Review: Rocky Mountain Thunderbolt Carbon 70

Editor’s note: This review was originally published in issue 206 of Dirt Rag Magazine. Want to see more? Subscribe today at to catch issue 208, coming soon!

Price: $5,999
Sizes: XS, S, M, L (tested), XL

Tester: Brett Rothmeyer
Age: 40
Weight: 165 lbs.
Height: 6’1”
Inseam: 32”

Reach: 17.9”
Stack: 24.0”
Top Tube: 24.7”
Head Tube: 65.9°
Seat Tube: 73.9°
BB Height: 13.2”
Chainstays: 16.7”
Weight: 27.7 lbs (as tested, and without pedals)

Have you ever had a friend or a roommate bring a date home and you just can’t take your eyes off of them? I know, it’s not cool, but you just can’t help yourself. Your friend leaves the room for a minute and you start making small talk with their date, desperately hoping that they’ll think you’re an idiot or hoping that they will say something that completely offends your senses so that you can move on and be a good friend. Of course that’s not the case, the two of you have so many things in common it’s making you ill. You both like the same bands, the same books, you both drink your coffee black. Maybe you even both approach trail riding in the same way? All-day pedals with the occasional rawkus downhill, a pile of rocks here and there and rollers ducking in and out of the trees. How can this be, that your friend and roommate found your perfect match while you sit on the couch trying to care about the new season of “The X-Files”?

Perhaps this person isn’t a person at all but a shiny new bike that was sent to your workmate Scott. One morning Scott rolls in with the brand new Rocky Mountain Thunderbolt Carbon 70 strapped to his hitch rack, and I fawn over it immediately. The bright teal paint scheme, the angles, I fell hard. A week went by and some of us around the office were going for a ride; Scott suggested that I take the Thunderbolt out, and I jumped on the opportunity. After some small adjustments to the saddle height and suspension, we headed out and I felt right at home on the Thunderbolt. After the first few sections of trail, I kept remarking to Scott how much fun I was having on the bike, so he asked if I would be interested in taking over the review for the Thunderbolt since I had already ridden the bike as much as he had. I said yes, and now here we are, a few hundred miles later, and I’m having just as much fun as I did on the first ride.

Why is the bike so much fun? I keep me asking myself that question every time out on it. For starters, this bike rips, plain and simple. Born on the trails of British Columbia where things can get just a tad rowdy, I find it hard to believe that this bike falls into the XC category even if it also has “Trail” in the title. The 130 mm front and rear travel will never have you second-guessing the drops and jumps on your local track. In fact, I began to go out of my way to find more and more challenging terrain to see how far I could push the Thunderbolt until it felt squirrely. After countless loose and rocky descents and washed out rooty runs, my nerve gave out long before the bike felt like it couldn’t handle the terrain.

Set up with 27.5 wheels and a Maxxis Minion 2.3 in the front and the latest version of Maxxis Crossmark II 2.3 on the rear, hooking up through fast, sharp turns has yet to be an issue. On a particularly greasy day on the trail, the Crossmark on the rear was sliding around quite a bit, but the Minion kept things on track in the front. Kitted out with the SRAM GX Eagle group and Shimano XT brakes, componentry has been flawless on every ride but one where I tweaked the hanger a slight bit (obvious user error). I’d like to have seen this bike come with the same Stan’s Arch rims from the BC edition of the Thunderbolt. While I encountered no issues with the Crest wheels, the wider Arch rims would be a better choice for modern wider tires.

The Fox 34 fork and Fox Float DPS are near works of art when combined with the Rocky Mountain Smoothlink four-bar suspension design. Both the front and rear suspension offer almost full lockout modes making long pedals to the top of gravel forest roads or cutting through traffic to your inner-city singletrack loop efficient and enjoyable. Wide open, however, is where this suspension platform performs the best out on the trails. Roots, rocks, berms, jumps and whatever else the trail had to offer the Thunderbolt gladly gobbled it up all while pedaling remained snappy and responsive.

Perhaps this is where the Thunderbolt straddles the line between cross-country and trail. While its ability to get loose and wild seduces you, its efficiency and snappiness while putting power into the pedals convinces you that this is true love. Chasing friends down, sprinting over rollers all while tackling technical terrain without issue, the Thunderbolt almost dares you to find its limits.

We have entered a time in mountain biking where suspension design and technology has become so efficient that bikes are blurring lines between categories. If we look back even just a few years ago and someone tried to convince you that a 130 bike fell into the cross-country category, you would have scoffed and just pointed at your hardtail. With the gifts of modern technology, riders are finding a distinct advantage in bikes that not only pedal well but also allow trails to become a two-wheeled playground. I understand that we may not see World Cup cross-country racers lining up on trial-inspired geometry with more than 110 mm of travel, but the Thunderbolt could be the next bike purchase to do all things you like to do on a bike.

The Thunderbolt has the capability to take the fun up several notches on your normal routes, and if you were someone that dabbles in either cross-country or Enduro every now and again, there would be little to no penalty lining up with this bike. When the day comes that I have to box the Thunderbolt up and send it back to Rocky Mountain, I will likely shed a tear and go home and eat ice cream while watching John Hughes films. In the growing market of the cross-country trail bike, the Rocky Mountain Thunderbolt has proved itself a dreamboat that I may just have to lock down for my own.