2020 Nukeproof Reactor 275c RS Bike

(discontinued)

What’s a trail bike? That was always a difficult question to answer, and even more so over the last couple of years. A bit less travel is about the only constant we find if we look at a cross-section of trail bikes from different manufacturers, and even that is still up for debate it seems. Beefed up XC bike or scaled down enduro? It’s not always easy to tell, but it’s crucial that you understand the implications, especially if you’re out to buy just one bike to do it all. Nukeproof’s new Reactor is jumping right into this red-hot market segment, and it’s got some pretty solid arguments going for it – especially this hooligan RS version. After five months on the trail we’re here to take an in-depth look at this rowdy little rascal, so keep on reading!

Nukeproof Reactor Highlights

• T700/800 monocoque carbon fibre frame
• 27.5 or 29” wheel size
• Head angle: 66 degree in "Trail" mode / 65.5 degree in "Rail" mode
• Travel: 27.5” 150mm / 140mm // 29" 140mm / 130mm
• Seat angle: 75.5 Trail / 75 Rail
• Threaded 73mm BSA
• Boost 148mm rear axle spacing
• Shock size: 210x55mm
• Headtube: 44-56mm Tapered Semi-Integrated
• Headset: ZS44-28.6 – T2 / ZS56/40 – B8
• Seatpost:31.6mm (internal routing for dropper seatpost)
• Brake Mount: 180mm direct post
• Protection: 3D contoured rubber frame protection for DT/SS/CS
• Sizes: 275: S, M, L, XL // 290: M, L, XL
• Alloy Options: Comp, Expert
• Carbon Options: Elite, Pro, Factory and RS 
• Prices from $2749.00 USD ($5399.99 as tested)

Video Review

The Reactor is a bit of a fresh start for Nukeproof, in many aspects. It may carry the name of a 25-year old model, but this is strictly a 2020 bike. For starters, it’s made entirely out of carbon, which is a first for Nukeproof (their carbon Mega has an alloy rear triangle). It was also designed from the ground up to be an aggressive trail bike, instead of just a Mega with shorter travel. This means that Nukeproof was able to concentrate on giving it suspension and geometry characteristics that complement the intended primary use case: go hard and have fun on a variety of trails. There is a 29 and a 27.5-inch version, and different spec levels with both carbon and alloy frames. We were sent the top-level RS spec, which in addition to featuring a smattering of delicious SRAM parts also gets a bump in fork travel – up to 160 mm for the 27.5-inch model. The rear travel sits at 140 mm for the 27.5-inch bike and 130 mm for the 29er. The production bike features clear frame protection applied in critical areas, something that our test bike lacked.

Checking out the geometry in more detail reveals a modern bike but not one that pushes things to the extreme. Our size Large provides a fairly generous 478 millimeters of reach, with a 65-degree headangle (when setting the flip chip to the slackest setting). The seat tube is fairly short on the Large, at 456 mm it will allow you to run a pretty long dropper if you want – the 170 shown here fit this 1m84 tester with no issues at all. The seat tube also offers plenty of insertion depth which is good. On the slightly more negative side, we would have loved to see Nukeproof go one degree or so steeper with the effective seat tube angle, but since the actual seat tube angle is comparatively steep, it balances out fairly well, especially for slightly taller riders. At 430 mm, the chainstays are short.

Diving into the suspension curves, we discover a progressive bike with anti-squat numbers that are optimized for efficient pedaling in the easier gears with less kickback in the harder gears. Note that the anti-squat is on the low side of “average”, particularly for this version with a 10mm longer fork. The goal here was to design a bike that would be easy to get up the hill but more importantly, Nukeproof wanted to squeeze the most out of the 140 mm of rear travel on the way down. There is a moderate amount of anti-rise as well, to help the bike settle down under braking. A previously mentioned, there is a flip chip that allows you to switch between Trail and Rail mode – Rail mode drops the BB by 6 mm and slackens the head angle and seat tube angle by 0.5 degrees.

Using the bike industry's leading linkage analysis software, André Santos was able to determine a close approximation of the Reactor's kinematics for the purpose of this review. Though they don't always tell the full story, these charts provide great insight into several key factors that impact how the bikes ride. 

André's observations:

• The Nukeproof Reactor 275 RS has progressive rear suspension kinematics. Considering both the amplitude and the shape of the leverage ratio curve, the Reactor has a progressivity of 32%, meaning that it needs more 32% of force to bottom-out when compared to any linear bike equipped with same shock and similar SAG% amount. Therefore, the Reactor has a very good amount of progression for most riders and it should provide a significant resistance against harsh bottom-outs without being excessively progressive at the end of the travel.
• Regarding pedaling efficiency, while most trail bikes in the market have near 100% anti-squat (or slightly higher), the Reactor has anti-squat of 85% and 75% for the 50T and 24T rear cogs, respectively. On the small 10T rear cogs the anti-squat can drop significantly to near 50% at SAG zone. Therefore, the Reactor should have slightly less pedaling efficiency than most trail bikes in the market equipped with the same shock. On the other hand, and as a consequence, the Nukeproof Reactor has slightly less chain-growth and pedal kickback than most of the competitors.
• The anti-rise is near 80% at SAG which is a typical value for a Horst-link with a vertical rocker arm design, meaning that bike geometry is mostly preserved under rear braking forces.
• Overall, the Nukeproof Reactor 275 RS combines quite progressive rear suspension kinematics with fair pedaling efficiency.

Looking over the parts, the RS version tested here features the excellent RockShox Lyrik Ultimate RCT3 and the Super Deluxe RCT shock, with a SRAM Eagle X01 transmission and Code RSC brakes. A set of Mavic Deemax DH wheels fitted with a Maxxis Assegai/DHR II combo and Reverb C1 round out the build, with Nukeproof’s own brand components taking care of the cockpit and the touchpoints.

On The Trail

The elaborate lines of the frame look a little bit quirky from some angles, but overall the bike looks like it means business and the aggressive stance had us eager to come out and play from the minute we met it. Hitting the trail for the first time, our initial impression was of a poppy and dynamic trail bike. It moves out quickly under power, and although a certain amount of pedal bob is present when pedaling, the bike never feels sluggish – quite the contrary. Yes, the anti-squat is moderate, but the short-ish travel and a progressive leverage ratio curve help the bike sit up in its travel. The tires are seriously meaty, but they roll surprisingly well here. The effective seat tube angle is somewhat slack on paper, but the actual angle is pretty steep, and this translated to a bike that was comfortable on any climb, even for this tester’s long legs.

Pointing the bike down the hill, its playful nature was immediately at the forefront. It loves to pick up speed down the slightest incline, and it carries momentum through turns and over undulations really well. It rewards rider input with a direct response but it never feels chattery or unsettled. The RockShox suspension components specced here really shine with regards to comfort and small-bump compliance, and the rear shock tune is particularly impressive in the way it makes use of the 140 millimeters of travel available. Nukeproof ships the bike with a token in the shock which was the perfect set-up for this 88-kg tester, but you can easily remove it if you want a little bit more linear behavior. The progressive linkage design will help control bottom-out in either scenario.

In this RS version, the geometry of the Reactor truly delivers a confidence-inspiring ride, and the bike wasted no time becoming our go-to for…well...pretty much any trail!

As the speeds pick up, the bike continues to shine. Remember how we said the suspension is compliant and comfortable? Well it remains that way even as things get way hairier, never losing control but also never becoming harsh. At this point, we also started to really appreciate the geometry of the bike. Note that we were on the 160 millimeter fork version, and we also found ourselves using the lower, “Rail” setting of the flip chip for the majority of the testing. Set up this way, the Reactor is a real Jekyll and Hyde act –but it’s Jekyll and Hyde at the same time, somehow. Did you ever find yourself loving the forgiving and confidence-inspiring nature of your long-travel enduro bike, but you wished it had a bit more pop to it for those mellower trails? The Reactor RS is that bike. We’ve ridden quite a few mid- to long-travel trail and enduro bikes recently, and the Reactor stands out from the bunch with the amount of confidence it provides on rowdier trails. Simply put, we never felt like the geometry had us out of our depth, regardless of how steep and rough a trail we pointed it down. In that aspect, it will outpunch most trail bikes out there. There does come a point where the 140 millimeters of travel out back won’t be able to cash the checks that the front end is writing, but when that happens, it’s not a disaster either. You’ll get tossed around a bit but we never felt properly overwhelmed. This bike will happily head out for a full-day XC jaunt one day only to hit the bike park the following day, and we’ll say it again: that applies in particular to the longer-forked versions. Just keep in mind that this bike will have you pushing the limits, because that’s where it wants to be!

Going over the bike after 5 intensive months of riding revealed that it had held up just fine (and this media bike had actually already been out with another publication before landing with us). The component scorecard is mostly excellent, with a few remarks: these all-new Mavic Deemax wheels feature pretty lackluster engagement, and in typical Mavic fashion, they are 2 millimeters narrower than the now-standard 30mm. We also struggled with the tubeless seal on one of them, and we did find that the rim was prone to pinching the tires, despite the EXO+ casing specced by Nukeproof. On the plus side, the wheels feel good on the trail and they have stayed true despite plenty of abuse. On the topic of the tires, we’ve been very impressed with the Assegai/DHR II combo. Predictable grip in most conditions, good rolling speed – nothing else to ask for. The Code RSC brakes have been equally impressive, delivering tons of dependable braking power, day in and day out with no fuss. The Eagle X01 shifting has proven itself up to the task many times over, make sure your hanger is straight and your b-tension is set properly and it’s smooth sailing from there on in. Nukeproof’s cockpit and saddle have put in a great showing here as well, the finishing kit looks good and performs well. We were slightly taken aback at first at the sight of a 31.8mm cockpit, it looks a bit whimsy compared to the beefy 35-mm set-ups we’ve gotten used to over the past couple of years, but it’s been very comfortable on the trail both in terms of compliance and angles. 

What’s The Bottom Line?

Coming back to the question we asked in the intro, what’s a trail bike? It’s really what you want it to be, and that’s one of the strong points of Nukeproof’s new Reactor. You can get it as a 130 mm 29er with a 140mm fork, switch the flip chip to the Trail setting, and you’d have a super lively mile-muncher that rolls over stuff with ease. Or you can get the 160 mm forked, 27.5-inch, RS-spec hooligan we’ve been reviewing here, drop the flip chip into the Rail setting and have the closest thing to an enduro bike you can get without sacrificing the playfulness and the dynamic performance on mellower trails. In this RS version, the geometry of the Reactor truly delivers a confidence-inspiring ride, and the bike wasted no time becoming our go-to for…well...pretty much any trail!

More information at: https://www.nukeproof.com.

Vital MTB Rating

• Climbing: 4 stars
• Descending: 4.5 stars
• Fun Factor: 5 stars
• Value: 4 stars
• Overall Impression: 4.5 stars - Outstanding

About The Reviewer

Johan Hjord - Age: 46 // Years Riding MTB: 14 // Weight: 190-pounds (87-kg) // Height: 6'0" (1.84m)

Johan loves bikes, which strangely doesn’t make him any better at riding them. After many years spent practicing falling off cliffs with his snowboard, he took up mountain biking in 2005. Ever since, he’s mostly been riding bikes with too much suspension travel to cover up his many flaws as a rider. His 200-pound body weight coupled with unique skill for poor line choice and clumsy landings make him an expert on durability - if parts survive Johan, they’re pretty much okay for anybody. Johan rides flat pedals with a riding style that he describes as "none" (when in actuality he rips!). Having found most trail features to be not to his liking, Johan uses much of his spare time building his own. Johan’s other accomplishments include surviving this far and helping keep the Vital Media Machine’s stoke dial firmly on 11.

Video by Nils Hjord, Tal Rozow and Johan Hjord // Photography by Johan Hjord