Test – Rocky Mountain Thunderbolt Carbon 70

Faster than lightning

Rocky Mountain was established in 1981 when the founders began modifying Nishiki road bikes with wide tires, straight handlebars and thumb shifters. Based on Vancouver’s North Shore, Rocky Mountain’s engineers were forced to build bikes burly enough to handle the rugged terrain that would soon spark the freeride movement. Rocky Mountain helped create Race Face Components in 1993, and in 2001 claimed the first win at the inaugural Red Bull Rampage with Wade Simmons, the “Godfather of Freeride,” piloting the newly introduced Slayer. The Canadian company would later go on to win multiple victories in elite-level cross-country and downhill races around the world. Today, Rocky Mountain offers a wide range of bikes for racers, freeriders and everyone in between. The all-new Thunderbolt sits in the cross-country category of Rocky’s lineup; however, its aggressive geometry says otherwise. We decided to invite this Canadian cross-country ripper into our test fleet this month to see how it would perform on our local trails.

WHO IS IT MADE FOR?

It’s hard to call the Thunderbolt a cross-country bike, with its 27.5-inch wheels, 130mm of travel and 66.4-degree head tube angle. The all-new Thunderbolt leans more towards trail than it does XC. Riders looking for a balance of cross-country performance on the climbs and aggressive descending prowess will be right at home aboard the updated Thunderbolt. With an additional 10mm of travel and an improved suspension design, the new Thunderbolt blurs the lines between cross-country and trail.

WHAT IS IT MADE FROM?

The Thunderbolt Carbon 70 is the top-of-the-line model before jumping up to the longer-travel B.C. Edition. The frame is constructed from Rocky’s Smoothwall Carbon, a process that improves the Thunderbolt’s stiffness-to-weight ratio through the use of rigid internal molds instead of traditional air bladders. Rocky further minimizes the overall weight and increases impact resistance by utilizing different types of carbon in high-stress areas of the frame.

The Thunderbolt features Rocky Mountain’s Ride 9 system, which gives its riders the ability to customize geometry to best match their needs. Head tube angles can be adjusted from a slack 66.4 degrees to a steeper 67.6 degrees. The Ride 9 also changes the reach by 11mm between the two extremes. Rocky Mountain designed the Thunderbolt with a four-bar suspension design called Smoothlink. The bike also features fully sealed cartridge bearings, a Press-Fit bottom bracket, internal cable routing and size-specific suspension tunes.

WHICH COMPONENTS STAND OUT?

The Carbon 70 model has many standout components, such as a SRAM Eagle GX drivetrain, Fox suspension, Shimano XT brakes and Maxxis tires. Starting with the Thunderbolt’s drivetrain, Rocky Mountain spec’d SRAM’s GX Eagle 12-speed system, which we have thoroughly tested with positive results on many of our test bikes. Performance Elite Fox suspension soaks up the trails well and provides great adjustability. Shimano XT brakes provide excellent control while descending fast. Stan’s Crest wheels, wrapped in an aggressive Maxxis Minion DHR II tire up front and a fast-rolling Crossmark II in back, help boost confidence; however, the rear tire may not be aggressive enough for some trail riders.

HOW DOES IT PERFORM?

Setting sag: The Thunderbolt’s Ride 9 system plays a major role when setting up sag. With the Ride 9 adjustable geometry chips in the back position, the Thunderbolt gets a steeper head tube and a more linear suspension feel. Riders who like this position may find 20–25-percent sag to be ideal. In the forward position, Ride 9 slackens the head tube angle to give the suspension a more progressive feel. With this setup, riders can set the sag in the rear shock to 25–30 percent without blowing through the travel. Up front, our testers adjusted sag between 15 and 20 percent based on riding style and preference.

Ride-9: Rocky Mountain’s Ride-9 system gives riders the ability to fine-tune their suspension to best match their needs. Our testers enjoyed riding the Thunderbolt in the slackest setting, which increased the bikes descending capabilities. Cross-country riders may want to consider running the Thunderbolt in a less aggressive setting, offering a more quick and nimble feel for their local racecourse.

Moving out: Before tossing a leg over the Thunderbolt, our testers didn’t know whether the bike would lean towards cross-country or trail. While the Thunderbolt may feel more like a cross-country bike in its steepest setting, the slack setting is undeniably designed for trail. The 760mm-wide handlebars and shorter 50mm stem add to the overall trail feel of the Thunderbolt.

Climbing: Rocky Mountain increased the Thunderbolt’s travel over the previous model, but don’t assume this new bike is any less of a climber. In fact, Rocky took extra steps to enhance the Thunderbolt’s ascending performance. The Thunderbolt has the climbing prowess of a cross-country machine, but retains a playful geometry for blasting back down the trails. Our tester found he could easily power up technical sections, as well as long smooth climbs, with the shock set in the open position.

Cornering: The Thunderbolt’s geometry can be tuned to your liking, but our testers enjoyed the slackest setting most. With just 130mm of travel, short chainstays and an aggressive 66.4-degree head tube angle, the Thunderbolt dances around the trails. Some riders may want to swap the rear tire for something with a little more bite, as we often found the rear end sliding around turns. The suspension offered great support and stayed high in its travel when we were pushing hard into corners, while the 27.5-inch wheels further enhanced the Thunderbolt’s playful attitude.

Descending: Short-travel trail bikes can often feel outgunned when flying into a rough section of trail. The Thunderbolt is not one of those bikes. Its progressive suspension helps give the bike a bottomless feel when hopping off drops or blasting through rocks. The slack position will give riders the utmost confidence when barreling down steep and gnarly trails, while the steep position provides a quick and nimble feel, great for attacking local cross-country courses. It’s important to remember that the Thunderbolt is still a 130mm-travel bike, but compared to other bikes in this category, the Thunderbolt excels when the trails get rowdy.

TRICKS, UPGRADES OR TIPS?

When purchasing a new bike, riders often swap parts or make adjustments to their bikes. Ride 9 offers riders the ability to further tailor their bikes to their needs. The Ride 9 system, however, can be a bit confusing, so we recommend closely reading Rocky Mountain’s Ride 9 setup guide found on its website. One great tip Rocky Mountain provides is that riders should make minimal adjustments to their bike in order to see how the changes affect ride characteristics. From there, riders can hone in on the best setup for their riding style.

BUYING ADVICE

While most pure cross-country racers will lean towards a 29er race bike, the Thunderbolt appeals to the rider who wants a fun trail bike that can handle XC racing. At the end of the day, the Thunderbolt is best categorized as a lightweight and efficient trail bike, but with changes to its geometry made possible by Ride 9, the Thunderbolt becomes an adaptable bike for many styles of riding. The Thunderbolt will feel quick and nimble to a baggy-shorts rider, while the spandex-wearing crowd will find it aggressive and capable. If you want a bike that blurs the lines between XC and trail, the Rocky Mountain Thunderbolt may suit your needs well.

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