The YT Jeffsy trail bike is turning seven years old this year, though in model years it’s still only three. The third generation, YT Jeffsy MK3 sees a new in-frame storage hatch on carbon models, less rear squish, and sweeping geometry updates.
YT Jeffsy frame updates
Buyers can choose from Jeffsy builds featuring an aluminum alloy or carbon frame. The carbon frame adds a new STASH in-frame storage spot inside the downtube beneath the bottle cage mount. YT says the hatch is double sealed against water to keep gear clean and dry.
Speaking of that bottle mount, the shock position hasn’t changed much so riders on the smaller size frames will still be limited to carrying short and stubby water bottles. One new addition to the frames, however, is a pair of accessory mount bolts located beneath the top tube on both alloy and carbon frames.
The YT Jeffsy MK3 is UDH-compatible, and the two most expensive builds (Core 5 and Core 4) come with a SRAM XO and GX Eagle Transmission drivetrains, respectively.
Perhaps to better position the Jeffsy in the YT lineup, the MK3 tones the rear travel down to 145mm from the MK2 models which offered 150mm of travel. The YT Capra, on the other hand, remains solidly enduro, and while YT positioned the Jeffsy as an all-mountain bike, this update seems to nudge it toward the middle of the trail bike of the spectrum, perhaps leaving the YT Izzo to embrace the downcountry label. A couple previous Jeffsy builds had 160mm forks, though this time around it appears 150mm forks are specced across the board.
A two-position flip chip located at the lower shock mount swaps the geometry between high and low modes.
It’s also worth noting the latest Jeffsy builds feature the YT Postman V2 dropper post, with up to 230mm of drop available on size XXL frames. The dropper post is adjustable which allows riders of all sizes to maximize the amount of drop available given their measurements.
YT Jeffsy MK3 geometry
The latest YT Jeffsy sees the head tube angle going slightly more slack down to 65° with the two-position flip chip in the low position. The 77° seat tube angle stays roughly the same while the reach has been extended by 5mm across all sizes.
Once again, YT is speccing two different chainstay lengths depending on frame size. Sizes small, medium, and large have 435mm or 437mm stays depending on the position of the flip chip, while the stays on sizes XL and XXL range from 440-442mm long.
Aluminum Core 1 Jeffsy builds are priced at $2,799 and feature a SRAM NX Eagle drivetrain and Rockshox Lyrik Base fork for a claimed weight of 16kg (about 35lb). At the other end of the spectrum, the carbon $5,999 Core 5 build comes with a SRAM X0 Transmission drivetrain and Fox Factory suspension and is said to weigh 14.8kg (about 32.6lb) for size small frames.
