For a while nobody knew who JEFFSY was. Just when we had accepted ‘he’ was a great 29er, YT went and dropped a 27.5” version and everyone’s heads just exploded. While we would argue that it’s nice to have a choice, can the YT JEFFSY AL ONE 27 live up to the high standard set by the award-winning 29er?
For an overview of the test fleet head to the group test: Seven trail bikes around 3.000 € in review
Starting with the spec, even though we have grown used to the impressive buying power of the direct sales brands, at just €2,599 even we were surprised to see a Pike Solo Air RC and RockShox Deluxe RT rear shock. That’s a great start to any build! The good news continues with a SRAM X1 1×11 drivetrain and the ever-reliable SRAM Guide RS brakes, which although noisy in the wet, are trustworthy stoppers. Full points to YT for fitting big 200/180 mm rotors for maximum control – important for a bike this fast. All the finishing kit is high end too: the SDG Fly Mtn seat is superb, as are the Sensus Lite grips. The 60 mm (50 mm on S/M) RaceFace Turbine stem and 770 mm handlebar feel great, in tune with the bike, and the new 35 mm standard provides a dose of stiffness and confidence.
The geometry of the aluminium YT is an exercise in balance: enough reach without being long, slack enough without being lazy. The result is that you can hop onto the 13.5 kg 150/150 mm bike and instantly feel at home. No matter if you are hauling up a steep mountain climb, hooning down a crazy trail, or sending the local jumps, the JEFFSY is ready. The 75° seat angle and V4L Virtual 4-Link rear suspension is very efficient on the climbs, stable and supportive, but when asked, it delivers its travel effectively and the progressive end stroke gives plenty of pop to rack up some air time. The RockShox Pike and Deluxe are a potent package; with some adjustment of bottomless tokens, in no time you are howling with joy as you rally down the hill, the excellent Maxxis High Roller II tires delivering huge grip. The bike is damn near perfect, but not quite.
The DT Swiss M1900 Spline wheelset accelerates well, but the 22.5 mm internal width is a bit narrow for good support at lower pressures, and the mixture of boost rear end and non-boost fork will make replacement more difficult in the future. The e*thirteen TRS dropper is a great post, but the insert depth is longer than most and cannot be fully inserted into the frame. This frustrated some of our hobbit-legged testers who could not size up for increased reach – keep that in mind if you are borderline.
The YT JEFFSY AL ONE 27
Fork RockShox Pike RC 150 mm
Rear shock RockShox Deluxe RT 150 mm
Brakes SRAM Guide RS
Drivetrain SRAM X1
Seatpost e*thirteen Dropper Post
Stem Race Face Turbine
Handlebar Race Face Turbine 35
Tires Maxxis Highroller II
Wheelset DT Swiss M100 Spline
Price € 2,599
The geometry of the YTJEFFSY AL ONE 27
| Size | S | M | L | XL |
|---|---|---|---|---|
| Seat tube | 410 mm | 450 mm | 480 mm | 520 mm |
| Top tube | 573 mm | 602 mm | 625 mm | 648 mm |
| Head angle | 66.5 / 67° | 66.5 / 67° | 66.5 / 67° | 66.5 / 67° |
| Seat angle | 75.0 / 75.5° | 75.0 / 75.5° | 75.0 / 75.5° | 75.0 / 75.5° |
| Chainstays | 430 mm | 430 mm | 430 mm | 430 mm |
| BB Drop | 15/9 mm | 15/9 mm | 15/9 mm | 15/9 mm |
| Wheelbase | 1138 mm | 1169 mm | 1200 mm | 1224 mm |
| Reach | 415 mm | 440 mm | 460 mm | 480 mm |
| Stack | 584 mm | 597 mm | 611 mm | 620 mm |
| Wheelsize | 27.5″ | 27.5″ | 27.5″ | 27.5″ |
Conclusion
The JEFFSY is the definitive trail bike: with fun at its core, it shreds towards the horizon while cheekily flipping the bird to far more expensive bikes. All the bikes in this test are great, but the JEFFSY is fantastic. The YT JEFFSY AL ONE 27 wins this test with ease, but be warned, you will be left with a tough decision: 27.5” or 29”?
Strengths
– Perfect balance and poise
– Effortless to ride fast
Weaknesses
– Special water bottle is an expensive extra
– e*thirteen TRS dropper too long for frame
For more info head to yt-industries.com
The test fleet
For an overview head to the main article: Seven trail bikes around 3.000 € in review
All bikes in test: Canyon Spectral AL 6.0 EX | Marin Rift Zone 3 | MERIDA ONE-TWENTY 7.800 | ROSE Granite Chief 2 | Vitus ESCARPE 29 VRX | Whyte T-130 S | YT JEFFSY AL ONE 27
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