on being in the fully-locked position. That gave the Enduro a sportier feel on mellower terrain and while climbing, a change in the bike's manners that had me pedaling harder on that type of terrain than I would have without Flight Attendant, simply because of how much more efficient the bike felt. Rather than being content to sit and cruise to the top at a more relaxed pace, I found myself more likely to go a little harder due to the extra support that the firmer mode created.
I did get an odd noise to come out of the rear shock when I hit a big root in the middle of a mode change, sort of like what I imagine it'd sound like if you hit a robotic duck with a hammer. That was the only tiny hiccup, and I'd hesitate to even call it that since the performance didn't change at all.
The new ButterCups found on the bottom of the air spring and damper use a rubber bumper that's designed to absorb high frequency vibrations.
Pressure relief valves are located on the back of each leg.
The Non-Electric Bits
The algorithms, servos and such are the main focus of this launch, but the new suspension tech that's been rolled out at the same time shouldn't be overlooked. RockShox's official statement is that “We have introduced new technologies with the new chassis, which includes the new Pressure Relief Valves. We are always working on new product and cannot comment on any current or future developments.”
I'll eat my hat if the next generation of the Zeb and Pike don't have those relief valves or the Buttercups – I'm sure they were developed to work with more than just Flight Attendant. Honestly, the Buttercups are probably my favorite feature of this whole package. That's due in part to how deceptively simple the design is. It's not a totally new concept (it's used in the automotive world), but I haven't seen anything like it on any modern suspension fork.
I'm curious if the performance will change at all in cold temperatures – will that little rubber puck firm up and diminish some of the Buttercups' benefits? That's a test that'll have to wait until the winter. In the meantime, I will say that this is hands down the best feeling Zeb I've been on. It manages to take the edge of the small chatter while still retaining enough support to keep it from diving too deep into its travel, a trait that was appreciated on the chunky trails of Vancouver's North Shore and on the end-of-season brake bumps in the Whistler Bike Park. I've only had one harsh bottom out, on a decent sized drop to flat, but otherwise there's been plenty of ramp up to keep that from occurring even with only one volume spacer installed.
With similar set ups, the Fox 38 feels a little softer off the top, but the Zeb does seem to muffle the trail chatter a little better. So far the changes to the Zeb don't seem to be enough to make it a clear winner over the 38 – the battle between those two forks continues to be too close to call, and it really comes down to personal preference. The one downside to this Flight Attendant configuration is that there's no high speed compression adjustment – that's been taken off the table to allow for the different low speed compression modes. I'm more of a set-and-forget rider when it comes to that adjustment, so I didn't miss it much, but riders who want access to as much fine tuning as possible may find themselves wishing for its existence.
I am glad to see the addition of pressure relief valves, a feature that should make sticking a zip tie down past the dust seals to allow any trapped air to escape a thing of the past. They work, too; I've heard a 'psst' of air escape when I've pushed the buttons. The final battery-free feature worth mentioning is the addition of a hydraulic bottom out to the SuperDeluxe shock. That's going to be an option that companies can choose when spec'ing this shock depending on the bike's kinematics and intended use. I was glad to have it on the Enduro - the ramp up was nice and smooth, and it matched well with what the fork was doing up front.
The pedal sensor is housed inside the crank arm spindle, and is powered by a AAA lithium battery that's said to have a run time of 200 hours.
Downsides
Personally, the 'bzzt bzzt' of the mode changes annoyed me a little, especially when I was out on a long climb by myself. It's an almost identical noise to that of the SRAM AXS derailleur, so if that noise doesn't bother you then Flight Attendant likely won't either. On the descents, where there's more noise from the trail, and the mode changes are less frequent, the electronic 'bzzt' didn't get under my skin as much.
Adding Flight Attendant to a bike also means there are two more batteries to keep charged, three counting the one in the crank sensor. If you're running the complete AXS 'ecosystem' (sorry, that word makes me cringe too), then you're looking at a total of 4 batteries that will need regular charging, plus three batteries that are worth checking once a year – one in each shifter and one in the aforementioned crank sensor). Fingers crossed SRAM is working on a multi-port charger, since having four separate chargers going at once seems a little silly. Wireless seems like a great selling point, and it does simplify setup, but I feel like if there was a way to connect everything so that it could all be charged from one port that would make things easier.
The cost of the system is undoubtedly a hurdle as well, although that could become less of an obstacle in the future when the price comes down, or if the system ends up being available on its own. RockShox didn't release any specific prices, since at the moment it's only available on complete bikes, but for reference the Specialized S-Works Enduro I was on is priced at $12,500, or $2,000 more than the current non-Flight Attendant equipped S-Works Enduro.
Future Dreaming
I'm sure there's an article out there that says Flight Attendant is 'game changing', but I'm not going to use that tired cliché. Is it novel? 100%. Is it an absolute necessity? Not at all, but that doesn't mean it shouldn't exist, especially considering all of the other potential doors that it opens.
I like Flight Attendant because it makes me think, not so much about its performance, but about what the future of the system could be like. As it is, it's an incredibly strong debut - it does exactly what it's supposed to with an intuitive interface for fine-tuning its performance. That doesn't mean there aren't some things I'd like to see somewhere down the road, though.
There's no denying that firming up the fork and shock improves the efficiency of a bike, especially on a longer travel machine like the Enduro. Not needing to think about making those changes on the fly is nice, and makes it easier to focus on the trail, or think about what's for dinner. That being said, I'd be content with a simple wireless shock lockout. I'm not as worried about the fork being in the open position, but I would love to see a less expensive version of this system that makes it possible to cycle through the three settings via a little thumb lever or a blip button.
I also think a suspension control that correlates with the seatpost height makes a lot of sense - open when the seat is fully dropped, firm when the seat is fully extended, etc... BMC tried it with their TrailSync system with mixed results, but there's certainly still room for a better execution of the concept.
It's going to be interesting to see where Flight Attendant goes in the future - will RockShox keep adding more and more features, like an integrated ShockWiz unit in the air spring side, or will they roll out simpler, pared-down versions to hit more affordable pricepoints? Or all of the above? We'll have to wait and see - for now, I have a feeling tracking down a bike with Flight Attendant on it will be challenging enough.
Pros
+ Dramatically improves climbing performance
+ Intuitive interface makes on-the-fly adjustments easy, no phone required
+ The non-electrified features of the Zeb fork and Super Deluxe shock are excellent improvements.
Cons
- More electronics means more batteries to charge
- The sound of the suspension switching modes can be distracting
- Along with the substantial cost, Flight Attendant comes with a 300 gram (.7 lb) weight penalty.
 | Electronically controlled mountain bike suspension isn't exactly new - I'm old enough to remember the 9-volt battery powered K2 Smart Shock from the late 90's. Thankfully, there have been massive advances in technology since that time, which has allowed RockShox to cook up the best execution of the concept yet. Flight Attendant has the potential to turn more gravity-oriented bikes into potent all-rounders, or to make mid-travel options more XC-oriented nature on the climbs, all without sacrificing anything on the descents.— Mike Kazimer |
