The Transition Regulator CX XT is a whole new all-mountain e-bike, it gets 150mm travel, the Bosch SX Gen 5 motor, great spec at a killer price… but the Schwalbe Radial tyres spoiled it for me

Product Overview

Pros:

  • • Great use of power from the Bosch CX Gen 5 motor, always ready to pull whichever gear you’re in
  • • Suspension components are top drawer, the Charger 3.1 damper is supple enough to do ballet
  • • Well made full carbon frame, with proportional geometry and neat touches like magnetic charge port
  • • Geometry is spot on in the Low setting for a 150mm travel e-bike
  • • Good spec for the price, with flawless Shimano XT drivetrain, TRP brakes and DT Swiss wheels
  • • Lightweight build, at 21.5kg

Cons:

  • • Bosch 600Wh battery limits the range of the Repeater
  • • Schwalbe Albert Radial tyres didn’t hook up for me
  • • Potentially too stiff for my kind of riding

Product:

The new Regulator from Transition looks like a Santa Cruz Vala beater, with a Bosch CX motor and primo spec, but I had a hard time getting the most from it

Manufacturer:

Price as reviewed:

£8,498.00

I’d argue that Bosch’s fifth generation CX drive unit is the most significant mountain bike motor of 2025. Not the DJI Avinox with its ludicrous power, but Bosch’s humble 85Nm torque power pack. The German brand’s biggest motor is the dominant force in e-bikes because it’s available right now on a host of new bikes – not just one – and that gives consumers real choice, and at scale too.

Transition Regulator CX XT 2025

Transition’s got its hands on one of the hottest motors of 2025, the Gen 5 Bosch CX

Instead of picking a motor and then being forced into just two models of the same bike (no matter how good you think the Amflow PL Carbon might be), Bosch Gen 5 lets you pick between many, and to suit your riding style. We’re talking about the Santa Cruz Vala, Trek Rail+, Cube Stereo Hybrid One44, Focus Jam2 and so on. And the newest bike of all, Transition’s Regulator CX here.

– Short of time? Click here to skip to the verdict –

A great motor doesn’t immediately transform the Regulator into one of the best electric mountain bikes on the market though, so keep reading to hear why I don’t think it’s the bike for me.

Transition Regulator CX XT 2025

The Regulator definitely gives of Vala vibes, probably because it as a similar suspension layout, suspension travel, sizing and intentions

Transition Regulator CX need to know

  • All new e-bike from Transition, with 150mm travel, 160mm fork and mullet wheels
  • Powered by Bosch CX Gen 5 motor, and a 600Wh non-removable battery
  • Full carbon frame with four sizes, two chainstay lengths, new cable routing and chainstay protection
  • XT build comes with Shimano XT drivetrain, 150mm SRAM cranks, OneUp finishing kit
  • Premo RockShox Zeb Ultimate and new for 2025 Super Deluxe shock
  • XT bike costs £8,499
  • Check out range details of the Transition Regulator CX and the less powerful SX bike in my Transition Regulator news story

The Regulator is Transition’s third e-bike, and the US brand’s fourth motor, meaning it’s very sensibly not wedded to any particular power unit, preferring to use whatever’s the most important for the application.

Transition Relay

I loved how the lightweight Relay rode when I tested it back in 2023, it’s a properly playful ride

The big-hitting Repeater with 170mm travel started out using Shimano EP8 before working as a launch partner for SRAM’s Powertrain. And the Transition Relay lightweight e-bike, which I absolutely love to ride by the way, used Fazua’s Ride 60.

The new Regulator CX gets less travel than both those bikes, at 150mm, with a 160mm fork up front, a mixed wheel setup and a 600Wh battery. There are two models in the range, this XT and a Deore spec, and the pricing is actually pretty sensible compared to the Santa Cruz Vala, with the Transitions at xx and xx.

Transition Regulator SX 2025

The SX bike naturally gets a lower-torque Bosch SX motor, and a lighter build with a Lyrik fork

There’s one more thing to know before we get started on the review – the Regulator also comes as an SX build, meaning it gets Bosch’s lighter, smaller and less torquey motor. It also has some implications for the way Transition’s built the bikes, and how they ride, which I’ll get to later.

Frame and geometry

The Regulator’s full carbon frame is much slimmer and better looking than the bulky Repeater. This is in part down to the motor choice, with the Bosch CX motor much smaller and neater than SRAM’s Powertrain, which looks like it’s made from my kids’ Duplo blocks.

Transition Regulator CX XT 2025

Check out that sculpting, wrapping the CX motor in the Repeater’s frame

Transition has gone to great lengths to integrate the CX unit into the bike too, forming the shell so it almost wraps around the motor like a sleeve. It makes for a really clean look, more so than bikes like the Mondraker Dune RR, and in theory it should keep more mud and water off the motor too.

The latest 600Wh battery also plays a part in this joined up bike design, it’s less broad than the 625Wh Powertube it replaces and the means Transition can build a relatively skinny downtube when you’re looking down from above.

Transition Regulator CX XT 2025

Transition’s chainstay protection is thorough, with really squishy lugs to take the whip out of your chain

There aren’t true size-specific chainstays on the new Repeater, but as with bikes like the YT Jeffsy Core 5, Transition has made two different sized back ends for the four sizes of bike. There’s new damping to the chainstays too, big rubbery blocks running the length of the driveside and mimicking most modern designs I’ve seen.

The Repeater isn’t going to challenge the new Geometron G1 GPI gearbox bike on geometry Top Trumps, in fact I’d say it’s pretty mainstream, in a good way. There’s a flip chip built into the lower shock mount but I can’t see anyone riding this bike in a high setting with a 350mm bottom bracket height.

Transition Regulator CX XT geometry chart

In low I measured 64.3º at the head angle, with a 77.4º effective seat tube angle, and a 339mm bottom bracket height. So on a par with Merida’s new e-OneSixty SL 8000 that shares the same travel.

Transition Regulator CX XT 2025

Transition Regulator CX XT 2025

Finally there are some great little touches to the bike, like a magnetically-secured charge port door, new head tube cable routing ports (not headset, praise be!), and a mudguard covering the gap between the back end and front triangle.

Transition Regulator CX XT 2025

The Super Deluxe Ultimate is smooth as butter with an action soft as a sponge cake… but with a solid base to back it up

Suspension

Transition calls its four-bar suspension design Giddy-Up, here it’s generating 150mm travel through a new for 2025 RockShox Super Deluxe Ultimate. When I first pulled it out of the box I was struck by how similar it is to the Santa Cruz Vala e-bike, after that brand dropped its VPP design for the first time in years.

At the other end there’s a RockShox Zeb Ultimate, with 160mm travel. That’s a pretty burly fork for an e-bike with modest travel and weight, and perhaps points to the big-hit use Transition expects riders to put the bike to.

Transition Regulator CX XT 2025

With a Zeb up front the Regulator is prime for enduro riding or tackling big features

Bosch CX motor

Set into the top tube is a standard Smart System Controller, with five lights to flash up your battery range and current power mode, and a button to control the power mode. That’s pretty pathetic in 2025 when brands like DJI and TQ have touch screen colour displays giving out all kinds of data streams, from power to range, distance and so on.

Transition Regulator CX XT 2025

Still waiting for that touch screen display… never mind, the lights and buttons are at least reliable and intuitive to use

It’s all the more frustrating when I’ve heard rumours of a new display for years now, ever since the brilliant Whyte ELyte 150 RSX launched back in 2023. Transition obviously believes something really is in the works, just as Whyte did back then, with the same oversized cutout in the top tube to accommodate a newer and bigger display. Some brands have been putting the more detailed Kiox 300 display into their bikes, the Ghost E-Riot springs to mind, but it’s lights and buttons only here.

Transition Regulator CX XT 2025

I like that you can remove the wireless remote entirely for a cleaner bar, and the motor will work just fine without it

Ah well, at least it’s really simple and intuitive to use – press a button and you’re cooking. The best way to control the power setting is not through the System Controller though, it’s via the wireless handlebar remote. I flicked it into EMTB mode for most of my riding because it’s the best compromise of power and battery management, and I reckon I added some 200m vertical range by using this approach.

The actual motor is far more impressive, I won’t go into all the details here because Danny’s already done a really thorough first ride review of the Bosch CX Gen 5 motor here, but it’s a huge improvement. The power hasn’t actually increased over Gen 4, you’re still getting 85Nm of torque and 600W of power, but it’s all about how it’s used.

Transition Regulator CX XT 2025

The latest Gen 5 CX motor uses its power wisely, it seems to get more support across all the gears

It seems to me there’s more support than ever before, making it easier to get the motor to do the work rather than your legs, while the torque seems to kick in lower down too, for a wider range of usable gears. I’ll get more into this when I talk about the bike’s Performance and my experience of it.

Finally, I don’t think the CX motor will have just 85Nm for long. I’ve heard from some pretty reliable sources that a firmware update will boost the power to 101Nm and that technicians are already being trained on how to do this. Bosch wouldn’t comment when I asked, but I’d bet good money on it coming this summer.

Transition Regulator CX XT 2025

A skinny downtube seems like a poor compromise for the reduced range of a 600Wh battery

Bosch CX battery

Opting for a non-removable 600Wh battery when you could have an 800 seems a strange choice to me on Transition’s part, but it could be there’s method in the madness. First up it’s 10mm narrower across the downtube, which makes for a smarter looking bike.

Transition Regulator CX XT 2025

I’m loving the magnetically latched charging point, there’s almost no way to leave it open by mistake

More importantly though, the 600 weighs just 3kg to the 800’s 3.9kg, which combined with the carbon frame and some of the components gives a complete bike weight of just 21.5kg in size large. Some SL e-bikes don’t come up that light, with the Marin Rift Zone EL XR weighing 21kg, for example.

The cells inside the latest 600Wh (and the 800Wh) are more energy dense than the older power packs too, so in theory you get the same energy for less size and weight. Take that one step further and – like a virtuous circle – the reduction in weight should lead to even less energy use too, and even more range.

Transition Regulator CX XT 2025

Schwalbe’s new Radials claim to offer more contact with the ground than a similarly sized tyre

Components

It takes a great tyre, or perhaps some great marketing, to coax a brand away from trusty Maxxis, but which one Transition has succumbed to isn’t immediately obvious. The Repeater comes with the latest Schwalbe Albert Radial tyres, not the Gravity carcass version Mick tested for us last year, instead the bike uses the Trail carcass.

Presumably that makes them lighter and more supple, but perhaps also more prone to punctures and less supportive. The Radials are mounted to some of the best e-bike wheels I’ve tried, the DT Swiss Hybrid 1.

Transition Regulator CX XT 2025

Super short 150mm cranks are designed to improve ground clearance and smooth out power delivery… but honestly I didn’t like the feel

As you can probably guess from the name, Shimano XT covers all the shifting duties with the exception of a SRAM S1000 crank. Get ready for this though, they come in a 150mm length option, something we’ve not seen stock on any bike before. Hope’s been offering a 155m Evo crankset for a few years now, something Mick tested, but otherwise it’s a pretty new concept to me.

Transition Regulator CX XT 2025

TRP DH Evo brakes with 203mm rotors, an 800mm OneUp bar, Anvl Swage stem, and Transition’s own chain device compound some brilliant components for an £8,500 e-bike

TRP brakes, a OneUp dropper, OneUp carbon bar, ANVL stem and SDG Bel Air saddle finish things up nicely.

Performance

I’ve never been more shaken in my expectations than my first ride on the Regulator. On paper it’s a stunning looking bike, with brilliant spec for the money, the right motor, and geometry that looks about spot on. The fact I didn’t gel with the bike straight away was honestly a shock, honestly though, this is exactly why testing bikes is so imporant.

I’ll get this down straight away, I don’t think the Regulator is necessarily a bad bike. But I do think it would take more time I had to and some careful setup to get the most from it… and, for me, it might even need some parts swapping out.

Transition Regulator CX XT 2025

Techie climbs are easy on the Regulator thanks to its active suspension… and I can’t say I noticed any loss of power here from the short crank arms

Climbing

I ticked off 1,000m of climbing over 32km around the Surrey Hills, on the Regulator in full power Turbo mode. That doesn’t sound that great but my range tester ride took place the day after a full on week of winter rain, and the trails could not have been slower.

My guess is that I could get some 1,200m out of the bike in more normal conditions, which really isn’t bad at all for a 600Wh battery. Of course an 800Wh battery would have been better, and I’d take more capacity and its 900g weight penalty any day of the week.

The Bosch CX motor is like driving a good automatic car, after struggling with Citroen Grand Picasso for years. (For accuracy, this isn’t an idle simile.) It’s just incredibly easy to use, the support is strong enough to work in some pretty inappropriate gears, pulling you along with seemingly very little effort.

It’s also very controlled, especially compared with systems like Shimano’s EP801 Race Tune that dollops out its power in great wheelspins. On the Bosch I always seem to have just the right amount of power, and that really helps control the back wheel on techie climbs or tight switchbacks.

There are definitely limits to the power of course, especially when riding alongside the mighty DJI-powered Amflow, which can drop you at any time. But it can certainly hold its own against systems like Brose, Shimano and Yamaha.

Climbing on the Repeater reveals just how active its Super Deluxe shock is, quickly diving into its travel to keep that rear wheel tracking over every imperfection in the ground. The bike’s relatively long chainstays and steep enough seat tube angle give a decent weight balance too.

Transition Regulator CX XT 2025

Transition Regulator CX XT 2025

Descending

The Repeater is almost completely silent on the descents, there’s no cable rattle, no motor tick and no discernible creaking. That’s because Bosch has cured the rattle on its CX motor that plagued the previous generation, while Transition’s new cable routing and chainstay protection is obviously doing its job. In the dry, the only sound you’ll hear descending is the purr of well damped rubber.

Add in a fair chunk of mud though and the XT cassette sounds pretty graunchy in gears three and four, but proved silent in the biggest sprockets. That’s probably because the two lowest gears are made from more malleable alloy while the rest is made from steel. It’s not a problem though because XT still shifted flawlessly throughout.

Transition Regulator CX XT 2025

Transition Regulator CX XT 2025

Where the Repeater does really well is over rough terrain at speed, the Super Deluxe shock and Zeb move so quickly and with such control it seems to follow every bump in the trail. I’m pretty sure the shock fitted has a bottom out bumper fitted to, which explains why harsh landings and square edge hits don’t seem to phase the bike much. It’s almost the opposite of kicky, smooth enough to float you through nasty rough sections.

Transition Regulator CX XT 2025

Transition Regulator CX XT 2025

It’s all the more puzzling then that I didn’t gel with the bike in most Surrey Hills riding. I had the sensation that the front end was too high and the head angle too steep, although my careful measurements of the bike reveal that’s not actually the case. I wound on more compression damping and added more air than recommended to try and rebalance the Repeater and put more pressure through the front wheel. Much better for sure, but I didn’t get a 100% satisfactory setup up, despite plenty of fettling.

Transition Regulator CX XT 2025

Transition Regulator CX XT 2025

That high bar feeling is there again with the bike lent over and cornering, and I just didn’t feel the grip was there for a bike with such an accomplished shock. My theory is that the Repeater is very stiff, perhaps too much so for the kind of riding I enjoy – muddy, off-camber, rooty, steep jank, found throughout Surrey and South Wales.

What’s causing the stiffness then? Mostly it’ll come down to the carbon layup Transition’s built around the battery, and I wouldn’t be surprised to find the SX version of this bike is more compliant. The Zeb fork on front is also going to stiffen things up plenty, most e-bikes I like have something less stiff like the Fox 36 or RockShox Lyrik.

Transition Regulator CX XT 2025

Schwalbe’s new Radials claim to offer more contact with the ground than a similarly sized tyre

There’s one final piece of the puzzle I’m not sure about either, and that’s the Schwalbe Albert Radial tyres. ‘Add in five psi more than you’re [sic] usual setup’ the internet told me, so I tried it. The result was harsh, overinflated-feeling tyres lacking in grip. I dropped them down to my usual pressures, perhaps one psi more than normal and they felt better.

Not great though, the fact is I don’t like the angled lugs that don’t seem to develop much in the way of cornering grip on loose or muddy stuff. They’re also pretty far away from being 2.5in tyres, mine measured up at 2.4in from the widest triangular point on each lug, and 2.3in carcass to carcass.

Transition Regulator CX XT 2025

Transition Regulator CX XT 2025

Compare that with a Maxxis Assegai, which is 2.5in across the whole face of each outer lug, and 2.4in from tyre edge to tyre edge. I think the Albert is giving away everything it gains from its ‘radial’ design simply by putting down less contact with the ground.

Transition Regulator CX XT 2025

Transition Regulator CX XT 2025

Verdict

The Repeater isn’t my favourite bike of 2025, but fixing it for me could come down to something as simple as changing the tyres over for something with more cushioning and better grip when lent over. With more time to play around I’d also want to try Bottomless Tokens to prop the shock up more. I also tend to prefer bikes that are on the flexier and more compliant side of things, meaning I enjoy the Orbea Rise LT more than the mighty Specialized Turbo Levo. Plenty of riders who hit bigger, rockier and faster terrain than me (and who weigh more too) might disagree with my take on the Repeater then.  As it is though I’m really looking forward to trying out the Repeater SX - yes it’s got a punier motor in it, but the more compliant Lyrik fork and smaller battery could work wonders for me.

Details

Frame :150mm (146mm measured)
Shock :RockShox SuperDeluxe Ultimate
Fork :RockShox Zeb Ultimate, 160mm travel
Motor :Bosch Performance Line CX Gen 5
Battery :600Wh
Control unit :Bosch System Controller, with Bosch Wireless Mini Remote
Wheels :DT Swiss H1900 rims, DT Swiss Hybrid 370 hubs, Schwalbe Radial Ultra Soft / Soft
Drivetrain:SRAM 150mm cranks, Shimano XT mech, shifter, cassette and chain, E*Thirteen Helix 34t chainring 
Brakes :TRP DH-R EVO brakes with 203mm rotors
Components:OneUp 800mm carbon bar, ANVL 40mm Swage stem, OneUp 210mm dropper post, SDG Bel Air V3 Lux saddle
Weight:21.5kg
Sizes :S, M, L, XL
Contact :windwave
Size ridden :L
Rider height :185cm
Geometry :low setting
Head angle :64.3º
Seat angle :74.8º
Effective seat angle :77.4º
BB height :339mm
Chainstay :446mm
Front centre :830mm
Wheelbase :1276mm
Down tube :760mm
Seat tube :440mm
Top tube :615mm
Reach :485mm