The Best E-Mountain Bike of 2025? Transition Regulator CX XT on Test

The Transition Regulator CX XT stands for rugged trail power. With its 160/150 mm of travel (f/r), 600 Wh battery and powerful Bosch Performance Line CX motor, it came straight from Bellingham, USA, to the trails of Finale Ligure to take on the competition in our massive 2025 eMTB comparison test. How did it fare in the home of the Bella Vita?

This bike is part of our big group test: The Best E-Mountainbike of 2025 – Featuring the 30 Most Exciting E-MTBs of the Year. Click here for the full intro, key takeaways, and all the bikes we tested.

Transition have long been a part of the furniture in the mountain biking world. However, when it comes to eMTBs, the American manufacturer was something of a late bloomer. It wasn’t until 2022 that Transition entered the electric game with the Repeater, which, back then, relied on a Shimano motor and Transition’s unmistakable, albeit slightly dated look. Fast forward to 2025, and a lot has changed. Transition switched to a Bosch drive and now offer the new Regulator in two variants: the full-power Regulator CX we tested, and the lighter Regulator SX with Bosch’s slimmed-down motor and a smaller battery.

We went all-in for this test: the mullet-wheeled Regulator CX with Bosch Performance Line CX motor and a 600 Wh battery. Tipping the scales at 22 kg in size L and priced at €9,990 in the XT spec, it’s ready to take on the competition in our 2025 group test.

What Sets the Transition Regulator CX XT Apart From the Competition?

The Transition Regulator CX XT rolls into the test field with an understated look, with itsclean frame silhouette, sharp edges and Horst-link four-bar rear triangle making it feel purposeful and functional. The “Glacier White” paint job is a bold choice for an eMTB that’s more likely to live in a muddy forest rather than in a showroom– but when it’s clean, it looks all the sharper.

In purely visual terms, the differences between the SX and CX variants are only marginal – at first glance, they’re nearly identical twins. For this test, we rode the full-power version with a BoschPerformance Line CX motor, which delivers 85 Nm of torque and up to 600 watts peak power. The 600 Wh battery is permanently integrated into the slim downtube, which has a slight bulge below the bottle cage mounts. Just above it, on the bottom side of the top tube, two additional bosses allow you to secure a tool kit or puncture repair pack directly to the frame. The charging port is positioned on the left above the motor and protected by a high-quality plastic cover with magnetic and clip closure. The Regulator forgoes a display altogether, which ensures a clean cockpit and underlines the bike’s sporty aesthetic. Instead, Transition rely on a Bosch System Controller integrated into the top tube, with five LEDs displaying battery level in 10% increments and colour-coded support modes. The system is operated via the Bosch Mini Remote on the left side of the handlebar.

For a quiet ride on the trail, Transition fitted a large chainstay protector with soft, Lego-brick-like ridges that effectively dampen chain slap. The cables are neatly routed internally, disappearing into the frame through thoroughly-clamped, easily accessible cable ports behind the head tube. The system makes it easy to work on the bike while at the same time ensuring a clean look. A small fender at the rear protects the main pivot from trail grime, while a flip chip in the lower shock mount lets you adjust the head and seat tube angle by 0.5°.

The Transition Regulator CX XT comes equipped with a proven, trail-focused component mix. For the suspension Transition rely on a 160 mm RockShox ZEB Ultimate fork with the latest Charger 3.1 damper, which offers countless adjustment options. At the rear, a RockShox Super Deluxe Ultimate shock controls 150 mm of travel, delivering strong control and traction. With adjustable compression and rebound, the suspension setup is versatile and easy to fine-tune. OneUp supply the 180 mm V3 dropper post, which works reliably but could do with a little bit more of travel – especially for taller riders.

Shifting is taken care of by a cable-operated Shimano XT 12-speed drivetrain – robust, precise, and a solid choice for trail riding. The brake spec is a bit more unusual: instead of Shimano or SRAM, Transition went for TRP’s DH-R EVO four-piston stoppers. While they’ve since been replaced by the EVO Pro, the DH-R EVOs still provide powerful, reliable deceleration in combination with the 200 mm rotors front and rear. The robustDT Swiss H1900 alloy wheelset is well suited to rowdy trail sessions, and paired with Schwalbe Albert tires in the Radial Super Trail casing: grippy Ultra Soft compound up front, and the more durable Soft compound at the rear. Aggressive and heavy riders should consider upgrading the rear tire to a Super Gravity casing for added puncture protection. Overall, the spec isn’t flashy or super-fancy, but ratherfunctional, trail-ready, and totally reliable.

Tuning Tip: Heavier and aggressive riders should switch to a more robust tire with Super Gravity casing at the rear as soon as the original tire wears out.

What Is The Transition Regulator CX XT Capable Of on the Trail?

Riding uphill, the Transition Regulator CX XT presents itself as a spacious and comfortable climber. The pedalling position is pleasantly upright without feeling cramped, ensuring an efficient, relaxed climbing performance.. The sensitive suspension absorbs small bumps early in the travel, ensuring a high level of comfort on long climbs. In steeper, technical sections, it’s worth dropping the saddle slightly and shifting your weight forward to keep the front end planted. The rear end generates excellent traction, and the Bosch Performance Line CX Gen5 motor pushes powerfully and confidently, even through steep, technical rock gardens. On fire roads, the rear suspension bobs slightly, so it’s worth reaching for the climb switch if you’re aiming for maximum efficiency. Overall, the Regulator delivers a very solid climbing performance– on par with our Best Buy pick and the Haibike HYBE.

The Transition Regulator CX XT comes with a well-rounded, performance-focused spec– though everyday features are few and far between.

When you point its nose downhill, the Regulator places you in a central riding position, integrating you nicely between its wheels. Together with the high front end and low centre of gravity, this inspires huge amounts of confidence and makes you feel at ease from the get go – which is especially helpful on steep and rough descents. The bike’s also extremely composed, meaning that you can really let it run and trust it through chunky terrain.

Downhill, the Transition impresses with loads of composure and a strong sense of security. It welcomes you straight away and encourages you to ride fast.

Big hits and drops? The suspension swallows them without batting an eye, and there’s still travel left for botched landings. As a result, the Transition lines up right next to the UNNO Mith Pro in terms of suspension performance, although with a more forgiving character– and while it doesn’t quite match the outright capability of the test winner or the YT DECOY SN, it comes impressively close. Although high levels of composure often come at the cost of agility, that’s not the case with the Regulator. Even on tight trails, it’s always easy to control, and has your back with spontaneous direction changes. The suspension has enough pop to pump through rollers and berms, which makes it easy to carry speed. On flowing trails, it even keeps up with lighter bikes like the Rocky Mountain Instinct Powerplay SL. Only bikes like the Orbea Rise and FOCUS JAM² outshine the Transition on fast, flowy descents– but they do so at the cost of composure when the trail gets rougher. All in all, the Transition Regulator CX XT is strongly reminiscent of the Santa Cruz Vala,both visually and in terms of downhill performance, and stands out as a clear recommendation in this test.

Who Should Take a Closer Look at the Transition Regulator CX XT?

The Transition Regulator CX XT is aimed at performance-focused eMTBers who prioritise trail capability and downhill fun– because that’s exactly where this bike comes alive. In fast corners, on technical descents and flowy trails, the Regulator shows off its handling strengths and delivers a hefty dose of dopamine. Those who value all-day touring comfort might miss a display, and the permanently integrated battery can be a limitation in day-to-day use. But if you’re after a trail bike built for fun, the Regulator is a true do-it-all machine that feels at home across a wide range of trails.

Conclusions about the Transition Regulator CX XT

While the crew from Bellingham didn’t dominate our group test with the Transition Regulator CX XT, they certainly made an impression. While the Regulator doesn’t set any new benchmarks but really shines wherever the trail points downhill. Its everyday practicality may be limited, which holds it back from claiming the overall win as best all-rounder. But if you love to send it downhill and ride both flowy and technical trailson a regular basis, the Transition Regulator delivers with a well-honed trail DNA and serious fun factor.

Tops

• High composure on rough trails
• Intuitive handling
• High front end inspires lots of confidence

Flops

• Limited everyday practicality

For more info, visit transitionbikes.com

The test field

For an overview of the test field head to our “Best E-Mountainbike of 2025” comparison test – 30 of the most exciting trail bikes in our 2025 group test

All bikes in test: AMFLOW PL Carbon Pro, Canyon Spectral:ONfly CF LTD, FOCUS JAM² 6.0, GHOST E-RIOT LTD, Haibike HYBE CF 11, MERIDA eONE-SIXTY SL 10K, Orbea WILD M-LTD, Orbea Rise LT M-Team, R RAYMON Tarok Ultra, Rocky Mountain Instinct Powerplay SL, Santa Cruz Vala X0 AXS RSV, SCOTT Patron ST 900 Tuned, Specialized S-Works Turbo Levo 4, Transition Regulator CX XT, UNNO Mith Pro, YT DECOY SN MX CORE 3.

Words: Julian Schwede Photos: Peter Walker