YT Jeffsy Core 2 Action



Photos by Max Rhulen & Dusten Ryen
Video by Brian Niles / Treeline Cinematic


YT Industries has offered some of the best and affordable mountain bikes for a long time, with their direct sales model cutting out the middleman of a bike shop or wholesaler. However, in recent years they’ve moved towards the premium, performance-oriented side of the market, and their prices have risen as a result. The entry-level model of their all-mountain bike, the Jeffsy, comes in at a dollar under $3,000, meaning we were able to include it in this Budget Bike Shootout. Does the YT Jeffsy manage to deliver the same performance in its budget guise as the Core 4 we’ve previously tested, and how does it compare to the other affordable mountain bikes? We were excited to find out. 


• 150mm V4L Horst Link Suspension
• HTA 66
• STA 77 (effective)
• REACH 470 (Large)

Price: $2,999 (Core 2) – $5,499 (Uncaged 8)


The Jeffsy is the YT Industries all-mountain machine. Offered in either 27.5 inch or 29-inch wheel size options with 160mm or 150mm travel respectively, it sits between their Capra and Izzo to blend pedaling performance with descending capability. The rear end uses the classic YT Industries “V4L” Horst Link suspension design, which YT has tuned to be relatively progressive and deliver reasonable pedaling efficiency. There are currently four spec levels offered in the Jeffsy – three of the “Core” series builds, and one “Uncaged” model with a more exotic build kit. All of these specs share the same UM Carbon fiber frame, aside from the Core 2 tested which has a cheaper aluminum alloy frame, but retains the same features and geometry throughout.  

YT Jeffsy Core 2 Profile Shot

The Jeffsy frames are well protected by rubber chainstay and seat stay guards, and a generous bolt-on PA66 plastic downtube protector. The linkage bearings are given an extra level of protection thanks to rubber seals, keeping the water and dirt out to prolong their life. Chainsuck damage is prevented by stainless steel plates on the inside of the chain and seat stays and close to the front chainring. The head tube has the headset bearing races integrated, giving a zero-stack headset with no need to press in cups. Fully guided internal cable routing offers clean looks and easier maintenance, with the ports at the head tube clamping the cables to keep them in place and free from rattling.  

The geometry of the Jeffsy was designed to offer a good mix of capability and agility that should produce a fun ride regardless of the terrain encountered. It can be tweaked slightly by changing the position of the flip chip on the rear shock mount between the “low” and “high” settings. As standard, it is supplied in the “low” mode, which gives the most stable and aggressive ride. Flipping it into the “high” mode raises the bottom bracket by 8mm, and steepens the head tube and seat tube angles by half a degree to give a more agile feel. The 29er in the low setting shares a 66° head angle; 77° effective seat tube angle and 32mm bottom bracket drop across the S-XXL size range. The rear end grows from 435mm on sizes Small through Large to 440mm on XL and XXL, aiming to improve the fore-aft balance as the reach lengths grow. Reach figures stretch from 430mm to 510mm; and the stack goes from 618-640mm, with the Large sitting at 470mm and 627mm respectively. The wheelbase adds up to 1218mm for the Large size tested, sitting in the middle of the range for this Budget Bike Shootout.  

YT Jeffsy Core 2 Geo

The aforementioned model range of the Jeffsy goes from the Core 2 model tested at $2,999 to the Uncaged 8 at $5,499, with the Core 3 and Core 4 models in between. The aluminum alloy frame of the Jeffsy Core 2 is equipped with a purposeful parts spec that’s absent of any fancy coatings or lightweight materials. The suspension package is Fox’s Performance level, with a 150mm travel 36 fork (160mm on 27.5”) and a Float X rear shock (which replaces the DPX2 currently listed on YTs website). The fork is equipped with the GRIP damper featuring low-speed compression and rebound adjustments, and the shock has a 3-position lever to give open, trail, and lockout settings as well as rebound damping adjustment. SRAM handles drivetrain and braking duties; with their NX Eagle 12-speed groupset with 11-50T cassette and Descendant alloy crank; and G2 R brakes stopping on 200mm rotors on both ends. There’s an e*thirteen Base 35 alloy cockpit; YT Postman dropper post (with SDG Tellis internals); SDG Bel Air 3.0 saddle; and DT Swiss M1900 alloy wheelset. As standard the tire duties are handled by a pair of Maxxis DHR2 EXOs in 2.4” width, however, for this test, all of the bikes were equipped with Versus All-Mountain tires to give consistent performance across the board. The large YT Jeffsy Core 2 tips the scales at 34.8 lbs as tested. 

YT Jeffsy Core 2 Action


Out of the box, the YT Jeffsy Core 2 is a quick build. Much of the set-up is a fairly quick process and is made all the easier by YT’s neat axle stands and step-by-step guide in the manual. Riders of all abilities should be able to get their Jeffsy together without having to venture to a bike shop, that said if you’re uncomfortable with any of the steps then we’d highly recommend getting a professional mechanic involved. Incorrect installation and poor maintenance of mountain bikes is dangerous! 

Once the Jeffsy was set up, we removed the OE spec’d Maxxis Tires and installed our Versus All-Mountain Trail Casing tires, while also converting to a tubeless set-up. All our test bikes ran 25psi in the front tires and 27psi in the rear tires for a level playing field. Our fork air pressure was similar on all bikes whereas the rear shock took a bit of figuring out to get the right pressure for recommended sag. YT does have a suspension set-up guide on their website, which you can find here. However, the Jeffsy Core 2 was not listed during our test period. We’d love to see a table of suggested shock pressures for specific rider weights added to the manual or website for all current models, to help speed up the initial suspension setup process. 

The YT Jeffsy’s climbing prowess was not anything special, however, it was not terrible either. Some of our testers felt the bike bobbed a bit more than others in our roundup, creating extra effort on steeper ascents, while a couple of other riders did not notice an issue at all. Thankfully the 3-position compression lever on the Fox shock is easily accessed to quickly add some extra support to improve its manners on the way up. One thing we all agreed on was the less than desirable shifting performance of the SRAM NX Eagle drivetrain. Compared to the Shimano 12-speed equipped bikes in our lineup, the shifting was dull and not always exact, usually requiring a stiffer push on the shifter to get it into the next gear, whether that be up or down.

YT Jeffsy Core 2 Action

Robert did a great job summarizing the Jeffsy’s downhill capabilities in his review of the Core 4 model and not much is different on the Core 2 model tested here. Obviously, the biggest difference comes in the form of Fox’s Factory spec versus their Performance line of suspension parts. The 36 Performance fork is a solid spec at this price point (and the top spec in this group review) and performed well during a test period. The Performance DPX2 also held its own for the most part, however, an additional volume reducer may have helped liven the Jeffsy up a bit more. The Jeffsy Core 2 was not the liveliest of bikes in our round-up. It had a tendency to mute some of the trails out and stay stuck to the ground. That is not necessarily a bad thing and was a highlight for some of our testers as it provides a more comfortable and predictable ride.

Outside of our issues with the poor shift feeling of the NX Eagle drivetrain, there are a couple of other specs we have some qualms with. The 150mm Postman dropper post is too short for large frames, a 170mm+ option would be the better spec in our opinion. The G2 R brakes are another area of concern (for some of our riders), these SRAM brakes can get overheated quickly on steep terrain and braking can become an issue. On some of our laps, these brakes were the only ones to show signs of brake fade intermittently. We don’t think they need to be replaced right away, but we do believe they should be one of the first upgrades made on this particular bike. When it comes to the remainder of the build, YT did an excellent job with the spec they chose, certainly offering the most bang for the buck in this test, in our opinion.

The Wolf’s Last Word

The YT Industries Jeffsy Core 2 as an affordable mountain bike, is an impressive all around machine that will let you progress as a rider. It stood out amongst the other bikes in our sub-3k group review. While the Jeffsy is efficient enough going uphill, the bike much prefers going with gravity than against it…like the rest of our crew. The YT Jeffsy is capable of eating up everything that comes its way: whether it be techy rock gardens, flow trails or catching air, it will do it all with ease. It is also one of the only bikes that we would consider bringing to the bike park.  

Who do we think this bike is for you might ask? For the ripper or the beginner. Those who like to shred trail or play on side hits will be at home the YT Jeffsy Core 2, though the limit will be found sooner or later as components and travel will become barriers if you’re repeatedly hitting the gnarliest of descents. For beginners, the YT Jeffsy Core 2 will allow them to grow into the bike, as it is not pigeon-holed into only being able to ride a certain type of trail while more advanced riders on a budget will appreciate they can push this bike hard and be rewarded with a capable mountain bike at a fair price. 

Price: $2,999 
Weight: 34.8 lbs (as tested)

YT Jeffsy Core 2


Frame: Alloy | 150mm
Fork: Fox 36 Performance | 150mm
Shock: Fox Float DPX2 Performance | 3-pos | 210x55mm 

Brakes: SRAM G2 R | 200mm rotors
Bar: e*thirteen Base 35 | width: 780mm | rise: 35mm | clamp: 35mm
Stem: e*thirteen Base 35 | length: 50mm | clamp: 35mm
Seatpost: YT Postman 31.6mm | S/M:125mm | L: 150mm | XL/XXL: 170mm
Saddle: SDG Bel Air 3.0 

Wheelset: DT Swiss M 1900 SPLINE 

Cassette: SRAM PG 1230 | 11-50T | 12spd
Cranks: SRAM Descendant 6K | 32t | 175mm
Shifter: SRAM NX Eagle | 12spd 
Derailleur: SRAM NX Eagle | 12spd 

We Dig

Best Bang for the Buck
Solid Spec
Looks the Most Refined
Comfortable All-Day Ride

We Don’t

Shift Performance or lack thereof
G2 Brake Fade
Short Dropper Post



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