With its Bosch motor and 625 Wh battery, the Trek Rail 9.9 X01 is an old acquaintance in our group test. This year’s model enters the race with a few small updates and brand new suspension. Despite the massive stanchions of the new fork, the bike is very light. But is that enough for a test victory and can the Trek finally secure the coveted Best in Test of this year’s big group test?

For an overview of the test fleet head to the group test: The best eMTB of 2021 – 25 models in review

Trek Rail 9.9 X01 | Bosch Performance Line CX/625 Wh | 160/150 mm (f/r)
22.60 kg in size L | € 10,499 | Manufacturer’s website

The elegant Trek Rail already impressed our test team last year with its high-quality carbon frame and seamless integration of the Bosch motor. While the 2021 model has remained pretty much unchanged, it’s still one of the most impressive Bosch bikes in this year’s test field. The internal 625 Wh battery can be removed from the side of the down tube within seconds and the Kiox display is elegantly mounted on the top tube, rather than sitting on top of the handlebars or stem where it would be exposed to impacts like all other Bosch bikes in this test. In its position, the display is well protected from impacts both in the event of a crash and during transport. Only the cable routing along the frame to the display could have been better solved. For the charge port and speed sensor, Trek have developed their own parts rather than settling for Bosch’s flimsy components. The signature Trek look of the 22.6 kg Rail is rounded off by a spectacular paint finish that literally comes to life in the sunlight.

Trek don’t do themselves any favours with their own tires: The spec of the Rail 9.9

Retailing at € 10,499, the Trek Rail 9.9 features RockShox suspension with a 160 mm RockShox ZEB fork taking care of the front and Super Deluxe Ultimate ThruShaft shock managing the rear end. Specially designed for Trek bikes, the shock has fewer seals and is claimed to allow super responsive rear suspension. SRAM Code RSC brakes with 220/200 mm rotors provide reliable and powerful deceleration and have consistently proved the best-performing brakes in the entire test field. The Bontrager carbon cockpit, dropper post and carbon wheels are all in-house components. Except for the dropper remote, they’re all light, functional and built to the highest quality. Unfortunately, the same cannot be said about the Bontrager 2.6″ SE5 tires, which offer no traction whatsoever and are very puncture prone too. We recommend upgrading your tires right away. One cool addition is the Quark TyreWiz sensors, which read your tire pressures. Particularly with expensive carbon rims, this system makes total sense, allowing you to check your pressures on the go and prevent rim strikes.

Helpful to a limited degree
The low-profile and puncture-prone Bontrager SE5 tires limit the potential of theTrek immensely. With the integrated TyreWiz pressure gauge, you can check the right pressure on the go and protect your rims from heavy blows.
Trek sidestep Bosch by using their own and significantly smaller speed sensor. This is integrated in the dropout and relies on a magnet attached directly to the brake rotor. The Rail also has a kickstand mount.
The ThruShaft shock and rear end of the Rail are perfectly tuned: the bike is extremely responsive and still provides tons of support and huge reserves.
The metallic wine-red finish looks incredibly beautiful and literally comes to life in the sunlight. Unfortunately, the gorgeous finish is susceptible to damage. After just one long day in the rain, the paint job of our test bike got scratched. We recommend using a frame protector.

Trek Rail 9.9 X01

€ 10,499


Motor Bosch Performance Line CX 85 Nm
Battery Bosch PowerTube 625 Wh
Display Bosch Kiox
Fork RockShox ZEB Ultimate 160 mm
Rear Shock RockShox Super Deluxe Ultimate RT3 150 mm
Seatpost Bontrager Line Elite 170 mm
Brakes SRAM CODE RSC 220/200 mm
Drivetrain SRAM X01 Eagle 1x12
Stem Bontrager Line Pro 45 mm
Handlebar Bontrager Line Pro 780 mm
Wheelset Bontrager Line Elite 30 29"
Tires Bontrager SE5 Team Issue 2.6"

Technical Data

Size S M L XL
Weight 22.60 kg
Perm. total weight 136 kg
Max. payload (rider/equipment) 113 kg
Trailer approval no
Kickstand mount yes

Specific Features


Side loader
The 625 Wh battery is very easy to remove from the side of the down tube. This is possible thanks to a clever locking system and a practical handle.
Crash proof
Many handlebar- and stem-mounted Kiox displays and holders gave up during our test. Instead, the Trek’s Kiox display is cleverly placed on the top tube where it’s less susceptible to knocks, both on and off the trail. However, readability and cable routing could still be improved.
Best brakes in the test
Trek pair SRAM’s Code RSC brakes with 220/200 mm (f/r) rotors. Stopping power, modulation and reliability? Check!

A flip chip allows for minor geometry adjustments. Depending on the setting, the seat tube angle varies by around 0.5°. As a result of the pronounced kink in the seat tube, its 77.5° angle is simply too slack, with the effective seat tube angle slackening ever further as the dropper extends. Riders with long legs will find themselves sitting back over the rear wheel and should push the saddle all the way forward, regardless of the geometry setting. Even then, the riding position is anything but compact, especially on flat terrain. If anything, the riding position is sporty but not uncomfortable. However, the Trek prefers sporty adventures over long rides.

Size S M ML L XL
Seat tube 395 mm 420 mm 435 mm 450 mm 500 mm
Top tube 584/ 585mm 609/ 610mm 628/ 629mm 647/ 649mm 683/ 684mm
Head tube 100 mm 100 mm 105 mm 115 mm 140 mm
Head angle 64.6°/ 64.1° 64.6°/ 64.1° 64.6°/ 64.1° 64.6°/ 64.1° 64.6°/ 64.1°
Seat angle 67.1°/ 66.6° 67.1°/ 66.6° 67.1°/ 66.6° 67.1°/ 66.6° 67.1°/ 66.6°
Chainstays 435/ 437 mm 435/ 437 mm 435/ 437 mm 435/ 437 mm 435/ 437 mm
BB drop 22/ 29mm 22/ 29mm 22/ 29mm 22/ 29mm 22/ 29mm
Wheelbase 1197/ 1197 mm 1212/ 1222 mm 1242/ 1243 mm 1263/ 1264 mm 1304/ 1305 mm
Reach 431/ 425 mm 456/ 450 mm 474/ 469 mm 491/ 486 mm 521/ 516 mm
Stack 618/ 621 mm 618/ 622 mm 622/ 626 mm 631/ 635 mm 654/ 658 mm

*Data for the Flipchip positions high/ low

Helmet Bell Sixer Mips | Glasses Oakley Flight Jacket | Jacket Zimtstern Timbaz
Jersey Zimtstern PureFlowz | Shorts Zimtstern Trailstar Evo
Kneepad POC Joint VPD System Knee | Shoes Leatt DBX 4.0 | Gloves POC Essential
Give it some!
Uphill, the Rail requires great physical effort to keep the front wheel tracking. If you manage to do so, it’s playful and fun to ride.

Flowing trails, downhill tracks or both? Downhill, the Trek Rail convinces in every situation

Depending on how high you run your saddle, the Trek places you either in a fairly central position or too far back over the rear wheel on climbs. If you’re in between sizes, you may want to consider sizing up. Apart from this, the bike is nimble and agile on narrow and winding climbs. Thanks to the powerful Bosch motor and lightweight wheelset, the Rail accelerates willingly out of corners and is fun to ride. Only on steep climbs and in slippery conditions does the Trek require more physical effort and good riding technique. The shock sits high in its travel and helps you to actively load the front end, preventing it from lifting. However, this position can cause the rear to spin out of control. Uphill, the SE5 tires quickly fail to generate enough traction and struggle to keep up with the huge potential of the Rail 9.9. When negotiating steps and obstacles on technical climbs, you’ll have to time your pedal strokes carefully to avoid clipping your cranks.

Downhill, the Trek Rail 9.9 is a master of all trades and strikes a perfect balance between agility and stability!

Tuning tips: tires with more grip and better puncture resistance | push the saddle all the way forward

If you want to ride fast on all sorts of descents and have fun in the process, the Trek Rail 9.9 might be exactly what you’re looking for. Whether you’re racking up high-speed party laps at your local bike park or traversing the Alps on technical terrain and flowing trails, the Rail 9.9 shines on all kinds of terrain and knows no limits, unless it’s raining. On wet, slippery trails, the tires struggle to generate enough grip and spoil the party – but hey, you changed the tires straight away, didn’t you? 🙂 Hardly any other bike in this test offers as much support and feedback while delivering such a sensitive response and generous reserves at high speeds. Seasoned riders, in particular, will appreciate the low bottom bracket, which rewards an aggressive riding style with tons of speed and plenty of fun. However, the Trek also requires an active and clean riding style in open, flat corners to generate enough grip on the front.

Fast, faster, Rail!
A split second before hitting this nasty compression at Mach 10, Jonas briefly regretted not writing his will. However, the Rail took the hit with composure and immediately asked for even more speed.

Riding Characteristics



  1. sluggish
  2. playful


  1. nervous
  2. stable


  1. demanding
  2. balanced

Riding fun

  1. boring
  2. lively

Motor feeling

  1. digital
  2. natural

Motor power

  1. weak
  2. strong

Value for money

  1. poor
  2. top


Forest road


Flow trail uphill


Flow trail downhill


Technical single trail uphill


Technical single trail downhill


Downhill tracks



The Trek Rail 9.9, stands out from the crowd for its killer looks, seamless integration of the Bosch system and, most importantly, outstanding handling. While it demands an active riding style, this is rewarded with a harmonious balance between playful handling and high-speed composure. It feels at home descending and is happy to take on any trail. However, we recommend replacing the Bontrager tires straight away.


  • constantly invites you to play with the trail
  • master of all trades downhill
  • high-quality frame details


  • tires
  • pronounced kink in the seat tube

You can find out more about at trekbikes.com

The test field

For an overview of the test fleet head to the group test: The best eMTB of 2021 – 25 models in review

All bikes in this test: Cannondale Moterra Neo Carbon 1 (Click for review) | Canyon Spectral:ON CF 9 (Click for review) | CENTURION No Pogo F3600i (Click for review) | CUBE Stereo Hybrid 140 HPC SLT Nyon (Click for review) | CUBE Stereo Hybrid 160 C:62 SLT Kiox (Click for review) | Ducati TK-01 RR (Click for review) | FLYER Uproc6 9.50 (Click for review) | FOCUS JAM² 6.9 NINE (Click for review) | GIANT Trance X E+ 1 (Click for review) | Haibike AllMtn 7 (Click for review) | KTM Macina Kapoho Prestige (Click for review) | Lapierre Overvolt GLP 2 Team (Click for review) | MERIDA eONE-SIXTY 10K (Click for review) | Mondraker Crafty Carbon XR (Click for review) | Moustache Samedi 29 Trail 8 (Click for review) | ROTWILD R.X375 ULTRA (Click for review) | Santa Cruz Bullit X01 RSV Air (Click for review) | SCOTT Ransom eRIDE 910 (Click for review) | SIMPLON Rapcon PMAX (Click for review) | Specialized S-Works Turbo Levo (Click for review) | Specialized S-Works Turbo Levo SL (Click for review) | STEVENS E-Inception AM 9.7 GTF (Click for review) | Thömus Lightrider E2 Pro (Click for review) | Trek Rail 9.9 X01 (Click for review) | Whyte E-150 RS 29ER V1 (Click for review)

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Words: Photos: diverse