New Transition Regulator SX on Test

Bellingham meets Stuttgart: With the new Regulator, Transition rely on Bosch’s proven technology for the first time. How well did this American-German collaboration work and how does the 18.98 kg Transition Regulator SX fare on the trail? Is it the ultimate trail weapon?

With the Regulator, Transition have introduced a new frame platform that is designed to be the all-purpose weapon in their eMTB lineup. It boasts a sleek look and playful, agile handling. To match this, the Regulator is rolling exclusively available on a mullet wheel setup with a 29” wheel at the front and a smaller 27.5” wheel at the rear. With 160/150 mm of travel (f/r), the Regulator expands Transition’s e-Bike portfolio with a shorter-travel alternative to the already well-known Repeater and Relay models, which generate more travel and are powered by a SRAM and Fazua motor, respectively.

The Regulator is available in two variants: the Regulator SX and the Regulator CX. As you may have figured out, the name suffix stands for the Bosch motor model used – the powerful Performance Line CX and the more compact Performance Line SX. Transitions engineering team have leveraged the differences between these motors to give the Regulator distinct characteristics depending on its intended use. The SX model we tested is designed for riders looking for a lightweight eMTB with a natural ride feel. According to Transition, not only is it meant to look like an analogue mountain bike, but also to ride like one. The XT spec variant we tested tips the scales at 18.98 kg in size L and will be available from the 5th of April 2025 for €9,990.

The new Transition Regulator SX in detail

The Transition Regulator SX relies on a clean, streamlined design language and is distinctly recognisable as a Transition. Subtle and defined by clear lines – much like the recently introduced analog Sentinel, which was tested by our sister magazine ENDURO – the Regulator seamlessly integrates into Transition’s model lineup. To round off the sleek look, Transition rely on a neat internal cable routing, threading the cables into the carbon frame through conventional cable ports behind the head tube. The main frame offers ample space for a big water bottle, with the bottle cage securely fastened to the downtube thanks to four mounting points. Using the dedicated mounting plate, you can use one of the mounts to carry the optional range extender. Practical: a tool mount on the underside of the top tube allows you to secure all your trail essentials directly to the frame.

A generously sized chainstay protector prevents chain slap and paint chips, while an additional fender prevents dirt and small stones from accumulating between the seat tube and chainstays, preserving the “Madrone Gold” matte finish of our test bike. The elegantly designed motor cover also does its job reliably, protecting the motor from impacts and flying debris.

The spec of the Transition Regulator SX

The centerpiece of the new Regulator models is clearly the Bosch drive system. The Transition Regulator SX follows a minimalist approach: as little as possible, as much as necessary. At its core is the compact Bosch Performance Line SX motor, delivering 55 Nm of torque and up to 600 watts peak power. The motor draws its power from an integrated, 400 Wh CompactTube battery. The charging port is positioned near the bottom bracket, and protected against the elements by a magnetic cover. The wireless Mini Remote is mounted on the handlebar, while the System Controller with LED indicators is prominently positioned on the front section of the top tube. Additionally, you can fine-tune the motor characteristics via the Bosch Flow App. The optional 250 Wh Bosch PowerMore range extender bumps the total capacity to 650 Wh, enabling epic backcountry expeditions – though it’s only compatible with frame sizes MD-XL.

Race Face Era carbon cranks transfer the motor power to the rear wheel via the chain, where shifting is taken care of by a cable-operated 12-speed Shimano XT drivetrain, that delivers reliable and smooth gear shifts.

For the wheels, Transition rely on a DT Swiss alloy wheelset and proven Maxxis tires, with a Minion DHR II at the front and Assegai at the rear, both in the harder MaxxTerra compound and EXO+ casing – a solid choice for the intended use. We recommend upgrading to a front tire with MaxxGrip compound at the front for more traction. Riders looking for extra durability and impact resistance may even consider a rear tire with a DoubleDown casing.

Tuning tip: Swap the front tire with a softer model with MaxxGrip rubber compound to improve traction and control.

For the Regulator SX, Transition rely on a top-tier RockShox suspension,with a Lyrik Ultimate fork and matching Super Deluxe Ultimate shock, both of which offer countless adjustment options and deliver a tremendous performance on the trail.

TRP DH-R EVO brakes deliver powerful deceleration and good modulation, and have already proven themselves in the big brake comparison test of our sister magazine ENDURO. Our test bike in size L comes with a 210 mm OneUp Components dropper post, which provides plenty of freedom of movement on the trail.

Model variants

As already mentioned, the Regulator is available in two variants: the CX and SX models. Each version comes in two build kits and two color options, resulting in a total of eight different configurations. The Deore and XT builds not only differ in drivetrain components but also in terms of tires, brakes, wheels, and suspension.
The CX variant of the Transition Regulator is designed for riders seeking more power and greater range compared to the SX version. While both models share the same 600 watt peak power, the CX model comes equipped with a Bosch Performance Line CX motor, which delivers 85 Nm of torque and draws its power from a 600 Wh Bosch PowerTube battery. Additionally, the CX model features a flip chip in the frame, allowing you to adjust the geometry.
We have also extensively tested the CX variant, which is almost three kilograms heavier than the lightweight SX version. Stay tuned for our in-depth review of the CX model in our upcoming eMTB group test!
In terms of color options, the SX model is available in Stormshadow Grey and Madrone Gold, while the CX model comes in Salish Sea Blue and Glacier White.

Pricing is set at € 7,999 for the Deore build and € 9,990 for the XT build – for both the SX and CX models. Given the higher torque, bigger battery capacity, and adjustable geometry of the CX version, it appears to offer better value for money compared to the SX model.

The Geometry

The Transition Regulator SX is available in four frame sizes, SM, MD, LG, and XL. The geometry values are identical to the CX model in the “High” flip chip setting, while the reach on our test bike in size LG is an average 480 mm. The chainstays grow from 442 mm to 448 mm between sizes MD and LG. The seat tube length ranges from 375 mm to 470 mm depending on the frame size, accommodating dropper posts with adjustment ranges from 150 to 240 mm. Our size L test bike comes equipped with the 210 mm version.

The New Transition Regulator SX on the Trail

We put the Transition Regulator SX through its paces both in sunny Finale Ligure and on our home trails. Starting off from a standstill doesn’t require much effort with the Regulator SX : as is typical for Bosch drives, the system is activated at the push of a button on the system controller in the top tube, and both the remote and display are intuitive and easy to use. Off we go! From the moment you swing your leg over the saddle, you’ll notice the comfortable yet slightly sporty seating position. The suspension smoothly absorbs small bumps, ensuring a high level of comfort. Riding uphill, the Regulator climbs efficiently, and the rear suspension generates good traction. The sporty pedalling position complements the SX motor’s character, which performs best at high pedalling cadences and rewards the rider with natural assistance. On fire roads, the rear Riders looking for more efficient climbing can quickly and effectively counteract this by using the easily accessible lockout on the shock.

When gravity takes over, the Transition integrates you nicely between its wheels, with the weight evenly distributed between the front and rear. As a result, the Transition makes you feel at ease from the get go, encouraging you to cruise down the trail in a relaxed manner. The Regulator feels reassuringly compact, carving through corners playfully, and bringing serious fun to the trail jungle! The Transition Repeater SX scores high in agility, handling quick direction changes without breaking a sweat. The low system weight makes it easy to flick between lines, ensuring a playful character, which makes it easy to stick to your line, even through nasty rock gardens. Overall, it impresses with excellent tracking stability and inspires huge amounts of confidence.

And even when you miss the perfect line from time to time, the Regulator always remains in control. As a result, you won’t get thrown off mercilessly, and simply have to slow down a little rather than plowing through rough terrain at mach-10. The fun is only slightly dampened during short bursts of pedaling on the trail – in these moments, the motor’s freewheel ratchet can be heard briefly due to the overrun.

Who is the Transition Regulator SX for?

The Regulator SX is designed for sporty riders who want to rip lap after lap on their home trails in the limited time between work and sunset – while at the same time enjoying the ride feel of an analogue bike. The predictable, intuitive handling also makes the Regulator SX an exciting option for riders with less technical skill. If you venture on longer rides from time to time, you can boost the range with the optional Range Extender, significantly expanding the bike’s versatility.

Conclusions about the new Transition Regulator SX

With the Regulator SX, Transition created a lightweight and playful eMTB with well-thought-out details and intuitive handling. The spec is well-balanced throughout, proving that, despite the low system weight, the bike’s downhill capability and durability were key considerations in development. Thanks to the sporty riding position, it delivers excellent traction, while the sensitive support of the Bosch SX motor ensures plenty of fun – even on climbs.

Tops

• Solid spec
• Low overall system weight
• High comfort factor
• Agile, playful handling

Flops

• Motor rattling
• No price difference to the CX model

For more information, visit the Transition website.

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Words: Lars Engmann Photos: Robin Schmitt