It's been almost five years since YT's top-selling all-mountain bike Jeffsy received its last update. Now the Forchheim-based mail order company wants to continue the Jeffsy's success story with a completely revised version. The key data remains the same: 150 millimetres of travel, 29-inch wheels and geometry adjustment via a flipchip on the shock mount. But that's about it. Beyond that, the developers have pulled out all the stops to drive the evolution of the All Mountain forward.
More weight thanks to the new shape
In addition to a modernised design language and thicker tube cross-sections, the most striking innovation is in the down tube. For the first time on one of its bikes, YT has integrated a storage compartment for tools and food on the go under a stylish plastic cover. Although this provides added value for all backpack opponents on tour, it also has an impact on the weight due to the increased material thickness around the opening. At 2900 grams in size L, the chassis of the 2024 Jeffsy weighs around 150 grams more than its predecessor.
The total weight of our test bike without pedals was 15.1 kilograms. This means that YT is far from setting a record in this category. For comparison: In our last All-mountain comparison test up to 5000 euros the candidates weighed an average of 14.75 kilos.
The YT Jeffsy also shows a completely new face in terms of geometry data - fortunately. Over the years, the dimensions of its predecessor have become increasingly dusty. The head angle on the current Jeffsy has been slackened by one and a half degrees and now measures 64.5 degrees. The wheelbase has also grown: in size L from 1222 millimetres to 1244 millimetres. These changes are particularly effective downhill and give the newcomer more poise at high speeds.
Playful and smooth-running
But don't worry: despite the smoother ride, the bike is still easy to handle and playful. The new geometry is modern, but avoids extremes. In other words, the steering angle is slacker, but not so much that the rider has trouble getting enough weight on the front wheel. On the contrary, the moderate reach places the rider in the centre of the bike, which with its 338 mm chainstays can still be pushed comfortably around tight bends without appearing nervous on high-speed sections. Acclimatisation time? Not a chance! Sit on it and feel good is the motto of the new Jeffsy.
The Forchheim-based company has also done a great job with the chassis: Compared to its predecessor, the rear is slightly more progressive. A good thing, we think. This allows the bike to be manoeuvred more efficiently through the terrain, easily pulling into flight mode and still offering plenty of reserves on rough trails or hard landings. The rear end also filters out fine bumps cleanly and generates top traction - both uphill and downhill. Speaking of uphill: even when pedalling uphill, the Float-X shock remains stable in its travel and bobs comparatively little.
If you want to eliminate the last drive influences on long tarmac climbs, you can also reach the platform lever in a relaxed manner while riding. The steep seat angle in combination with the moderate reach places the rider comfortably upright above the frame triangle. Thanks to the relatively long chainstays, the front wheel stays reliably on the ground even on steep ramps. However, there is still potential for tuning the 5564 gram wheels. They require a lot of effort to get going and rob the bike of its liveliness.
Otherwise, there is nothing to criticise about the equipment of the € 5999 Jeffsy Core 5: Sram's new XO transmission drivetrain, Fox suspension from the Factory series and Sram Code stoppers with large 200 mm discs - nothing is left to be desired.
Conclusion on the YT Jeffsy Core 5 by Max Fuchs, BIKE test editor:
The latest version of the YT Jeffsy remains a bike for all occasions. However, thanks to the geometry update and the massive tyres, the core competencies for the 2024 model year have shifted slightly further towards downhill riding.
Technical data and notes on the YT Jeffsy Core 5
Manufacturer information
- Price¹: 5999 Euro
- Available by mail order
- Frame material: Carbon
- Frame size: S, M,L, XL, XXL (tested in size L, 44 cm)
Measured values
- Weight without pedals: 15.09 kg
- Frame weight: 2900 g
- Weight of wheels: 5564 g
- Acceleration wheels: 4618 kg x cm²
- Handlebar width: 780 mm
- Frame rigidity (absolute): 43 N/mm
Equipment
- Wheels: Crankbrothers Syntesis E
- Tyres: Maxxis Minion DHF/ DHR II; 3C Maxxterra Exo+ Protection TR 29 x 2.40/2.50
- Fork: Fox 36 Float Factory Grip2
- Shock: Fox Float X
- Front / rear suspension travel: 151 / 150 mm
- Brakes: Sram Code RSC / 200/200 mm
- Gear system: Sram X0 Eagle Transmission 1x12
- Gear ratio / bandwidth: 32; 10-52 / 520 %
- Telescopic post / stroke / Ø: YT Postman V2 / 170 mm / 31.6 mm
Valuation
- Driving behaviour uphill: 21.25 out of 25 points
- Chassis efficiency: 17 out of 20 points
- Rolling resistance: 8 out of 10 points
- Weight: 1.5 out of 15 points
- Inertia impellers: 3 out of 10 points
- Bottle cage: 3 out of 10 points
- Driving behaviour downhill: 31.5 out of 35 points
- Front suspension: 20 out of 20 points
- Rear suspension: 22.5 out of 25 points
- Saddle retractability: 10 out of 10 points
- Brakes: 12.75 out of 15 points
- Tyre grip: 13.5 out of 15 points
- Driving stability: 4 out of 10 points
TOTAL BERGAUF: 53.75 out of 90 Points
TOTAL REVENUE: 114.3 out of 130 Points
- Other: 26.5 out of 30 points
Bike test rating²: very good - 194.5 out of 250 points
¹Price may be subject to additional costs for packaging, dispatch and coordination.
²The BIKE judgement reflects the laboratory measurements and the subjective impression of the test riders. The BIKE judgement is independent of price. BIKE judgements: super (250-205 P.), very good (204.75-170 P.), good (169.75-140 P.), satisfactory (139.75-100 P.), with weaknesses, unsatisfactory.
Max Fuchs
Editor
