If there was ever a bike that was ready for anything, the new generation of the Trek Rail 9.9 would be it. Accompanying the 150 mm travel carbon frame, with geometry inspired by their Slash enduro bike, is the Bosch CX motor and 750 Wh PowerTube battery that delivers a 125 Wh power boost compared to the previous generation. The bike is spec'd with two 29" wheels, but thanks to a flip-chip adjustment a 27.5" rear wheel can be fitted in the high bottom bracket setting.
Retailing for a jaw dropping $13,499 USD, our size large Rail 9.9 weighed in at 23.78 kg / 52.4 lb, without pedals. The first thing that you'll notice against the flashy red foil graphics and candy paint are more blinking lights. This no-holds-barred build has all the carbon and latest MTB tech, including SRAM AXS electronic shifting, TireWiz, and all new AirWiz pressure sensors.
Trek Rail 9.9 Details
• Wheel size: 29" (27.5" rear compatible)
• Travel: 150 mm rear / 160 mm front
• Carbon frame with magnesium rocker link
• 1.8" tapered steer tube
• 750 Wh PowerTube Battery
• Bosch Performance Line CX Smart System
• ABP suspension design
• Knock Block 2.0
• SRAM AirWiz suspension pressure monitors
• 64.2º (LO) / 64.6° (HI) head tube angle
• 76.7° (LO) / 77.1° (HI) seat tube angle
• 448 mm chainstays
• Weight: 23.78 kg / 52.4 lb (size LG)
• Sizes: S, M, L, XL
• MSRP: $5,599 - $13,499 USD
Brand new from SRAM, the AizWiz pressure monitors on the 160 mm RockShox ZEB and Super Deluxe Ultimate RT3 keep track of the suspension's air pressure, operating just like the TireWiz units found on each wheel. The lights blink green when set to the desired pressure and flash red if it is beyond the upper or lower limit, making it easier to grab the bike and go ride with peace of mind. These use the SRAM AXS app and are a breeze to sync and set to your preference. By simply moving the bike to "wake up" the electronics, the app will detect the sensors.
Bontrager parts round out an almost complete SRAM spec on the 9.9, such as the tires, cockpit, Line Pro 30 mm internal width carbon wheels, with the exception of the E*thirteen E*Spec Race carbon cranks. At the heart of the bike is the Bosch Performance Line CX Smart System motor, which puts out 85 Nm of torque and 250 W of maximum power. There are four different power settings, in addition to zero assist, that can be tuned to your riding style.
The all new AirWiz monitors the shock pressures, so you won't have to waste time double checking your suspension before a ride.
You don't have to fork over all of savings, because there are five North American Rail models which utilize the new frame design to choose from. $8,999 will get you out the door with the Rail 9,8 GX build. For the same price, you can also choose a Shimano XT group set. Another $1000 will give you the option of electronic shifting from the SRAM GX AXS kit. A full Shimano XTR trim will break into the 5-digit price bracket at $12,499.
Trek has really gone all out with this bike. There is no shortage of features, like the Kiox display that is removable, but the mount is integrated into the top tube. Just ahead of that is the Knock Block 2.0 with 72-degrees of turning radius. This can be swapped for an infinite radius chip, but is strongly advised against to protect the display unit. Leading the charge at the front of the frame is the massive 1.8" lower head tube and eMTB rated version of the RockShox ZEB for maximum single crown stiffness. The frame can accept a 170 mm fork, should you wish to boost the travel.
To accept that new steer tube, Trek redesigned the 9.9 and 9.8 frames, while the other models in the family use the carry-over chassis from last year. The previous generation is not backwards compatible with the new power components (the motor, battery, display, and remote). For riders choosing the size small frame, it's worth noting that it comes with a 625 Wh battery due to the packaging constraints of the curved top tube, a compromise that was done for increased standover height. It will also need to use Bontrager's Voda 15 water bottle, but all other sizes will fit a regular 650 mL vessel.
On the non-driveside of the downtube is a lock for the side-release battery and its clever handle that pops into action when released. This means you'll need to have the keys on hand to totally remove the battery, but that's not necessary to charge the bike. A port is located at the bottom of the 34.9 mm seat tube, just above the motor. A full charge will take six hours, but the 4-amp charger will get you 50% capacity in just two hours.
The battery has a clever handle that springs up when disconnecting the battery.
Rear suspension duties are handled with 150 mm of rear wheel travel via Trek's Active Braking Pivot (ABP) linkage and a trunnion mount Thru-Shaft Super Deluxe RCT3, a shock with a three position climb switch and rebound adjustment. The maximum rotor sizes are already fitted, with a 220mm up front and 200mm out back. Also on the rear triangle near the brake caliper is a kickstand mount, not something often seen on an enduro eMTB, but it's on unobtrusive option, should you want to add that component.
As mentioned, the Rail can rock a mullet wheel setup if you flip the Mino Link chip at the seat stay pivot to the high setting, also yielding the most aggressive geometry. Changing just the wheel isn't enough though. You'll need to visit a dealer to re-program the motor to gain the best output for the smaller rear wheel.
To set the stage as Trek's most capable eMTB, the 9.9 and 9.8 Rail 29er setups rest with a contemporary 64.6º for the Hi setting or a slacker 64.2º when the Mini Link is flipped to the Lo side. That number can be furthered to 63.9-degrees in the mixed wheel configuration. All of these changes will affect the seat tube angle of course, changing the numbers from 77.1º to 76.7º and finally 76.4-degrees, respectively.
The Rail comes in four sizes, starting with a 431.7 mm reach on the size small in the low setting. A medium gains 20 mm of reach, while the large and extra large jump up by a bigger gap of 30 mm per size. Our size large had a reach of 486.8 mm, which is slightly longer than most other brands. One length that doesn't change for each size is the chainstay, measuring in at 448 mm.
My first thought about the Rail 9.9 is how it resembles a new school American muscle car, with a ton of carbon fiber and lots of digitally integrated sensors, and as always, more power than its predecessor. When in the driver's seat, the Kiox display is tucked out of harms way behind the stem, but the handlebar remote is susceptible to damage in a crash as it sits high above the contour of the handlebar. It's also a little cluttered and not easy to locate the power assist buttons when you're focusing on the trail. Add in the dropper post remote and it's a lot to operate on the fly.
Handling on the Rail 9.9 is intuitive in that geometry is fairly standard for a modern enduro bikes, plus the suspension design doesn't do anything unexpected. It's easy to predict through the chunder and steeps. The motor was also extremely quiet and didn't emit any clunky noises while descending, unlike the bikes we tested with the rattling Shimano EP8 motor at our Summer Field Test. In terms of engagement, it's on par with the Shimano, but a back-to-back comparison will be necessary to get into the nitty gritty differences.
The Kiox display has all the stats on display, but the remote buttons could be more pronounced.
My first few outings took place in between rain showers in Pemberton, BC. I quickly got up to speed and was able to get a handle on cornering the bike both up and downhill, but I did find that the hard 50/70a durometer tires were very skittish on wet rocks and roots. I tried dropping the pressure well below what I would normally aim for on an eMTB, but I really had to tip-toe across any polished surface.
I began with 185psi in the rear shock for the slippery conditions, but after checking Trek's suspension calculator
, I upped that to 200, choosing to run a little less sag than recommended for the generally steep trails here in Pemberton. The Rail 9.9 ships with zero volume spacers installed, but I'll be adding more for the next ride, since the bottom outs were somewhat abrupt.
The dual compound 50/70a durometer Bontrager tires were sketchy climbing and descending on the wet bedrock in Pemberton.
For climbing, the climb switch firmly holds the suspension, but I still prefer to have maximum traction for climbing and kept that open. The ground clearance on the 165 mm cranks is manageable when the shock is fully open and the seat angle doesn't tip back too far. Knock Block 2.0 is a big improvement in turning radius and didn't hinder the Rail, even on the tightest uphill switchbacks.
Aside from the tires, which will have to be swapped for something much tackier, there haven't been too many concerns to note. All of the widgets and trick features are well thought out, with the exception of the subtle power mode buttons. The only long-term thing to keep an eye on is the lack of any paint protection like a rubberized flap for the main pivot at the base of the seat tube. A few chips are already present on the otherwise superbly packaged eMTB. We'll see how the rest of the paint and other electronic components fare through the undoubtedly drizzly Pacific Northwest winter in our full length review over the next few months.