2025 Transition Regulator SX XT E-Bike

Transition released two new eMTBs that are essentially a motorized version of their highly praised do-it-all Sentinel V3. The 150/160mm-travel Regulator as its called, comes in a light and not-as-light version using Bosch SX and CX drive systems. Besides the 400wh vs 600wh battery capacities and differently powered motors, the Regulator SX and CX appear to be identical. But don't let the appearances fool you. While the nuances may be subtle, each front end is uniquely designed with different tube shapes, diameters and drive unit areas. Color options and component spec details aside, the other frame distinction is that the beefier CX features a geometry-adjusting flip chip while the more svelte SX does not. Vital has had a chance to swing legs over both bikes for initial test rides and each were exceptionally fun on the trail; a balanced blast to ride. The hardest thing to overcome, should you choose to mount up, may be getting Warren G out of your head every time you hop on your new bike. 

Similarities - Transition Regulator CX and SX

• 4 Sizes - S-XL
• Carbon frame
• Mixed wheel (29 front, 27.5 rear) only
• Size-specific chainstay lengths (442mm S/M, 448mm LG/XL)
• 160mm fork travel, 150mm rear travel (160mm rear travel compatible with 65mm stroke shock)
• Bosch wireless two-button Mini Remote
• Toptube-mounted System Controller LED display
• New headtube cable routing ports
  a. Compatible with 0,1 or 2 cables per side
  b. Ideal routing for either right/rear or left/rear brake assemblies
• New chainstay protector design - includes separate cable routing grommet or closed plug for wireless rear derailleur
• Integrated Transition top chain guide included
• Custom charge port cover with integrated range extender cable management
• 250wh range extender compatible, sold separately (size small SX will not fit range extender)
• $6,999 (Deore builds), $8,999 (XT builds, tested)

 Differences - Transition Regulator CX and SX

Build Kits

Both Regulators are offered in two trims — Deore at $6,999 and XT at $8,999. The Deore SX and CX share most of the same parts as do the XT SX and CX. While identical in many pieces of componentry, the SX and CX vary in forks, tires, wheels and cranks. The CX XT is the only model to offer Schwalbe radial tires, but the SX XT is the only build with carbon cranks (Race Face ERA). Both CX builds run 150mm cranks and 34t chainrings compared to 160mm and 32t on the SX bikes. We tested CX and SX XT builds which roll on different DT Swiss wheelsets.

It should be noted that the new TRP Pro EVO brakes will come stock on the XT builds. Our test bikes had DH-R EVO brakes.

If we're comparing the bikes head-to-head, the SX marginally wins in the value department (without factoring in motor and battery cost) due to the carbon cranks and debatably nicer wheelset (which may be splitting hairs). Both the Deore and XT builds, however, are in the premium price range at $7,000 and $9,000. The frame is full carbon, the RockShox suspension bits on our XT builds are top-of-the-line, the OneUp cockpit and dropper are home runs and though reliable and durable, some shoppers may scoff at a cable-actuated drivetrain on a bike in this price range. 

Geometry

The size, fit and angle numbers on the Regulator are nice and classic with a touch of modern. As fans of sporty, playful bikes, this was refreshing for us with our size medium reach preferences landing in the 450-460mm range. Pair that reach with a 10mm-ish higher stack height than what's offered on the Sentinel and the Regulators are primed for action. Some of you long-bike lovers may be stuck wondering where to land with 25-30mm reach increments between sizes. The size-specific chainstays for S/M and L/XL keep the bike feeling even and balanced. They definitely did on our size medium. We kept the CX in the high setting throughout the test knowing consistently steep terrain was not in our immediate future. Why the SX doesn't offer a flip chip like its chunkier twin is a mystery to us and the lack of 29er rear wheel option on both bikes (especially on the SX) may be a deal-breaker for some. 

Bikes Are So Good These Days

First Ride Highlights of the Regulator SX by Brad Howell

For the past few years, the mountain bike community has been echoing the sentiment of “bikes are so good these days.” It’s not untrue, and as tired as you may be of hearing it, so are we tired of saying it. The gains as of late have been incremental, which has caused many (present company included) to hang on to our bikes rather than grabbing what’s new. While the e-bike segment has gotten pretty good lately, the SL category, in particular, has seen some pretty rapid growth and advancements. From this side of the handlebars, “peak e-bike” is one that rides most like a mountain bike. Many brands are crushing it, but it is nonetheless surprising when we get aboard a new bike that seems to be thaaaaat much better. Enter the Transition Regulator SX.

The trouble with a March launch date is that the preceding months are typically cold and snowing in the mountains. That meant we only had a couple of rides with the Regulator SX to gather some initial impressions. Vital will have a proper long-term review dropping later this year. For now, take this first look for what it is.

Initial Set Up

Setting up the Regulator began with converting the wheels to tubeless, an otherwise often innocuous event. If you purchase direct from Transition, your bike will ship with tubes installed, but it does come with all the fixins to get it set up tubeless. When it's all said and done, you have a spare tube.

I set the RockShox Super Deluxe Ultimate with 30% sag and left all the clickers in the neutral position. Sitting on the bike in the garage, it felt on the softer side, but with the Hydraulic Bottom Out and new air can, I wanted to see how it translated to the trail. The Lyrik Ultimate was set up for a 180-pound rider (10 more than I weigh) and still felt very supple during the cul-de-sac test.

It’s fantastic to see Transition throw the longest dropper possible on a bike and then make use of the manufacturer’s travel reduction feature to let riders dial in their ride. In this case, the OneUp 190mm dropper post was a welcome sight and, even with a 30” inseam, had lots of post exposed when set to my correct height.

Something that did not have to be changed was the spacer placement with the stem. With a 632mm stack height and OneUp’s 35mm riser bar, the Regulator’s front end was Goldilocks dialed out of the box. 

On the Trail

On paper, the Regulator SX is a direct comparison to one of my all-time favorite e-bikes: the Devinci e-Troy Lite. They have the same motor and ride on the same suspension, although Transition does have the updated RockShox bits. With Transition's 15mm taller stack and nearly 1.5-pound weight cut, I was truly curious to see how the two line up. It’s going to take more than a few rides on winter trails to draw a direct conclusion, but I’ll say the Regulator SX is off to a banging start.

The Regulator SX is a happy climber. The rider position is upright, and the seat angle keeps your weight where it should be, preventing a light front end or looping out. Utilizing the two lowest assist levels makes for a bike that scoots right up the hill while maximizing battery life. It is right on par with any of our experiences with the Bosch system. I tapped Boost on a particularly steep and loose climb, which the Regulator made short work of, showcasing what will hopefully be a trend of apt performance throughout the summer.

The Regulator SX feels light and natural enough to ride with the motor turned off, a temptation I had not felt since testing the Orbea Rise nearly four years ago. I dipped my toes in the water at the trail center with my 5-year-old. Hardly a mountain bike ride, but I did raise my eyebrow a bit with the ease at which the Regulator handled the kiddie pump track. We’ll see if I can keep my hand out of the cookie jar on a real ride.

Now for the sexy part: descending. With only a few rides on the local hill, I’m reticent to draw sweeping conclusions, but as it sits, the Regulator SX is intuitive and rides far lighter than the scales indicate. With the suspension on the more supple side, the bike still has a lively feel and is ready to make use of the terrain to pop over little jibs. These are sentiments typically thrown at 150mm trail bikes, not an e-bike, so yeah, we’re off to a good start.

Whether you want to keep feet glued to the pedals or have a seat and throw a foot out, the Regulator is fabulous in the corners. I even got a few braps out of it. It may not (yet) be on par with the GasGas in terms of outright arc dominance, but wow, it’s up there. Much of this comes from an “in the bike” feeling that the taller front end and slammed seat create. That low center of gravity is no joke!

I was able to find a few rocks to run over with the Regulator SX, and it made light work of those segments. The true test of its mettle will come as the steeper and boulder-strewn trails thaw out this spring. I would be surprised if the Transition didn’t hold its own, but won’t sign off until the moon dust settles. For now, I’ll say that we expect big things from the little purple machine from up north.

First Ride Highlights of the Regulator CX by gordo

I won't go into the setup detail like Brad as it is a very similar experience (30% sag, fork pressure a smidge higher than recommend and tire pressure 3psi higher compared with Maxxis I usually run). I will echo many of the points he made above, however. Even the full-power CX Regulator is an e-bike that rides with a feeling that's well below its 48-pound weight. Our CX with the bigger battery and stronger motor isn't even 6 pounds heavier than the SX, but it has a beefy RockShox Zeb fork and Schwalbe's impressive new radial tires which beg for hard charging.

Climbing is a no-brainer in any mode as body position is nice and neutral. The 600wh battery can be taxed in Turbo for a fun couple hours of speed laps or it can be nursed for all-day epic rides. The chainstay lengths ensure the front wheel stays in the dirt during steep climbs with the powerful motor, yet the overall balance descending feels controllable and stable but lively. Brad says the SX hints at pedaling with the power turned off, but the CX does not. As a rider with a short inseam, and one who rides 150mm cranks on his personal pedal bike, the stock 150mm cranks on the Regulator CX were a welcome surprise. In high geo mode, pedal strikes should be a distant memory when pedaling chunky terrain. I fully recognize, however, that some riders may dislike the uber-short crank spec. On that same note, the inability to run a 29-inch rear wheel on either the SX or CX may chap some folks' hides, too. 

Between the SuperDeluxe with HBO and the 27% progression (3% more than the non-motorized Sentinel), the bottom of the bike was never met in conflict, even with multiple plops to flat on a local broken concrete trail. I wouldn't say the bike feels like it has more travel than it does, but overwhelmed isn't a word found in the Regulator's lexicon. In contrast to the bike's ability to handle abuse, it also flowed, cornered and cruised extremely well on mellower trails, and the traction provided by the Schwalbe radial tires was exceptional in rocky terrain. Brad and I (along with Steve Wentz on a Relay) rode together in Reno to wrap things up. At the end of the day, we hit the long, flowy, mellow-but-oh-so-fun Reno Vista trail on Peavine. The CX was not left behind because of heft or lack of agility. It popped, shimmied and rolled right along with the other lighter bikes, solidifying that trails of all varieties are on the menu for the CX. 

My mind went to straight to over-biking the CX. I confirmed with Transition that a 170mm fork would be acceptable and its ability to run a 205x65mm shock to get 160mm of rear travel sure sounds enticing. A full power system, travel bump and some DH tires? Expensive and unrealistic? Definitely, but...

Long Term Durability?

Our test is hardly long enough to reveal and significant issues with durability. Historically, Transitions have been solid and we see nothing out of the sync with the Regulators beneath us. Both bikes did have bolts on the cable guide covers near the head tube loosen up, and they were snugged up. We'll keep an eye on them to see if the bolts remain secure.

What's the Bottom Line?

The Regulator, in SX or CX trim, is an exceptionally fun and versatile ripper that rides less like an e-bike and more like a traditional mountain bike. Balanced geometry in a full-carbon frame with capable components and options for going light or beefy open up riding experiences in every direction for any type of rider. There's something to be said for simplicity and the Regulator ensures there ain't no need to tweak 213 different settings, so you can focus on where to ride on that clear black night under that clear white moon.

Visit www.transitionbikes.com for more on the Regulator and stay tuned for our long-term review of the Regulator SX.

View key specs, compare e-bikes, and rate all the new Transition Regulator models in the Vital MTB Product Guide.