Trek Rail Gen 4

Before I introduce the Trek Rail 9.9 X0 AXS T-Type Gen 4 that we're tire-kicking today, let's do a quick recap. Several years ago, I long-term tested a Trek Rail 9.8 XT. It was the first Bosch-equipped e-bike I'd spent any time on, and my experience echoed what a lot of reviewers and customers had been saying: it was a reliable platform with great handling and plenty of performance. The Bosch unit was powerful, smooth, and efficient, the spec was bang on with a few minor gripes, and that bike is still being happily ridden today.

In the intervening years, a lot of related tech has been released. Bosch has rolled out a smart system which adds new software and tweaked power level modes, an app that includes loads of functionality as well as a lock and alarm, and OTA (over-the-air) updates. Trek has updated the geo of the Rail line and the frames themselves, enabling them to use Bosch's new remote and controller options. And SRAM released Transmission, which builds on UDH and Eagle AXS to create a family of components that delivers robust, durable shifting capable of standing up to the rough treatment eMTBs dish out. SRAM has also just released Powertrain, but that review is still in the future as Trek isn't one of its early buyers.

In short, in the two years since I reviewed the Trek Rail, the e-bike landscape has changed quite a bit, so this new Trek Rail presented an opportunity to check out some of those advances all at once.

This review was organized earlier this year, and I was most curious to see how SRAM's new Transmission would behave on an e-bike, since one of the big selling points they were touting was its robustness and the fact that it was designed to shift better while under load. I would have loved to have tested GX T-Type instead of X0, but Trek has yet to release a Rail spec'd with it, so X0 it is. I mention this because it meant I was a bit cornered into testing a $11,299 US Rail 9.9 if I wanted it to come with Transmission. The only Rail priced above this one is the $13,299 Rail 9.9 CXR Gen 4, so named for the special race edition Bosch CXR motor it comes with.

Trek Rail Gen 2, 3, and 4

Trek doesn't really go with annual model years for their bikes and colours, which can make their site a bit confusing at times (there are past model bikes still listed but out of stock). In the case of the Rail, what you get are Gen 2, 3, and 4 model designations which indicate what Bosch system tech the bike is running (Bosch hasn't updated the Performance Line CX motor since 2020). The Rail I tested a few years ago was a Gen 2 which means no smart system, and it had a monochromatic bar-mounted remote and display which was reasonably ergonomic and easy to use, if a bit exposed in the event of a crash. Gen 3 and 4 both employ Bosch's smart system, which includes app integration to their eBike Flow app, and are distinguished primarily by the remote and controller combinations. Gen 4, as tested, comes with a System Controller & display that is flush-mounted to the top tube, and a three-button mini remote on the bar, activated by the left hand. The top tube-mounted controller is your on/off for the system, indicates battery level and what ride mode you're in (colour-coded LEDs for easy reference while riding), and acts as the central nervous system, including your connection to the app via bluetooth. The mini remote has three buttons and simply controls ride mode (including walk mode). There is no display on the bike to indicate things like speed, remaining range, trip or total distance, etc. Those things can all be accessed through the app, for better or worse.

So let's dig into what I ended up with. Full spec is a little lower down.

Trek Rail 9.9 X0 AXS T-Type Gen 4 Key Features

The Rail 9.9 is a carbon-framed, 150mm travel eMTB aimed at trail/enduro riding. It comes with a 160mm fork (RockShox Zeb Ultimate in this case) but the frame is rated for 170mm if you're inclined (and I am). As with most of Trek's frames, the Rail is chock full of features: Trek's well-known ABP, a removable battery (that can also be locked in the frame), geo adjust via Mino Link, Knock Block, and frame protection. Spec across the board is without compromise: RockShox Super Deluxe Thru Shaft shock and Zeb Ultimate fork (both w/ AirWiz), Bontrager Line Pro 30 carbon wheels (w/ TyreWiz), SRAM X0 T-Type throughout (no corners cut on cassette or chain), SRAM Code Silver brakes with HS2 rotors - 220mm front, 200mm out back. Furthermore, a RockShox AXS 170mm dropper (seriously, SRAM, where's the 200mm+ AXS dropper?) and one-piece carbon Bontrager RSL MTB bar and stem. And of course, let's not forget the aforementioned Bosch Performance Line CX motor, smart system, and 750Wh battery.

This sucker retails for 11,299 USD / 14,799 CAD. There is no way to argue that isn't an amazing amount of money. A similarly spec'd Santa Cruz Heckler comes in at 15,049 CAD, though it has a Shimano EP-801 motor rather than Bosch, and Reserve carbon wheels instead of the Rail's house brand Bontrager carbon wheels. Maybe those two things cancel each other out, depending on personal preference. Either way, they're both Porsche pricing, and not pedestrian 911s either - these are Turbo S type packages. If you dig a little deeper, there are some pretty dramatic savings you could make on this Rail without giving up any meaningful performance, in my opinion. With apologies to Trek's PM, I'm going to pick at some loose ends here, because if I were buying an e-bike, I'd want either Transmission or LinkGlide on it. Both were designed with the needs of e-bikes in mind, and you're going to save in the long run on drivetrain components if you go in one of those two directions.

Spec Regrets - AirWiz and TyreWiz

I made a comparison to the Heckler up above for good reason. Santa Cruz was never a bargain brand, but their pricing has increased relative to their already heady sticker cost. You do get incredible quality and support, free lifetime bearing replacements, and good resale values, and those are all worth something. So, for less than a $500 premium, why am I picking on Santa Cruz? Because the slightly lower priced Trek has quite a bit of extra money wrapped up in its spec package, notably due to the presence of AirWiz, TyreWiz, and that one-piece carbon bar and stem.

Quarq TyreWiz has been around since 2018 (TyreWiz 2.0 was just released). It is a tire pressure monitoring system that includes small LEDs mounted near each tire valve that shine green when you're within a prescribed pressure range, and blink red when you're high or low of that range. Control and monitoring is via SRAM's AXS app, and it works as advertised. You can watch your phone screen while you add air to your tires and make adjustments within a tenth of a psi (or other units). I've had TyreWiz on my Sentinel since 2019, and used it until the coin cell batteries died - and I never replaced them. That's how much I cared when it didn't work anymore, and I have the batteries right here in a drawer. Checking air pressure before every ride is an enjoyable part of my routine, and having to pull out my phone to do it adds a step - as does having to watch my phone to dial in pressure. I'd rather just use a floor pump and digital gauge and be done with it. At an aftermarket street price of $214 US per pair, I don't know how much TyreWiz is adding to the MSRP of this bike, but judging by how seldom we see it spec'd elsewhere, I'm guessing it's not generating a ton of margin for brands.

On to AirWiz. This is also a pressure monitoring system, integrated into the RockShox fork and shock on the Rail, also controlled by the AXS app. Like TyreWiz, you can feed a few data points into it, like rider weight, and it'll spit out setup guidelines. Like TyreWiz, you can use it to monitor your suspension's pressure using the app, and be alerted if it falls outside of your prescribed settings range. Like TyreWiz, I find it completely unnecessary. Actually, I find it less necessary than TyreWiz, because I actually use TyreWiz. Tire pressure needs to be checked before every ride (sometimes during) while suspension pressure is a once a month, maybe change of seasons or drastic change in ride conditions kind of thing. Together, I'm guessing they add $3-500 of MSRP. Listen, I understand they both provide some sort of utility and that there's a market for that, and I've had quite a few raised eyebrows over the years in response to TyreWiz - people are genuinely impressed by it (but don't buy it) - but it's just more batteries and complexity and really, they're not performance upgrades. Racing could be a use case for one or both, but for just grabbing the bike and going riding, I'm not going to check my suspension pressure, but I'm always going to check my tire pressure, and even if the LEDs are green, I still want to know precisely what pressure I start with.

More Spec Regrets - RSL MTB bar/stem and that damn saddle

Deniz and Cam have both written about the Bontrager RSL MTB bar/stem combo, and they both liked it. It's an engineering marvel that saves weight and uses pretty standard measurements, so if you are middle of the road with your cockpit setup, it may work for you. I find myself generally liking the position it puts me in, but occasional sore wrists have me wanting slightly more backsweep so I may try a swap - no big deal as I have stuff I can use on hand to do that. But for the consumer, that's a bar and a stem you'll need to buy. Bummer. Although I guess you could sell the RSL bar/stem combo or trade it back to the shop for credit. Anyway, at 365 US / 450 CAD (retail) that's another addition to the MSRP. Are we at $500 yet? It's adding up now.

Taken all together, the Wizzes and the one-piece bar and stem are spec'd here for a clear purpose: to appeal to a certain type of buyer. The one with a more casual eye when it comes to the budget, who will be impressed by a few more Wiz-bang doodads on the shop floor. That's fine. It's just not for me.

Last thing: the saddle. Over the years, everyone at NSMB has universally hated the Bontrager Arvada, and that includes everyone to whom I leant the last Rail as well. It's awful. Beware.

Dear Trek: I want a LinkGlide or GX T-Type equipped Rail, carbon wheels optional, skip the AXS post and put one on that's a proper length, delete fancy carbon integrated bar/stem, and the Wizzes, and let's get it down by 2-2.5k, mmkay?

Changes incoming

I couldn't wait any longer and swapped a SQlab 60X saddle in almost right away. More on that soon, but it is made for me - a new favourite.

I haven't swapped out the bar/stem yet. Will at least cut it down from its stock 820 to 790mm although I didn't mind it at full width for the steeps in Whistler over Crankworx.

The Bontrager SE6 and SE5 tires have to go now that the rain is here. They were great in dry conditions and terrific on slabs, but no bueno as soon as there's a hint of moisture on the trail.

The RockShox Super Deluxe Thru Shaft shock is leaking and burping oil. We're going to have it serviced and see if that helps. It's otherwise boinging really well and providing tons of traction.

Geometry

I'm going to leave the two geo charts here and let you be the judge. The last Rail I tested was an XL. Trek basically bumped everything up a size, and effective seat tubes got steeper, but most other changes were small other than increased stacks. I liked how the last gen's XL fit, but this gen's L is even better for me. We're getting long so I'm going to save some of the geo talk for the review.

Spec

Frame: Trek OCLV Carbon, Removable Integrated Battery (RIB), Knock Block 2.0, guided internal routing, 34.9mm seat tube, magnesium rocker link, Motor Armor, Mino Link, ABP, Boost148, 12mm thru axle, 150mm travel

Shock: RockShox Super Deluxe Thru Shaft, AirWiz, 230mm x 57.5mm
Fork: RockShox ZEB Ultimate, 160mm travel, AirWiz, eMTB optimized crown, 44mm offset (170mm max compatible fork travel)

Wheels: Bontrager Line Pro 30, OCLV Mountain Carbon, 6-bolt, Boost148
Tires: Bontrager SE6 (F) and SE5 (F), 29 x 2.5" (max 2.6") 120 tpi
Brakes: SRAM Code Silver 4-piston
Rotors: SRAM HS2, 220mm (F), 200m (R)

Shifter: SRAM AXS POD Ultimate
Rear Derailleur: SRAM X0 Eagle AXS, T-Type
Crank: SRAM X0 Eagle, 34T, T-Type, 160mm
Chainring: SRAM XX T-Type, 34T, steel
Cassette: SRAM Eagle XC-1295, T-Type, 10-52, 12-speed
Chain: SRAM X0 Eagle, T-Type, 12-speed

Saddle: Bontrager Arvada, austenite rails, 138mm width
Seatpost: RockShox Reverb AXS, 170mm travel (S: 100mm, M: 150mm), 34.9mm
Bar/stem: Bontrager RSL Integrated handlebar/stem, OCLV Carbon, 27.5mm handlebar rise, 820mm width, 0 degree stem rise, 45mm stem length
Grips: Bontrager XR Trail Elite, nylon lock-on

Motor: Bosch Performance Line CX, smart system, magnesium motor body, 85 Nm
Battery: Bosch PowerTube 750Wh*, smart system (size S Rails come with a 625 Wh battery)
Controller: Bosch System Controller, smart system
Remote: Bosch Mini Remote BRC3300

Weight: Trek lists a size M at 23.75 kg / 52.36 lbs. My size L tester with Shimano Saint clipless pedals (porky suckers at 546g) weighs 24.67 kg / 54.4 lbs.

There's a lot to talk about with this bike, which is why I wanted to review it. I'm not going to get into ride impressions here, but the early indications are excellent. I expected this based on the predecessor, but I like this Rail even more, which I'll put down to the more capable Zeb (the last Rail had a Lyrik), the higher stack, and a more composed ride from the shock. So far, Transmission is as idiot-proof as it's meant to be, and I have differing opinions on that, but if I tuck my elitism aside, it's pretty astounding how well it shifts in really brutal conditions. And finally, Bosch's new smart system is just that. Love or hate all the whizz bang and integration, the application of technology on bikes these days is pretty incredible. I understand the desire to have no batteries and no assistance, but that's a separate conversation. For what it is, this Trek Rail is an absolute beast.

Trek Rail 9.9 X0 AXS T-Type Gen 4 - 11,299 USD / 14,799 CAD