The Power of Love… err, friendship! This has been the motto of the YT JEFFSY since the first iteration was launched a few years back. YT’s trail cannon is now in its third generation and should be the ideal companion for all types of adventures. Is it your best mate or just a false friend?

YT JEFFSY CORE 5 CF | 150/145 mm (f/r)
15.3 kg in size L | € 5,999 | Manufacturer’s website

As the newest bike in our 2024 trail bike group test, the YT JEFFSY CORE 5 made it into our van just a few hours before we set off for Italy. Tipping the scales at 15.3 kg, the CORE 5 is the flagship model in the JEFFSY range, and comes equipped with all kinds of high-end goodies. Pleasingly, at € 5,999, it’s still the most affordable bike in the entire test field, which comes as no surprise since YT have always been known for offering awesome specs at great prices. Generating 150/145 mm of travel, the JEFFSY sits right between YT’s enduro rig, the CAPRA, and their downcountry rocket, the IZZO. According to the German manufacturer, it’s suitable for both rowdy trail sessions and long days in the saddle – a versatile wingman for all situations.

For an overview of the test fleet head to the group test: The best trail bike 2024 – 15 of the most exciting trail bikes in our 2024 comparison test

The 2024 YT JEFFSY CORE 5 in detail

The JEFFSY is available in both alloy and carbon versions. The CORE 5 variant we tested is the only one in the JEFFSY range to rely on an Ultra Modulus carbon frame, which is meant to provide the same degree of stiffness at a lighter weight. The frame silhouette is similar to the previous JEFFSY, albeit with more angular, straighter lines and without the striking hole in the seat tube. The tool mount on the top tube comes standard with a Crankbrothers tool strap including tire levers and a tubeless repair kit. All you have to do is add a spare inner tube and a pump! If there’s anything that doesn’t fit there, you can throw it in the STASH box storage compartment, which is integrated into the down tube just below the bottle cage and also includes two STASH bags to keep things organised. The compartment cover seals tightly and doesn’t rattle on the trail, but the compartment is difficult to open with a bottle in the cage. The STASH box comes standard with all carbon models, but not with the alloy variants – what a shame! The cables are routed internally and disappear into the frame just behind the steerer tube. The cables aren’t clamped at the ports, but secured with small rubber plugs. However, these tend to slip out of the ports far too easily, so we recommend securing them with zip ties. If you do so, the JEFFSY is as quiet as a mouse, and the chain doesn’t slap against the frame on the trail.

The spec of the 2024 YT JEFFSY CORE 5

The suspension of the YT JEFFSY CORE 5 consists of a FOX 36 Factory GRIP2 fork and matching FOX FLOAT X Factory shock, which both deliver a tremendous performance on the trail and offer countless adjustment options. For the dropper post, YT rely on their in-house 170 mm Postman dropper, which offers butter smooth action and performed flawlessly throughout this test. SRAM CODE RSC brakes with 200 mm rotors front and rear ensure reliable, powerful deceleration, even on long descents. The levers feature tool-free bite point and lever reach adjustments, as well as SRAM’s proprietary SwingLink technology, which was designed to minimise deadland and optimise modulation, thus reducing arm pump significantly. Shifting is taken care of by a SRAM X0 Transmission drivetrain, which relies on a direct-mount rear derailleur and forgoes a mech hanger and limit screws. We like the fact that YT paired the new drivetrain with an old AXS shifter paddle, which, in our opinion, offers better ergonomics than the new AXS pods that usually come with Transmission drivetrains. Renthal supply the cockpit, combining a 50 mm Apex stem with 780 mm alloy handlebars – a sturdy aluminium cockpit with a clever handlebar width for a trail bike! The JEFFSY rolls on a Crankbrothers Synthesis E.29 alloy wheelset and a classic MAXXIS tire combo, with a Minion DHF at the front and Minion DHR II at the rear, both in the sturdier EXO+ casing and hard MaxxTerra rubber compound. However, we would recommend upgrading to the softer MaxxGrip compound at the front for more traction.

The JEFFSY comes standard with a tool strap and storage compartment in the down tube, allowing you to leave your backpack at home.

Old meets new
YT combine a new SRAM X0 Transmission drivetrain with an old AXS paddle shifter instead of the new AXS pods.
Quick Fix
We recommend using a couple of zip ties to secure the rubber plugs in the cable ports.
The storage compartment in the down tube allows you to stow away all your trail essentials, no matter what you want to carry with you.
Emergency backup
The standard tool strap makes it easy to carry a small emergency puncture kit directly on your bike.
Small and compact
The YT comes standard with tire levers and tubeless plugs – nice!


€ 5,999


Fork FOX 36 Factory GRIP2 150 mm
Rear Shock FOX FLOAT X Factory 145 mm
Seatpost YT Postman 170 mm
Brakes SRAM CODE RSC 200/200 mm
Drivetrain SRAM X0 Transmission 1x12
Stem Renthal Apex 50 mm
Handlebar Renthal Fatbar Alu 780 mm
Wheelset Crankbrothers Synthesis E.29 Alu 29"
Tires MAXXIS DHF, EXO+, MaxxTerra/MAXXIS DHR II, EXO+, MaxxTerra 2.5"/2.4"

Technical Data

Weight 15.3 kg

Specific Features

storage compartment

Tuning tips: Softer MaxxGrip rubber compound for the front tire | Secure the rubber plugs to the cable ports with zip ties

Helmet Giro Tyrant MIPS | Glasses Oakley Sutro | Jersey Northwave Bomb Flower Jersey
Pants Northwave Bomb Long Pants | Shoes Crankbrothers Mallet Speedlace

The geometry of the YT JEFFSY 2024

The YT JEFFSY is available in five sizes, S to XXL, offering a suitable option for riders between 153 cm and 203 cm tall. Our test bike in size L combines a rather short 475 mm reach and short 435 mm seat tube, which ensures plenty of freedom of movement on the bike. A flip chip in the shock mount allows you to adjust the 65° head tube angle and 77.2° seat tube angle by 0.6° while at the same time dropping the 33 mm bottom bracket by a further 8 mm. Following YT’s Rider Centered Geometry concept, the chainstays grow with the frame size, measuring 437 mm in sizes S to L and 442 mm in sizes XL and XXL.

Top tube 578 mm 593 mm 609 mm 627 mm 645 mm
Seat tube 385 mm 410 mm 435 mm 460 mm 485 mm
Head tube 100 mm 108 mm 116 mm 124 mm 132 mm
Head angle 65.0° 65.0° 65.0° 65.0° 65.0°
Seat angle 76.9° 77.5° 77.9° 78.3° 78.6°
Chainstays 437 mm 437 mm 437 mm 442 mm 442 mm
BB Drop 33 mm 33 mm 33 mm 33 mm 33 mm
Wheelbase 1,191 mm 1,214 mm 1,238 mm 1,266 mm 1,289 mm
Reach 435 mm 455 mm 475 mm 495 mm 515 mm
Stack 613 mm 620 mm 627 mm 634 mm 642 mm

The 2024 YT JEFFSY CORE 5 on the trail

Riding uphill, the YT JEFFSY CORE 5 places you in a comfortable pedalling position, with very little pressure building up on your hands, even on level ground. Nevertheless, the front end always remains planted on the trail even on steeper climbs, meaning that you don’t have to actively weight the front wheel to keep it tracking. The suspension is pleasantly firm, providing a lively feeling that encourages you to challenge your mates with cheeky uphill sprints. At the same time, this means that you don’t have to reach for the climb switch on long, monotonous uphills.

The JEFFSY turns every trail into a round of Wild Mouse. No other bike in the test is this much fun.

When you turn its nose downhill, the JEFFSY really behaves like a good mate, letting you know with its intuitive handling how it will react to your input, and even forgiving the odd riding mistake when you get a little too excited. The JEFFSY is super comfortable and makes you feel at ease from the get go, giving you the impression that you’ve ridden this bike all your life. When approaching a corner, all you have to do is think about turning and the YT does it for you. In fast consecutive corners, it encourages you to flick the rear end from one side to the other and play with the trail. Cornering has never been this much fun! Needless to say, the suspension plays a major role in this, providing shed-loads of pop and support, allowing you to shralp out of berms and pump through your local flowline as if you were fighting for the pump track world championship title. At the same time, the suspension is progressive enough to take on nasty drops – only the suspension’s small-bump sensitivity can’t keep up with the best in this test. But hey, who needs that last smidge of traction when you can float over technical sections instead? However, despite its insane nimbleness, the YT is incredibly composed, so you can sit back and relax while bombing down high-speed sections or ploughing through nasty rock gardens. All of this makes the JEFFSY a fun, reliable riding companion that doesn’t mind getting rowdy. When you get to the bottom of a trail with the YT JEFFSY, the only reason why your smile doesn’t circle 360º around your head is because your ears are in the way!

Who should take a closer look at the 2024 YT JEFFSY CORE 5 for?

The YT JEFFSY CORE 5 isn’t just the cheapest bike in the test, but also the best one! This makes it the first bike in the history of ENDURO to secure both our Best in Test and Best Buy titles! Everyone can have fun with the JEFFSY, regardless of your skill level or the type of trail. It’s more agile than any other bike in this test but still provides enough reserves for more challenging trails. No matter how and where you ride it, the JEFFSY is a belter!



  1. sluggish
  2. efficient


  1. cumbersome
  2. playful


  1. nervous
  2. confident


  1. demanding
  2. balanced


  1. harsh
  2. plush


  1. planted
  2. poppy


  1. terrible
  2. very good


Cross Country




Our conclusions about the 2024 YT JEFFSY CORE 5

Fu** fake friends! With its top-tier spec, sensible frame features and unbeatable price, the YT JEFFSY CORE 5 already looks great on paper. On the trail, it’s exactly that friend everyone should have, encouraging you to do crazy things but at the same time sticking up for you when you most need it – together, you’ll have the best time of your life! The poppy suspension paired with the agile yet predictable handling, make the JEFFSY the undisputed Queen of Fun in this test – a well-deserved Best in Test!


  • Trail bike with fun guarantee
  • Mind-boggling price/performance ratio
  • Super intuitive handling
  • Pure agility!
  • Countless clever frame details


  • No storage compartment on the alloy model

You can find out more about at

The test field

For an overview of the test fleet head to the group test: The best trail bike 2024 – 15 of the most exciting trail bikes in our 2024 comparison test

All bikes in test: Cannondale Habit LT 1 (Click for review) | Cube ONE55 C:62 SLT 29 (Click for review) | Ghost RIOT Trail Full Party (Click for review) | Merida ONE-FORTY 10K (Click for review) | Mondraker Neat RR SL (Click for review) | Nicolai Saturn 14 Swift HRZ (Click for review) | Orbea Occam LT M10 (Click for review) | Santa Cruz Heckler SL XX AXS RSV (Click for review) | Santa Cruz Hightower X0 AXS RSV (Click for review) | Scor 2030 X01 (Click for review) | SCOTT Genius ST 900 Tuned (Click for review) | Specialized S-Works Turbo Levo SL (Click for review) | Trek Fuel EX 9.9 X0 AXS T-Type (Click for review) | Yeti SB140 LR T3 X0 (Click for review) | YT JEFFSY CORE 5 CF

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Words: Simon Kohler Photos: Peter Walker

About the author

Simon Kohler

​​Simon loves speed. He has many years of racing experience as a longboard downhill skater, blasting down alpine passes on his board. In the meantime, he’s swapped four wheels for two, charging down trails and bike park lines aboard his mountain bike instead. He’s savoured some of Europe’s finest trails on various road trips through the Alps. Having lived in Austria for some time, he knows the local Austrian bike parks like the back of his hand. He’s a tech nerd through and through, using the skills and know-how from his engineering degree and his attention to detail to put the latest bikes and components through their paces for our reviews. As an early riser and self-declared muesli connoisseur, he lives his life powered by oats and the strength of his legs.