The Transition Regulator CX launched last week, a new e-bike with 150mm travel, Bosch CX Gen 5 Performance motor, geometry & sizing to die for, and a claimed weight of 21.3kg.

I’ve had the bike in the mbr workshop to figure out whether the claims stack up against reality. I’ve measured pretty much every angle and span worth knowing, weighed the bike and even checked the rear wheel travel. Here’s what I found…

Lighter than expected, the Regulator comes up at a cool 21.5kg

Weight

The Transition Regulator CX XT e-bike that I did my first ride review on has a claimed weight of 21.3kg in size medium. When a size large turned up I lost no time getting it onto our workshop scales, where it came up just 200g heavier, at 21.5kg.

Honestly, I’m surprised it wasn’t more than that though, with all the extra material needed to make a bigger size – a longer downtube, top tube, seat tube and headtube.

The ‘longer’ chainstay of the medium won’t actually weigh any more, of course, because it’s actually the same piece, just mounted further rearward to create the proportional geometry effect.

Perhaps Transition was being conservative in its estimates. Perhaps the tyres came up slightly heavier on this exact bike. Who knows, but it means the Regulator is very light for a full power e-bike – the Santa Cruz Vala is slightly heavier even with the same battery, and the DJI-powered Amflow PL Carbon Pro weighs a full kilo more, thanks to its 800Wh battery.

The head angle’s slack enough for trail riding

Head angle

In the bike’s low setting the head angle is 64°, according to Transition, and half a degree steeper in the high setting (it uses a flip chip for geometry adjustments). In fact the bike came out 0.3° steeper when I measured it in both the high and low settings, which is close enough to be well within tolerances.

What causes this kind of variance? Hopefully not my measurements! I zeroed my angle finder on a spirit level laid between the bike’s wheels before I started, and then took multiple measurements.

More likely is discrepancy in the frame or components: small variations in build and machining are always going to happen, even on carbon bikes coming out of the same mould. Add them together and a fraction of a millimetre here and there can quickly add up.

With 150mm cranks I reckon the BB could be lower still

Bottom bracket height

The BB height of a bike is really important to get right for a bike builder: too high and the bike will feel unstable; too low and you’ll bonk your pedals on the ground. I’m happy to say the Repeater looks bang on for a 150mm bike, at 348mm measured in the high setting. That’s just 2mm lower than Transition said it would be. In the low setting it’s 339mm.

That’s not the end of the story though because where the BB sits at sag, when you’re actually riding the bike, is a whole other thing entirely. Here it is influenced by the shock pressure, and the balance of the bike fore and aft – add in more air and it’ll effectively jack up the bike.

I’m also surprised Transition didn’t drop the bike – and your centre of gravity – lower still. It’s fitted ultra short 150mm cranks to the Regulator, meaning there’s much less chance of clipping a pedal anyway. Why didn’t it take advantage of that and lop 5mm more off the BB height? Maybe because in the low position I measured it at 339mm, which is average, or slightly below.

With a 485mm reach the Regulator is a good size for a large… but the jump to XL at 510mm is too much of a stretch

Reach and size

Reach is arguably the best indicator of whether a bike will fit you or not, because it does away with the variation in seat tube angles that can skew top tube measurements. After all, it’s when we’re descending and stood up on the pedals that matters most most on a bike, right? Not the room you have in the cockpit when sat down and pedalling.

The Regulator comes up 5mm bigger in real life than it does on paper, at 485mm in the bike’s high setting. That puts it squarely in line with many modern all-mountain bikes in terms of reach, and right where we’d expect to find a size large – the Santa Cruz Heckler SL is 478mm measured in size large, for example.

But with only four sizes to choose from the Regulator might leave some riders to fall through the cracks. Step up to the size XL and you’ll have to be well over 6ft to make it work, thanks to a claimed 510mm reach in the high setting – that’s 30mm longer than the Large here.

Cranking the bike down into its travel

Rear wheel travel

Transition says the Regulator is a 150mm travel bike with a 160mm fork – the latter is really simple to check because its movement is in a straight line. The bike’s travel is harder though because it moves in an arc, but I can still check the vertical suspension distance though.

I did this by measuring the difference between the rear wheel height at maximum and minimum compression. Or to put it another way. with the shock fully compressed, and then fully extended. The Regulator has pretty much its claimed travel, coming up just 4mm shy on my tape measure, and again well within the kind of tolerances I’d expect

However, with a big hydraulic bottom out bumper in the new RockShox Super Deluxe Ultimate shock it’s quite likely the bike will achieve full travel when you’re actually riding it. I couldn’t squish it down hard enough to measure the last 4mm of travel, something only your weight could do off a big drop.

With long chainstays the Regulator is primed for tackling steep descents and climbs

Front centre, chainstays and wheelbase

I split the bike in half when measuring its length, meaning the front centre is the horizontal distance between the front hub and the centre of the BB: and the chainstay is the rear hub to the BB.

Working out the rear wheel travel

The Regulator is 7mm longer in the front than claimed, and 2mm shorter at the chainstays. You probably won’t be surprised to learn the wheelbase is slightly longer than claimed too, thanks to more length in the front. At 1,276mm in the high setting it’s a pretty big bike, comparable with Whyte’s ELyte Evo Stag Works e-bike.