WRITER’S RIDES: CUSTOM ROCKY MOUNTAIN GROWLER HARDTAIL BUILD

By: Traece Craig

While out riding the latest mountain bikes on the market, we often get asked questions like, “Is that your bike? How does it ride on this trail?” For some test bikes, the answer is, “No, it’s just for a review and will be sent back.” While many bikes come and go, some are, however, a perfect fit, and our answer is, “This bike is so good, we can’t let it go.” That was the case with the Rocky Mountain Growler (tested in October 2020). I couldn’t get over how much of a blast it was riding a long and slack hardtail on my local trails, so I bought the bike with customization in mind. While the stock spec was sufficient for most, I wanted to save some weight and make the Growler a bit livelier. While I’ve owned a variety of hardtails designed for cross-country and bikepacking, the aggressive, more trail-oriented style of riding the Growler resonated with me.

The Growler offered some differences that I had yet to experience on a hardtail up until my first ride on it. It could be a bit of a learning curve to direct the front end of a slacked-out, long-travel hardtail, but that all changes when pointing the Growler downhill. It made me take lines I would typically try on an enduro or trail bike, but not on a hardtail. It’s stable, great in high-speed situations, and surprisingly well-behaved in corners considering how long the wheelbase is. Sure, it wasn’t a full-squish sensation, but the short rear end could be moved quickly, while the 29er wheels mowed over chunks unlike any other hardtail I have ever ridden.

As I put in more time with the Growler, I got hungry to push the limits even further. Cutting down the 34-pound stock build was a priority, but I also wanted to add to the stock 140mm of travel. I mostly ride this bike in dry, kitty-litter hardpack and on the sharp desert surfaces found in Southern California. It’s no KOM killer on the climbs, but I am glad it’s not. It lets me get up into the mountains from the town efficiently and can tame most of the ridgeline singletrack that is common in the area. It fits the bill as a capable package for most riders’ experience levels and those who want to push a hardtail like an enduro bike.

 

FRAME

Rocky Mountain uses 6061 alloy for the frame material of the Growler. Alloy is still being used on the newer models that are found on the current Growlers, but the colors have changed. As mentioned, the chainstay length is nice and short for a responsive rear end that has adequate tire clearance to run a 2.6-inch-wide tire. Occasionally, debris, such as rocks and sticks, gets sucked up by the tire and smacks against the frame. There are even a few spots on the head tube where the cables could brush up against the tube. There is already some protection on the frame, but just to be safe and keep the paint shiny, I applied some clear 3M protective film on areas at risk of abuse—mainly on the back of the seat tube near the tire as well as on the chainstays, downtube and top tube.

I love the geometry and the amount of travel the Growler has, and it has all the modern features I need. As for upgrades, I’m not one to let parts go to waste. I was able to keep some of the stock parts (like the bottom bracket and headset) that there was no sense in changing, since I had other parts on hand that were a lighter weight that could be used. I was able to exchange some light components from my cross-country bike (that just happens to be a Rocky Mountain Element) straight over to the Growler. Although the internal cable routing is not my favorite, this alloy frame can take a beating and should last me a lifetime of riding. Overall, this bike charges terrain and likes steep sections that are wide open. It makes me laugh keeping up with trail bikes, surprises me through rock gardens, and lets me take in the scenery during a climb before finding the next fast singletrack.

SUSPENSION

Although the Growler came with plenty of travel, I did want more performance and adjustability than the RockShox 35 Gold RL offered. To make things lighter, I went with a 160mm RockShox Lyrik Ultimate. Not only did I save weight, I was also able to add 20mm of travel. Each fork was straightforward to “set and forget” before a ride; however, the upgrade to the Lyrik offered more adjustability with high- and low-speed compression dials to maximize how the fork responded to the terrain. After all, I really liked how the bike responded in steep terrain, and adding the extra travel made the bike a bit slacker. This sacrificed some of the climbing efficiency, but after all, I am all about taking this hardtail down steep terrain, and going with more travel only made it feel more stable in those scenarios.

 

DRIVETRAIN

The SRAM X0 12-speed drivetrain has seen some serious wear over the years. It was pulled off of my Element with a few updates to revive its performance for this Growler build. The derailleur pulleys had seen better days. With the knuckles and cage in solid condition, I upgraded to Enduro Bearings XD-15 ceramic hybrid pulleys. Not only do they provide smoother shifting, but the high-end materials will make the derailleur more durable. Other weight-saving upgrades included swapping to a lighter SRAM XO1 cassette, a new hollow-pin chain, and the Stylo cranks with a OneUp chainring in place of the heavier SRAM NX components that came stock. This wasn’t the most budget-friendly upgrade for me to do, but luckily there were some items in the parts bins to pull from.

WHEELS

I got picky and wanted to drop as much weight as possible at the wheels while still having a set of hoops that I could depend on for anything. Believe it or not, it’s been tough for me—and even MBA—to source parts these past few years. Hubs were tricky, but I finally nailed down a steal through eBay on a compatible set of no-longer-made ISO Chris Kings still in the box. For hoops, I went with the latest WTB CZR i30 28-hole carbon rims (tested in the June 2021 issue). With all parts gathered, I got this custom set built by our trustworthy friends over at WheelBuilder. These wheels have remained true through some pretty brutal conditions, and the robust carbon rim helped immensely in dropping weight from the bike. Not only is it lighter, but I could flick the bike quicker and roll faster in the dirt.

TIRES

This bike came with WTBs, and they just happen to be my favorite combo; however, I did end up dropping the width down from a 2.6-inch at the front and rear. Instead, I went with a 2.5-inch Vigilante Light/Fast Rolling casing at the front with a 2.4-inch Trail Boss with the Light/Fast Rolling casing in the rear. The smaller tire width gave the Growler a bit less rolling resistance, and the lighter casing saved weight. These tires have been a reliable combo in a wide variety of conditions, and when more are back in stock, I will likely switch to the Tough/High Grip option offered in these WTB tires. Typically, I run 1 to 2 psi less in the 2.6-inch tires, so going to the smaller widths, I stuck right at 25 psi in the rear with 24 psi in the front and no tire inserts.

SEALANT

I usually run Stan’s, Orange Seal or Finishline, but I decided to try out WTB’s latest formula. Their TCS tubeless tire sealant uses a tackifier compound process rather than the evaporative technique used by many ammonia-based formulas to seal punctures. By design, WTB’s latest sealant is great in wet and unforgiving conditions where other brands have trouble clotting due to reduced evaporation. On top of that, the synthetic latex used reduces the risk of an allergic reaction for those like myself with sensitivities/allergies to natural latex products.

BRAKES

The Growler came with a very reliable set of Shimano MT420 four-piston brakes that performed okay in most scenarios, yet I still wanted more power, a different feel, higher performance, and less weight. So, I ditched the Shimano brake set and went to Magura MT TRAIL SLs. These feature a dual-piston caliper for the rear and a four-piston caliper at the front. The biggest takeaway is their weight difference from the Shimanos. The Maguras impressively hit the scales at 459 grams. That’s the caliper, lever and hydraulic hosing cut down for this large hardtail build, which is just over 100 grams less than a set of even higher-end Shimano XTs than the MT420s. I am still biased towards having Shimano braking systems, but, overall, I’ve dialed in these Maguras to feel great. They perform well when maintained properly, but it can also take some getting used to this particular brake set with how light and delicate they feel at first. In spite of the light materials, there is more than enough stopping power. I paired the chrome-finished calipers with 180mm Galfer MTB Wave rotors (120g each). Honestly, this is my first time running these rotors, and I have been pleased with their value and how they’ve matched with the Maguras. It’s worth noting that Magura does recommend using their own rotors; however, I have had no problems and only confident and predictable braking power using this combination of Galfer and MT Trail SLs.

 

AT THE BARS

I messed around with a few different handlebars and stems. I rode the bike with carbon bars, longer stems, different rise/sweeps, and at the end of the day, I put the stock alloy bars and 50mm stem back on. The 800mm handlebars were too long for me. Flat bars with no rise or sweep just didn’t feel right to control the front end, and the weight/length of Rocky’s stock stem ticked the boxes already. While I could have saved weight with a carbon handlebar, I enjoyed how the stock handlebars felt from day one with their 780mm width, 38mm rise, 9-degree backsweep and 5-degree upsweep. For grips, I went with the thicker GA2 Fat Ergon grips and changed a few other bits for controls, but more on that shortly.

DROPPER POST/SADDLE

More often than not, modern hardtails are equipped with a dropper post. Dropper posts are one of the best things since sliced bread. A dropper post will benefit anyone’s riding experience/abilities. While I could have gone to something else to drop the weight, I couldn’t hang up the Rocky Mountain Toonie with 150mm of travel that came stock. No sense in letting parts go to waste when they perform well. Of course, to make it even better, I swapped out the stock remote for a Shimano SL-MT800 that has a smoother bearing feel with a tighter throw needed to actuate the dropper.

I could’ve gone with a longer-travel post to give me even more space over the Growler, but the 150mm hasn’t shown any hold-ups for the trails I’ve tested it on. Without the dropper, it would be tougher to get off the back on the technical, steep trails that I prefer to push my limits on. Attached to the post, I also stuck with the WTB Volt Race 142 seat that the wrecking crew and I spent lots of time on. This model is seen on lots of builds for good reason. It’s not my first choice if I had to be nitpicky, but it’s proven to be comfortable for me on various bikes with a proper trail-riding chamois.

PEDALS

I often jump between flats and clipless and can say I don’t have a firm opinion on what you “have to use” on a hardtail. For this particular bike, I’ve preferred flat pedals, but I will swap over to clipless for efficiency if I’m planning a long day out in the mountains. I save weight with most clipless systems, but the Xpedo Spry flat pedals hit the mark on this build. They are light, coming in at 270 grams for the set, but they are robust with a chromoly spindle and have seven pins per side. I would have liked to have one or two pins in the center for additional grip, but they offer ample grab for the hi-top Vans I often wear for flat pedaling flow trails. When things get enduro rough on the downhill with long climbs in between, I prefer to stay connected with Shimano XT PD-M8120 pedals that use an SPD cleat. I just feel more confident when the rear end is bouncing on harsh terrain and I’m using clipless pedals with this hardtail.

ACCESSORIES AND ADD-ONS

The thin 3M film was sufficient coverage for the seat tube, but in order to avoid chain slap and knicks in the frame, it needed more. After the first few rides, there were a few nicks close to the chainstay and chainring. I used a thin piece of rubber with 3M that I cut down to fit and stuck it around this vulnerable area. While it added protection, this small addition also helped cut down chain slap noise to nil. I also added a few functional items that I’ve grown to like over the years. I went with a OneUp EDC Lite (reviewed in April 2021 issue) for easy access to a tool for trailside repairs, a OneUp Switch direct-mount chainring (reviewed in September 2020 issue), and an Arundel Looney Bin water bottle cage. The chainring gives me the ability to easily change the teeth count without removing the SRAM crankset. It’s simple enough that I can change between a 30t or 32t in the parking lot before a ride if needed. The Arundel cage allows me to carry a large beverage no matter the shape and lock it down with the ratchet dial. Since there is only one water bottle mount within the frame, I also will run a frame bag to fill the large space if I need to bring along extra riding essentials for a longer trail day.

It may not be everyone’s ride of choice, but I can’t get over how much this trail-worthy hardtail offered with the stock setup and how much more fun it became after dropping 5 of the hefty 34 pounds, adding more travel, and adding more performance-oriented features for the long haul. 

 

ROCKY MOUNTAIN GROWLER 

Estimated value: $4500

Weight: 29 pounds (as shown)

Size: Large

STOCK GEOMETRY

Head tube angle: 64°

Seat tube angle: 75°

Chainstay length: 435mm (17.1″)

Reach: 470mm (470″)

Bottom bracket height: 330.2mm (13″)