Review: Rocky Mountain Thunderbolt 799 MSL

A no-expense-spared build is just the icing on the cake

Every year, one bike inevitably earns the distinction of 'most ridiculously expensive bike,' and this year the title went to the Rocky Mountain Thunderbolt 799 MSL, coming in at about the cost of a down payment on a home. That aside–note that Rocky Mountain offers a base-level version of the Thunderbolt for $2,000–this bike rides like a product with its pricetag should.

It "climbs like a cheetah on speed," wrote one tester, while another noted: "This bike is built to go fast. However, it has a tight wheelbase, which makes it maneuverable in technical areas, and solid suspension that handles better than I expected for how well it climbs."

This version of the Thunderbolt was the only bike in the test decked out with a Shimano XTR Di2 electronic shifting, which came with an XTR 11-speed 11-40 cassette and Race Face Next SL crank with a 38/28 double. The rest of the build includes XTR Trail brakes, a 120-millimeter-travel Fox Factory Series 32 Fit4 fork and Float DPS shock, a 740-mil-wide carbon RaceFace Next handlebar, Reverb dropper post and Stan's Valor carbon wheelset shod with Maxxis Ardent 2.2 tires.

The parts are hung on the Thunderbolt's Di2-ready, full carbon-fiber Smoothwall frame with Ride-9 adjustable geometry, which allows the rider to configure one of nine geometries based on riding style, rider weight and suspension. Adjusting the geometry chip affects the headtube angle, which can range between 67.2 and 68.4 degrees, the bottom-bracket height and the seat tube angle.

Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
Rocky Mountain Thunderbolt 799 MSL
We should note now that the 799 MSL is not marketed as a women's-specific bike, however, according to Rocky Mountain, the120 mil-travel, 27.5-inch-wheeled Thunderbolt has been overwhelmingly popular with women since it launched a few years back. Part of this could be because the adjustable geometry allows lighter riders to easily dial-in an appropriate suspension setup. Arranging the chips in the 'Up' position, for example, means the shock requires more air pressure, allowing lighter riders to avoid the harshness of an under-pressured shock. The Thunderbolt also comes in a petite-friendly XS frame size.

The XC-trail nature of the Thunderbolt was a perfect match for the Kingdom Trails network, which largely consists of buttery-smooth dirt ribbons twisting through tight trees, with an occasional root section mix in, and short, punchy climbs and descents.

The 27.5-inch wheels, 16.6-inch chainstays and 44-inch wheelbase (size medium) no doubt aided in the Thunderbolt's exceptional maneuverability through the forest mazes, and its rocket-like acceleration points to its astounding 25.5-pound weight. Testers also remarked that the bike descended with more authority than expected, with its 120 millimeters of rear travel feeling deeper than the number purports.

Gripes about the Thunderbolt were unsurprisingly limited. There's the obvious: the astronomical price. Again, the Thunderbolt comes in five more-attainable builds including the 730 MSL, which offers a carbon front triangle frame and a Shimano XT/Deore drivetrain for $3,400. Testers also questioned the necessity of an electronic drivetrain, while recognizing the attraction some riders would have to the top-of-the-line technology.

"The shifting was crisp as hell and the ability to geek-out on the shifting is limitless," wrote one tester. Another tester was confused by Shimano's Firebolt shifter, which felt like it shifted gears in the opposite direction as a conventional setup does. But, as with pretty much everything on Di2, that can be programmed to the rider's liking–any button can be set up to shift up or down. Putting it into Synchro Shift mode allows the system to shift the front derailleur for you based on programmable shift maps, making it possible to operate a 2×11 with a single shifter.

With this no-expenses-spared build, we wondered why Rocky didn't round out the Shimano XTR drivetrain with the matching crankset and chainrings, which would ensure the best possible shifting performance. Race Face rings shift well, but nothing comes close to the speed and accuracy of Shimano.

Despite this, the Thunderbolt remains a solid platform for XC racers looking for more bike, or trail riders who favor a quick and efficient climber, regardless of the model they can afford. If it happens to be the 799 MSL, you'll find that there are many worthy reasons for its weighty title in this year's Bible.

MSRP: $11,500

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See more women’s bikes from the 2016 Bible of Bike Tests


Q&A with Rocky Mountain

Before this year's test bikes rolled into our barn, we had questions about them–some of the same questions that you might be asking yourself when you start poking around at a new bike. We mentioned it in the video, but it's worth repeating–Rocky doesn't actually position the Thunderbolt 799 MSL as a women's-specific model, but the bike is available in very small sizes and has been gaining a lot of traction with women riders. For that matter, another version of the Thunderbolt gained traction with us during last year's Bible testing, so we thought it high time to bring another one into the mix and see how it fared against some of the best bikes of 2016. –Vernon Felton, Bible of Bike Tests Moderator

Vernon Felton: What kind of rider did you have in mind when you designed this bike?

Rocky Mountain: Folks who enjoy gaining vertical as much as they love shredding it back down. It's absolutely an XC weapon for Strava warriors looking for pedaling efficiency in a longer-travel package, but it's also a trail warrior's ginsu knife for singletrack slashing. Shorter riders looking for low standover height, and suspension tunable for a smaller person will love the Thunderbolt.

 

VF: Are there conditions in which you feel this bike really excels and, if so, what specific design attributes of the bike make that so?

RM: Definitive singletrack is where this bike excels. Rolling trail with small and mid-sized features, plenty, quick changes of direction and punchy climbs. The rigid chassis, short chainstays, and supportive mid-stroke suspension allow the Thunderbolt to play on the smallest trail features, slash from one side of the trail to the other, and pick-up speed whenever the opportunity allows.

 

VF: Are there any aspects of the frame design that you guys are particularly proud of? If so, what are they and why?

RM: Definitely. Our Pipelock main pivot axle came out of our Maiden downhill bike project and adds a huge amount of stiffness to the rear end, which really compliments the short 422-millimeter chainstays. We also added grease ports, which make service really simple. Our Ride-9 geometry-adjustment feature is also something we really believe expands the bikes abilities for each rider, and can take the bike into the XC category or make it an aggressive trail bike to tame some of B.C. and the world's biggest epic trail rides.

 

VF: Are there any details/features on this bike that you think are particularly critical to its performance that might be easily overlooked by consumers at first glance?

RM: Ride-9 is certainly a feature that we've have integrated into the frame in a compact and seamless way, but it has huge implications on the range of abilities and the fine-tuning of our bikes. With over a degree of head-angle adjustment, the ability to tune for rider weight and suspension rate you can really suit any rider or trail needs.

 

VF: How short of a rider can fit the size Small Thunderbolt MSL?

RM: A small Thunderbolt MSL can fit a rider down to 5'4". And we make an X-Small frame that fits down to 5'1". Of course keeping in mind arm, torso, and leg length differences between riders. The Thunderbolt MSL offers a very low standover that can accommodate smaller riders, which from the beginning was a key design criteria.

 

VF: This thing is dressed to the nines–what were you aiming for with the spec on this bike?

RM: In a nutshell, all that you could desire without any stone unturned. Shimano XTR Di2, Stan's Valor carbon wheelset, Race Face Next SL crankset, Fox Factory Kashima suspension. A sturdy, modern, performance build with no compromises, coming in at 24.9 pounds.

 

VF: The price on this top-end bike is high, no doubt about it. If people are interested in it, but need a more affordable version, they are probably looking at your Thunderbolt 750 MSL model. Is the frame on this 799 MSL identical to that of the Thunderbolt 750 MSL?

RM: Yes, the carbon used, and the lay-up process for the Thunderbolt 799 MSL–750 MSL are the same. The same goes for the front triangle of the 730 MSL, where the rear triangle is aluminum. The Thunderbolt 799 MSL frame does get tricked out with a Ti bolt kit though.

 

Related:

Juliana Furtado CC – 2016 Bible of Bike Tests

Liv Intrigue SX – 2016 Bible of Bike Tests