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Ibis has unveiled a fat bike version of the company’s existing carbon hardtail. For Ibis, development is easier than most: The existing 29er hardtail has a sliding/removable rear triangle, so the bike can be converted into a singlespeed, equipped with a belt drive, or broken down for travel. The Trans-Fat version uses the same front triangle as the 29er mountain bike, with a fat tire-optimized rear triangle. It has 177mm rear-axle spacing, clearance for 4-inch-wide tires, and is designed around a 120mm RockShox Bluto fork. Claimed frame weight is 1,474 grams.
Wide tires mean wider rear-axle spacing, which in turn means a wider bottom bracket shell. Fat bikes typically have 100mm BBs, but the Trans-Fat has the same press-fit BB92 as the 29er hardtail it's based upon. Ibis’ solution: A set of press-in adapters so Trans-Fat can accept a threaded 100mm BB. (Ibis recommends the BB cups be threaded into the adapters before pressing them into the frame.)
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Ibis offers three ways to get more Trans-Fat in your diet. First, you can get the frame only for $1,700. Owners of Ibis' 29er hartail can also purchase a $699 conversion kit, which includes the rear triangle; the BB adapters; and a new crown race to accommodate a 120mm RockShox Bluto.
Option three is a complete bike for $5,099, with Shimano XT 1x group; 120mm Bluto fork; KS LEV dropper; Sun Ringle Mulefut 80SL wheels; and 4-inch Schwalbe Jumbo Jim tires. Of note: Ibis specs Shimano XT brakes that use mineral oil in the Trans-Fat. Theoretically, DOT fluid—used in Avid/SRAM disc brakes—is more stable at very-low temperatures than mineral oil. However, with time, DOT fluid absorbs water (mineral oil does not), and must be regularly flushed or the water in the fluid can freeze.
The Trans-Fat is available now in limited quantities, but Ibis representatives say more inventory should arrive in February. Can't seem to get your hands on one? Make sure you're the first to know about the best new bikes and updates by subscribing to Bicycling.
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