Bike Test: Rocky Mountain Thunderbolt 770MSL

For years the Rocky Mountain Thunderbolt has been a trusty trailbike for those looking to ride nearly any terrain without being sandbagged by the rest of the group. Considered by many to be the unofficial bike of the BC Bike Race, the Thunderbolt has proven to be capable of overcoming the most unrelenting climbs and technically demanding descents. While the base Thunderbolt models are still available with aluminum frames, the new MSL line has been carbonated for 2015. Carbon fiber is always a nice touch, but it was the complete package of shorter chainstays, Ride-9 geometry adjustability and a lower standover height that had us itching to put one through its paces.


From the long-distance endurance racer to the trail rider who chases epics across the continent to the rider who enjoys after-work rides with his or her buddies, the Thunderbolt 770 MSL delivers. It would be easier to sum up who the bike isn’t made for—namely downhill and bike park riders. For the rest of you, it would be difficult to find a trail that didn’t vibe well with the Thunderbolt 770 MSL.


Rocky Mountain’s Smoothwall carbon fiber uses rigid internal molds rather than air bladders during the carbon layering process. This allows the engineers to optimize the strength-to-weight ratio by minimizing any excessive use of resin or carbon layers. The Thunderbolt 770 MSL suspension linkage moves through its travel using bushing pivots on hardened alloy inserts. Coupled with grease ports on each pivot, bushing pivots are low maintenance as long as periodical greasing is carried out. The frame is compatible with Shimano Di2 electronic drivetrains and includes stealth battery storage fully integrated into the downtube. Across the board, stiff riding characteristics were a priority with 142-millimeter thru-axle spacing and a BB92 bottom bracket shell.

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The Ride-9 technology integrated into the shock mount is the standout feature on the Thunderbolt 770 MSL, but we’ll cover that in more depth later. We’re all pleased to find a bike donning Shimano XTR components. While the entire drivetrain isn’t Shimano XTR, it makes its appearance where we appreciate it most—the rear derailleur. The RockShox Reverb stealth seatpost provides adjustment at the push of a thumb without additional clutter down the top tube.

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Moving out: Smooth and shiny saddles are always difficult for us to cope with. We swapped out the saddle for one that held us in place a little better and then hit the trails.
Ride-9: As good as it sounds, the idea of a quiver-killing bike has always been a bit of a pipe dream for mountain bikers who ride a wide variety of trails and terrain. While it may still be difficult committing to a single bike, Rocky Mountain’s Ride-9 technology surely brings the dream one step closer to reality. With nine different settings to choose from, riders can tailor their bikes’ geometry and suspension characteristics to their specific riding style and needs. The small amount of adjustment at the shock mount may not look like it would alter much, but the difference between a 67.2–88.4-degree head tube angle and 12.6–13.5-inch bottom bracket is enough to completely redefine how a bike pedals, descends and corners. We found setting 7 to be our favorite for aggressive riding that isn’t overly steep or technical, but the ease of adjustability also made it possible for us to change settings at the trailhead or even mid-ride. One geometry matches many bikes to a specific location, but nine settings make the Thunderbolt 770 MSL a Moab-to-Pennsylvania-to-Vancouver kind of bike. While Ride-9 is integrated into all MSL versions of the Thunderbolt, it’s not included on the non-MSL versions.

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Climbing: The pedaling platform of the Thunderbolt MSL had us steering clear of the Climb setting and keeping it in Trail mode for all of our climbing endeavors. The anti-squat characteristics of the modified four-bar suspension prevented bobbing while also absorbing variances in the trail and keeping the rear tire glued to the ground. The stiffness of the frame provided plenty of snappy power when we got out of the saddle to crank up a steep climb.
Cornering: On the loose-over-hardpack trails of Southern California, we often find ourselves cornering in an upright position in order to keep our weight over the contact patch of the tire. The low standover height enabled us to lay the bike over very low with no interference between the top tube and our legs. The relatively low bottom bracket height (12.7 inches in setting 7 of the Ride-9 system) had us railing through high-speed corners with confidence. We certainly were conscious of our inside pedal when leaning hard in corners, but it never snagged on trail obstacles. The Stan’s ZTR Crest wheels were plenty stiff; we were able to snap out of corners without any hesitation.

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Descending: As long as you’re not looking to explore the white-knuckle offshoots that rip straight down the mountain, the Thunderbolt 770 MSL will meet the demands of any trail riding. The Smoothlink technology of Rocky Mountain’s four-bar linkage remained supple at the top end of the travel and didn’t dive into the remainder too quickly. It provided the precise amount of travel needed without pushing further and feeling like a La-Z-Boy recliner. Steep descents had us pushing out over the back tire with arms locked; however, if we anticipated riding such trails, we would take a moment at the trailhead to utilize setting 9 of the Ride-9 system for the slackest head tube angle of 68.4 degrees.
Braking: Bikes designed for speed must also be able to slow it all down at a moment’s notice. Shimano XT brakes tackle the challenge with ease and do so without fading toward the end of a long descent. While it may not be a standout feature (since most suspension designs have found a way to eliminate brake jack), we didn’t lose any braking performance through big hits or corners.

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Without constantly securing them to the internal cable routing ports on the frame, we lost a majority of the cable insertion plugs within a few rides. We suggest riders consistently check their positioning and possibly purchase extras if living in a wet and muddy climate where they could end up with a mud puddle in the frame.
For more aggressive riders, we could see the Fox 32 Float fork falling short of their demands. We suggest bumping it up to a fork with stanchions that are at least 34 millimeters in diameter. There never seems to be a pleasing way of mounting the Fox CTD remote; however, in order to avoid an unpleasant surprise during a crash, we suggest rotating it down as much as possible before it begins to interfere with the rear shifter.


The question we’re most often asked is, which is the best do-it-all trailbike? The dream of an all-encompassing one-bike solution may be unattainable for many, but the Thunderbolt 770 MSL holds its own among the most versatile trailbikes we’ve ever ridden. From coast to coast, it’ll flow through any section of trail with the right amount of finesse and confidence. Looking for identical frame features with more affordable components? The Thunderbolt 750 MSL utilizes the same Ride-9 technology with a lower price tag of $5499.



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