Transformers—fat bikes in disguise


Versatility is the Pivot Les Fat’s first priority. Pivot’s highly transformable bike, the Les Fat, was built to tackle any terrain at any time of year (it could easily have been named Optimus Prime). This shapeshifter has the ability to swap wheel sizes with ease while still providing riders the same overall fit. Pivot sent us two wheelsets (although the Les Fat only comes stock with fat tires) for this test. One set had 26×4-inch fat tires and the other set had 27.5×3-inch, plus- size tires. Pivot’s Les Fat is a unique bike with a clever design, and we couldn’t wait to get our hands on it. We put this bike through the full MBA-style test in order to see if this thing could transform itself from a snow-trekking fat bike into a traction-grabbing trailbike. As the Transformers would say, “Pivot Les Fat, transform and roll out.”


Pivot’s Les Fat is made to satisfy the needs of just about every rider. Although this sounds too good to be true, we found ways the Les Fat could benefit an entirely different group of riders every time we rode it. To a die-hard fat biker, the Les Fat offers clearance to run up to 5-inch-wide tires, allowing riders to rip through the snow or bulldoze down the trails. Adventure riders will find the Les Fat to be an exceptional choice for their riding style due to its integrated rear rack mounts and ability to carry three water bottles. Trail riders will find themselves having a blast, shredding the trails with endless amounts of traction from the 27.5-inch-plus tires. Transformability is the Les Fat’s signature feature.

M6Pivot9Plus-sized: The Les Fat has the capability to run plus- sized tires such as the Maxxis Chronicle 27.5×3-inch tires shown in this picture.

M6Pivot8Fat tires: The Les Fat comes stock with Maxxis Mammoth 26×4-inch tires; however, the Les Fat can fit up to a 5-inch- wide fat tire on its stock rims.

M6Pivot7Swinger II dropout system: The key to the Les Fat’s wheel-changing ability is a result of Pivot’s innovative Swinger II dropout system. The dropouts not only allow multiple wheel sizes, but they also give the Les Fat the shortest chainstays possible, and even keep the bottom bracket height consistent with multiple wheel-size options.



The frame is carbon, with a suspension fork and the wheel size of your choosing. Pivot’s XX1 build kit uses its house- brand Phoenix carbon handlebars and seatpost, along with an XX1 drivetrain and a Rockshox Bluto fork. The Les Fat’s frame is also constructed from carbon and uses proprietary hollow-core internal molding technology and an oversized downtube claimed to make the Les Fat lighter, stiffer and stronger than any other bike in its class. Wheel size is the next thing that sets the Les Fat apart, as it can fit 26-inch fat tires, 27.5-inch-plus tires or 29-inch-plus tires. Pivot had its hands full when it set out to build this bike, and the hard work definitely paid off. Pivot also offers their own carbon fork for those who would like to ride this bike rigid.


The most important feature of the Pivot Les Fat is the patented Swinger II dropout system. These impressive-looking and easy- to-use dropouts are the key to the Les Fat’s versatility. Not only do these dropouts allow the use of just about any fat or plus-size wheels, they also allow riders the ability to adjust chainstay lengths. Swapping wheel sizes doesn’t affect the Les Fat’s geometry, because riders can simply slide the rear wheel closer to the frame for the shortest chainstays possible. These short stays provide the Les Fat with its uniquely playful and agile feel, normally unheard of in the fat bike category.

M6Pivot3Stealth routing: Pivot’s Cable Port system not only offers a clean and sleek look, it also protects the Les Fat’s frame during foul-weather riding.

M6Pivot4Wide spacing: The RockShox Bluto fork has a large 150- millimeter axle allowing clearance for tires as wide as 5-inches.

M6Pivot6Power to the wheel: The Les Fat’s drivetrain is top of the line with SRAM’s smooth-shifting XX1 rear derailleur and E*Thirteen’s fat bike-specific TRS crank.


Setting sag: When setting up the Les Fat, it’s important to pay as much attention to tire pressure as sag. Air pressure on our fat, 4-inch-wide tires worked best around 8 to 9 psi, while our 3-inch- wide tires needed between 16 and 17 psi. The Bluto’s air pressure was set to our testers’ recommended rider weight, but low-speed compression needed to be adjusted differently for each wheel size. This was most likely due to the amount of compliance each tire size offered.

Moving put: We found the Les Fat to have a comfortable cock- pit, even after we pointed the stem down and dropped the bars 5 to 10 millimeters. The Les Fat’s fit falls between that of a trailbike and a cross-country bike, allowing riders to be slightly leaned forward while still being comfortable and ready to tackle steep descents. The 197-millimeter rear axle and 150-millimeter front, coupled with a wide bottom bracket, may feel unusual to riders not familiar with fat bikes. Riders new to fat bikes will get used to it quickly, and current fat bikers will be more than pleased with the Les Fat’s overall feel.

M6Pivot12Charge through: The Les Fat is just about unstoppable when equipped with fat tires. The 26×4-inch tires cruise over snow, mud or sand with ease, making the Pivot Les Fat a true year-round bike.

M6Pivot10RockShox Bluto: The Les Fat’s suspension fork gave our test riders confidence during descents and great climbing efficiency during steep climbs.

Climbing: The Pivot Les Fat climbs surprisingly well with either size tires due to its stiff and efficient frame and fork. The RockShox Bluto provided us with a stiff platform to get out of the saddle, and the stiff carbon hardtail frame transferred power to the ground well. Long climbs with either wheelset quickly revealed the added weight, but rolling hills and even some punchy climbs were shown no mercy by the Les Fat. For a big-tire bike, the Les Fat has some serious gumption.

M6Pivot13Rip it: Who said big tires are slow? The Pivot Les Fat is a blast to rip on the trails. Bolt on whatever wheel size you want and push this bike to the limit.

Cornering: Traction was no concern with either our 4-inch- wide Maxxis Mammoth tires or our 3-inch-wide Maxxis Chronicle tires, but handling was slightly affected. Our 4-inch-wide tires steered slower, which wasn’t a bad thing—it just took some get- ting used to. A shorter stem could remedy the issue, but many fat bikers are accustomed to the unique feel of big-tire steering already. The 3-inch-wide tires, on the other hand, felt more natural, allowing us to toss the bike around on the trails easily. These tires gave us the ability to go into corners just as fast, but seemed to maintain speed better as we exited the turns. For foul-weather riding, the fat tires had their benefits, but for a normal day on the trails, the plus tires excelled.

Descending: The Les Fat is a trail-shredding machine in disguise. Equipped with 3-inch-plus-sized tires, the Les Fat rolled faster, held traction well and offered snappier handling than with the 4-inch-wide tires. Don’t be fooled, though; the fat tires still had good descending capabilities. When fat tires entered the equation, the Les Fat turned into a beast, ready to run over anything in its path. With both wheel sizes, the RockShox Bluto was the unsung hero, providing a plush feel with its 100 millimeters of travel. Bottom line: don’t get in the Les Fat’s way.

M6Pivot11Quick and nimble: Compared to fat tires, the 27.5-inch- plus tires gave the Pivot Les Fat a quick and nimble feel on singletrack. These tires rolled fast while still providing tons of traction. The fat tires, however, excel in foul-weather conditions.

Braking: Big tires need big brakes, which is why Pivot spec’d SRAM Guide Ultimates on the Les Fat. These four-piston brakes mean business and will stop any big-tire bike dead in its tracks. Getting braking power to the ground is the next important issue, and Maxxis’ Mammoth and Chronicle tires both did a great job of grabbing the earth and stopping its rotation underneath our Les Fat. During wheelset swaps we noticed the brakes needed a slight adjustment, but with the Guide’s tool-free contact point adjuster, we moved the dial a few clicks and were ready to go.


The Les Fat’s versatility is truly amazing, and we could easily see ourselves getting carried away with having multiple wheelsets, adventure racks, a shorty stem, dropper post and tons of other accessories. The list could go on and on. Les Fat owners should be forewarned that this bike’s transformability is addictive and may cause them to break the bank on upgrades. Keeping the bike bone stock, however, will not disappoint, as the Les Fat is built with tons of top-of-the-line parts, great attention to detail and a well- thought-out geometry.



So many bikes these days are built with a certain purpose in mind, but riders are often looking for a bike that can do it all. Sure, the Pivot Les Fat is never going to transform into a full-suspension, aggressive trailbike, but it can take you through foul-weather conditions in the winter and still be a great trailbike the rest of the year. Riders interested in adding a fat bike or plus bike to their quivers should consider the Les Fat. Who knows? It might just check all your boxes for a do-it-all bike. In any case, the Les Fat offers riders a long list of top-notch components, a wheel-size accommodation that will stand the test of time, and a well-built bike that’s flat-out fun to ride.



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