Jeffsy was the first 29″ mountain bike from YT and, at the time, first real push out of pure gravity-driven riding and into the world of trail riding. At just shy of 150mm travel, it’s a long-legged trail bike, to be sure. But compared to the DH Tues and the bruiser Capra, it is the YT with the broadest appeal.
With the third generation, or Jeffsy MKIII, that all-around approach remains. YT isn’t transforming Jeffsy into a specialist or overhauling it into a little enduro bike. It is still a platform squarely focused on finding the most enjoyment on the widest variety of trails. It’s just a more refined version of the Jeffsy. And it has a downtube storage compartment.
Prior to its release, we had the chance to ride the new Jeffsy for a few days in properly damp British weather. Here’s what we learned about the new bike over a few days of splashing around in the Forest of Dean and in Wales.
YT Jeffsy MKIII: What’s new
YT aims to keep the Jeffsy as an all-purpose trail bike. There are no crazy changes to make it lower and way slacker to turn it into a mini-enduro bike. YT already has a Capra for enduro and wants Jeffsy to keep its own personality and purpose. There’s also no mullet option, with all models coming with matching 29″ wheels. That leaves the Jeffsy to be a generalist. It’s good for everyday riding, whatever trails you want to ride. Jeffsy is squarely focused on fun, but with a supportive enough platform to tackle long pedals.
Jeffsy keeps the familiar YT silhouette, with simple lines brought together at the headtube by the German brand’s “head box” area, though that is smoothed out considerably compared to previous generations. Travel on the Jeffsy actually drops five millimeters to 145mm rear travel with a 150mm fork. But YT says that travel is more progressive at the end of its travel so you still get the “pop” out of corners without a harsh bottom out. In fact, the brand says it improved pedaling efficiency by upping anti-squad to 105 per cent (at 30 per cent sag), which drops off quickly to prevent pedal kick-back.
YT does make some small, but significant changes to the Jeffsy. There is a slightly longer reach to bring it up to date. Seat tube angles are size-specific, getting steeper as the sizes get larger with the goal of putting more riders in the best position while seated. YT aims for a 77-degree effective STA at each size’s average or typical seat height. Two chainstay sizes (one for S-L, one for…