Mountain Bike Action’s Bike Test: Nukeproof Reactor 275C Factory

Nukeproof Reactor 275C Factory

Category: Trail
Suspension front/rear: 150mm / 140mm
Tire Size: 27.5™

The Reactor might not be a new name to Nukeproof’s lineup, dating back to 1996, but for 2020, it’s an all-new model looking to dominate the aggressive trail market. With updated geometry and new suspension kinematics, the Reactor targets riders looking for a well-rounded rig that can handle any trail at any time. This month the wrecking crew set out to see if Nukeproof’s promise could hold true on our Southern California terrain. Get ready as we descend and bomb our local riding spots and trails.

The stock handlebar has a 31.8mm diameter, which worked fine but didn’t give our bike the aggressive look a 35mm handlebar and stem could.


Our Reactor 275c Factory test rig was built with both carbon front and rear triangles; however, an aluminum model can be found in the lineup for budget-minded riders. Nukeproof designed this bike with features such as internal cable routing, Boost hub spacing and a threaded bottom bracket.


While Nukeproof labels the Reactor as a trail bike, riders will find its geometry is well-suited for high-speed runs down rowdy trails. This is thanks to the bike’s 66-degree head tube angle, short 430mm chainstays and long reach per frame size. When it’s time to climb, the 75.5-degree seat tube angle places riders in an optimal, forward seated position.

An adjustable Flip Chip is spec’d across all Reactor models, offering riders the option between T Trail mode or Rail mode. The first setting, as its name suggests, is designed for long days riding the trails, while Rail mode drops the bottom bracket by 6mm and slackens the head tube angle by a half degree, turning this shredder into a bike-park junky.


The Reactor is designed around a four-bar Horst-link suspension system with 140mm of travel.


Reactor models are available with six different specification levels, including components from Shimano, SRAM, Rockshox and Fox; there are options for every rider preference. All spec levels are available in both 27.5- or 29-inch frames. The model seen here features a full Shimano XT groupset and brakes, along with DT Swiss wheels wrapped in Maxxis rubber. Our Factory model was more than capable of pleasing even the most affluent riders, while Nukeproof’s Elite model brings value to a more approachable range.


Nukeproof designed this bike around a four-bar Horst link system, providing 140mm of travel. Tweaks were made to this new model to increase climbing performance while keeping the suspension active to handle small bumps during descents. Up front this bike soaks up the trails, thanks to a 150mm-travel Fox 36 Factory fork. Larger-wheeled 29er models reduce travel by 10mm front and rear.


Once the top of the trail is reached, it’s time to enjoy the Reactor’s playfulness during the journey back down.


The Reactor finds itself mixed between an enduro bike’s geometry and the travel category of a trail bike, making it an ideal option for riders looking to handle steep and rowdy terrain. From long climbs to quick and twisty descents, this Nukeproof comes to the trails composed and ready to rip.

Our test bike made the best of every descent by seeking out bonus lines.


Climbs are met with an efficient platform once riders flip the compression switch to a firmer setting.


During climbs, we found the NukeProof received pedaling efficiency with the shock set in the firmer settings. When left in the open setting, especially on smoother long climbs, our riders found the rear end sat lower in its travel than other bikes in a similar travel category. That said, the firmer shock settings aided in climbing efficiency whether seated or standing. The Reactor’s steep seat tube angle places riders in a balanced position, and the longer reach provided plenty of room when hopping up out of the saddle.


Smashing down the trails at high speeds brings the Reactor to life. Between its active suspension and relaxed geometry, the Reactor provides comfort and confidence even when the trails get challenging. Steep chutes, rock gardens and jumps are all things this Nukeproof is ready for. Riders who enjoy pushing the limits of their equipment during descents will find the Reactor perfectly suited to meet their needs.


Nukeproof does a nice job of offering multiple build kit options to best suit rider preferences should they be a fan of Fox/Shimano or RockShox/SRAM. Our Factory build kit came with a solid spec at a value-driven price; however, there was one component we decided to change. The 31.8mm handlebar that came on our build didn’t quite give our bike the tough look we were looking for and seemed to offer more rise than our tester wanted. We opted for a carbon 35mm handlebar and stem to replace the OEM cockpit and to give our ride a more aggressive look.


The Reactor gets along with riders ready to tackle the rough stuff on a mid-travel machine. Nukeproof made sure this bike would be well-composed when pushing it at a fast pace while also focusing on pedaling efficiency to get riders back up to the top. The rider the Reactor will suit most is one looking for a blend of enduro bike geometry and trail bike suspension. It’s a bike built for the “sender” crowd looking to get as rowdy as possible off every trail feature.

Watch MBA’s First Look: Nukeproof Reactor


Mountain Bike Action is a monthly magazine devoted to all things mountain biking (yes, that’s 12 times a year because we never take a month off of mountain biking). It has been around since 1986 and we’re still having fun. Start a subscription by clicking here or calling (800) 767-0345.

Available from the Apple Newsstand for reading on your iPad, iPhone or iPod Touch.

Subscribe Here

You might also like