The Jeffsy Core 3 is available in S, M, L, XL and XXL.
Reach on the Medium (tested here) is 450mm with a seat tube at 415mm. Head angle is 66.5 degrees in high and 66 in low, courtesy of the flip chip. Head angle is similarly adjustable to 77 or 77.5 degrees. Chainstays on the Medium are 435mm with a wheelbase of 1196mm.
After dialling in the Jeffsy in Dunkeld’s infamous Craigvinean Forest, the YT machine has been and done everything from laps of the woods to big mountain missions. Since then, the only things holding the bike back was brakes that tended to fade hard on longer descents and two holes in the rear tyre.
The latter was entirely my fault. A late day run saw me less focused than usual and clang, the back wheel hit a rock I don’t think I’d ever even had to consider before. Pinch at the bead and tread. Game over… It did make me think that maybe a 150mm 29er should come with at least a rear EXO+ tyre (or other brand equivalent). On the braking front, I swapped the standard SRAM rotors out with some HSC numbers as these have always seen a considerable improvement in power and heat management when fitted.
With fresh rear rubber fitted, off we went and the Jeffsy continued to cover the ground in between trails much faster than a bike this big should. Despite the rear end being slightly wallowy, especially out of the saddle, this didn’t really hold me back and there’s the ‘Firm’ switch on the Float X should you feel the need.
That opening plushness visible on the smoother climbs does come into its own on techy climbs as the bike just deals with whatever the back wheel has hit and up you go. Combined with the low overall weight of the Jeffsy, climbing on this thing really is a treat.
On the downs, the HSC rotors immediately made their presence felt. Much more bite at all speeds, and a greater level of control thanks to much more heat control on the longer descents meaning that pushing on for longer was now back on the cards. In some cases, the rear 200mm rotor might be a touch overkill for shorter runs.
With a measure of control when pushing on restored thanks to the increased ability to rein everything in, I could fully enjoy the Jeffsy’s ability to get down the hills fast in a way that I felt the Capra couldn’t. That being, to provide a fully engaging, lively ride from top to bottom. Despite offering a fun ride, it never feels uncomposed, and will happily plough through the chunder if you prefer to ride that way.
Beyond the rear tyre and rotors, the components have been faultless. The GX drivetrain has been crisp and reliable every time, the wheels may show a couple of dents but haven’t lost any air when the tyres have held up, YT’s own dropper is a solid unit. I am a big fan of Fox’s Performance Elite units for the way they offer up pure mechanical grip. When you consider the asking price too, it becomes even more impressive.
If I was being really picky, the only thing I’d change on the Jeffsy is the seat tube length. This only became something I noticed after the Deviate Highlander’s ability to get the saddle like it’s between your feet made me realise that even with the saddle slammed is noticeable between your legs. I’d guess this is due to the interrupted seat tube on the YT and the desire to run a full length dropper. The Jeffsy frame is a few years old now, having been launched with the help of Christopher Walken, so perhaps an update isn’t too far off?
What do we think?
The YT Jeffsy Core 3 offers me the same experience I had with the Santa Cruz Hightower but for almost six grand less money. Yes, the Hightower was a better spec, but you might not actually need it.
The only other bike that offers this kind of full ride fizz for the cash is the Vitus Sommet 297 CRX, but that’s a very different bike and twelve hundred quid the dearer.
Serious fun to ride
Could do better:
EXO+ casing rear tyre required
HSC rotors as standard please (on all SRAM equipped bikes)
You can check out the YT Industries Jeffsy Core 3 over on their website here.