3 Top Mountain Bikes for Off-Road Triathlons

Do-it-all rigs at every price point.

Giant Fathom 1 27.5

$1,450, Giant-bicycles.com
The draw: Killer value
Rider stats: 6 feet, 165 pounds

In the ’90s, mountain bike legend Gary Fisher developed something called Genesis Geometry with slightly longer top tubes and tight rear triangles—bikes that could climb like an XC racer and go downhill without fear of flying over the bars. The Giant Fathom reminds us of those good ol’ Fishers: a capable climber and a confident descender.

Just like those Fishers, the Fathom also has an aluminum frame. Unlike those old rigs, Giant’s ALUXX SL grade aluminum has a smooth ride that’s light enough to take down long climbs and steep pitches. The short, 425mm chainstays add to the Fathom’s snap.

We rode the 27.5 version (29er also available). It has a relaxed 67-degree head tube angle, a rock garden-worthy 120mm travel Suntour fork and a rarity on a hardtail: a dropper post. All three features made it easy to stay back and stay low as we bombed steep, rough descents.

The Fathom clears 2.25-inch-wide tires, but we’d like to see a little more room for mud or plus-size tires. And while the Giant Connect Upright saddle made us yearn for our usual perch, the SLX group performed well above its third-tier position in the Shimano hierarchy.

When we unboxed the Fathom, we noticed a sticker on the handlebar that reads: This bicycle is specifically designed for off-road use and competition. We have no reason to disagree. Enter it in an XTERRA or take it on trail rides, the Fathom is up for the job without breaking the bank.

Salsa Spearfish GX1

$3,700, Salsacycles.com
The draw: Descends like a dream
Rider stats: 6 feet, 165 pounds

Two things stand out on the Salsa Spearfish spec list: 80mm of rear travel and the Split Pivot suspension. Both are Salsa’s ways of saying, “Ride far, ride fast and ride comfortably.” Our lengthy test rides found no reason to doubt that claim.

Eighty millimeters of rear travel is short, even by cross-country standards. But Salsa wanted to keep the back end tight, and they wanted to send a statement about what kind of bike the Spearfish is: an endurance machine that offers relief. The rear travel was enough to smooth out our rocky trails, yet we never bottomed out the shock on bigger hits.

Simply put, Split Pivot separates pedaling forces from braking forces and allows the shock to do what it’s supposed to: absorb bumps. The Spearfish is a steady climber that doesn’t waste pedal strokes. But it really impressed under hard braking on loose descents. The front half of the Spearfish is high modulus carbon, suspended by Fox’s new Step-Cast fork with 100mm of travel. The relaxed head tube angle (69.3 degrees) had us cleaning tricky downhills, even after fatigue set in.

We were surprised to find that the Spearfish—a bike built for long rides and races—comes with just one difficult-to-reach water bottle mount. Not a deal breaker—just leave some room in the budget for a hydration pack. (See page 40 for four great options.)

Specialized Era FSR Comp Carbon

$3,800, Specialized.com
The draw: A custom feel
Rider stats: 5 feet 7 inches, 125 pounds

Women’s-specific mountain bikes have been around for about a decade. They generally have shorter top tubes to accommodate compact female torsos. They also tend to feature a relaxed head tube angle to keep your toes from whacking the front wheel and to elongate the wheelbase for better stability. And a steeper seat angle for longer femurs.

Besides the adjusted geometry, you’ll often find narrower handlebars, smaller brakes and shifters, a wider saddle and shocks and materials adjusted in stiffness for lighter riders.

The result of all of this is supposed to be a bike that feels like a (fun, trail-crushing) extension of you, and for us, the Era delivers. All it took were quick adjustments to the seat height and rear shock to make this flashy rig feel like a custom ride.

The 29-inch wheels made rolling through sandy sections a breeze compared to the 26ers we rode in the past. The shifting felt poppy at first, but by the second ride it was smooth and reliable. The 2x chainring (34/24t) paired with an 11-speed cassette (11–42t) meant we never ran out of gears climbing or hauling on the flats. The rear shock has a “brain” that stiffens it up when you’re climbing, but don’t expect it to lock out like a hardtail. The front shock, however, locks out easily with the flick of a lever on the top of the right shock tube. One-finger braking was a breeze.

The big wheels combined with the nicely tuned front shock (90/100mm travel) let us conquer some fat curbs we’ve wussed out of before. The lack of a quick-release lever on the front wheel was weird (it runs a 15mm thru-axle) but Specialized cleverly stashed Allen wrenches under the top tube for quick adjustments or wheel releases. All in all, the Era made us feel like natural-born mountain bikers.

One (Is) Sometimes Better Than Two

Both Shimano and SRAM offer 1x and 2x drivetrains (indicating the number of front chainrings). Each system is great, but the key for the rider is to decide what fits their needs best.

“One by, one by, one by!” says three-time off-road tri world champion Lesley Paterson. “When you lose the left shifter, you save weight, don’t drop your chain and have few moving parts to break. This is a no-brainer.”

Paterson loves SRAM’s Eagle group with its 12-cog, 10-50 cassette. That massive range has erased an old 1x criticism that it didn’t have the high and low end of a bike with a double chainring. The 50-tooth, low gear and a wide range of front rings means anyone can ride 1x, not just strong riders.

But a dedicated 2x rider can always point to those big gear changes: The shift from the 46 to the 50, for instance, is a big jump and can cause a major change in cadence. Shimano contends that smaller jumps between gears create a more natural and easier way to pedal. A 2x system with an 11–40 cassette keeps gear changes tight and cadences more consistent.

“A non-professional or even a professional triathlete may not want to ride a 1x on a particularly steep course because it will hurt their run split,” says three-time XTERRA world champ Melanie McQuaid. “I think having more choices is always better.”

And if money is no object, Shimano’s Mountain Di2 can do the front shifting for you. The $2,800 electronic system is programmable, allowing the rider to preselect when the front derailleur moves. Automatic shifting eliminates the need for the second shifter: Simply shift the rear, and the software takes care of the front. —Michael Hotten

Size Matters (For Wheels, Anyway)

Are you a 27.5 (or 650b) person or a 29er? It’s less than a two-inch change, but the difference can seem miles apart. The ragtag group that first started putting together dedicated off-road bikes wanted to run 29-inch wheels, but they couldn’t find knobby tires in that size. So they went with 26 inch. When tire companies finally came around to the idea of bigger wheels and the 29er began to dominate trails, another argument emerged claiming that bigger—at least 3 inches bigger—is not always better. And so 27.5 was born.

Most off-road multisport pros we spoke to are predominantly in the 29er camp.

“A bigger wheel carries momentum better, it rolls better over obstacles and soft/rough terrain and it provides more stability,” says Conrad Stoltz, who has multiple world titles in XTERRA and ITU cross tri. The 29-inch tire also has a larger contact area with the dirt for more grip.

Giant Bicycles has dedicated research and marketing dollars educating off-roaders on the benefits of the 27.5 wheel size, and weight is a primary factor. The smaller wheel is 7 percent lighter than its bigger cousin, and weight savings equate to better acceleration.

Fit can be another reason to choose one size over another. “Most will be better off with 29-inch wheels—with the exception of some smaller riders, who will find a better fit and handling with the 27.5-inch wheel size,” says eight-time XTERRA USA national champion Josiah Middaugh. —Michael Hotten